Road salt alters the ecological effects of atrazine–cypermethrin mixtures in freshwater microalgae

Road salt alters the ecological effects of atrazine–cypermethrin mixtures in freshwater microalgae | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Road salt alters the ecological effects of atrazine–cypermethrin mixtures in freshwater microalgae Arif Ahmed, Matthew S. Schuler This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9306322/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Freshwater ecosystems are increasingly exposed to multiple chemical stressors, such as pesticides and road salts, yet the role of salinity in modifying pesticide mixture toxicity remains poorly understood. Here, we investigated the individual and combined effects of the herbicide atrazine, the insecticide cypermethrin, and elevated salinity (NaCl) on the freshwater microalga Chlorella vulgaris in controlled microcosms. We quantified biotic responses (chlorophyll, cell abundance, biomass) alongside abiotic parameters (total nitrogen, dissolved organic matter, dissolved oxygen, pH, electrical conductivity, and temperature). Salinity emerged as the dominant driver of algal response, with atrazine reducing chlorophyll at 50 µg L⁻¹, while cypermethrin alone showed no detectable effect. In contrast, the three-way mixture of atrazine, cypermethrin, and NaCl produced a synergistic increase in chlorophyll, demonstrating strong non-additive interactions under combined stress. Although cell abundance and biomass were not significantly altered, nutrient dynamics were highly sensitive to treatment: total nitrogen and colored dissolved organic matter exhibited pronounced non-linear, synergistic reductions under binary and ternary mixtures. In contrast, dissolved oxygen and pH remained stable across treatments. These results demonstrate that salinity can fundamentally alter both the direction and magnitude of pesticide mixture effects, shifting responses from inhibitory to stimulatory depending on stressor combinations. Our findings highlight the importance of incorporating realistic salinity regimes into mixture toxicity assessments and suggest that increasing freshwater salinization may reshape how chemical pollutants influence primary production and nutrient cycling. Atrazine Road salt Chlorella vulgaris Microcosms Multi-stressor interactions Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 1. INTRODUCTION Anthropogenic activities are increasingly degrading aquatic ecosystems through the introduction of individual and combined chemical stressors, creating complex exposure scenarios that challenge ecosystem structure and function. Agricultural pesticides and road deicing salts are among the most widespread and persistent contaminants entering freshwater systems via runoff, leaching, and stormwater discharge (Kaushal et al., 2005 ; Stehle & Schulz, 2015 ). Because these stressors often co-occur (Ahmed et al., 2025 ), aquatic organisms such as microalgae are routinely exposed to chemical cocktails rather than isolated molecules. Yet, most toxicity assessments used for regulatory actions rely on single-stressor response data, despite the complexity of real-world environmental exposures​ (Proctor et al., 2017 ; Ahmed et al., 2026 ). Freshwater microalgae play a foundational role in aquatic ecosystems by driving primary production, regulating nutrient cycling, and supporting higher trophic levels (Updhyay et al., 2025 ). Chlorella vulgaris is a cosmopolitan green alga widely used as a model organism in ecotoxicological research due to its rapid growth, well-characterized physiology, and sensitivity to chemical stressors (Liang et al., 2024 ; Matejczyk et al., 2023 ). Therefore, changes in C. vulgaris growth, chlorophyll content, and biomass can serve as early indicators of ecosystem-level impairment (Calderón-Delgado et al., 2019 ). However, ​​ Chlorella vulgaris exhibits varying responses to pesticides and salinity, with its physiological and biochemical reactions being dependent on both the concentration of the stressor and the duration of exposure​ (Adochite & Andronic, 2021 ; Camuel et al., 2017 ; Esteves et al., 2025 ). Atrazine is a widely used triazine herbicide that inhibits photosystem II by blocking electron transport at the D1 protein, thereby reducing photosynthetic efficiency in target plants and non-target algae (Singh et al., 2022 ; Solomon et al., 2008 ; Zhu et al., 2009 ). Cypermethrin, a synthetic pyrethroid insecticide, is highly toxic to aquatic organisms and can induce oxidative stress, membrane damage, and pigment disruption in algae, either directly or indirectly through altered water chemistry (Baruah & Chaurasia, 2020 ; Sáenz et al., 2012 ). Atrazine and cypermethrin are regularly found in surface waters at low to moderate concentrations. Yet their sublethal impacts on freshwater algae, especially when combined with other environmental stressors, require further investigation, given the expanding range of co-occurring contaminants (Ahmed et al., 2026 ). One such co-contaminant, sodium chloride (NaCl), has gained considerable attention in the past two decades due to its global ubiquity as a contaminant in freshwater ecosystems (Hintz et al., 2022 ). A common mode of NaCl pollution in temperate regions is the widespread overuse of rock salt as a road deicer. The misuse of road deicers has led to increasing freshwater salinization across temperate regions (Hintz et al., 2022 ). Elevated salinity alters ionic balance, osmotic regulation, and nutrient availability, with cascading effects on algal physiology, community composition, and ecosystem processes (Hintz & Relyea, 2019 ; Dugan et al., 2017 ). Importantly, salinity has been shown to modify the toxicity of pesticides, potentially amplifying or attenuating their biological effects (DeLorenzo et al., 2009; Khouni et al., 2023 ). In this study, we address two primary research questions: 1) How do atrazine, cypermethrin, and NaCl individually affect the growth, chlorophyll content, biomass, and water quality parameters associated with Chlorella vulgaris ? 2) How does co-exposure to NaCl alter the toxicity of atrazine and cypermethrin? We hypothesized that there would be synergistic effects of NaCl and the pesticides on algal physiology and water chemistry under combined exposures compared to single-stressor treatments. This synergy is expected due to ionic interactions under saline conditions that may alter cell membrane permeability and amplify oxidative and metabolic stress induced by atrazine and cypermethrin. 2. MATERIALS AND METHODS 2.1 Experimental Design A controlled laboratory microcosm experiment was conducted to evaluate the individual and interactive effects of atrazine, cypermethrin, and sodium chloride (NaCl) on the freshwater microalga Chlorella vulgaris and associated water quality parameters. The study employed a fully-factorial design consisting of single-stressor treatments and their mixtures. Experiments were conducted using static-renewal microcosms over a 29-day exposure period, with repeated sampling to capture both short-term and longer-term responses. 2.2 Algal Culture and Growth Conditions A unialgal culture of Chlorella vulgaris was obtained from CAROLINA biological supply, North Carolina, USA, and maintained in COMBO water, a nutrient medium for culturing algae. The COMBO water was prepared according to the standard protocol (Kilham et al., 1998 ). The stock culture of algae was grown under controlled laboratory conditions with a 12 h light: 12 h dark photoperiod (60 µmol photons/m²/s) at 25°C using a hotplate. The culture was continuously aerated to maintain homogeneous suspension, and a sterilized metallic rod was used for stirring at 280 rpm to prevent sedimentation. Before experimental initiation, cultures were acclimated to experimental conditions to ensure stable growth. 2.3 Preparation of Experimental Microcosms Experimental units consisted of 250 mL, acid-washed borosilicate glass containers; each filled with 250 mL of freshly prepared COMBO water (Supplementary Table 1) . Microcosms were inoculated with 5 mL of algal stock culture, resulting in comparable initial cell densities across treatments. The culture was homogenized, and all microcosms received approximately the same number of cells. Microcosms were inoculated in random order, ensuring that any accidental variation would not favor a particular treatment. All microcosms were maintained under identical light and temperature conditions throughout the exposure period. We let algae grow for a week to establish in microcosms. 2.4 Chemical Preparation and Treatments Analytical grade Atrazine (> 95% purity) and cypermethrin (> 98% purity) were purchased from Thermo Fisher Scientific and Sigma-Aldrich, and their stock solutions were prepared in dimethyl sulfoxide (DMSO). We used < 0.1% v/v Dimethyl Sulfoxide (DMSO) solvent to prepare the atrazine stock solution. DMSO is used over other vehicles such as methanol, ethanol, and acetone due to its low demonstrated toxicity to algae (Ma & Chen, 2005 ; Chen et al., 2025 ). Sodium chloride (NaCl) stock solutions were prepared in reverse-osmosis water. Treatments were applied to achieve the nominal concentrations: Atrazine: 50 µg L⁻¹ and 100 µg L⁻¹, Cypermethrin: 50 µg L⁻¹, and NaCl: 860 mg L⁻¹. The treatment matrix included controls (COMBO medium only), DMSO solvent controls, single-stressor exposures, binary, and the tertiary combination of atrazine, cypermethrin, and NaCl. Final DMSO concentrations were identical across all pesticide treatments and solvent controls. 14 treatments (Supplementary Table 2) were replicated 5 times and resulted in 70 test units in total. 2.5 Biological Response Variables For algal cell abundance, 1 mL of sample was collected from each test unit into sampling tubes, and 1–2 drops of Lugol’s iodine were added immediately to preserve cell integrity and prevent decay. Microcosms were sampled four times throughout the experiment: 96 h, day 15, day 22, and day 29 following treatment application. Preserved samples were analyzed using a flow cytometer (Attune™ NxT Acoustic Focusing Cytometer, Thermo Fisher Scientific) to count the cell abundance. Samples were homogenized using a mechanical shaker before analysis to minimize cell settling and ensure uniform distribution. A 200 µL subsample was then analyzed using the tube method. Samples were processed at a low flow rate, and the cytometer was set to acquire 10,000 events from a 50 µL sample volume. Algal populations were identified and gated using forward scatter (FSC) versus side scatter (SSC) density plots, enabling discrimination of algal cells from background particles and debris based on size distribution patterns. Cell count per sample was recorded as the primary metric and used as a measure of algal abundance (Marie et al., 2014 ). In parallel, chlorophyll fluorescence was measured using a Turner Designs Trilogy laboratory fluorometer (Turner Designs, San Jose, CA) equipped with the Chlorophyll In Vivo Module. The module uses a blue light-emitting diode with peak excitation around 460 nm, and an excitation band centered at approximately 441 nm to excite photosynthetic pigments within intact algal cells. Upon absorption of excitation energy, chlorophyll pigments emit red fluorescence due to the Stokes shift. Emitted fluorescence was selectively detected using an emission filter spanning 660 to 710 nm, corresponding to the characteristic red fluorescence region of chlorophyll in vivo , while minimizing detection of scattered excitation light. Fluorescence intensity was quantified by an internal photodiode detector and recorded as relative fluorescence units. Because measurements were performed on live, unextracted cell suspensions, the signal represents total in vivo chlorophyll fluorescence and serves as a non-destructive proxy for algal biomass. Chlorophyll measurements provided an independent indicator of photosynthetic activity, complementing flow cytometry data to assess algal health and metabolic activity. At day 29, algal biomass was quantified gravimetrically by filtering 50 mL of culture from each treatment onto pre-weighed 47 mm diameter Whatman 934-AH glass microfiber filters. Before filtration, filters were pre-weighed to obtain the initial mass. Following filtration, filters containing algal biomass were air-dried for 72 h and reweighed after reaching constant mass. Biomass was calculated as the difference between the final filter weight and the pre-filtration filter weight and expressed as dry weight per unit volume of culture. This method provided an integrated estimate of algal standing biomass within each experimental unit. 2.6 Water Quality Measurements Dissolved oxygen (DO) concentrations were measured using a portable dissolved oxygen analyzer to assess treatment-induced changes associated with atrazine and sodium chloride (NaCl) exposure. pH was monitored using a calibrated PCTS5 multiparameter tester, which also recorded water temperature and electrical conductivity (EC), providing an integrated assessment of physicochemical conditions across experimental units. Colored dissolved organic matter fluorescence was measured using a Turner Designs Trilogy laboratory fluorometer equipped with the CDOM module. The module uses near-ultraviolet excitation centered at approximately 350 nm with a bandwidth of ± 40 nm to excite fluorescent components of dissolved organic matter. Emitted fluorescence was detected within the 410 to 450 nm spectral range using an internal bandpass filter to minimize detection of scattered excitation light. Fluorescence intensity was recorded as relative fluorescence units (RFU). Because this method quantifies fluorescence within defined excitation and emission windows, the reported values represent operationally defined CDOM fluorescence rather than a direct measure of total dissolved organic carbon concentration. These measurements were used to evaluate treatment-related variation in nutrient levels and organic matter dynamics within the microcosms. Total Nitrogen (TN) in water samples was measured using the TNTplus® 826 Low Range method (Hach Company; 1–16 mg L⁻¹ N). The method quantifies both organically and inorganically bound nitrogen by oxidation to nitrate using peroxodisulfate digestion. Briefly, 1.3 mL of sample was combined with 1.3 mL of Sodium Hydroxide solution (A) and 1 oxidant tablet (B) in a 20-mm reaction tube. Tubes were immediately sealed and heated in a reactor at 120°C for 30 minutes. After cooling to room temperature, 0.5 mL of the digested sample was mixed with 0.2 mL of solution D, and the reaction vials were inverted to ensure complete mixing. The resulting nitrophenol formed was measured spectrophotometrically at 410 nm using a DR 6000 spectrophotometer. Slight sample turbidity or transient pink coloration during reaction did not interfere with measurement. 2.7. Bliss Independence Model Application To evaluate whether the combined effects of atrazine, cypermethrin, and sodium chloride (NaCl) on chlorophyll, colored dissolved organic matter (CDOM), and total nitrogen (TN) were additive, synergistic, or antagonistic, the Bliss Independence model was applied. This model assumes independent action among stressors and estimates the expected combined response under the null hypothesis of no interaction (Demidenko & Miller, 2019 ; Liu et al., 2018 ). All analyses were conducted using treatment means, with responses expressed relative to the control. Proportional effects were calculated as: $$\:E=\frac{{\text{Mean}}_{\text{Treatment}}-{\text{Mean}}_{\text{Control}}}{{\text{Mean}}_{\text{Control}}}$$ For binary mixtures, the Bliss expected effect was calculated as: $$\:{E}_{\text{Bliss}}={E}_{X}+{E}_{Y}-({E}_{X}\times\:{E}_{Y})$$ where \(\:{E}_{X}\) and \(\:{E}_{Y}\) are the proportional effects of the individual stressors. For tertiary mixtures, the Bliss expectation was extended to three stressors as: $$\:{E}_{\text{Bliss}}=1-(1-{E}_{A})(1-{E}_{C})(1-{E}_{S})$$ \(\:{E}_{A}\) = effect of atrazine alone, \(\:{E}_{S}\) = effect of NaCl alone and \(\:{E}_{C}\) = effect of cypermethrin alone Observed combined effects were calculated using the same proportional response equation. Interactions were classified as synergistic when observed effects exceeded Bliss expectations, additive when observed and expected effects were similar, and antagonistic when observed effects were lower than expected (See supplementary materials for details). 2.8. Statistical Analysis All statistical analyses were performed using R (version 4.2.3) (Team, 2022 ). Before hypothesis testing, all response variables were screened for normality using the Shapiro–Wilk test (shapiro.test). Several variables, including chlorophyll, dissolved oxygen (DO), electrical conductivity (EC), temperature, pH, and total nitrogen (TN), violated assumptions of normality and were therefore transformed using rank-based inverse normal transformation calculated with rank() and qnorm() before parametric analyses. CDOM and cell abundance met normality assumptions and were analyzed using untransformed values. The individual and interactive effects of atrazine, cypermethrin, and NaCl were evaluated using three-way factorial analyses of variance (ANOVA) implemented with the aov() function. Atrazine, cypermethrin, and NaCl were treated as fixed factors, and all two-way and three-way interactions were included in the models. Statistical significance of main effects and interactions was assessed at α = 0.05 using summary.aov(). To assess treatment-specific effects relative to the control, one-way ANOVA models were fitted using a combined treatment factor for each response variable. Post hoc comparisons were conducted using Dunnett’s test to compare each treatment to the control while controlling for family-wise error rates (Hothorn et al., 2008 ). Dunnett contrasts were implemented using the glht() function with mcp(Treatment = "Dunnett") from the multcomp package, with the control treatment set as the reference level using relevel(). Mixture toxicity and interaction outcomes were further evaluated using the Bliss independence model by comparing observed mixture responses to Bliss-predicted effects. Deviations between observed and expected responses were interpreted as synergistic, antagonistic, or additive interactions, depending on the direction and magnitude of the difference. All graphical analyses were conducted using the ggplot2 package (ggplot()). Boxplots were generated using geom_boxplot() to visualize treatment effects, and scatter-based visualizations for mixture analyses were produced using geom_point(). Reference lines and statistical annotations were added using geom_hline() and annotate(). 3. RESULTS 3.1. Biotic responses Total Chlorophyll was significantly influenced by salinity and by interactions involving atrazine ( Table 1 ) . The two-way ANOVA results indicate a strong main effect of NaCl (F₁,₁₂₈ = 49.18, p < 0.001), as well as significant Atrazine × Cypermethrin (F₂,₁₂₈ = 8.74, p < 0.001) and an Atrazine × NaCl interaction (F₂,₁₂₈ = 19.04, p < 0.001). A three-way interaction among chemicals was not detected. Table 1 ANOVA results for biotic responses (Chlorophyll and Cell abundance) of freshwater phytoplankton Chlorella vulgaris to Atrazine, Cypermethrin, NaCl, and their interactions. Significant effects are indicated in bold. Response Source Df Sum Sq Mean Sq F value p-value Chlorophyll Atrazine 2 2.18 1.091 1.882 0.156 Cypermethrin 1 0.32 0.322 0.555 0.458 NaCl 1 28.51 28.511 49.184 < 0.001 Atrazine × Cypermethrin 2 10.13 5.065 8.738 < 0.001 Atrazine × NaCl 2 22.07 11.037 19.04 < 0.001 Cypermethrin × NaCl 1 0.03 0.026 0.045 0.832 Atrazine × Cypermethrin × NaCl 2 1.28 0.641 1.105 0.334 Residuals 128 74.2 0.58 Cell Abundance Atrazine 2 1,372,243 686,121 1.248 0.289 Cypermethrin 1 47,865 47,865 0.087 0.768 NaCl 1 2,489,294 2,489,294 4.529 0.034 Atrazine × Cypermethrin 2 758,389 379,195 0.69 0.503 Atrazine × NaCl 2 545,787 272,893 0.496 0.609 Cypermethrin × NaCl 1 271,285 271,285 0.494 0.483 Atrazine × Cypermethrin × NaCl 2 1,104,574 552,287 1.005 0.368 Residuals 268 147,302,247 549,635 Dunnett’s post hoc comparisons indicate ( Table 3 & Fig. 1 ) that atrazine at 50 µg L⁻¹ significantly reduced chlorophyll relative to the control (estimate = − 0.98, p = 0.040), whereas atrazine at 100 µg L⁻¹ and cypermethrin alone did not differ from controls. Salinity alone (NaCl 860 mg L⁻¹) did not significantly alter chlorophyll. However, the combined exposure to atrazine (50 µg L⁻¹), cypermethrin (50 µg L⁻¹), and NaCl (860 mg L⁻¹) increased chlorophyll (estimate = + 1.63, p < 0.001), indicating a strong interactive effect under multi-stressor conditions. Table 3 Dunnett’s post hoc comparisons of treatment effects on Chlorella vulgaris relative to control. Biotic endpoints include chlorophyll and cell abundance, while abiotic endpoints include DO, EC, temperature, pH, TN, and CDOM. Adjusted p-values and significance levels are reported for each treatment. Significant effects are indicated in bold. Treatment Chlorophyll Cell abundance DO EC Temp pH TN CDOM Atrazine 50 0.039 0.826 0.995 0.998 1.000 0.797 0.382 0.489 Atrazine 100 0.161 0.366 1.000 0.468 0.989 0.846 0.046 0.654 Cypermethrin 50 0.872 0.707 0.999 1.000 0.989 1.000 0.226 1.000 NaCl 860 1.000 1.000 1.000 < 0.001 0.999 0.998 0.002 0.346 Atrazine 50 * Cypermethrin 50 0.181 0.226 0.943 0.974 1.000 0.998 < 0.001 1.000 Atrazine 100 * Cypermethrin 50 0.972 0.498 1.000 0.375 1.000 0.991 < 0.001 0.079 Atrazine 50 * NaCl 860 0.184 0.439 1.000 < 0.001 1.000 1.000 0.010 0.006 Atrazine 100 * NaCl 860 0.909 0.599 1.000 < 0.001 1.000 0.996 < 0.001 0.002 Cypermethrin 50 * NaCl 860 0.800 1.000 1.000 < 0.001 0.956 1.000 0.001 0.003 Atrazine 50 * Cypermethrin 50 * NaCl 860 < 0.001 0.988 0.992 < 0.001 1.000 1.000 < 0.001 < 0.001 Atrazine 100 * Cypermethrin 50 * NaCl 860 0.392 1.000 1.000 < 0.001 1.000 1.000 1.000 0.003 DMSO Low 0.821 0.221 1.000 1.000 0.936 1.000 0.470 0.747 DMSO High 0.974 0.700 0.192 1.000 0.960 0.742 0.999 < 0.001 Cell abundance was affected by salinity (F₁,₂₆₈ = 4.53, p = 0.034), but there were no detected effects of atrazine, cypermethrin, or in combined treatments ( Table 1 and Fig. 2 ) . The post hoc ( Table 3 ) results did not suggest any individual treatment that differed from the control, indicating that the overall salinity effect reflected small, but consistent shifts rather than strong treatment-specific deviations. Biomass did not differ significantly among treatments ( Fig. 3 ) . Values varied within a narrow range (0.0091–0.0155 g/50 mL) and were comparable to the control (0.0128 g/50 mL), indicating that neither individual exposures nor combined treatments measurably affected biomass. 3.2. Abiotic responses Total nitrogen exhibited strong and complex responses to both single and combined stressors ( Fig. 4 ). ANOVA showed significant main effects of atrazine (F₂,₅₈ = 16.01, p < 0.001) and NaCl (F₁,₅₈ = 7.68, p = 0.008), as well as significant Atrazine × Cypermethrin, Atrazine × NaCl, Cypermethrin × NaCl, and three-way interactions (all p ≤ 0.038) ( Table 2 ). Table 2 ANOVA results for abiotic water quality parameters (DO, EC, Temp, pH, TN, and CDOM) in response to Atrazine, Cypermethrin, NaCl, and their interactions. Significance levels are denoted in bold. Response Source Df Sum Sq Mean Sq F value p-value DO Atrazine 2 1.83 0.9143 0.903 0.407 Cypermethrin 1 0.01 0.0113 0.011 0.916 NaCl 1 1.72 1.7189 1.697 0.194 Atrazine × Cypermethrin 2 0.17 0.0862 0.085 0.918 Atrazine × NaCl 2 4.19 2.0947 2.069 0.129 Cypermethrin × NaCl 1 0.12 0.117 0.115 0.734 Atrazine × Cypermethrin × NaCl 2 0.1 0.052 0.051 0.95 Residuals 198 200.51 1.0127 EC Atrazine 2 0.1 0.05 0.155 0.856 Cypermethrin 1 0.14 0.14 0.429 0.513 NaCl 1 136.63 136.63 423.331 < 0.001 Atrazine × Cypermethrin 2 1.95 0.97 3.02 0.051 Atrazine × NaCl 2 0.94 0.47 1.456 0.235 Cypermethrin × NaCl 1 0.01 0.01 0.032 0.859 Atrazine × Cypermethrin × NaCl 2 3.79 1.89 5.867 0.003 Residuals 198 63.91 0.32 Temp Atrazine 2 0.74 0.3695 0.369 0.691 Cypermethrin 1 0.62 0.6213 0.621 0.431 NaCl 1 2.3 2.2981 2.297 0.131 Atrazine × Cypermethrin 2 0.75 0.377 0.377 0.686 Atrazine × NaCl 2 0.35 0.1741 0.174 0.840 Cypermethrin × NaCl 1 0.16 0.1551 0.155 0.694 Atrazine × Cypermethrin × NaCl 2 4.74 2.3683 2.367 0.096 Residuals 198 198.13 1.0007 pH Atrazine 2 6.26 3.1317 3.26 0.040 Cypermethrin 1 0.66 0.659 0.686 0.408 NaCl 1 0.27 0.2667 0.278 0.598 Atrazine × Cypermethrin 2 0.51 0.2574 0.268 0.765 Atrazine × NaCl 2 3.31 1.6555 1.723 0.181 Cypermethrin × NaCl 1 0.29 0.2869 0.299 0.585 Atrazine × Cypermethrin × NaCl 2 1.83 0.9139 0.951 0.388 Residuals 198 190.21 0.9606 TN Atrazine 2 11.269 5.635 16.009 < 0.001 Cypermethrin 1 0.059 0.059 0.167 0.684 NaCl 1 2.702 2.702 7.677 0.007 Atrazine × Cypermethrin 2 3.873 1.936 5.502 0.006 Atrazine × NaCl 2 17.63 8.815 25.045 < 0.001 Cypermethrin × NaCl 1 1.582 1.582 4.495 0.038 Atrazine × Cypermethrin × NaCl 2 11.204 5.602 15.917 < 0.001 Residuals 58 20.414 0.352 CDOM Atrazine 2 69,064 34,532 0.4 0.670 Cypermethrin 1 540,488 540,488 6.264 0.013 NaCl 1 5,082,025 5,082,025 58.894 < 0.001 Atrazine × Cypermethrin 2 1,148,469 574,235 6.655 0.001 Atrazine × NaCl 2 1,233,047 616,524 7.145 0.001 Cypermethrin × NaCl 1 13,323 13,323 0.154 0.694 Atrazine × Cypermethrin × NaCl 2 1,470,336 735,168 8.52 < 0.001 Residuals 198 17,085,626 86,291 Dunnett tests ( Table 3 ) indicated that atrazine at 100 µg L⁻¹ significantly reduced TN relative to the control (estimate = − 1.08, p = 0.046), whereas atrazine at 50 µg L⁻¹ did not. NaCl alone significantly reduced TN (estimate = − 1.44, p = 0.003). All binary mixtures involving atrazine or cypermethrin with NaCl resulted in significant reductions in TN (p ≤ 0.01). Similarly, both atrazine–cypermethrin combinations significantly decreased TN (p < 0.001). The three-way mixture at the lower atrazine concentration further reduced TN (estimate = − 1.76, p < 0.001), whereas the higher-dose three-way treatment did not differ from the control. CDOM was strongly influenced by salinity and interaction effects ( Fig. 5 ). ANOVA ( Table 2 ) identified significant effects of cypermethrin (F₁,₁₉₈ = 6.26, p = 0.013), NaCl (F₁,₁₉₈ = 58.89, p < 0.001). Post hoc comparisons ( Table 3 ) showed that NaCl-containing mixtures consistently reduced CDOM. Atrazine × NaCl, cypermethrin × NaCl, and both three-way combinations resulted in a reduced concentration relative to the control (p ≤ 0.006). The strongest reduction occurred under the three-way mixture with atrazine 50 µg L⁻¹, which reduced CDOM by more than 550 units (p 0.05; Table 2 ). Dunnett tests confirmed that no individual treatment caused significant increases or decreases in either parameter relative to controls. Electrical conductivity (EC) responded strongly to salinity and higher-order interactions, and ANOVA indicated a pronounced main effect of NaCl (F₁,₁₉₈ = 423.33, p < 0.001). pH was modestly affected by atrazine (F₂,₁₉₈ = 3.26, p = 0.041), while no interaction terms were significant. However, Dunnett post hoc tests did not identify any atrazine treatment that differed significantly from the control, indicating that the observed ANOVA effect was small and distributed across treatment levels rather than driven by a single exposure. 3.3. Interactive stressor effects Bliss Independence analysis indicated distinct interaction patterns among atrazine, cypermethrin, and NaCl across chlorophyll, CDOM, and total nitrogen (TN) ( Table 4 & Fig. 6 ) . For chlorophyll, the atrazine + NaCl and cypermethrin + NaCl binary mixtures exhibited observed responses that exceeded Bliss expected effects, indicating synergistic interactions. In contrast, the atrazine + cypermethrin mixture produced a chlorophyll response substantially lower than the Bliss prediction, indicating antagonism. When all three stressors were combined, the observed chlorophyll response remained below the Bliss expected value, indicating an overall antagonistic interaction under tertiary exposure. Table 4 Summary of Day-29 mixture effects on freshwater microcosm endpoints (chlorophyll, CDOM, and total nitrogen (TN) relative to control, analyzed using the Bliss independence model. Observed effects (E_obs) and Bliss-expected effects (E_Bliss) are reported, along with the classification of interactions as synergistic, antagonistic, or additive. Endpoint Mixture Observed Effect (E obs ) Bliss Expected (E Bliss ) Interaction Chlorophyll Atrazine + NaCl 0.680 0.456 Synergistic Chlorophyll Cypermethrin + NaCl −0.296 −0.535 Synergistic Chlorophyll Atrazine + Cypermethrin 0.102 0.429 Antagonistic Chlorophyll Atrazine + Cypermethrin + NaCl 0.257 0.311 Antagonistic CDOM Atrazine + NaCl −0.011 0.016 Antagonistic CDOM Atrazine + Cypermethrin + NaCl −0.024 −0.023 Additive TN Atrazine + NaCl −0.242 −0.287 Synergistic TN Atrazine + Cypermethrin + NaCl −0.278 −0.455 Synergistic For CDOM, binary mixtures generally resulted in observed responses that were lower than Bliss expectations, indicating antagonistic interactions. Under tertiary exposure to atrazine, cypermethrin, and NaCl, the observed CDOM response closely matched the Bliss expected effect, indicating an approximately additive interaction. Additionally, for total nitrogen (TN), all individual stressors produced negative proportional responses relative to the control. However, both binary and tertiary mixtures involving NaCl exhibited observed reductions that exceeded Bliss's expected effects, indicating synergistic interactions despite the overall negative direction of response. 4. DISCUSSION ​ 4.1. Response of Chlorophyll to individual and mixture effects The observed changes in total chlorophyll concentration indicate complex mechanistic interactions among atrazine, cypermethrin, and salinity (NaCl), moving beyond simple additive effects. ​The chlorophyll reduction observed at 50 µg L⁻¹ atrazine is consistent with its well-established mode of action as a PSII inhibitor, as atrazine directly disrupts the electron transport chain, particularly PSII, leading to oxidative imbalance and impaired photosynthetic performance in algae (Bai et al., 2015 ; Yang et al., 2020). Cypermethrin alone did not alter chlorophyll in this study, which aligns with reports showing that pyrethroid effects on photosynthetic pigments are often concentration-dependent and primarily associated with oxidative stress–mediated pigment disruption at higher or prolonged exposures (Huang et al., 2005 ; Xi et al., 2020 ). Synergistic chlorophyll responses observed in cypermethrin + NaCl and atrazine + NaCl mixtures may reflect salinity-induced modifications of PSII photochemistry that alter cellular sensitivity to chemical stressors (Lu et al., 2002). This synergism suggests that salinity, while not individually toxic for C. vulgaris at the tested concentration, might enhance the toxicity of atrazine and cypermethrin by increasing cellular uptake, altering membrane permeability, or exacerbating cellular stress responses (Farghl et al., 2015 ), leading to a greater impact on chlorophyll than either stressor alone (Wen et al., 2023 ; Giudici, 2020). In contrast, the antagonistic chlorophyll responses observed for atrazine + cypermethrin are consistent with mixture studies demonstrating that combined pesticide stress can reduce photosynthetic performance through overlapping impacts on chloroplast structure, PSII efficiency, and cellular energy balance, resulting in effects lower than additive expectations (Wang et al., 2022 ). The specific mechanisms by which the combined exposure to atrazine, cypermethrin, and NaCl interacts to increase chlorophyll in Chlorella vulgaris ​ is unclear, and future research should explore the underlying mechanisms. We assume that the presence of one stressor might alter the toxicity pathway or uptake of another. ​For example, a low concentration of atrazine or NaCl might induce stress-response proteins that coincidentally offer some protection against cypermethrin's chlorophyll-degrading effects, or vice versa (Wang et al., 2011 ; Wang et al., 2012 ). This could lead to a net increase in chlorophyll as the negative impacts are partially mitigated, and the stimulatory effects are enhanced. When combined, the stressors synergistically lead to an upregulation of chlorophyll biosynthesis genes or a reduction in chlorophyll degradation rates, as the microalga tries to adapt to the complex environment. ​​ 4.2. Overall stressor effects on algal physiology and water quality Ionic stress imposed by NaCl caused alterations in algal physiology, likely through osmotic effects (Ogawa et al., 2005; Kiełkowska, 2017 ; Wolny et al., 2021 ). Biomass remained relatively stable across treatments, indicating that sublethal levels of atrazine, cypermethrin, and their combinations did not strongly inhibit algal growth. The highest biomass under atrazine 100 µg L⁻¹ suggests that low-level herbicide exposure may trigger mild compensatory growth or acclimation responses (Yang et al., 2004 ; Ya, 2013), whereas the lowest values in solvent controls point to minor solvent effects rather than treatment toxicity. Total nitrogen decreased in response to combined stressors, with reductions being strongest in NaCl-containing mixtures. This indicates that salinity may interfere with nitrogen uptake or assimilation (Ashraf et al., 2018 ; Dluzniewska et al., 2006; Botella et al., 1997 ), and when combined with atrazine or cypermethrin, the effect is amplified, suggesting a synergistic impairment of nutrient acquisition. Salinity plays a significant role in interfering with nitrogen uptake and assimilation in Chlorella vulgaris . When salinity is combined with stressors like atrazine or cypermethrin, this impairment of nutrient acquisition is amplified, leading to reduced total nitrogen (TN) (Dassanayake, 2008 ; Herbst & Bradley, 1989 ). The largest reductions in TN were observed in tertiary mixtures with lower atrazine concentrations, indicating that multiple stressors intensify nutrient limitation. This suggests a metabolic shift where the algae struggle to efficiently acquire and process essential nutrients under combined stress. C. vulgaris has robust metabolic flexibility, enabling it to grow in autotrophic, mixotrophic, and heterotrophic modes (Arora & Philippidis, 2021 ; Zuñiga et al., 2016 ; Miotti et al., 2024 ). CDOM responses were dominated by salinity and interaction effects. NaCl-containing mixtures consistently reduced CDOM, with binary mixtures generally showing antagonistic effects and tertiary mixtures approximating additive effects. This pattern indicates that algal exudation of dissolved organic matter or its transformation in the medium is modulated by both osmotic and chemical stress, possibly due to altered metabolism or reduced production of extracellular compounds (Maršálek & Rojíčková, 1996 ). ​The presence of NaCl increases the ionic strength of the solution, which can affect the optical properties and stability of CDOM (Gonsior et al., 2009 ; Song et al., 2017 ). ​​High salinity environments can lead to a "salting-out" effect, where dissolved organic molecules, including CDOM, become less soluble and may aggregate or precipitate out of the solution, thereby reducing the measured CDOM concentration​ (Gonsior et al., 2009 ). ​For instance, in riverine environments transitioning to estuaries, CDOM often exhibits an inverse relationship with salinity due to conservative mixing and removal processes like flocculation (Chen et al., 2012 ). The largest CDOM decrease under the three-way mixture with lower atrazine concentration suggests that metabolic shifts are strongest when multiple stressors are simultaneously present, aligning with observed TN reductions. Electrical conductivity responded predictably to salinity, confirming effective ionic stress in the microcosms. pH showed only minor changes under atrazine and DO, and temperature remained largely stable across all treatments. This indicates that the observed changes in chlorophyll, TN, and CDOM were driven by physiological and metabolic responses of the algae, rather than by secondary changes in the abiotic environment. Under multi-stressor conditions, changes in chlorophyll occur, suggesting that nutrient limitation directly influences pigment synthesis and photosynthetic capacity. Similarly, CDOM reductions appear connected to altered nitrogen availability and chlorophyll status, likely reflecting coordinated metabolic adjustments, such as changes in carbon allocation or exudation patterns under stress. Together, these responses illustrate tight physiological coupling between nutrient dynamics, photosynthesis, and organic carbon release, which is amplified under multi-stressor conditions. 5. CONCLUSIONS In this study, we demonstrated that salinity from NaCl was a strong driver of stress responses in Chlorella vulgaris, particularly when combined with the herbicide atrazine and the insecticide cypermethrin. CDOM and chlorophyll content were significantly altered under NaCl-containing treatments, with multi-stressor combinations producing the strongest effects, while biomass and cell abundance remained relatively stable. These results suggest that ionic stress can amplify or modulate the physiological impacts of chemical pollutants, highlighting the importance of considering co-occurring stressors in ecotoxicological assessments. Abiotic parameters such as total nitrogen were also sensitive to combined exposures, whereas pH, dissolved oxygen, and temperature remained stable, indicating that the observed effects were primarily driven by chemical interactions rather than changes in basic water chemistry. Overall, this work emphasizes the ecological relevance of multi-stressor frameworks and suggests that environmental salinization may increase the vulnerability of freshwater primary producers to pesticide exposure. These findings can inform future risk assessments and support management strategies aimed at mitigating combined chemical and salinity stress in freshwater ecosystems. Declarations CONFLICT OF INTEREST “The authors declare no conflict of interest.” AUTHOR CONTRIBUTIONS Arif Ahmed – Conceptualization, Investigation, Methodology, Validation, Visualization, Software, Formal analysis, Data curation, Writing - original draft, Writing - review & editing. Matthew Schuler – Validation, Writing - review & editing, Project administration, Supervision, Resources. Ethical Approval Not Applicable Funding This study did not receive any funding Availability of data and materials Data is available in the supplementary materials section. If needed in other formats, data is available upon request from the corresponding author. References Adochite, C., & Andronic, L. (2021). Toxicity of a binary mixture of TiO2 and imidacloprid applied to Chlorella vulgaris. International Journal of Environmental Research and Public Health , 18 (15), 7785. https://doi.org/10.3390/ijerph18157785 Ahmed, A., Chien, S. C., & Schuler, M. S. (2026). 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9306322","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":629196819,"identity":"66c6d0d2-502e-4729-a390-17a10a1b68eb","order_by":0,"name":"Arif Ahmed","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA9klEQVRIiWNgGAWjYBACNgkgwcNQw8MP4VswsDGARXADfoiWYzKSDUDGAQYJwlokZ4AVMNsYHIBqYSCkxeB2d+KDNzVsPMbXDh97/KFGQp5P+gDjg7dteLTcObvZcM4xGR6z22npBgeOSRi28SUwG87Fp+VG7jZpHjY2oJYcM4mDDRKMbTwMbNK8eLTY38jd/pvnHzOP8WyIFnugFvbf+LSAbGHmbWPmMZCGaEkE2cJMQMtmybl9x3gkbqelSZw5JpHcxsPYLDnnHF4tGz+8+VZjzz87+ZhERY2N7fwe5oMf3pTh1oINMDaQpn4UjIJRMApGAQYAAEeXTTkCC2EGAAAAAElFTkSuQmCC","orcid":"","institution":"Montclair State University","correspondingAuthor":true,"prefix":"","firstName":"Arif","middleName":"","lastName":"Ahmed","suffix":""},{"id":629196822,"identity":"8a71db2b-7fbd-4f46-9969-625d940446a5","order_by":1,"name":"Matthew S. 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Variability and shifts in fluorescence among individual and combined treatments illustrate differential algal stress responses. Asterisks (*) indicate statistically significant differences relative to the control.\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-9306322/v1/634b9510e68a1a67e7f4834b.png"},{"id":107931873,"identity":"223e9535-b741-4b06-8ddc-d2f5f1124f60","added_by":"auto","created_at":"2026-04-27 16:44:56","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":401228,"visible":true,"origin":"","legend":"\u003cp\u003eBox plot showing cell abundance distribution across various treatments, including Control, Atrazine (50 and 100), Cypermethrin (50), combinations of these chemicals, and DMSO controls. Each treatment is color-coded with vertical whiskers indicating variability, highlighting median cell abundance.\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-9306322/v1/3adb4c37672870190e6bf605.png"},{"id":107931875,"identity":"e475fff5-98d2-4134-aed5-403ae562c59c","added_by":"auto","created_at":"2026-04-27 16:44:56","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":496349,"visible":true,"origin":"","legend":"\u003cp\u003eLine graph showing biomass measurements (g/50 mL) for various treatment groups, including Control, Atrazine, Cypermethrin, NaCl, combinations of Atrazine and Cypermethrin with NaCl, and DMSO controls. Biomass peaks at Atrazine 100 and Atrazine 50 + Cypermethrin 50 + NaCl 860, with the lowest biomass observed at DMSO Low, indicating treatment effects on biomass production.\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-9306322/v1/844a3ba74077aefb1a98250b.png"},{"id":108006185,"identity":"2358ce3e-8507-4fdc-8aaf-6f8d4bfff533","added_by":"auto","created_at":"2026-04-28 12:54:22","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":408726,"visible":true,"origin":"","legend":"\u003cp\u003eBox plot showing total nitrogen levels (mg/L) across various treatments, including controls, Atrazine, Cypermethrin, NaCl, and DMSO at different concentrations and combinations. Color-coded boxes indicate data distribution and variability for each treatment group. Asterisks (*) indicate statistically significant differences relative to the control.\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-9306322/v1/cec3322f29e7c4c3bd29fb98.png"},{"id":107931880,"identity":"10337c3f-7015-4cea-9a8f-b02e4cae8f57","added_by":"auto","created_at":"2026-04-27 16:44:56","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":409370,"visible":true,"origin":"","legend":"\u003cp\u003eBox plot chart showing CDOM (RFU) levels across various treatments, including Control, Atrazine (50 and 100), Cypermethrin (50), combinations of these chemicals, and DMSO controls. Treatments are color-coded with statistical significance indicated by asterisks above specific groups, highlighting notable decreases in CDOM levels for combined chemical exposures compared to Control.\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-9306322/v1/73d17b417b068a7807165e32.png"},{"id":108006825,"identity":"f70ddfd3-460e-480e-af78-c702985fc503","added_by":"auto","created_at":"2026-04-28 12:57:31","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":367199,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea) \u003c/strong\u003eScatter plot showing Bliss Independence Analysis for CDOM with proportional effect (E) on the y-axis and treatment combinations on the x-axis. Data points include Bliss expected (triangles in red) and observed (circles in blue) values for treatments A + C + NaCl and A + NaCl, highlighting a positive expected effect for A + NaCl and negative observed effects for both treatments. \u003cstrong\u003eb) \u003c/strong\u003eScatter plot showing Bliss Independence Analysis for Total Nitrogen (TN) with proportional effect € on the y-axis and treatment combinations on the x-axis for treatments A + C + NaCl and A + NaCl, highlighting differences between expected and observed effects. \u003cstrong\u003ec) \u003c/strong\u003eScatter plot showing Bliss Independence Analysis for chlorophyll across four treatment combinations: A + C, A + C + NaCl, A + NaCl, and C + NaCl. Data points highlight positive proportional effects for most treatments, except for a negative observed effect for C + NaCl.\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-9306322/v1/df5080146e620051574ddd2b.png"},{"id":109220322,"identity":"9a0c059b-d8ef-4a28-a1d6-5f719d20d7b9","added_by":"auto","created_at":"2026-05-13 20:21:08","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2749295,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9306322/v1/a36ff90f-6962-4df5-8d53-2c6b9b86ef23.pdf"},{"id":108006197,"identity":"0ba91aaa-4024-40f9-b0ab-9c5affec8c48","added_by":"auto","created_at":"2026-04-28 12:54:27","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":15567,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSupplementary Table 1\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Table1COMBOmediumcomposition.docx","url":"https://assets-eu.researchsquare.com/files/rs-9306322/v1/8950d0c98542ef9c951a61d1.docx"},{"id":108006568,"identity":"1edede2f-a766-4f10-8a19-6e811c237c69","added_by":"auto","created_at":"2026-04-28 12:56:07","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":15821,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSupplementary Table 2\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Table2Experimentaldesignandtreatmentcombinations.docx","url":"https://assets-eu.researchsquare.com/files/rs-9306322/v1/60e6cec0e8192a72b0a430c4.docx"},{"id":108006824,"identity":"e860db5e-d154-4aa1-9ea6-9bd6fcf7a5b4","added_by":"auto","created_at":"2026-04-28 12:57:31","extension":"docx","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":25011,"visible":true,"origin":"","legend":"","description":"","filename":"BlissIndependenceModelCalculationandInteractionCategory.docx","url":"https://assets-eu.researchsquare.com/files/rs-9306322/v1/e35bd15030fbc320d149b8bd.docx"},{"id":107931878,"identity":"9a550ad3-4906-4365-8c36-b1ed18d07584","added_by":"auto","created_at":"2026-04-27 16:44:56","extension":"csv","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":19573,"visible":true,"origin":"","legend":"","description":"","filename":"Data.csv","url":"https://assets-eu.researchsquare.com/files/rs-9306322/v1/ab85fd0f89f59473a38c073b.csv"},{"id":108007450,"identity":"700b53d6-88ed-4eb6-aa6b-9310c7c391a0","added_by":"auto","created_at":"2026-04-28 13:00:06","extension":"docx","order_by":5,"title":"","display":"","copyAsset":false,"role":"supplement","size":13760,"visible":true,"origin":"","legend":"","description":"","filename":"SUPPLEMENTALMATERIAL.docx","url":"https://assets-eu.researchsquare.com/files/rs-9306322/v1/48856080be65e56fcd57cbab.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Road salt alters the ecological effects of atrazine–cypermethrin mixtures in freshwater microalgae","fulltext":[{"header":"1. INTRODUCTION","content":"\u003cp\u003eAnthropogenic activities are increasingly degrading aquatic ecosystems through the introduction of individual and combined chemical stressors, creating complex exposure scenarios that challenge ecosystem structure and function. Agricultural pesticides and road deicing salts are among the most widespread and persistent contaminants entering freshwater systems via runoff, leaching, and stormwater discharge (Kaushal et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Stehle \u0026amp; Schulz, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Because these stressors often co-occur (Ahmed et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2025\u003c/span\u003e), aquatic organisms such as microalgae are routinely exposed to chemical cocktails rather than isolated molecules. Yet, most toxicity assessments used for regulatory actions rely on single-stressor response data, despite the complexity of real-world environmental exposures​ (Proctor et al., \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Ahmed et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2026\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFreshwater microalgae play a foundational role in aquatic ecosystems by driving primary production, regulating nutrient cycling, and supporting higher trophic levels (Updhyay et al., \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). \u003cem\u003eChlorella vulgaris\u003c/em\u003e is a cosmopolitan green alga widely used as a model organism in ecotoxicological research due to its rapid growth, well-characterized physiology, and sensitivity to chemical stressors (Liang et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Matejczyk et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Therefore, changes in \u003cem\u003eC. vulgaris\u003c/em\u003e growth, chlorophyll content, and biomass can serve as early indicators of ecosystem-level impairment (Calder\u0026oacute;n-Delgado et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). However, ​​\u003cem\u003eChlorella vulgaris\u003c/em\u003e exhibits varying responses to pesticides and salinity, with its physiological and biochemical reactions being dependent on both the concentration of the stressor and the duration of exposure​ (Adochite \u0026amp; Andronic, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Camuel et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Esteves et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2025\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAtrazine is a widely used triazine herbicide that inhibits photosystem II by blocking electron transport at the D1 protein, thereby reducing photosynthetic efficiency in target plants and non-target algae (Singh et al., \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Solomon et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Zhu et al., \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). Cypermethrin, a synthetic pyrethroid insecticide, is highly toxic to aquatic organisms and can induce oxidative stress, membrane damage, and pigment disruption in algae, either directly or indirectly through altered water chemistry (Baruah \u0026amp; Chaurasia, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; S\u0026aacute;enz et al., \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Atrazine and cypermethrin are regularly found in surface waters at low to moderate concentrations. Yet their sublethal impacts on freshwater algae, especially when combined with other environmental stressors, require further investigation, given the expanding range of co-occurring contaminants (Ahmed et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2026\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eOne such co-contaminant, sodium chloride (NaCl), has gained considerable attention in the past two decades due to its global ubiquity as a contaminant in freshwater ecosystems (Hintz et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). A common mode of NaCl pollution in temperate regions is the widespread overuse of rock salt as a road deicer. The misuse of road deicers has led to increasing freshwater salinization across temperate regions (Hintz et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Elevated salinity alters ionic balance, osmotic regulation, and nutrient availability, with cascading effects on algal physiology, community composition, and ecosystem processes (Hintz \u0026amp; Relyea, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Dugan et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Importantly, salinity has been shown to modify the toxicity of pesticides, potentially amplifying or attenuating their biological effects (DeLorenzo et al., 2009; Khouni et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn this study, we address two primary research questions: 1) How do atrazine, cypermethrin, and NaCl individually affect the growth, chlorophyll content, biomass, and water quality parameters associated with \u003cem\u003eChlorella vulgaris\u003c/em\u003e? 2) How does co-exposure to NaCl alter the toxicity of atrazine and cypermethrin? We hypothesized that there would be synergistic effects of NaCl and the pesticides on algal physiology and water chemistry under combined exposures compared to single-stressor treatments. This synergy is expected due to ionic interactions under saline conditions that may alter cell membrane permeability and amplify oxidative and metabolic stress induced by atrazine and cypermethrin.\u003c/p\u003e"},{"header":"2. MATERIALS AND METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Experimental Design\u003c/h2\u003e \u003cp\u003eA controlled laboratory microcosm experiment was conducted to evaluate the individual and interactive effects of atrazine, cypermethrin, and sodium chloride (NaCl) on the freshwater microalga \u003cem\u003eChlorella vulgaris\u003c/em\u003e and associated water quality parameters. The study employed a fully-factorial design consisting of single-stressor treatments and their mixtures. Experiments were conducted using static-renewal microcosms over a 29-day exposure period, with repeated sampling to capture both short-term and longer-term responses.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Algal Culture and Growth Conditions\u003c/h2\u003e \u003cp\u003eA unialgal culture of \u003cem\u003eChlorella vulgaris\u003c/em\u003e was obtained from CAROLINA biological supply, North Carolina, USA, and maintained in COMBO water, a nutrient medium for culturing algae. The COMBO water was prepared according to the standard protocol (Kilham et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1998\u003c/span\u003e). The stock culture of algae was grown under controlled laboratory conditions with a 12 h light: 12 h dark photoperiod (60 \u0026micro;mol photons/m\u0026sup2;/s) at 25\u0026deg;C using a hotplate. The culture was continuously aerated to maintain homogeneous suspension, and a sterilized metallic rod was used for stirring at 280 rpm to prevent sedimentation. Before experimental initiation, cultures were acclimated to experimental conditions to ensure stable growth.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Preparation of Experimental Microcosms\u003c/h2\u003e \u003cp\u003eExperimental units consisted of 250 mL, acid-washed borosilicate glass containers; each filled with 250 mL of freshly prepared COMBO water \u003cb\u003e(Supplementary Table\u0026nbsp;1)\u003c/b\u003e. Microcosms were inoculated with 5 mL of algal stock culture, resulting in comparable initial cell densities across treatments. The culture was homogenized, and all microcosms received approximately the same number of cells. Microcosms were inoculated in random order, ensuring that any accidental variation would not favor a particular treatment. All microcosms were maintained under identical light and temperature conditions throughout the exposure period. We let algae grow for a week to establish in microcosms.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Chemical Preparation and Treatments\u003c/h2\u003e \u003cp\u003eAnalytical grade Atrazine (\u0026gt;\u0026thinsp;95% purity) and cypermethrin (\u0026gt;\u0026thinsp;98% purity) were purchased from Thermo Fisher Scientific and Sigma-Aldrich, and their stock solutions were prepared in dimethyl sulfoxide (DMSO). We used\u0026thinsp;\u0026lt;\u0026thinsp;0.1% v/v Dimethyl Sulfoxide (DMSO) solvent to prepare the atrazine stock solution. DMSO is used over other vehicles such as methanol, ethanol, and acetone due to its low demonstrated toxicity to algae (Ma \u0026amp; Chen, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Chen et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). Sodium chloride (NaCl) stock solutions were prepared in reverse-osmosis water. Treatments were applied to achieve the nominal concentrations: Atrazine: 50 \u0026micro;g L⁻\u0026sup1; and 100 \u0026micro;g L⁻\u0026sup1;, Cypermethrin: 50 \u0026micro;g L⁻\u0026sup1;, and NaCl: 860 mg L⁻\u0026sup1;. The treatment matrix included controls (COMBO medium only), DMSO solvent controls, single-stressor exposures, binary, and the tertiary combination of atrazine, cypermethrin, and NaCl. Final DMSO concentrations were identical across all pesticide treatments and solvent controls. 14 treatments \u003cb\u003e(Supplementary Table\u0026nbsp;2)\u003c/b\u003e were replicated 5 times and resulted in 70 test units in total.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Biological Response Variables\u003c/h2\u003e \u003cp\u003eFor algal cell abundance, 1 mL of sample was collected from each test unit into sampling tubes, and 1\u0026ndash;2 drops of Lugol\u0026rsquo;s iodine were added immediately to preserve cell integrity and prevent decay. Microcosms were sampled four times throughout the experiment: 96 h, day 15, day 22, and day 29 following treatment application. Preserved samples were analyzed using a flow cytometer (Attune\u0026trade; NxT Acoustic Focusing Cytometer, Thermo Fisher Scientific) to count the cell abundance. Samples were homogenized using a mechanical shaker before analysis to minimize cell settling and ensure uniform distribution. A 200 \u0026micro;L subsample was then analyzed using the tube method. Samples were processed at a low flow rate, and the cytometer was set to acquire 10,000 events from a 50 \u0026micro;L sample volume. Algal populations were identified and gated using forward scatter (FSC) versus side scatter (SSC) density plots, enabling discrimination of algal cells from background particles and debris based on size distribution patterns. Cell count per sample was recorded as the primary metric and used as a measure of algal abundance (Marie et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn parallel, chlorophyll fluorescence was measured using a Turner Designs Trilogy laboratory fluorometer (Turner Designs, San Jose, CA) equipped with the Chlorophyll \u003cem\u003eIn Vivo\u003c/em\u003e Module. The module uses a blue light-emitting diode with peak excitation around 460 nm, and an excitation band centered at approximately 441 nm to excite photosynthetic pigments within intact algal cells. Upon absorption of excitation energy, chlorophyll pigments emit red fluorescence due to the Stokes shift. Emitted fluorescence was selectively detected using an emission filter spanning 660 to 710 nm, corresponding to the characteristic red fluorescence region of chlorophyll \u003cem\u003ein vivo\u003c/em\u003e, while minimizing detection of scattered excitation light. Fluorescence intensity was quantified by an internal photodiode detector and recorded as relative fluorescence units. Because measurements were performed on live, unextracted cell suspensions, the signal represents total in vivo chlorophyll fluorescence and serves as a non-destructive proxy for algal biomass. Chlorophyll measurements provided an independent indicator of photosynthetic activity, complementing flow cytometry data to assess algal health and metabolic activity.\u003c/p\u003e \u003cp\u003eAt day 29, algal biomass was quantified gravimetrically by filtering 50 mL of culture from each treatment onto pre-weighed 47 mm diameter Whatman 934-AH glass microfiber filters. Before filtration, filters were pre-weighed to obtain the initial mass. Following filtration, filters containing algal biomass were air-dried for 72 h and reweighed after reaching constant mass. Biomass was calculated as the difference between the final filter weight and the pre-filtration filter weight and expressed as dry weight per unit volume of culture. This method provided an integrated estimate of algal standing biomass within each experimental unit.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.6 Water Quality Measurements\u003c/h2\u003e \u003cp\u003eDissolved oxygen (DO) concentrations were measured using a portable dissolved oxygen analyzer to assess treatment-induced changes associated with atrazine and sodium chloride (NaCl) exposure. pH was monitored using a calibrated PCTS5 multiparameter tester, which also recorded water temperature and electrical conductivity (EC), providing an integrated assessment of physicochemical conditions across experimental units. Colored dissolved organic matter fluorescence was measured using a Turner Designs Trilogy laboratory fluorometer equipped with the CDOM module. The module uses near-ultraviolet excitation centered at approximately 350 nm with a bandwidth of \u0026plusmn;\u0026thinsp;40 nm to excite fluorescent components of dissolved organic matter. Emitted fluorescence was detected within the 410 to 450 nm spectral range using an internal bandpass filter to minimize detection of scattered excitation light. Fluorescence intensity was recorded as relative fluorescence units (RFU). Because this method quantifies fluorescence within defined excitation and emission windows, the reported values represent operationally defined CDOM fluorescence rather than a direct measure of total dissolved organic carbon concentration. These measurements were used to evaluate treatment-related variation in nutrient levels and organic matter dynamics within the microcosms.\u003c/p\u003e \u003cp\u003eTotal Nitrogen (TN) in water samples was measured using the TNTplus\u0026reg; 826 Low Range method (Hach Company; 1\u0026ndash;16 mg L⁻\u0026sup1; N). The method quantifies both organically and inorganically bound nitrogen by oxidation to nitrate using peroxodisulfate digestion. Briefly, 1.3 mL of sample was combined with 1.3 mL of Sodium Hydroxide solution (A) and 1 oxidant tablet (B) in a 20-mm reaction tube. Tubes were immediately sealed and heated in a reactor at 120\u0026deg;C for 30 minutes. After cooling to room temperature, 0.5 mL of the digested sample was mixed with 0.2 mL of solution D, and the reaction vials were inverted to ensure complete mixing. The resulting nitrophenol formed was measured spectrophotometrically at 410 nm using a DR 6000 spectrophotometer. Slight sample turbidity or transient pink coloration during reaction did not interfere with measurement.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.7. Bliss Independence Model Application\u003c/h2\u003e \u003cp\u003eTo evaluate whether the combined effects of atrazine, cypermethrin, and sodium chloride (NaCl) on chlorophyll, colored dissolved organic matter (CDOM), and total nitrogen (TN) were additive, synergistic, or antagonistic, the Bliss Independence model was applied. This model assumes independent action among stressors and estimates the expected combined response under the null hypothesis of no interaction (Demidenko \u0026amp; Miller, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Liu et al., \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAll analyses were conducted using treatment means, with responses expressed relative to the control. Proportional effects were calculated as:\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:E=\\frac{{\\text{Mean}}_{\\text{Treatment}}-{\\text{Mean}}_{\\text{Control}}}{{\\text{Mean}}_{\\text{Control}}}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eFor binary mixtures, the Bliss expected effect was calculated as:\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e\n$$\\:{E}_{\\text{Bliss}}={E}_{X}+{E}_{Y}-({E}_{X}\\times\\:{E}_{Y})$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{E}_{X}\\)\u003c/span\u003e\u003c/span\u003eand \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{E}_{Y}\\)\u003c/span\u003e\u003c/span\u003eare the proportional effects of the individual stressors.\u003c/p\u003e \u003cp\u003eFor tertiary mixtures, the Bliss expectation was extended to three stressors as:\u003cdiv id=\"Equc\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equc\" name=\"EquationSource\"\u003e\n$$\\:{E}_{\\text{Bliss}}=1-(1-{E}_{A})(1-{E}_{C})(1-{E}_{S})$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:{E}_{A}\\)\u003c/span\u003e \u003c/span\u003e = effect of atrazine alone, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{E}_{S}\\)\u003c/span\u003e\u003c/span\u003e= effect of NaCl alone and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{E}_{C}\\)\u003c/span\u003e\u003c/span\u003e= effect of cypermethrin alone\u003c/p\u003e \u003cp\u003eObserved combined effects were calculated using the same proportional response equation. Interactions were classified as synergistic when observed effects exceeded Bliss expectations, additive when observed and expected effects were similar, and antagonistic when observed effects were lower than expected \u003cb\u003e(See supplementary materials for details).\u003c/b\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e2.8. Statistical Analysis\u003c/h2\u003e \u003cp\u003eAll statistical analyses were performed using R (version 4.2.3) (Team, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Before hypothesis testing, all response variables were screened for normality using the Shapiro\u0026ndash;Wilk test (shapiro.test). Several variables, including chlorophyll, dissolved oxygen (DO), electrical conductivity (EC), temperature, pH, and total nitrogen (TN), violated assumptions of normality and were therefore transformed using rank-based inverse normal transformation calculated with rank() and qnorm() before parametric analyses. CDOM and cell abundance met normality assumptions and were analyzed using untransformed values.\u003c/p\u003e \u003cp\u003eThe individual and interactive effects of atrazine, cypermethrin, and NaCl were evaluated using three-way factorial analyses of variance (ANOVA) implemented with the aov() function. Atrazine, cypermethrin, and NaCl were treated as fixed factors, and all two-way and three-way interactions were included in the models. Statistical significance of main effects and interactions was assessed at α\u0026thinsp;=\u0026thinsp;0.05 using summary.aov().\u003c/p\u003e \u003cp\u003eTo assess treatment-specific effects relative to the control, one-way ANOVA models were fitted using a combined treatment factor for each response variable. Post hoc comparisons were conducted using Dunnett\u0026rsquo;s test to compare each treatment to the control while controlling for family-wise error rates (Hothorn et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). Dunnett contrasts were implemented using the glht() function with mcp(Treatment = \"Dunnett\") from the \u003cem\u003emultcomp\u003c/em\u003e package, with the control treatment set as the reference level using relevel().\u003c/p\u003e \u003cp\u003eMixture toxicity and interaction outcomes were further evaluated using the Bliss independence model by comparing observed mixture responses to Bliss-predicted effects. Deviations between observed and expected responses were interpreted as synergistic, antagonistic, or additive interactions, depending on the direction and magnitude of the difference.\u003c/p\u003e \u003cp\u003eAll graphical analyses were conducted using the \u003cem\u003eggplot2\u003c/em\u003e package (ggplot()). Boxplots were generated using geom_boxplot() to visualize treatment effects, and scatter-based visualizations for mixture analyses were produced using geom_point(). Reference lines and statistical annotations were added using geom_hline() and annotate().\u003c/p\u003e \u003c/div\u003e"},{"header":"3. RESULTS","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Biotic responses\u003c/h2\u003e \u003cp\u003eTotal Chlorophyll was significantly influenced by salinity and by interactions involving atrazine \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. The two-way ANOVA results indicate a strong main effect of NaCl (F₁,₁₂₈ = 49.18, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), as well as significant Atrazine \u0026times; Cypermethrin (F₂,₁₂₈ = 8.74, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and an Atrazine \u0026times; NaCl interaction (F₂,₁₂₈ = 19.04, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). A three-way interaction among chemicals was not detected.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eANOVA results for biotic responses (Chlorophyll and Cell abundance) of freshwater phytoplankton \u003cem\u003eChlorella vulgaris\u003c/em\u003e to Atrazine, Cypermethrin, NaCl, and their interactions. Significant effects are indicated in bold.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eResponse\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSource\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDf\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSum Sq\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMean Sq\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eF value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChlorophyll\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.091\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.882\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.156\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.322\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.555\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.458\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e28.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e28.511\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e49.184\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5.065\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e8.738\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e22.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e11.037\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e19.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.026\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.045\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.832\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.641\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.105\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.334\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eResiduals\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e128\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e74.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCell Abundance\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1,372,243\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e686,121\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.248\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.289\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e47,865\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e47,865\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.087\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.768\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2,489,294\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2,489,294\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.529\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.034\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e758,389\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e379,195\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.503\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e545,787\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e272,893\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.496\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.609\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e271,285\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e271,285\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.494\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.483\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1,104,574\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e552,287\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.368\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eResiduals\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e268\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e147,302,247\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e549,635\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eDunnett\u0026rsquo;s post hoc comparisons indicate \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e3\u003c/span\u003e \u003cb\u003e\u0026amp;\u003c/b\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e that atrazine at 50 \u0026micro;g L⁻\u0026sup1; significantly reduced chlorophyll relative to the control (estimate\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.98, p\u0026thinsp;=\u0026thinsp;0.040), whereas atrazine at 100 \u0026micro;g L⁻\u0026sup1; and cypermethrin alone did not differ from controls. Salinity alone (NaCl 860 mg L⁻\u0026sup1;) did not significantly alter chlorophyll. However, the combined exposure to atrazine (50 \u0026micro;g L⁻\u0026sup1;), cypermethrin (50 \u0026micro;g L⁻\u0026sup1;), and NaCl (860 mg L⁻\u0026sup1;) increased chlorophyll (estimate\u0026thinsp;=\u0026thinsp;+\u0026thinsp;1.63, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), indicating a strong interactive effect under multi-stressor conditions.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDunnett\u0026rsquo;s post hoc comparisons of treatment effects on \u003cem\u003eChlorella vulgaris\u003c/em\u003e relative to control. Biotic endpoints include chlorophyll and cell abundance, while abiotic endpoints include DO, EC, temperature, pH, TN, and CDOM. Adjusted p-values and significance levels are reported for each treatment. Significant effects are indicated in bold.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTreatment\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eChlorophyll\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCell abundance\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDO\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eEC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eTemp\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003epH\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eTN\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eCDOM\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAtrazine 50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e0.039\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.826\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.995\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.998\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.797\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.382\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.489\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAtrazine 100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.161\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.366\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.468\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.989\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.846\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e0.046\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.654\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCypermethrin 50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.872\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.707\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.999\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.989\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.226\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNaCl 860\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.999\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.998\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e0.002\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.346\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAtrazine 50 * Cypermethrin 50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.181\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.226\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.943\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.974\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.998\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAtrazine 100 * Cypermethrin 50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.972\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.498\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.375\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.991\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.079\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAtrazine 50 * NaCl 860\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.184\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.439\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e0.010\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e\u003cb\u003e0.006\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAtrazine 100 * NaCl 860\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.909\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.599\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.996\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e\u003cb\u003e0.002\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCypermethrin 50 * NaCl 860\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.956\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e\u003cb\u003e0.003\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAtrazine 50 * Cypermethrin 50 * NaCl 860\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.988\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.992\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAtrazine 100 * Cypermethrin 50 * NaCl 860\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.392\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e\u003cb\u003e0.003\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDMSO Low\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.821\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.221\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.936\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.470\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.747\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDMSO High\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.974\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.700\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.192\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.960\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.742\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.999\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eCell abundance was affected by salinity (F₁,₂₆₈ = 4.53, p\u0026thinsp;=\u0026thinsp;0.034), but there were no detected effects of atrazine, cypermethrin, or in combined treatments \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e \u003cb\u003eand\u003c/b\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. The post hoc \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e results did not suggest any individual treatment that differed from the control, indicating that the overall salinity effect reflected small, but consistent shifts rather than strong treatment-specific deviations.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eBiomass did not differ significantly among treatments \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. Values varied within a narrow range (0.0091\u0026ndash;0.0155 g/50 mL) and were comparable to the control (0.0128 g/50 mL), indicating that neither individual exposures nor combined treatments measurably affected biomass.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Abiotic responses\u003c/h2\u003e \u003cp\u003eTotal nitrogen exhibited strong and complex responses to both single and combined stressors \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e\u003cb\u003e).\u003c/b\u003e ANOVA showed significant main effects of atrazine (F₂,₅₈ = 16.01, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and NaCl (F₁,₅₈ = 7.68, p\u0026thinsp;=\u0026thinsp;0.008), as well as significant Atrazine \u0026times; Cypermethrin, Atrazine \u0026times; NaCl, Cypermethrin \u0026times; NaCl, and three-way interactions (all p\u0026thinsp;\u0026le;\u0026thinsp;0.038) \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e2\u003c/span\u003e\u003cb\u003e).\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eANOVA results for abiotic water quality parameters (DO, EC, Temp, pH, TN, and CDOM) in response to Atrazine, Cypermethrin, NaCl, and their interactions. Significance levels are denoted in bold.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eResponse\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSource\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDf\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSum Sq\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMean Sq\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eF value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.9143\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.903\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.407\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.0113\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.011\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.916\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.7189\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.697\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.194\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.0862\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.085\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.918\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.0947\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2.069\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.129\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.117\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.115\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.734\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.052\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.051\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.95\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eResiduals\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e198\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e200.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.0127\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.155\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.856\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.429\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.513\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e136.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e136.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e423.331\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.051\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.456\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.235\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.032\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.859\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.867\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e0.003\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eResiduals\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e198\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e63.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTemp\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.3695\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.369\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.691\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.6213\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.621\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.431\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.2981\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2.297\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.131\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.377\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.377\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.686\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.1741\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.174\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.840\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.1551\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.155\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.694\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.3683\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2.367\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.096\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eResiduals\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e198\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e198.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.0007\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.1317\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e0.040\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.659\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.686\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.408\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.2667\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.278\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.598\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.2574\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.268\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.765\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.6555\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.723\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.181\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.2869\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.299\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.585\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.9139\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.951\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.388\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eResiduals\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e198\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e190.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.9606\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTN\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11.269\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5.635\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e16.009\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.059\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.059\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.167\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.684\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.702\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.702\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e7.677\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e0.007\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.873\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.936\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.502\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e0.006\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.815\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e25.045\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.582\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.582\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.495\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e0.038\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11.204\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5.602\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e15.917\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eResiduals\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20.414\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.352\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCDOM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e69,064\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e34,532\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.670\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e540,488\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e540,488\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.264\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e0.013\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5,082,025\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5,082,025\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e58.894\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1,148,469\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e574,235\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.655\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1,233,047\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e616,524\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e7.145\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13,323\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13,323\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.154\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.694\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine \u0026times; Cypermethrin \u0026times; NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1,470,336\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e735,168\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e8.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eResiduals\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e198\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17,085,626\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e86,291\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eDunnett tests \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e indicated that atrazine at 100 \u0026micro;g L⁻\u0026sup1; significantly reduced TN relative to the control (estimate\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;1.08, p\u0026thinsp;=\u0026thinsp;0.046), whereas atrazine at 50 \u0026micro;g L⁻\u0026sup1; did not. NaCl alone significantly reduced TN (estimate\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;1.44, p\u0026thinsp;=\u0026thinsp;0.003). All binary mixtures involving atrazine or cypermethrin with NaCl resulted in significant reductions in TN (p\u0026thinsp;\u0026le;\u0026thinsp;0.01). Similarly, both atrazine\u0026ndash;cypermethrin combinations significantly decreased TN (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The three-way mixture at the lower atrazine concentration further reduced TN (estimate\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;1.76, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), whereas the higher-dose three-way treatment did not differ from the control.\u003c/p\u003e \u003cp\u003eCDOM was strongly influenced by salinity and interaction effects \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e\u003cb\u003e).\u003c/b\u003e ANOVA \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e2\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e identified significant effects of cypermethrin (F₁,₁₉₈ = 6.26, p\u0026thinsp;=\u0026thinsp;0.013), NaCl (F₁,₁₉₈ = 58.89, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Post hoc comparisons \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e showed that NaCl-containing mixtures consistently reduced CDOM. Atrazine \u0026times; NaCl, cypermethrin \u0026times; NaCl, and both three-way combinations resulted in a reduced concentration relative to the control (p\u0026thinsp;\u0026le;\u0026thinsp;0.006). The strongest reduction occurred under the three-way mixture with atrazine 50 \u0026micro;g L⁻\u0026sup1;, which reduced CDOM by more than 550 units (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). In contrast, single-compound treatments did not significantly alter CDOM.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eDO, and temperature did not respond to any single stressor or interaction (all p\u0026thinsp;\u0026gt;\u0026thinsp;0.05; Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Dunnett tests confirmed that no individual treatment caused significant increases or decreases in either parameter relative to controls. Electrical conductivity (EC) responded strongly to salinity and higher-order interactions, and ANOVA indicated a pronounced main effect of NaCl (F₁,₁₉₈ = 423.33, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). pH was modestly affected by atrazine (F₂,₁₉₈ = 3.26, p\u0026thinsp;=\u0026thinsp;0.041), while no interaction terms were significant. However, Dunnett post hoc tests did not identify any atrazine treatment that differed significantly from the control, indicating that the observed ANOVA effect was small and distributed across treatment levels rather than driven by a single exposure.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e\u003cb\u003e3.3. Interactive stressor effects\u003c/b\u003e\u003c/h2\u003e \u003cp\u003eBliss Independence analysis indicated distinct interaction patterns among atrazine, cypermethrin, and NaCl across chlorophyll, CDOM, and total nitrogen (TN) \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e \u003cb\u003e\u0026amp;\u003c/b\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. For chlorophyll, the atrazine\u0026thinsp;+\u0026thinsp;NaCl and cypermethrin\u0026thinsp;+\u0026thinsp;NaCl binary mixtures exhibited observed responses that exceeded Bliss expected effects, indicating synergistic interactions. In contrast, the atrazine\u0026thinsp;+\u0026thinsp;cypermethrin mixture produced a chlorophyll response substantially lower than the Bliss prediction, indicating antagonism. When all three stressors were combined, the observed chlorophyll response remained below the Bliss expected value, indicating an overall antagonistic interaction under tertiary exposure.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSummary of Day-29 mixture effects on freshwater microcosm endpoints (chlorophyll, CDOM, and total nitrogen (TN) relative to control, analyzed using the Bliss independence model. Observed effects (E_obs) and Bliss-expected effects (E_Bliss) are reported, along with the classification of interactions as synergistic, antagonistic, or additive.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEndpoint\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMixture\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eObserved Effect (E\u003csub\u003eobs\u003c/sub\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eBliss Expected (E\u003csub\u003eBliss\u003c/sub\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eInteraction\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChlorophyll\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine\u0026thinsp;+\u0026thinsp;NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.680\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.456\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSynergistic\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChlorophyll\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCypermethrin\u0026thinsp;+\u0026thinsp;NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026minus;0.296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026minus;0.535\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSynergistic\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChlorophyll\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine\u0026thinsp;+\u0026thinsp;Cypermethrin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.102\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.429\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAntagonistic\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChlorophyll\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine\u0026thinsp;+\u0026thinsp;Cypermethrin\u0026thinsp;+\u0026thinsp;NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.257\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.311\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAntagonistic\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCDOM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine\u0026thinsp;+\u0026thinsp;NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026minus;0.011\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.016\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAntagonistic\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCDOM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine\u0026thinsp;+\u0026thinsp;Cypermethrin\u0026thinsp;+\u0026thinsp;NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026minus;0.024\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026minus;0.023\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAdditive\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTN\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine\u0026thinsp;+\u0026thinsp;NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026minus;0.242\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026minus;0.287\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSynergistic\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTN\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAtrazine\u0026thinsp;+\u0026thinsp;Cypermethrin\u0026thinsp;+\u0026thinsp;NaCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026minus;0.278\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026minus;0.455\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSynergistic\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFor CDOM, binary mixtures generally resulted in observed responses that were lower than Bliss expectations, indicating antagonistic interactions. Under tertiary exposure to atrazine, cypermethrin, and NaCl, the observed CDOM response closely matched the Bliss expected effect, indicating an approximately additive interaction. Additionally, for total nitrogen (TN), all individual stressors produced negative proportional responses relative to the control. However, both binary and tertiary mixtures involving NaCl exhibited observed reductions that exceeded Bliss's expected effects, indicating synergistic interactions despite the overall negative direction of response.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. DISCUSSION","content":"\u003cp\u003e​\u003cb\u003e4.1. Response of Chlorophyll to individual and mixture effects\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThe observed changes in total chlorophyll concentration indicate complex mechanistic interactions among atrazine, cypermethrin, and salinity (NaCl), moving beyond simple additive effects. ​The chlorophyll reduction observed at 50 \u0026micro;g L⁻\u0026sup1; atrazine is consistent with its well-established mode of action as a PSII inhibitor, as atrazine directly disrupts the electron transport chain, particularly PSII, leading to oxidative imbalance and impaired photosynthetic performance in algae (Bai et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Yang et al., 2020). Cypermethrin alone did not alter chlorophyll in this study, which aligns with reports showing that pyrethroid effects on photosynthetic pigments are often concentration-dependent and primarily associated with oxidative stress\u0026ndash;mediated pigment disruption at higher or prolonged exposures (Huang et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Xi et al., \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSynergistic chlorophyll responses observed in cypermethrin\u0026thinsp;+\u0026thinsp;NaCl and atrazine\u0026thinsp;+\u0026thinsp;NaCl mixtures may reflect salinity-induced modifications of PSII photochemistry that alter cellular sensitivity to chemical stressors (Lu et al., 2002). This synergism suggests that salinity, while not individually toxic for \u003cem\u003eC. vulgaris\u003c/em\u003e at the tested concentration, might enhance the toxicity of atrazine and cypermethrin by increasing cellular uptake, altering membrane permeability, or exacerbating cellular stress responses (Farghl et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), leading to a greater impact on chlorophyll than either stressor alone (Wen et al., \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Giudici, 2020).\u003c/p\u003e \u003cp\u003eIn contrast, the antagonistic chlorophyll responses observed for atrazine\u0026thinsp;+\u0026thinsp;cypermethrin are consistent with mixture studies demonstrating that combined pesticide stress can reduce photosynthetic performance through overlapping impacts on chloroplast structure, PSII efficiency, and cellular energy balance, resulting in effects lower than additive expectations (Wang et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The specific mechanisms by which the combined exposure to atrazine, cypermethrin, and NaCl interacts to increase chlorophyll in \u003cem\u003eChlorella vulgaris\u003c/em\u003e​ is unclear, and future research should explore the underlying mechanisms. We assume that the presence of one stressor might alter the toxicity pathway or uptake of another. ​For example, a low concentration of atrazine or NaCl might induce stress-response proteins that coincidentally offer some protection against cypermethrin's chlorophyll-degrading effects, or vice versa (Wang et al., \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Wang et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). This could lead to a net increase in chlorophyll as the negative impacts are partially mitigated, and the stimulatory effects are enhanced. When combined, the stressors synergistically lead to an upregulation of chlorophyll biosynthesis genes or a reduction in chlorophyll degradation rates, as the microalga tries to adapt to the complex environment.\u003c/p\u003e \u003cp\u003e​​\u003cb\u003e4.2. Overall stressor effects on algal physiology and water quality\u003c/b\u003e\u003c/p\u003e \u003cp\u003eIonic stress imposed by NaCl caused alterations in algal physiology, likely through osmotic effects (Ogawa et al., 2005; Kiełkowska, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Wolny et al., \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Biomass remained relatively stable across treatments, indicating that sublethal levels of atrazine, cypermethrin, and their combinations did not strongly inhibit algal growth. The highest biomass under atrazine 100 \u0026micro;g L⁻\u0026sup1; suggests that low-level herbicide exposure may trigger mild compensatory growth or acclimation responses (Yang et al., \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Ya, 2013), whereas the lowest values in solvent controls point to minor solvent effects rather than treatment toxicity.\u003c/p\u003e \u003cp\u003eTotal nitrogen decreased in response to combined stressors, with reductions being strongest in NaCl-containing mixtures. This indicates that salinity may interfere with nitrogen uptake or assimilation (Ashraf et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Dluzniewska et al., 2006; Botella et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e1997\u003c/span\u003e), and when combined with atrazine or cypermethrin, the effect is amplified, suggesting a synergistic impairment of nutrient acquisition. Salinity plays a significant role in interfering with nitrogen uptake and assimilation in \u003cem\u003eChlorella vulgaris\u003c/em\u003e. When salinity is combined with stressors like atrazine or cypermethrin, this impairment of nutrient acquisition is amplified, leading to reduced total nitrogen (TN) (Dassanayake, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Herbst \u0026amp; Bradley, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e1989\u003c/span\u003e). The largest reductions in TN were observed in tertiary mixtures with lower atrazine concentrations, indicating that multiple stressors intensify nutrient limitation. This suggests a metabolic shift where the algae struggle to efficiently acquire and process essential nutrients under combined stress. \u003cem\u003eC. vulgaris\u003c/em\u003e has robust metabolic flexibility, enabling it to grow in autotrophic, mixotrophic, and heterotrophic modes (Arora \u0026amp; Philippidis, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Zu\u0026ntilde;iga et al., \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Miotti et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eCDOM responses were dominated by salinity and interaction effects. NaCl-containing mixtures consistently reduced CDOM, with binary mixtures generally showing antagonistic effects and tertiary mixtures approximating additive effects. This pattern indicates that algal exudation of dissolved organic matter or its transformation in the medium is modulated by both osmotic and chemical stress, possibly due to altered metabolism or reduced production of extracellular compounds (Marš\u0026aacute;lek \u0026amp; Roj\u0026iacute;čkov\u0026aacute;, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e1996\u003c/span\u003e). ​The presence of NaCl increases the ionic strength of the solution, which can affect the optical properties and stability of CDOM (Gonsior et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Song et al., \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). ​​High salinity environments can lead to a \"salting-out\" effect, where dissolved organic molecules, including CDOM, become less soluble and may aggregate or precipitate out of the solution, thereby reducing the measured CDOM concentration​ (Gonsior et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). ​For instance, in riverine environments transitioning to estuaries, CDOM often exhibits an inverse relationship with salinity due to conservative mixing and removal processes like flocculation (Chen et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). The largest CDOM decrease under the three-way mixture with lower atrazine concentration suggests that metabolic shifts are strongest when multiple stressors are simultaneously present, aligning with observed TN reductions.\u003c/p\u003e \u003cp\u003eElectrical conductivity responded predictably to salinity, confirming effective ionic stress in the microcosms. pH showed only minor changes under atrazine and DO, and temperature remained largely stable across all treatments. This indicates that the observed changes in chlorophyll, TN, and CDOM were driven by physiological and metabolic responses of the algae, rather than by secondary changes in the abiotic environment.\u003c/p\u003e \u003cp\u003eUnder multi-stressor conditions, changes in chlorophyll occur, suggesting that nutrient limitation directly influences pigment synthesis and photosynthetic capacity. Similarly, CDOM reductions appear connected to altered nitrogen availability and chlorophyll status, likely reflecting coordinated metabolic adjustments, such as changes in carbon allocation or exudation patterns under stress. Together, these responses illustrate tight physiological coupling between nutrient dynamics, photosynthesis, and organic carbon release, which is amplified under multi-stressor conditions.\u003c/p\u003e"},{"header":"5. CONCLUSIONS","content":"\u003cp\u003eIn this study, we demonstrated that salinity from NaCl was a strong driver of stress responses in Chlorella vulgaris, particularly when combined with the herbicide atrazine and the insecticide cypermethrin. CDOM and chlorophyll content were significantly altered under NaCl-containing treatments, with multi-stressor combinations producing the strongest effects, while biomass and cell abundance remained relatively stable. These results suggest that ionic stress can amplify or modulate the physiological impacts of chemical pollutants, highlighting the importance of considering co-occurring stressors in ecotoxicological assessments. Abiotic parameters such as total nitrogen were also sensitive to combined exposures, whereas pH, dissolved oxygen, and temperature remained stable, indicating that the observed effects were primarily driven by chemical interactions rather than changes in basic water chemistry. Overall, this work emphasizes the ecological relevance of multi-stressor frameworks and suggests that environmental salinization may increase the vulnerability of freshwater primary producers to pesticide exposure. These findings can inform future risk assessments and support management strategies aimed at mitigating combined chemical and salinity stress in freshwater ecosystems.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eCONFLICT OF INTEREST\u003c/p\u003e\n\u003cp\u003e\u0026ldquo;The authors declare no conflict of interest.\u0026rdquo;\u003c/p\u003e\n\u003cp\u003eAUTHOR CONTRIBUTIONS\u003c/p\u003e\n\u003cp\u003eArif Ahmed \u0026ndash; Conceptualization, Investigation, Methodology, Validation, Visualization, Software, Formal analysis, Data curation, Writing - original draft, Writing - review \u0026amp; editing. Matthew Schuler \u0026ndash; Validation, Writing - review \u0026amp; editing, Project administration, Supervision, Resources.\u003c/p\u003e\n\u003cp\u003eEthical Approval\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eNot Applicable\u003c/p\u003e\n\u003cp\u003eFunding\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis study did not receive any funding\u003c/p\u003e\n\u003cp\u003eAvailability of data and materials\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eData is available in the supplementary materials section. If needed in other formats, data is available upon request from the corresponding author.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAdochite, C., \u0026amp; Andronic, L. (2021). 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Genome-scale metabolic model for the green alga Chlorella vulgaris UTEX 395 accurately predicts phenotypes under autotrophic, heterotrophic, and mixotrophic growth conditions. \u003cem\u003ePlant physiology\u003c/em\u003e, \u003cem\u003e172\u003c/em\u003e(1), 589\u0026ndash;602. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1104/pp.16.00593\u003c/span\u003e\u003cspan address=\"10.1104/pp.16.00593\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Atrazine, Road salt, Chlorella vulgaris, Microcosms, Multi-stressor interactions","lastPublishedDoi":"10.21203/rs.3.rs-9306322/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9306322/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eFreshwater ecosystems are increasingly exposed to multiple chemical stressors, such as pesticides and road salts, yet the role of salinity in modifying pesticide mixture toxicity remains poorly understood. Here, we investigated the individual and combined effects of the herbicide atrazine, the insecticide cypermethrin, and elevated salinity (NaCl) on the freshwater microalga \u003cem\u003eChlorella vulgaris\u003c/em\u003e in controlled microcosms. We quantified biotic responses (chlorophyll, cell abundance, biomass) alongside abiotic parameters (total nitrogen, dissolved organic matter, dissolved oxygen, pH, electrical conductivity, and temperature). Salinity emerged as the dominant driver of algal response, with atrazine reducing chlorophyll at 50 \u0026micro;g L⁻\u0026sup1;, while cypermethrin alone showed no detectable effect. In contrast, the three-way mixture of atrazine, cypermethrin, and NaCl produced a synergistic increase in chlorophyll, demonstrating strong non-additive interactions under combined stress. Although cell abundance and biomass were not significantly altered, nutrient dynamics were highly sensitive to treatment: total nitrogen and colored dissolved organic matter exhibited pronounced non-linear, synergistic reductions under binary and ternary mixtures. In contrast, dissolved oxygen and pH remained stable across treatments. These results demonstrate that salinity can fundamentally alter both the direction and magnitude of pesticide mixture effects, shifting responses from inhibitory to stimulatory depending on stressor combinations. Our findings highlight the importance of incorporating realistic salinity regimes into mixture toxicity assessments and suggest that increasing freshwater salinization may reshape how chemical pollutants influence primary production and nutrient cycling.\u003c/p\u003e","manuscriptTitle":"Road salt alters the ecological effects of atrazine–cypermethrin mixtures in freshwater microalgae","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-27 16:44:51","doi":"10.21203/rs.3.rs-9306322/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e63dae13-8758-4c1c-85a1-e5773149b67f","owner":[],"postedDate":"April 27th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-17T19:43:50+00:00","index":38,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-09T02:31:41+00:00","index":37,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-27T16:44:51+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-27 16:44:51","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9306322","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9306322","identity":"rs-9306322","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}