Corrosion behavior of Limnoperna fortunei on carbon steel in freshwater environments

Corrosion behavior of Limnoperna fortunei on carbon steel in freshwater environments | 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 Article Corrosion behavior of Limnoperna fortunei on carbon steel in freshwater environments Yuhan Liu, Xiaoyan He, Ying Yang, Xianfu Yuan, Ziquan Zhou, Xiuqin Bai, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5751902/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 14 Jun, 2025 Read the published version in npj Materials Degradation → Version 1 posted 13 You are reading this latest preprint version Abstract Limnoperna fortunei (L. fortune) , a representative macrofouling organism in freshwater environments, causes significant degradation to the surfaces of hydraulic engineering materials through prolonged adhesion. The corrosion behavior of L. fortunei on Q345 carbon steel in river water environments was investigated employing topography detection, rust layer identification, corrosion rate analysis, electrochemical measurements, and molecular dynamics (MD) simulation. The results demonstrated that the attachment of mussels decreased the overall corrosion rate of the steel surface, but significantly aggravated pitting corrosion, a localized and highly destructive form of material degradation. The corrosion behavior of Q345 steel in a freshwater environment influenced by L. fortunei was primarily driven by the formation of a restricted microenvironment beneath the mussel shells, which promoted localized anion enrichment, bacterial colonization, and the accumulation of aggressive secretions. These factors collectively intensified electrochemical heterogeneity, accelerating pitting initiation and propagation. These findings emphasize the critical need for mitigation strategies to address localized corrosion caused by biofouling in hydraulic engineering applications. Physical sciences/Materials science Earth and environmental sciences/Environmental sciences Macrobiologically influenced corrosion Fouled steel surface Limnoperna fortunei Freshwater environments Pitting corrosion Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 1. Introduction Biofouling refers to the undesired accumulation of organisms or their secretions on surfaces, posing significant operational challenges across diverse industrial sectors. In aquatic environments, based on the dimensional scale, fouling organisms are categorized into microfouling species and macrofouling species. 1 Thereinto, in marine environments, typical macrofouling organisms include mussels, barnacles, and bryozoans. These species adhere to submerged surfaces such as ships, piers, and offshore platforms, causing significant damage and degradation to marine infrastructure. 2 Similarly, freshwater systems also face challenges from fouling organisms, with Limnoperna fortunei (commonly known as the golden mussel) being a notable example. As an invasive benthic species with exceptional environmental adaptability, it has successfully colonized freshwater ecosystems worldwide. 3 Upon invading hydraulic structures, L. fortunei forms extensive, high-density adhesions on surfaces, leading to metal corrosion and increased surface roughness. Furthermore, the attachment, reproduction, and eventual decay of these mussels foster bacterial growth and proliferation, exacerbating corrosion and posing severe threats to the integrity of water infrastructure. 4 A fundamental basis for devising effective anti-corrosion strategies can only be established through a comprehensive investigation into the mechanisms by which various fouling organisms affect surface corrosion behavior. Currently, research on biofouling-induced corrosion primarily focuses on marine biofouling. Blackwood et al. investigated the long-term behavior of stainless steel exposed to tropical marine seawater over 30 months. Their findings revealed that macrofouling in seawater induced localized corrosion on the steel surface. Furthermore, the susceptibility of stainless steel to corrosion varied among shellfish species. 5 To further detect the corrosion behavior and mechanisms of fouled steel surfaces induced by large biofouling organisms, Wang et al. 6 selected oysters and ascidians as representative specimens and conducted field immersion experiments as well as laboratory characterization techniques. The results revealed that attached oysters and ascidians induce complex marine corrosion on fouled steel surfaces. Specifically, the oyster/steel interface exhibited severe localized corrosion, while the ascidian/steel interface experienced uniform corrosion. These distinct corrosion patterns were attributed to differences in interfacial electrochemical processes, oxygen diffusion, ion transport pathways, and secretion dynamics. The underlying mechanisms involve the influences of O₂, Cl⁻, anaerobic bacteria, confined spaces, and biological secretions. Afterwards, Cai et al. 7 examined the influence of barnacles on the corrosion behavior of high-strength low-alloy steel. The findings demonstrated that barnacle adhesion mitigated the steel’s overall corrosion rate in immersion conditions by restricting the diffusion of corrosive ions. However, barnacle attachment significantly intensified localized corrosion. Cai et al. 8 explored cathodic protection efficiency and hydrogen permeation behavior of high-strength steel with barnacle adhesion in the tidal zone through a two-year study. The shielding effect of barnacles resulted in uneven calcareous deposits, a smoother morphology, and enhanced protection effect for the steel. However, barnacle adhesion also facilitated hydrogen permeation, as evidenced by elevated hydrogen permeation currents at the edges of the adhesion zones, driven by an increased hydrogen evolution rate. However, reports on the corrosion behavior of fouling organisms in freshwater environments are scarce. Wakai et al. 9 conducted a 22-month immersion study on nine types of steel in a freshwater reservoir with a history of microbiologically influenced corrosion (MIC). The experiments exhibited that accelerated corrosion was observed in carbon steels, chromium-containing steels, and cast iron. Microbial community analysis revealed that Fe(II)-oxidizing bacteria predominated during the early stages of general corrosion, while Fe(III)-reducing bacteria became more prevalent as corrosion progressed. In the final stages, sulfate-reducing bacteria were enriched within the corrosion products. Wakai et al. 10 examined the impact of microorganisms on corrosion on varied types of steels in freshwater environments. Microbial community analysis revealed significant differences between corroded and non-corroded stainless steel. The microbial diversity within corrosion products on the steel surface was lower, with an enrichment of Beggiatoaceae bacteria, iron-oxidizing bacteria, and Candidatus Tenderia sp. Moreover, localized corrosion processes displayed sulfur enrichment. The impact of macrofouling organisms on the corrosion dynamics of metals is undeniable, particularly the severe localized corrosion induced at the interface. Evidently, the aforementioned studies rarely address the mechanisms by which freshwater macrofouling organisms induce corrosion on metallic substrates, especially on the carbon steel surface. In this paper, the corrosion behavior and mechanism of Q345 carbon steel (commonly used in the metal structures of hydraulic engineering) influenced by L. fortunei in river environment was investigated via morphology observation, corrosion products characterization, corrosion rate analysis, electrochemical measurements and molecular dynamics simulation. The impact of adherent L. fortunei on fouled steel interfaces was examined, offering critical scientific and technological insights into macrofouling adhesion mechanisms to effectively address fouling challenges in freshwater environments. 2. Experimental 2.1 Preparation of specimens Q345 steel (Φ 5×0.5 cm) was exploited in this work and its chemical composition (in wt%) is C 0.20, Si 0.50, Mn 1.70, P 0.035, S 0.035, Cr 0.30, Ni 0.50, Mo 0.10, Cu 0.30, Ti 0.20, N 0.012, Nb 0.07, V 0.15 and Fe balance. Adult mussels and raw river water was obtained in Yangtze River, Wuhan, China (N 30°38′34.9″, E 114°22′28.1″). The surface of Q345 steel specimen was ground with 200, 800, 1500 and 3000 # silicon carbide (SiC) papers, polished with diamond polishing fluid, cleaned and dehydrated with ethanol, dried in vacuum drying oven at room temperature. Two types of experiments, immersion experiment and electrochemical experiment, were conducted using separated specimens. For the electrochemical experiments, the specimens were tinned with copper wire and non-working surfaces were sealed with epoxy resin. Highly active mussel individuals with body length of 1 ~ 1.5 cm were selected for experiments, whose shells were cleaned and byssus was cut. In average, 10 ~ 12 mussels were placed on each specimen. The raw river water was filtered and preliminarily sterilized through 0.45 µm PES filter membrane for experiments. 2.2 Immersion experiment and characterization The Q345 steels specimens covered with L. fortunei was called as QL; while the blankspecimens were denoted as control samples, QC. Those specimens were immersed in separate tanks filling with river water at 20 o C for 3, 7, 15 and 30 day, respectively (Fig. 1 A). The volume of river water in each tank was 1 L, and 50% of the water was refreshed every two days. Each tank contained only one disc specimen, and the water volume was determined based on the density of the mussels. 11 After immersion duration and removal of mussels, rust layers were collected and mixed with glycerol, dried by freeze-vacuum oven and stored in the vacuum container, Then, specimens were ultrasonically reacted in Clarke’s solution (1000 mL 37% HCl, 20 g Sb 2 O 3 , 50 g SnCl 2 ) for 90 s to remove the remaining corrosion products, cleaned with deionized water, dehydrated with ethanol, and dried in a vacuum drying oven to avoid surface reoxidation. The specific procedure was following previous studies protocols. 12 2.2.1 Surface morphology observation and corrosion product characterization After the removal of rust layers, surface morphologies were observed by scanning electron microscopy (SEM, TESCAN VEGA3, CZ) and the 20 largest pitting depths of each group were recorded by confocal laser scanning microscopy (CLSM, VK-X 1000 series, Keyence). Chemical components of rust layers were characterized through X-ray diffraction (D8 Advance) and Raman spectroscopy (RENISHAW InVia, UK). The laser wavelength of 633 nm, the power of 5%, the acquisition time of 30 s, and the grating engraved line density of 600 were adopted in Raman detections. Morphologies and elements of corrosion products on the surface of specimens were analyzed via SEM and energy‐dispersive spectrometer (EDS, X‐stream2 SDD, OXFORD Instrument Ltd.). 2.2.2 Weight-loss measurement and corrosion rate analysis Before immersion experiments and after the removal of rust layer, each specimen weights were measured by a high-precision analytical balance (METTLER TOLEDO‐MS1040TS/02, accurated to 0.1 mg) to calculate weightlessness rate. Then, the general corrosion rate was attained via the equation: $$\:{V}_{corr}=\frac{8.76\times\:{10}^{4}△m}{At\rho\:}$$ V corr — corrosion rate (mm·year − 1 ), △m — Weight loss (g), A— Sample surface area (cm 2 ), t — Culture time (h), ρ— Density (g·cm − 3 ) All data were independently repeated at least three times to ensure reliability and presented as mean ± standard deviation (SD). 2.2.3 Specimen surface film composition and bacteria species detection To identify the membrane composition and microbial species present on metal substrates after L. fortunei adhesion, eliminating the interference of corrosion products during detection, polished 304 stainless steel plates (Φ 5×0.5 cm) with mirror finishes were completely covered with mussels and submerged in sterilized river water for 30 days. Following this period, the mussels were removed, and the plates were dehydrated with alcohol and dried at room temperature. The film on the steel surface was characterized using Raman spectroscopy (RENISHAW InVia, UK). The laser wavelength of 532nm, the power of 100%, the acquisition time of 5 s, and the grating engraved line density of 600 were adopted in Raman detections. Subsequently, the film was scraped off for microbial analysis using 16S rDNA amplicon sequencing, with data processed by BMKCloud ( www.biocloud.net ). 2.3 Electrochemical measurements As shown in Fig. 1 B, specimens were immersed in river water for 30 days and an electrochemical workstation (CS2350M, Wuhan Corrtest Instrument Corp., Ltd.) was exploited for tests involving the open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves. A three-electrode cell was selected in which samples were employed as the working electrode (WE), a saturated calomel electrode (SCE) as the reference electrode (RE), a platinum plate (50× 50× 0.1 mm) as the counter electrode (CE) and 0.1 M NaCl as the electrolyte. Prior to measuring, the OCP was tested for 600 s to guarantee the system stability (with voltage floating within 5 mV). Afterwards, the EIS test was conducted in a frequency range from 10 5 to 10 − 2 Hz with an amplitude of 10 mV 13 and data was fitted via ZSimpWin software. Besides, Potentiodynamic polarization curves were obtained at a scan rate of 0.167 mV·s − 1 with potential range set from − 250 mV to + 250 mV vs. OCP 6 and the Tafel curves were analyzed using CS Analysis software. 2.4 Molecular dynamics (MD) simulation Molecular dynamics simulation was utilized to further examine the mechanism of L. fortunei ’s influence on carbon steel surface corrosion. In order to simplify the calculation, the peptide chain in mussel foot protein (Lffp) was selected for simulation. Forcite program in Materials Studio 2020 was exploited to run MD simulations through COMPASSⅢ force field. The iron crystal was designed and cleaved along the (110) plane, 14 and the Fe (110) surface increased to a supercell (15× 15× 4) 15 with lattice parameters of a = 37.24 Å, b = 37.24 Å, c = 8.11 Å, α = 90 o , β = 90 o , γ = 70.53 o . Additionally, to model the river water environment, the construction of solution system was based on main hydrochemical compositions of Yangtze River Basin as listed in Table 1 and the detection data originated from Wang et al. 16 Aiming at triggering significance of simulation results, the ionic concentration in models was enlarged 1000 times and the solution included 2000 H 2 O, 34 Ca 2+ , 12 Mg 2+ , 12 Na + , 2 K + , 72 HCO 3 − , 10 SO 4 2− , 8 NO 3 − , 2 Cl − and 4 OH − . The solution box was placed over the Fe (110) layer set with a 200 Å vacuum slab. The vibration of the atoms contained in the iron base can be ignored at the simulated temperature of 298K, so intending to simplifying the process, the spatial positions of these atoms were fixed. Then the geometry optimization was carried out to minimize the energy of the system and the fully-optimized system was the control group. Afterwards, Molecular Dynamics simulation was conducted in the canonical (NVT) with a time step of 0.1 femtosecond (fs) using COMPASSⅢ force field. The van der Waals energy and static energy of the system were calculated via Ewald method. The Nose-Hoover thermostat with an effective relaxation time of 0.01 picoseconds (ps) was used to stabilize the system temperature at 298 K for 20 ps and the last 5 ps of the results were adopted for characteristic analysis. 17 According to the sequence of L. fortunei loot protein (Lys-Hyp-Thr-Gln-Dopa-Ser-Asp-Glu-Tyr-Lys), amino acid residues were connected to obtain the whole atom model of Lffp peptide molecule. 18 After sufficient relaxation, two layers of peptides were placed in the above-mentioned control group system followed with the geometry optimization and dynamic simulation (Ditto for the parameters). Table 1 Average values of main water chemical characteristics in Yangtze River Basin. 16 Items Parameter (mg·L − 1 ) Yangtze River Basin pH 7.97 Ca 2+ 38.39 Mg 2+ 7.75 Na + 7.28 K + 4.27 HCO 3 − 120.75 SO 4 2− 27.99 NO 3 − 7.43 Cl − 4.80 3. Results and discussion 3.1 Effects of L. fortunei adhesion on corrosion rate and type Figure 2 A and B illustrate the weight loss rate and corrosion rate of carbon steel with or without mussel covering under varied immersion days, respectively. In general, the weight loss rate and corrosion rate of QC samples were higher than QL samples in the same immersion duration, but as time went on, the corrosion rate of QC samples gradually decreased, while the corrosion rate of QL samples did not change as obviously as QC. Besides, owing to L. fortunei attachment in the beginning of the experiments, surfaces of QL specimens were protected by shielding of mussels and the corrosion rate of the substrate was much lower than that of QC. However, the presence of mussels also led to uneven spread and insufficient production of rust layers on QL, which cannot fairly reduce the corrosion rate compared with QC samples. For localized corrosion, CLSM measured depths of the 20 greatest pits on steel surfaces. As shown in Fig. 2 C, during the short immersion time (3 days and 7 days), the average depths of corrosion pits on QL specimens were smaller than QC, but when the number of days reached 15 days, the average pit depths of QL group exceeded QC, and the difference was more obvious at 30 days. The largest pit depths of varying groups and days are demonstrated in Fig. 2 D and E, which showed the same results as average depths. To sum up, the occurrence of L. fortunei reduced the overall corrosion rate but exacerbates the local corrosion. After the 30-day long experiment and removal of corrosion products, corrosion types of varied samples can be identified via SEM as illustrated in Fig. 3 . The surface of QC was rough with uneven grooves uniformly distributed, and the main corrosion behavior was uniform corrosion. On the contrary, the surface roughness of QL samples was much lower than that of QC, but there were corrosion pits unevenly spread. According to the topography on the surface, local corrosion was more obvious in QL and the main corrosion behavior was pitting corrosion. In freshwater or seawater environments, carbon steel tended to undergo uniform corrosion controlled by oxygen diffusion, 19 , 20 while the attachment of macrofouling can lead to localized corrosion on the metal surface. 6 L. fortunei moved their feet to explore habitable areas, and then secreted byssus for colonization. The byssus attached to the surface of the substrate material via point contact tightly, while the mussel shell was surface contact without adhesion. Unlike other hard-fouling organisms such as oysters and barnacles that adhere by secreting adhesives, the weak adhesion effect caused by mussels reduced its shielding influence, 21 and meanwhile it was not capable to form crevice corrosion at the steel surface as oysters and barnacles are. 3.2 Effects of L. fortunei adhesion on the interfacial corrosion products The interfacial rust morphology of corrosion specimens has been observed by optical imaging. It was revealed as shown in Fig. 4 A that the corrosion products on the QC surface were homogeneously distributed and a relatively thick layer was formed, displaying an overall dark brown hue. With the extension of processing time, the corrosion products on the QC surface gradually accumulated and uniformly distributed, isolating the contact between the base and air as well as water, which played a significant anti-corrosion effect. In contrast, those on the QL surface were irregularly dispersed and a thinner layer was formed, characterized mainly by light brown and black tones. XRD technology was adopted to detect the composition of the rust layer after 30 days of the experiment. XRD profiles revealed that the main components of the rust layer of the two groups were goethite α-FeOOH, lepidocrocite γ-FeOOH, magnetite Fe 3 O 4 and Calcite CaCO 3 , while in addition to the above products, the samples with mussels covered also contained mackinawite FeS (Fig. 4 B). The sealed environment can urge the growth of anaerobic bacteria causing the generation of FeS. 22 Intending to identify the components of corrosion products on QC and QL samples more accurately, different groups of rust layers were stratified for Raman characterization, as shown in Fig. 5 . Thereinto, the green curves in Fig. 5 display the main composition of the layer without and with mussels. The peaks at 241–250, 298–301, 385–395, 478–483, 549–552, 680–687 and 1000 cm − 1 were assigned to α-FeOOH. 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 Additionally, the bule curves in Fig. 5 demonstrate the main components of inner layer without and with mussels. The peaks at 248–252, 378–380, 528–530 and 1300 cm − 1 resulted from γ-FeOOH. 23 , 24 , 25 , 26 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 The peaks at 298–302, 540–550 and 663–670 cm − 1 were assigned to Fe 3 O 4 24, 25, 26, 28, 29, 30, 31, 33, 34, 35, 36, 38 and the peaks at 218, 253 and 282 cm − 1 were assigned to FeS. 39 , 40 , 41 The morphology of the rust layer directly reflected the degree of anti-corrosion properties on the metal surface. 42 , 43 Fig. 6 A indicates that the corrosion products on the QC surface were granular, with a porous and loose structure. Nevertheless, Fig. 6 B- 2 and B- 3 demonstrate that the corrosion products on the QL surface exhibited a layered and flake-like structure, which was more compact and stable. On the top of that, bacteria were observed on the residual byssus of L. fortunei (Fig. 6 B- 1 ) and particularly on surfaces with deceased individuals, bacteria proliferated extensively (Fig. S1 ). In areas fully covered by mussels, compared to QC, elements such as P, N and S were detected. The detection of P may be attributed to organic substances secreted by the mussels (such as proteins, phospholipids, etc.) or components of the mussel shell. The specific anaerobic environment at the mussel/carbon steel interface has stimulated the activity of sulfate-reducing bacteria (SRBs), and the small amount of S detected likely originated from this. The proportion of element C on the QL surface was significantly higher than on the QC surface, indicating that a large amount of organic substances have formed on the carbon steel surface where mussels were attached. 3.3 Biofilm components and bacteria species identification of the mussel-covered surface Figure 7 presents the Raman spectrum of biofilm on the stainless steel specimens and Table 2 displays main Raman peaks corresponding to the biological components. Raman spectroscopy analysis reveals that the biofilm formed on the metal substrate after L. fortunei adhesion, predominantly comprised proteins, phospholipids, polysaccharides, carotenoids, and ammonia (NH₃). These components originated partially from mussel secretions and metabolic byproducts, and partially from the physiological activities of bacteria colonizing on the steel surface. Table 2 Raman peak assignments for biofilm on the surface. 44 , 45 , 46 , 47 , 48 , 49 Substance Raman band (cm − 1 ) Vibrational mode Proteins 751 (δ) ring 855 δ (CCH) 1007 Ring stretching modes of benzene derivatives Lipids 965 δ (= CH) wagging 1147 ν (C-C), ν (C-O) 1290 CH 3 CH 2 twisting, CH 2 mode Nucleic acids 1147 (O-P-O) backbone stretching Carbohydrates 1394 ν s (COO − ) Carotenoids 1510 C = C str carotenoids NH 4 + 3225 ν sa (NH 4+ ) 3402 ν sa (NH 4+ ) Utilizing 16S rDNA amplicon sequencing, the species composition and relative abundance within the biofilm were identified. As shown in Fig. 8 , the top 15 most abundant species involved Sphaerotilus , Duganella , Cetobacterium , Holophagaceae , Zoogloea , Flavobacterium , Curvibacter , Rivicola , Malikia , Dechloromonas , Holophaga , Novosphingobium , Geothrix and members of the Desulfovibrio family. Desulfovibrio , a genus of sulfate-reducing bacteria (SRB), possesses the capacity to utilize sulfate as an electron acceptor to sustain growth, resulting in the generation of significant quantities of hydrogen sulfide (H₂S). Moreover, SRB are characterized by the presence of diverse electron transfer proteins, along with a wide array of reductases and dehydrogenases. These biomolecules play a pivotal role in facilitating the dissimilatory reduction of sulfate, underpinning the metabolic processes of these microorganisms. 50 , 51 The identification of these microorganisms accounted for the previously observed FeS corrosion products on the QL sample surface. 3.4 Effects of L. fortunei adhesion on interface electrochemistry To detect the corrosion kinetics of varied groups, the potentiodynamic polarization curves of the steel in river water without mussel covered (QNC), with mussel covered (QMC) and with mussel removed (QMR) after the 30-day immersion treatment are illustrated in Fig. 9 . Meanwhile, Table 3 exhibits the electrochemical corrosion parameters of the potentiodynamic polarization curves. Table 3 The electrochemical corrosion parameters of potentiodynamic polarization curves. Specimen E corr (mV vs. SCE) I corr (µA/cm 2 ) Corrosion rate (mm/a) Not covered -779.93 7.13 0.0836 Mussel covered -779.04 0.92 0.0107 Mussel removed -769.05 6.13 0.0719 The polarization curves indicates that all anode curves remained smooth, both in the presence and absence of L.fortunei . No passivation zone was observed, suggesting that the anode primarily underwent active dissolution, while the cathodic process was associated with oxygen reduction. The Tafel slope extrapolation method was usually utilized to determine the corrosion current density (I corr ). 52 The I corr values for steel with and without macrofouling were derived by fitting the Tafel regions of both the anodic and cathodic branches. Typically, I corr serves as an indicator of the metal’s susceptibility to corrosion and the rate of corrosion, with a higher I corr signifying an accelerated corrosion rate. 53 For the steel specimen fully covered by mussels, I corr is 0.92 µA/cm², which was lower than that of the steel without macrofouling (I corr = 7.13 µA/cm²), suggesting that the attachment of L. fortunei provided a protective effect, reducing the corrosion rate when tightly adhered. Moreover, after removal of the mussels (steel with mussel coverage removed), I corr reached to 6.13 µA/cm², higher than the mussel-covered specimen but slightly lower than the control group. The results displayed that in spite of removal of mussels, the biofilm formed during their colonization still possessed the abilities to protect the surface of the carbon steel, but the anti-corrosion effect was significantly undermined. EIS tests can assess the extent of the steel degradation induced by the accumulation of adhered macrofouling organisms. 54 Fig. 10 presents the Nyquist and Bode plots for three sets of carbon steel specimens in 0.1 M NaCl solution. From the Nyquist plot, it is evident that specimens without mussel adhesion (QNC and QMR) exhibited an impedance spectrum characterized by a single capacitive arc, indicating that the corrosion of Q345 steel in 0.1 M NaCl was primarily activation-controlled. In contrast, carbon steels with L. fortunei adhesion displayed a combination of a high-frequency capacitive arc and a low-frequency Warburg impedance, with the presence of the Warburg impedance suggesting the occurrence of diffusion-controlled corrosion reactions. Notably, the radius of the capacitive arc was largest for the mussel-adhered specimens, while the control groups showed a smaller capacitive arc radius. This reveals that the attachment of mussels enhanced the specimen's resistance to corrosion in the testing solution, thereby improving the material's overall corrosion resistance. The protective effect of the oxide film on the specimen surface against the corrosive solution can be approximated by the impedance at 0.01 Hz (|Z|₀.₀₁ Hz). From the Bode plots, it is evident that the impedance values for the three specimens were as follows: 8590 Ω·cm² (QMC) > 2107.8 Ω·cm² (QMR) > 1060 Ω·cm² (QNC). The steel specimens entirely covered by macrofouling exhibits the largest capacitive arc radius at Z f = 0.01 Hz and demonstrates relatively high impedance values. The sequence confirmed the previous observation that the adhesion of L. fortunei protected the Q345 surface against corrosion. The underlying mechanism can be attributed to two potential factors. Similar to oysters, mussel shells primarily consist of calcium carbonate (CaCO₃), which has poor electrical conductivity. Additionally, the calcareous shell possesses a low ionic diffusivity, effectively hindering the transport of ions and oxygen. 55 Together, these properties rendered the shell an effective insulator, reducing the electrochemically active area and increasing the capacitive arc radius. Upon the removal of mussels, the diameter of the Nyquist plot decreased significantly. The EIS data for the QNC and QMR specimens were fitted using the equivalent circuit model shown in Fig. 10 A- 1 , whereas the QMC specimen employed the equivalent circuit depicted in Fig. 10 A- 2 . 56 Table 4 presents the fitted parameters of the EIS measurements, where R s , R f , R ct , and W correspond to solution resistance, corrosion product resistance, charge transfer resistance, and diffusion impedance, respectively. The constant phase elements (CPEs) include CPE f , which represents the capacitance (C f ) of the corrosion products and the dispersion factor (n f ), and CPE dl , which denotes the double-layer capacitance (C dl ) and its dispersion factor (n d ). The impedance of a CPE is calculated using the following formula: $$\:{Z}_{CPE}={C}^{-1}{\left(j\omega\:\right)}^{-n}$$ Z CPE — Impedance of the CPE (Ω), C — Capacitance value (Ω −1 ·cm − 2 ·s n ), ω— Angular frequency (rad·s − 1 ), n — Diffusion index The resistance R f is closely related to the structure and porosity of corrosion products. The R f value of the mussel-adhesion group reached 830.7 Ω·cm 2 , fairly exceeding that of the control group (264.8 Ω·cm 2 ). This result corresponded to Fig. 6 , which demonstrates that the corrosion products in the QL group exhibited a denser morphology compared to those in the QC group. During the electrochemical corrosion process, when charges (electrons and electrolyte ions) traverse the double electric layer at the material's surface, charge transfer resistance (R ct ) may arise. This resistance reflects the electrochemical reaction occurring within the solution. The sum of R f + R ct typically provides insights into the compactness of the rust film, which is strongly correlated with the corrosion rate: higher values indicate lower corrosion rates. 57 Conversely, parameters associated with the constant phase element (CPE), such as CPE dl−n and CPE f−n , are less significantly influenced. Depending on the value of n, CPE may represent a resistor (n = 0), a Warburg impedance (n = 1/2), or a capacitor (n = 1). 58 The n value is determined by the roughness of the electrode surface and the non-uniform distribution of corrosion current density. For all data sets, R ct consistently exceeds R f , indicating that charge transfer resistance plays a dominant role in corrosion protection compared to film resistance. A larger R ct suggests that the corrosive medium cannot penetrate further into the inner layers; in the absence of direct contact with the corrosive medium, dissolution cannot be activated, thereby enhancing corrosion resistance. Conversely, a smaller R ct value in the electrochemical parameters indicates reduced resistance to the electrochemical process and a higher susceptibility of the material to corrosion. As shown in Table 4 , the R ct values for the three samples, in descending order, are: 12040 Ω·cm² (QMC) > 4053 Ω·cm² (QMR) > 2265 Ω·cm² (QNC). Among these, QMC exhibits the best corrosion resistance in 0.1 M NaCl solution. Although, in real-world environments, the presence of crevices between mussels and substrates may trigger autocatalytic mechanisms that lead to the accumulation of anions such as SO 4 2− , Cl − and NO 3 − , thereby enhancing the solution's corrosivity and reducing R ct , the concentration of anions in freshwater systems is significantly lower than in marine environments. Consequently, under short-term experimental conditions, the increased corrosion rate caused by mussel adhesion is not pronounced. Table 4 Derived values of R s , CPE f , R f , CPE dl and R ct of the Nyquist diagrams. Specimen R s (Ω·cm 2 ) CPE f R f (Ω·cm 2 ) CPE dl R ct (Ω·cm 2 ) C f (Ω −1 ·cm − 2 ·s n ) n f C dl (Ω −1 ·cm − 2 ·s n ) n dl Not covered 136.4 1.35×10 − 2 0.754 264.8 6.80×10 − 2 0.854 2265 Mussel covered 134.2 3.92×10 − 4 0.713 830.7 3.28×10 − 4 0.841 12040 Mussel removed 72.9 1.15×10 − 3 0.785 339.4 3.20×10 − 3 0.906 4053 3.5 Corrosion mechanism of the steel with and without L. fortunei To further investigate the corrosion mechanisms on substrate surfaces, MD simulations were employed to analyze the adsorption of liquid layers and the distribution of ions within the liquid for two different systems (Fig. 11 ). The absence of significant fluctuations during the final 5 ps of the simulation indicates that the system reached equilibrium (Fig. S2). In both systems, water molecules form a compact hydration layer on the Fe (110) surface, as shown in Fig. 11 A. According to Fig. 11 B, the strongest peak in the water density profile appears at a distance of 10.30 Å from the Fe (110) surface. In the system without Lffp, the maximum water density is 31.33 g/mL, whereas in the system with Lffp, the water density is slightly lower at 30.17 g/mL. Figure 11 C illustrates the distribution of ions on the Fe (110) surface for the two systems. The ion density profiles reveal their strongest peaks at 10.04 Å from the surface, corresponding to the hydration layer. In the system without Lffp, the maximum ion density is 26.32 g/mL, whereas in the presence of Lffp, the ion density fairly increases to 36.22 g/mL. Considering the water density in the hydration layer for both systems, it is evident that the presence of Lffp facilitates ion accumulation on the Fe (110) surface. Under real-world conditions, however, the distribution of L. fortunei is uneven, suggesting that mussel adhesion accelerates localized corrosion on the substrate surface. The mechanisms by which L. fortunei coverage affects the corrosion behavior of steel surfaces can be discussed from several perspectives. Firstly, the form and rate of steel corrosion are directly linked to the concentration of dissolved oxygen. Oxygen levels have been identified as one of the critical parameters influencing the temporal variation of corrosion-induced weight loss. 59 For steel covered by mussels in natural environments, the weak adhesion of mussels transforms the corrosion system from an open riverwater environment to a closed or semi-closed system. Due to the oxygen concentration gradient between the area beneath the mussel shell and the external environment, the oxygen-rich external region serves as the cathode in an oxygen concentration cell, reducing the overall corrosion rate. In contrast, the oxygen-depleted region beneath the shell acts as the anode, promoting localized anodic corrosion and exacerbating corrosion severity. Secondly, the accumulation of ions such as SO 4 2− , NO 3 − , and Cl − plays a crucial role in the process. The synergistic action of SO 4 2− and Cl − significantly accelerates corrosion. 60 In freshwater environments, the ion concentration is much lower than in marine environments, making ion accumulation less apparent. Nevertheless, simplified molecular dynamics simulations with increased ion concentrations have demonstrated that L. fortunei -secreted foot proteins lead to the enrichment of ions on the substrate surface in simulated river water systems. Furthermore, the presence of oxygen in pitting corrosion cavities facilitates continuous autocatalytic reactions within the pits. This causes the accumulation of metal cations inside the pits and drives the inward migration of Cl − and SO 4 2− from outside the pits to maintain charge balance, thereby worsening the growth of corrosion pits. Thirdly, microbially influenced corrosion (MIC) contributes to the development of macrofouling and the corrosion process at the carbon steel interface. On surfaces covered by mussels, oxygen is partially blocked, resulting in low oxygen concentrations and limited replenishment, creating ideal conditions for the growth of anaerobic bacteria. 9 The proliferation of anaerobic bacteria such as sulfate-reducing bacteria (SRB) intensifies localized corrosion, leading to the formation of FeS. Previous SEM and microbial analyses confirmed the growth of anaerobic bacteria on mussel-attached substrates, while XRD and Raman spectroscopy validated the presence of FeS. Lastly, the adhesion process of mussels involves redox reactions that accelerate the consumption of dissolved oxygen around the foot. Additionally, cysteine thiols in the proteins secreted by mussels strongly deplete oxygen levels. 61 These processes collectively accelerate the corrosion of the steel substrate and promote the proliferation of anaerobic bacteria. On the other hand, the secretions can infiltrate the porous rust layer structure, altering its state to become more compact and enhancing its adhesion. Changes in the physicochemical properties of the rust layer also influence oxygen diffusion and microbial growth. According to the aforementioned discussion, the corrosion process on the carbon steel surface can be illustrated as shown in Fig. 12 . Initially, the primary corrosion product of carbon steel in river water is Fe(OH) 2 . Owing to its inherent instability, Fe(OH) 2 readily undergoes dehydration and decomposition to form protective layers of FeOOH和Fe 3 O 4 . 62 Over prolonged immersion, FeOOH may further react with Fe 2+ to produce Fe 3 O 4 , 63 as described by the following reaction equations: Fe→Fe 2+ +2e − O 2 + 2H 2 O + 4e − →4OH − Fe 2+ + 2OH − →Fe(OH) 2 2Fe(OH)+O→2FeOOH + 2HO; 3Fe(OH)+O→FeO + 3HO 2FeOOH + Fe→FeO + 2H Since the substrate with mussel attachment has the propagation of SRB and other microorganisms, the corrosion products will also contain FeS, and the equations are as follows: Fe→Fe 2+ +2e − H 2 O→OH − +H + H + +e − →[H] SO 4 2− +8[H]→S 2− +4H 2 O Fe 2+ +S 2− →FeS 4. Conclusion This study demonstrates that the prolonged adhesion of L. fortunei reduced the overall corrosion rate of carbon steel but exacerbatec localized corrosion. The corrosion products common to both sample groups include goethite (α-FeOOH), lepidocrocite (γ-FeOOH), and magnetite (Fe₃O₄). However, the presence of mussels fosters the growth of sulfate-reducing bacteria (SRB), resulting in FeS formation in the innermost corrosion layer. The corrosion mechanism of Q345 steel in a simulated river water environment influenced by L. fortunei can be attributed to factors such as the enclosed microenvironment created by mussel shells, bacterial proliferation, anion accumulation, and mussel secretions. Formostly, the mussel coverage altered the corrosion environment by creating oxygen concentration cells, where the oxygen-depleted region beneath the mussel shell acted as an anode, exacerbating localized corrosion, while the external oxygen-rich area served as a cathode, reducing overall corrosion rates. Furthermore, the accumulation of ions like Cl⁻ and SO₄²⁻, driven by mussel-secreted proteins, facilitated ion enrichment on the substrate surface, promoting pitting corrosion. In addition, the low-oxygen conditions beneath mussels supported the growth of anaerobic bacteria, such as sulfate-reducing bacteria (SRB), which intensified localized corrosion through the formation of FeS. The secreted proteins further altered the rust layer's compactness and adhesion, influencing corrosion dynamics and microbial activity. Over time, in real freshwater environments, the uneven attachment of mussels causes severe corrosion, such localized corrosion can compromise the structural integrity of materials, leading to premature failure and increased maintenance costs, highlighting the necessity of effective mitigation strategies. Declarations Data availability Data will be made available on request. CRediT authorship contribution statement All authors contributed to the study conception and design. The idea of the article was proposed by Yuhan Liu and Xiuqin Bai. The Investigation and data analysis were performed by Xiaoyan He and Xianfu Yuan. The first draft of the manuscript was written by Yuhan Liu. The work was critically revised by Ying Yang, Ziquan Zhou and Chengqing Yuan. The research activity was supervised by Ying Yang and Xiuqin Bai. All authors review the manuscript. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgements This work was financially supported by Innovation and Development Joint Fund Key Project of Hubei Provincial Natural Science Foundation (2022CFD029) and National Natural Science Foundation of China (52475212). References Vuong P, McKinley A, Kaur P. Understanding biofouling and contaminant accretion on submerged marine structures. npj Materials Degradation 7 , 50 (2023). Qiu Q , et al. Research progress on eco-friendly natural antifouling agents and their antifouling mechanisms. Chemical Engineering Journal 495 , 153638 (2024). 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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-5751902","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":398976649,"identity":"bd30081a-def4-496f-84d7-2b9d294c2713","order_by":0,"name":"Yuhan Liu","email":"","orcid":"","institution":"Hubei Longzhong Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Yuhan","middleName":"","lastName":"Liu","suffix":""},{"id":398976650,"identity":"8bda1d66-b1a1-4e7e-bf46-eb5ad9aa113c","order_by":1,"name":"Xiaoyan He","email":"","orcid":"","institution":"Hubei Longzhong Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Xiaoyan","middleName":"","lastName":"He","suffix":""},{"id":398976651,"identity":"a273bea3-be6d-466a-a464-f5e00680041c","order_by":2,"name":"Ying Yang","email":"","orcid":"","institution":"Keele University","correspondingAuthor":false,"prefix":"","firstName":"Ying","middleName":"","lastName":"Yang","suffix":""},{"id":398976652,"identity":"6adc5b82-382f-4e8f-8230-edeeca897652","order_by":3,"name":"Xianfu Yuan","email":"","orcid":"","institution":"Wuhan University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Xianfu","middleName":"","lastName":"Yuan","suffix":""},{"id":398976653,"identity":"f5108116-2310-40eb-91d2-d57ac9261f4e","order_by":4,"name":"Ziquan Zhou","email":"","orcid":"","institution":"Wuhan University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Ziquan","middleName":"","lastName":"Zhou","suffix":""},{"id":398976654,"identity":"a4647cce-b3f6-42c0-82e6-915605393be5","order_by":5,"name":"Xiuqin Bai","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAw0lEQVRIiWNgGAWjYFACHgaGhAqGBBibWC1ngFrYSNLC2EaKFoPjuQc/PJx3OM/gfgPjg7dtDPLmhLRI9rxLlkjcdrjY4BgDs+HcNgbDnQ0EtPBL5BgAtdxO3HCMgU2aF+hCgwMEtLBJ5Bj/SJwD1sL+mygtQFvMJBIbILYwE6UF6Jc0i4Rj/xNnHktslpxzTsJwAyEtwBA7fPNHTVpi3+HDBz+8KbORJ2gLAzTegYCxAUhIEFSPrGUUjIJRMApGAQ4AALnNQp2PQ2khAAAAAElFTkSuQmCC","orcid":"","institution":"Hubei Longzhong Laboratory","correspondingAuthor":true,"prefix":"","firstName":"Xiuqin","middleName":"","lastName":"Bai","suffix":""},{"id":398976655,"identity":"55e8eda4-9ee6-4f6e-8911-8b49963928bc","order_by":6,"name":"Chengqing Yuan","email":"","orcid":"","institution":"Hubei Longzhong Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Chengqing","middleName":"","lastName":"Yuan","suffix":""}],"badges":[],"createdAt":"2025-01-02 12:53:24","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5751902/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5751902/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41529-025-00618-2","type":"published","date":"2025-06-14T15:57:07+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":73241872,"identity":"1baa35dc-9faa-48f0-813a-987b6fb97d58","added_by":"auto","created_at":"2025-01-08 06:11:33","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":604343,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic diagram of the immersion experiment (A) and electrochemical measurement (B).\u003c/p\u003e","description":"","filename":"FIG.1.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5751902/v1/8b4e2caf1d940ba4edd8bf6f.jpg"},{"id":73241826,"identity":"481b7e11-6a5d-4fd0-b2db-9c00763242c9","added_by":"auto","created_at":"2025-01-08 06:11:31","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1214311,"visible":true,"origin":"","legend":"\u003cp\u003e(A) Weight-loss of Q345 steel immersion in river water with and without mussels covered after 3, 7, 15 and 30 days; (B) Corrosion rate of the steel in river water with and without mussels covered after 3, 7, 15 and 30 days; (C) The average pit depth of Q345 steel under different conditions and immersion days. The confocal images and maximum pit depth of the steel without mussels (D) and with mussels (E) after 3 days (-1), 7 days (-2), 15 days (-3) and 30 days (-4) of corrosion. The colored bars represent the surface topography parameters of the samples in μm, where red indicates protrusions and black indicates depressions.\u003c/p\u003e","description":"","filename":"FIG.2.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5751902/v1/124f72aa24d9092b20d60b85.jpg"},{"id":73242918,"identity":"ea6d815e-6b12-421a-bd50-e1cb0c848a53","added_by":"auto","created_at":"2025-01-08 06:27:31","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":2554899,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of corrosion morphology without (A) and with mussels (B) after 30 days immersion in the river water. (-1: 50×; -2: 200×; -3: 2000×)\u003c/p\u003e","description":"","filename":"FIG.3.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5751902/v1/46205a58a25d8d53e9fb6299.jpg"},{"id":73241846,"identity":"78084761-f340-4e9a-9d3d-d75640d5007d","added_by":"auto","created_at":"2025-01-08 06:11:32","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1034848,"visible":true,"origin":"","legend":"\u003cp\u003e(A) Macroscopic morphology of the rust layer on QC (upper) and QL (lower) specimens after immersion in river water for 30 days; (B) XRD spectrum of the corrosion products.\u003c/p\u003e","description":"","filename":"FIG.4.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5751902/v1/fed32fbbc3cf154ec0aa770e.jpg"},{"id":73241869,"identity":"5658e280-1f49-40d4-81c8-faed85958a5e","added_by":"auto","created_at":"2025-01-08 06:11:33","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":811035,"visible":true,"origin":"","legend":"\u003cp\u003eRaman spectra of varied layers of the rust on the surface without (A) and with mussels (B) after immersion on river water for 30 days. (-1: outer layer; -2, -3: inner layer)\u003c/p\u003e","description":"","filename":"FIG.5.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5751902/v1/e8944308e7f896510e02391c.jpg"},{"id":73241850,"identity":"a6c98783-3a77-48cf-a2e1-a6a75a2ec41e","added_by":"auto","created_at":"2025-01-08 06:11:32","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":1933431,"visible":true,"origin":"","legend":"\u003cp\u003eSEM views and EDS analysis of the interfacial rust layer after the specimens immersion in river water for xxx days. (A) The corrosion product on the steel surface without mussels covered; (B-C) The corrosion product on the steel surface with mussels covered. The orange arrows indicate the presence of bacteria.\u003c/p\u003e","description":"","filename":"FIG.6.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5751902/v1/9e67befff4a5a6f257c2ba95.jpg"},{"id":73241886,"identity":"7d41a0a3-b7ce-4831-905b-a3d9587f61fb","added_by":"auto","created_at":"2025-01-08 06:11:33","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":370151,"visible":true,"origin":"","legend":"\u003cp\u003eRaman spectra of the biofilm on the mussel adhered specimens.\u003c/p\u003e","description":"","filename":"FIG.7.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5751902/v1/90d8f5f1439bae371e364e50.jpg"},{"id":73242119,"identity":"ec01bb48-e526-4673-aecc-1d73b07bf953","added_by":"auto","created_at":"2025-01-08 06:19:33","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":593657,"visible":true,"origin":"","legend":"\u003cp\u003eThe image of the relative abundance of bacteria species.\u003c/p\u003e","description":"","filename":"FIG.8.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5751902/v1/251b390ae43677e2738e9514.jpg"},{"id":73241849,"identity":"98773db5-8b15-4d24-9d09-87a9f44e7657","added_by":"auto","created_at":"2025-01-08 06:11:32","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":284889,"visible":true,"origin":"","legend":"\u003cp\u003eThe potentiodynamic polarization curves of three types of specimens (without mussel covered, with mussel covered and with mussel removed) after immersion in river water for 30 days.\u003c/p\u003e","description":"","filename":"FIG.9.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5751902/v1/77beaefb59043d4bf99cbee2.jpg"},{"id":73241837,"identity":"bdcaf7b3-850d-4215-af3f-09d85e1ef86b","added_by":"auto","created_at":"2025-01-08 06:11:31","extension":"jpg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":1047302,"visible":true,"origin":"","legend":"\u003cp\u003e(A) The equivalent circuits of samples not covered by mussels or with removal of mussels (-1) and samples covered by mussels (-2); (B) Bode plots; (C) Nyquist plots.\u003c/p\u003e","description":"","filename":"FIG.10.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5751902/v1/aebedb061252cd3012ca99b9.jpg"},{"id":73241841,"identity":"b848617e-122e-4f48-986b-41aa421fdea7","added_by":"auto","created_at":"2025-01-08 06:11:31","extension":"jpg","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":2404665,"visible":true,"origin":"","legend":"\u003cp\u003e(A) System model diagrams at equilibrium configuration of the MD simulation about the interaction between simulated river water and Fe (110) without Lffp (-1) and with Lffp (-2); (B) Disperse of water molecules on Fe (110) surface; (C) Disperse of ions on Fe (110) surface. The atom coloring scheme is Fe: purple; O: red; H: light gray; Ca: grass green; Mg: dark green; Na: magenta; K: violet; S: yellow; N: bule; Cl: light green; C, gray.\u003c/p\u003e","description":"","filename":"FIG.11.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5751902/v1/e9a5ef0ef8d02ce70501a14d.jpg"},{"id":73241881,"identity":"1599fe5d-73c2-40af-8326-dc3ccf8b590c","added_by":"auto","created_at":"2025-01-08 06:11:33","extension":"jpg","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":698689,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic of the corrosion mechanism of \u003cem\u003eL. fortunei\u003c/em\u003e-covered carbon steel surface.\u003c/p\u003e","description":"","filename":"FIG.12.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5751902/v1/72886f65a06c995f7d65847b.jpg"},{"id":84727112,"identity":"006cc4bf-adfd-4a9c-9086-bbaeea31471a","added_by":"auto","created_at":"2025-06-16 16:09:13","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":14827187,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5751902/v1/49937e74-41f6-47b6-b21b-0b0831be4ed4.pdf"},{"id":73241835,"identity":"a0d27f68-93c3-4106-a56e-94b1e5068a02","added_by":"auto","created_at":"2025-01-08 06:11:31","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":2774346,"visible":true,"origin":"","legend":"","description":"","filename":"supplementaryinformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-5751902/v1/3b9142113216d63dbc1541bb.docx"},{"id":73242101,"identity":"bf474595-5a74-4654-b2b0-78e2199f6c4d","added_by":"auto","created_at":"2025-01-08 06:19:31","extension":"png","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":168211,"visible":true,"origin":"","legend":"\u003cp\u003eGraphical abstract\u003c/p\u003e","description":"","filename":"Graphicalabstract.png","url":"https://assets-eu.researchsquare.com/files/rs-5751902/v1/05fd187ea386249fbb5b3bfa.png"}],"financialInterests":"No competing interests reported.","formattedTitle":"Corrosion behavior of Limnoperna fortunei on carbon steel in freshwater environments","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eBiofouling refers to the undesired accumulation of organisms or their secretions on surfaces, posing significant operational challenges across diverse industrial sectors. In aquatic environments, based on the dimensional scale, fouling organisms are categorized into microfouling species and macrofouling species.\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e Thereinto, in marine environments, typical macrofouling organisms include mussels, barnacles, and bryozoans. These species adhere to submerged surfaces such as ships, piers, and offshore platforms, causing significant damage and degradation to marine infrastructure.\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e Similarly, freshwater systems also face challenges from fouling organisms, with \u003cem\u003eLimnoperna fortunei\u003c/em\u003e (commonly known as the golden mussel) being a notable example. As an invasive benthic species with exceptional environmental adaptability, it has successfully colonized freshwater ecosystems worldwide.\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e Upon invading hydraulic structures, \u003cem\u003eL. fortunei\u003c/em\u003e forms extensive, high-density adhesions on surfaces, leading to metal corrosion and increased surface roughness. Furthermore, the attachment, reproduction, and eventual decay of these mussels foster bacterial growth and proliferation, exacerbating corrosion and posing severe threats to the integrity of water infrastructure.\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e A fundamental basis for devising effective anti-corrosion strategies can only be established through a comprehensive investigation into the mechanisms by which various fouling organisms affect surface corrosion behavior.\u003c/p\u003e \u003cp\u003eCurrently, research on biofouling-induced corrosion primarily focuses on marine biofouling. Blackwood et al. investigated the long-term behavior of stainless steel exposed to tropical marine seawater over 30 months. Their findings revealed that macrofouling in seawater induced localized corrosion on the steel surface. Furthermore, the susceptibility of stainless steel to corrosion varied among shellfish species.\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e To further detect the corrosion behavior and mechanisms of fouled steel surfaces induced by large biofouling organisms, Wang et al.\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e selected oysters and ascidians as representative specimens and conducted field immersion experiments as well as laboratory characterization techniques. The results revealed that attached oysters and ascidians induce complex marine corrosion on fouled steel surfaces. Specifically, the oyster/steel interface exhibited severe localized corrosion, while the ascidian/steel interface experienced uniform corrosion. These distinct corrosion patterns were attributed to differences in interfacial electrochemical processes, oxygen diffusion, ion transport pathways, and secretion dynamics. The underlying mechanisms involve the influences of O₂, Cl⁻, anaerobic bacteria, confined spaces, and biological secretions. Afterwards, Cai et al.\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e examined the influence of barnacles on the corrosion behavior of high-strength low-alloy steel. The findings demonstrated that barnacle adhesion mitigated the steel\u0026rsquo;s overall corrosion rate in immersion conditions by restricting the diffusion of corrosive ions. However, barnacle attachment significantly intensified localized corrosion. Cai et al.\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e explored cathodic protection efficiency and hydrogen permeation behavior of high-strength steel with barnacle adhesion in the tidal zone through a two-year study. The shielding effect of barnacles resulted in uneven calcareous deposits, a smoother morphology, and enhanced protection effect for the steel. However, barnacle adhesion also facilitated hydrogen permeation, as evidenced by elevated hydrogen permeation currents at the edges of the adhesion zones, driven by an increased hydrogen evolution rate.\u003c/p\u003e \u003cp\u003eHowever, reports on the corrosion behavior of fouling organisms in freshwater environments are scarce. Wakai et al.\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e conducted a 22-month immersion study on nine types of steel in a freshwater reservoir with a history of microbiologically influenced corrosion (MIC). The experiments exhibited that accelerated corrosion was observed in carbon steels, chromium-containing steels, and cast iron. Microbial community analysis revealed that Fe(II)-oxidizing bacteria predominated during the early stages of general corrosion, while Fe(III)-reducing bacteria became more prevalent as corrosion progressed. In the final stages, sulfate-reducing bacteria were enriched within the corrosion products. Wakai et al.\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e examined the impact of microorganisms on corrosion on varied types of steels in freshwater environments. Microbial community analysis revealed significant differences between corroded and non-corroded stainless steel. The microbial diversity within corrosion products on the steel surface was lower, with an enrichment of \u003cem\u003eBeggiatoaceae\u003c/em\u003e bacteria, iron-oxidizing bacteria, and \u003cem\u003eCandidatus Tenderia\u003c/em\u003e sp. Moreover, localized corrosion processes displayed sulfur enrichment.\u003c/p\u003e \u003cp\u003eThe impact of macrofouling organisms on the corrosion dynamics of metals is undeniable, particularly the severe localized corrosion induced at the interface. Evidently, the aforementioned studies rarely address the mechanisms by which freshwater macrofouling organisms induce corrosion on metallic substrates, especially on the carbon steel surface. In this paper, the corrosion behavior and mechanism of Q345 carbon steel (commonly used in the metal structures of hydraulic engineering) influenced by \u003cem\u003eL. fortunei\u003c/em\u003e in river environment was investigated via morphology observation, corrosion products characterization, corrosion rate analysis, electrochemical measurements and molecular dynamics simulation. The impact of adherent \u003cem\u003eL. fortunei\u003c/em\u003e on fouled steel interfaces was examined, offering critical scientific and technological insights into macrofouling adhesion mechanisms to effectively address fouling challenges in freshwater environments.\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Preparation of specimens\u003c/h2\u003e \u003cp\u003eQ345 steel (Φ 5\u0026times;0.5 cm) was exploited in this work and its chemical composition (in wt%) is C 0.20, Si 0.50, Mn 1.70, P 0.035, S 0.035, Cr 0.30, Ni 0.50, Mo 0.10, Cu 0.30, Ti 0.20, N 0.012, Nb 0.07, V 0.15 and Fe balance. Adult mussels and raw river water was obtained in Yangtze River, Wuhan, China (N 30\u0026deg;38\u0026prime;34.9\u0026Prime;, E 114\u0026deg;22\u0026prime;28.1\u0026Prime;).\u003c/p\u003e \u003cp\u003eThe surface of Q345 steel specimen was ground with 200, 800, 1500 and 3000\u003csup\u003e#\u003c/sup\u003e silicon carbide (SiC) papers, polished with diamond polishing fluid, cleaned and dehydrated with ethanol, dried in vacuum drying oven at room temperature. Two types of experiments, immersion experiment and electrochemical experiment, were conducted using separated specimens. For the electrochemical experiments, the specimens were tinned with copper wire and non-working surfaces were sealed with epoxy resin.\u003c/p\u003e \u003cp\u003eHighly active mussel individuals with body length of 1\u0026thinsp;~\u0026thinsp;1.5 cm were selected for experiments, whose shells were cleaned and byssus was cut. In average, 10\u0026thinsp;~\u0026thinsp;12 mussels were placed on each specimen. The raw river water was filtered and preliminarily sterilized through 0.45 \u0026micro;m PES filter membrane for experiments.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Immersion experiment and characterization\u003c/h2\u003e \u003cp\u003eThe Q345 steels specimens covered with \u003cem\u003eL. fortunei\u003c/em\u003e was called as QL; while the blankspecimens were denoted as control samples, QC. Those specimens were immersed in separate tanks filling with river water at 20 \u003csup\u003eo\u003c/sup\u003eC for 3, 7, 15 and 30 day, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA). The volume of river water in each tank was 1 L, and 50% of the water was refreshed every two days. Each tank contained only one disc specimen, and the water volume was determined based on the density of the mussels.\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e After immersion duration and removal of mussels, rust layers were collected and mixed with glycerol, dried by freeze-vacuum oven and stored in the vacuum container, Then, specimens were ultrasonically reacted in Clarke\u0026rsquo;s solution (1000 mL 37% HCl, 20 g Sb\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, 50 g SnCl\u003csub\u003e2\u003c/sub\u003e) for 90 s to remove the remaining corrosion products, cleaned with deionized water, dehydrated with ethanol, and dried in a vacuum drying oven to avoid surface reoxidation. The specific procedure was following previous studies protocols.\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e \u003ch2\u003e2.2.1 Surface morphology observation and corrosion product characterization\u003c/h2\u003e \u003cp\u003eAfter the removal of rust layers, surface morphologies were observed by scanning electron microscopy (SEM, TESCAN VEGA3, CZ) and the 20 largest pitting depths of each group were recorded by confocal laser scanning microscopy (CLSM, VK-X 1000 series, Keyence).\u003c/p\u003e \u003cp\u003eChemical components of rust layers were characterized through X-ray diffraction (D8 Advance) and Raman spectroscopy (RENISHAW InVia, UK). The laser wavelength of 633 nm, the power of 5%, the acquisition time of 30 s, and the grating engraved line density of 600 were adopted in Raman detections. Morphologies and elements of corrosion products on the surface of specimens were analyzed via SEM and energy‐dispersive spectrometer (EDS, X‐stream2 SDD, OXFORD Instrument Ltd.).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.2.2 Weight-loss measurement and corrosion rate analysis\u003c/h2\u003e \u003cp\u003eBefore immersion experiments and after the removal of rust layer, each specimen weights were measured by a high-precision analytical balance (METTLER TOLEDO‐MS1040TS/02, accurated to 0.1 mg) to calculate weightlessness rate. Then, the general corrosion rate was attained via the equation:\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:{V}_{corr}=\\frac{8.76\\times\\:{10}^{4}△m}{At\\rho\\:}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003cem\u003eV\u003c/em\u003e \u003csub\u003e \u003cem\u003ecorr\u003c/em\u003e \u003c/sub\u003e\u0026mdash; corrosion rate (mm\u0026middot;year\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), \u003cem\u003e△m\u003c/em\u003e\u0026mdash; Weight loss (g), A\u0026mdash; Sample surface area (cm\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e), \u003cem\u003et\u003c/em\u003e\u0026mdash; Culture time (h), ρ\u0026mdash; Density (g\u0026middot;cm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e)\u003c/p\u003e \u003cp\u003eAll data were independently repeated at least three times to ensure reliability and presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.2.3 Specimen surface film composition and bacteria species detection\u003c/h2\u003e \u003cp\u003eTo identify the membrane composition and microbial species present on metal substrates after \u003cem\u003eL. fortunei\u003c/em\u003e adhesion, eliminating the interference of corrosion products during detection, polished 304 stainless steel plates (Φ 5\u0026times;0.5 cm) with mirror finishes were completely covered with mussels and submerged in sterilized river water for 30 days. Following this period, the mussels were removed, and the plates were dehydrated with alcohol and dried at room temperature. The film on the steel surface was characterized using Raman spectroscopy (RENISHAW InVia, UK). The laser wavelength of 532nm, the power of 100%, the acquisition time of 5 s, and the grating engraved line density of 600 were adopted in Raman detections. Subsequently, the film was scraped off for microbial analysis using 16S rDNA amplicon sequencing, with data processed by BMKCloud (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ewww.biocloud.net\u003c/span\u003e\u003cspan address=\"http://www.biocloud.net\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Electrochemical measurements\u003c/h2\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB, specimens were immersed in river water for 30 days and an electrochemical workstation (CS2350M, Wuhan Corrtest Instrument Corp., Ltd.) was exploited for tests involving the open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves. A three-electrode cell was selected in which samples were employed as the working electrode (WE), a saturated calomel electrode (SCE) as the reference electrode (RE), a platinum plate (50\u0026times; 50\u0026times; 0.1 mm) as the counter electrode (CE) and 0.1 M NaCl as the electrolyte.\u003c/p\u003e \u003cp\u003ePrior to measuring, the OCP was tested for 600 s to guarantee the system stability (with voltage floating within 5 mV). Afterwards, the EIS test was conducted in a frequency range from 10\u003csup\u003e5\u003c/sup\u003e to 10\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e Hz with an amplitude of 10 mV\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e and data was fitted via ZSimpWin software. Besides, Potentiodynamic polarization curves were obtained at a scan rate of 0.167 mV\u0026middot;s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e with potential range set from \u0026minus;\u0026thinsp;250 mV to +\u0026thinsp;250 mV vs. OCP\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e and the Tafel curves were analyzed using CS Analysis software.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Molecular dynamics (MD) simulation\u003c/h2\u003e \u003cp\u003eMolecular dynamics simulation was utilized to further examine the mechanism of \u003cem\u003eL. fortunei\u003c/em\u003e\u0026rsquo;s influence on carbon steel surface corrosion. In order to simplify the calculation, the peptide chain in mussel foot protein (Lffp) was selected for simulation. Forcite program in Materials Studio 2020 was exploited to run MD simulations through COMPASSⅢ force field. The iron crystal was designed and cleaved along the (110) plane,\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e and the Fe (110) surface increased to a supercell (15\u0026times; 15\u0026times; 4)\u003csup\u003e15\u003c/sup\u003e with lattice parameters of \u003cem\u003ea\u003c/em\u003e\u0026thinsp;=\u0026thinsp;37.24 \u0026Aring;, \u003cem\u003eb\u003c/em\u003e\u0026thinsp;=\u0026thinsp;37.24 \u0026Aring;, \u003cem\u003ec\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.11 \u0026Aring;, α\u0026thinsp;=\u0026thinsp;90\u003csup\u003eo\u003c/sup\u003e, β\u0026thinsp;=\u0026thinsp;90\u003csup\u003eo\u003c/sup\u003e, γ\u0026thinsp;=\u0026thinsp;70.53\u003csup\u003eo\u003c/sup\u003e. Additionally, to model the river water environment, the construction of solution system was based on main hydrochemical compositions of Yangtze River Basin as listed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and the detection data originated from Wang et al.\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e Aiming at triggering significance of simulation results, the ionic concentration in models was enlarged 1000 times and the solution included 2000 H\u003csub\u003e2\u003c/sub\u003eO, 34 Ca\u003csup\u003e2+\u003c/sup\u003e, 12 Mg\u003csup\u003e2+\u003c/sup\u003e, 12 Na\u003csup\u003e+\u003c/sup\u003e, 2 K\u003csup\u003e+\u003c/sup\u003e, 72 HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e, 10 SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e, 8 NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e, 2 Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e and 4 OH\u003csup\u003e\u0026minus;\u003c/sup\u003e. The solution box was placed over the Fe (110) layer set with a 200 \u0026Aring; vacuum slab. The vibration of the atoms contained in the iron base can be ignored at the simulated temperature of 298K, so intending to simplifying the process, the spatial positions of these atoms were fixed. Then the geometry optimization was carried out to minimize the energy of the system and the fully-optimized system was the control group. Afterwards, Molecular Dynamics simulation was conducted in the canonical (NVT) with a time step of 0.1 femtosecond (fs) using COMPASSⅢ force field. The van der Waals energy and static energy of the system were calculated via Ewald method. The Nose-Hoover thermostat with an effective relaxation time of 0.01 picoseconds (ps) was used to stabilize the system temperature at 298 K for 20 ps and the last 5 ps of the results were adopted for characteristic analysis.\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e According to the sequence of \u003cem\u003eL. fortunei\u003c/em\u003e loot protein (Lys-Hyp-Thr-Gln-Dopa-Ser-Asp-Glu-Tyr-Lys), amino acid residues were connected to obtain the whole atom model of Lffp peptide molecule.\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e After sufficient relaxation, two layers of peptides were placed in the above-mentioned control group system followed with the geometry optimization and dynamic simulation (Ditto for the parameters).\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\u003eAverage values of main water chemical characteristics in Yangtze River Basin.\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eItems\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eParameter (mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"8\" rowspan=\"9\"\u003e \u003cp\u003e\u003cb\u003eYangtze River Basin\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003epH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.97\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCa\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e38.39\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMg\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.75\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNa\u003csup\u003e+\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.28\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eK\u003csup\u003e+\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.27\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e120.75\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e27.99\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.43\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCl\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.80\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Effects of \u003cem\u003eL. fortunei\u003c/em\u003e adhesion on corrosion rate and type\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA and B illustrate the weight loss rate and corrosion rate of carbon steel with or without mussel covering under varied immersion days, respectively. In general, the weight loss rate and corrosion rate of QC samples were higher than QL samples in the same immersion duration, but as time went on, the corrosion rate of QC samples gradually decreased, while the corrosion rate of QL samples did not change as obviously as QC. Besides, owing to \u003cem\u003eL. fortunei\u003c/em\u003e attachment in the beginning of the experiments, surfaces of QL specimens were protected by shielding of mussels and the corrosion rate of the substrate was much lower than that of QC. However, the presence of mussels also led to uneven spread and insufficient production of rust layers on QL, which cannot fairly reduce the corrosion rate compared with QC samples.\u003c/p\u003e \u003cp\u003eFor localized corrosion, CLSM measured depths of the 20 greatest pits on steel surfaces. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC, during the short immersion time (3 days and 7 days), the average depths of corrosion pits on QL specimens were smaller than QC, but when the number of days reached 15 days, the average pit depths of QL group exceeded QC, and the difference was more obvious at 30 days. The largest pit depths of varying groups and days are demonstrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eD and E, which showed the same results as average depths. To sum up, the occurrence of \u003cem\u003eL. fortunei\u003c/em\u003e reduced the overall corrosion rate but exacerbates the local corrosion.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAfter the 30-day long experiment and removal of corrosion products, corrosion types of varied samples can be identified via SEM as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The surface of QC was rough with uneven grooves uniformly distributed, and the main corrosion behavior was uniform corrosion. On the contrary, the surface roughness of QL samples was much lower than that of QC, but there were corrosion pits unevenly spread. According to the topography on the surface, local corrosion was more obvious in QL and the main corrosion behavior was pitting corrosion.\u003c/p\u003e \u003cp\u003eIn freshwater or seawater environments, carbon steel tended to undergo uniform corrosion controlled by oxygen diffusion,\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e while the attachment of macrofouling can lead to localized corrosion on the metal surface.\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e \u003cem\u003eL. fortunei\u003c/em\u003e moved their feet to explore habitable areas, and then secreted byssus for colonization. The byssus attached to the surface of the substrate material via point contact tightly, while the mussel shell was surface contact without adhesion. Unlike other hard-fouling organisms such as oysters and barnacles that adhere by secreting adhesives, the weak adhesion effect caused by mussels reduced its shielding influence,\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e and meanwhile it was not capable to form crevice corrosion at the steel surface as oysters and barnacles are.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Effects of \u003cem\u003eL. fortunei\u003c/em\u003e adhesion on the interfacial corrosion products\u003c/h2\u003e \u003cp\u003eThe interfacial rust morphology of corrosion specimens has been observed by optical imaging. It was revealed as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA that the corrosion products on the QC surface were homogeneously distributed and a relatively thick layer was formed, displaying an overall dark brown hue. With the extension of processing time, the corrosion products on the QC surface gradually accumulated and uniformly distributed, isolating the contact between the base and air as well as water, which played a significant anti-corrosion effect. In contrast, those on the QL surface were irregularly dispersed and a thinner layer was formed, characterized mainly by light brown and black tones.\u003c/p\u003e \u003cp\u003eXRD technology was adopted to detect the composition of the rust layer after 30 days of the experiment. XRD profiles revealed that the main components of the rust layer of the two groups were goethite α-FeOOH, lepidocrocite γ-FeOOH, magnetite Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and Calcite CaCO\u003csub\u003e3\u003c/sub\u003e, while in addition to the above products, the samples with mussels covered also contained mackinawite FeS (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB). The sealed environment can urge the growth of anaerobic bacteria causing the generation of FeS.\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eIntending to identify the components of corrosion products on QC and QL samples more accurately, different groups of rust layers were stratified for Raman characterization, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. Thereinto, the green curves in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e display the main composition of the layer without and with mussels. The peaks at 241\u0026ndash;250, 298\u0026ndash;301, 385\u0026ndash;395, 478\u0026ndash;483, 549\u0026ndash;552, 680\u0026ndash;687 and 1000 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e were assigned to α-FeOOH.\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e Additionally, the bule curves in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e demonstrate the main components of inner layer without and with mussels. The peaks at 248\u0026ndash;252, 378\u0026ndash;380, 528\u0026ndash;530 and 1300 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e resulted from γ-FeOOH.\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e The peaks at 298\u0026ndash;302, 540\u0026ndash;550 and 663\u0026ndash;670 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e were assigned to Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e24, 25, 26, 28, 29, 30, 31, 33, 34, 35, 36, 38\u003c/sup\u003e and the peaks at 218, 253 and 282 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e were assigned to FeS.\u003csup\u003e\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe morphology of the rust layer directly reflected the degree of anti-corrosion properties on the metal surface.\u003csup\u003e\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eA indicates that the corrosion products on the QC surface were granular, with a porous and loose structure. Nevertheless, Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eB-\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and B-\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e demonstrate that the corrosion products on the QL surface exhibited a layered and flake-like structure, which was more compact and stable. On the top of that, bacteria were observed on the residual byssus of \u003cem\u003eL. fortunei\u003c/em\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eB-\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) and particularly on surfaces with deceased individuals, bacteria proliferated extensively (Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). In areas fully covered by mussels, compared to QC, elements such as P, N and S were detected. The detection of P may be attributed to organic substances secreted by the mussels (such as proteins, phospholipids, etc.) or components of the mussel shell. The specific anaerobic environment at the mussel/carbon steel interface has stimulated the activity of sulfate-reducing bacteria (SRBs), and the small amount of S detected likely originated from this. The proportion of element C on the QL surface was significantly higher than on the QC surface, indicating that a large amount of organic substances have formed on the carbon steel surface where mussels were attached.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Biofilm components and bacteria species identification of the mussel-covered surface\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e presents the Raman spectrum of biofilm on the stainless steel specimens and Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e displays main Raman peaks corresponding to the biological components. Raman spectroscopy analysis reveals that the biofilm formed on the metal substrate after \u003cem\u003eL. fortunei\u003c/em\u003e adhesion, predominantly comprised proteins, phospholipids, polysaccharides, carotenoids, and ammonia (NH₃). These components originated partially from mussel secretions and metabolic byproducts, and partially from the physiological activities of bacteria colonizing on the steel surface.\u003c/p\u003e \u003cp\u003e \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 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eRaman peak assignments for biofilm on the surface.\u003csup\u003e\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e, \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\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=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSubstance\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRaman band (cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eVibrational mode\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eProteins\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e751\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e(δ) ring\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e855\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eδ (CCH)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1007\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRing stretching modes of benzene derivatives\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eLipids\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e965\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eδ (=\u0026thinsp;CH) wagging\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1147\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eν (C-C), ν (C-O)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1290\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCH\u003csub\u003e3\u003c/sub\u003eCH\u003csub\u003e2\u003c/sub\u003e twisting, CH\u003csub\u003e2\u003c/sub\u003e mode\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNucleic acids\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1147\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e(O-P-O) backbone stretching\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCarbohydrates\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1394\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eν\u003csub\u003es\u003c/sub\u003e (COO\u003csup\u003e\u0026minus;\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCarotenoids\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1510\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eC\u0026thinsp;=\u0026thinsp;C str carotenoids\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eNH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3225\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eν\u003csub\u003esa\u003c/sub\u003e(NH\u003csup\u003e4+\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3402\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eν\u003csub\u003esa\u003c/sub\u003e(NH\u003csup\u003e4+\u003c/sup\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\u003eUtilizing 16S rDNA amplicon sequencing, the species composition and relative abundance within the biofilm were identified. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e, the top 15 most abundant species involved \u003cem\u003eSphaerotilus\u003c/em\u003e, \u003cem\u003eDuganella\u003c/em\u003e, \u003cem\u003eCetobacterium\u003c/em\u003e, \u003cem\u003eHolophagaceae\u003c/em\u003e, \u003cem\u003eZoogloea\u003c/em\u003e, \u003cem\u003eFlavobacterium\u003c/em\u003e, \u003cem\u003eCurvibacter\u003c/em\u003e, \u003cem\u003eRivicola\u003c/em\u003e, \u003cem\u003eMalikia\u003c/em\u003e, \u003cem\u003eDechloromonas\u003c/em\u003e, \u003cem\u003eHolophaga\u003c/em\u003e, \u003cem\u003eNovosphingobium\u003c/em\u003e, \u003cem\u003eGeothrix\u003c/em\u003e and members of the \u003cem\u003eDesulfovibrio\u003c/em\u003e family. \u003cem\u003eDesulfovibrio\u003c/em\u003e, a genus of sulfate-reducing bacteria (SRB), possesses the capacity to utilize sulfate as an electron acceptor to sustain growth, resulting in the generation of significant quantities of hydrogen sulfide (H₂S). Moreover, SRB are characterized by the presence of diverse electron transfer proteins, along with a wide array of reductases and dehydrogenases. These biomolecules play a pivotal role in facilitating the dissimilatory reduction of sulfate, underpinning the metabolic processes of these microorganisms.\u003csup\u003e\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e\u003c/sup\u003e The identification of these microorganisms accounted for the previously observed FeS corrosion products on the QL sample surface.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Effects of \u003cem\u003eL. fortunei\u003c/em\u003e adhesion on interface electrochemistry\u003c/h2\u003e \u003cp\u003eTo detect the corrosion kinetics of varied groups, the potentiodynamic polarization curves of the steel in river water without mussel covered (QNC), with mussel covered (QMC) and with mussel removed (QMR) after the 30-day immersion treatment are illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e. Meanwhile, Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e exhibits the electrochemical corrosion parameters of the potentiodynamic polarization curves.\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 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe electrochemical corrosion parameters of potentiodynamic polarization curves.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpecimen\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eE\u003csub\u003ecorr\u003c/sub\u003e (mV vs. SCE)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eI\u003csub\u003ecorr\u003c/sub\u003e (\u0026micro;A/cm\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCorrosion rate (mm/a)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNot covered\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-779.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.0836\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMussel covered\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-779.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.0107\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMussel removed\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-769.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.0719\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\u003eThe polarization curves indicates that all anode curves remained smooth, both in the presence and absence of \u003cem\u003eL.fortunei\u003c/em\u003e. No passivation zone was observed, suggesting that the anode primarily underwent active dissolution, while the cathodic process was associated with oxygen reduction. The Tafel slope extrapolation method was usually utilized to determine the corrosion current density (I\u003csub\u003ecorr\u003c/sub\u003e).\u003csup\u003e\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e The I\u003csub\u003ecorr\u003c/sub\u003e values for steel with and without macrofouling were derived by fitting the Tafel regions of both the anodic and cathodic branches. Typically, I\u003csub\u003ecorr\u003c/sub\u003e serves as an indicator of the metal\u0026rsquo;s susceptibility to corrosion and the rate of corrosion, with a higher I\u003csub\u003ecorr\u003c/sub\u003e signifying an accelerated corrosion rate.\u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e For the steel specimen fully covered by mussels, I\u003csub\u003ecorr\u003c/sub\u003e is 0.92 \u0026micro;A/cm\u0026sup2;, which was lower than that of the steel without macrofouling (I\u003csub\u003ecorr\u003c/sub\u003e = 7.13 \u0026micro;A/cm\u0026sup2;), suggesting that the attachment of \u003cem\u003eL. fortunei\u003c/em\u003e provided a protective effect, reducing the corrosion rate when tightly adhered. Moreover, after removal of the mussels (steel with mussel coverage removed), I\u003csub\u003ecorr\u003c/sub\u003e reached to 6.13 \u0026micro;A/cm\u0026sup2;, higher than the mussel-covered specimen but slightly lower than the control group. The results displayed that in spite of removal of mussels, the biofilm formed during their colonization still possessed the abilities to protect the surface of the carbon steel, but the anti-corrosion effect was significantly undermined.\u003c/p\u003e \u003cp\u003eEIS tests can assess the extent of the steel degradation induced by the accumulation of adhered macrofouling organisms.\u003csup\u003e\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e\u003c/sup\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e presents the Nyquist and Bode plots for three sets of carbon steel specimens in 0.1 M NaCl solution. From the Nyquist plot, it is evident that specimens without mussel adhesion (QNC and QMR) exhibited an impedance spectrum characterized by a single capacitive arc, indicating that the corrosion of Q345 steel in 0.1 M NaCl was primarily activation-controlled. In contrast, carbon steels with \u003cem\u003eL. fortunei\u003c/em\u003e adhesion displayed a combination of a high-frequency capacitive arc and a low-frequency Warburg impedance, with the presence of the Warburg impedance suggesting the occurrence of diffusion-controlled corrosion reactions. Notably, the radius of the capacitive arc was largest for the mussel-adhered specimens, while the control groups showed a smaller capacitive arc radius. This reveals that the attachment of mussels enhanced the specimen's resistance to corrosion in the testing solution, thereby improving the material's overall corrosion resistance. The protective effect of the oxide film on the specimen surface against the corrosive solution can be approximated by the impedance at 0.01 Hz (|Z|₀.₀₁ Hz). From the Bode plots, it is evident that the impedance values for the three specimens were as follows: 8590 Ω\u0026middot;cm\u0026sup2; (QMC)\u0026thinsp;\u0026gt;\u0026thinsp;2107.8 Ω\u0026middot;cm\u0026sup2; (QMR)\u0026thinsp;\u0026gt;\u0026thinsp;1060 Ω\u0026middot;cm\u0026sup2; (QNC). The steel specimens entirely covered by macrofouling exhibits the largest capacitive arc radius at Z\u003csub\u003ef\u003c/sub\u003e = 0.01 Hz and demonstrates relatively high impedance values. The sequence confirmed the previous observation that the adhesion of \u003cem\u003eL. fortunei\u003c/em\u003e protected the Q345 surface against corrosion. The underlying mechanism can be attributed to two potential factors. Similar to oysters, mussel shells primarily consist of calcium carbonate (CaCO₃), which has poor electrical conductivity. Additionally, the calcareous shell possesses a low ionic diffusivity, effectively hindering the transport of ions and oxygen.\u003csup\u003e\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e\u003c/sup\u003e Together, these properties rendered the shell an effective insulator, reducing the electrochemically active area and increasing the capacitive arc radius. Upon the removal of mussels, the diameter of the Nyquist plot decreased significantly.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe EIS data for the QNC and QMR specimens were fitted using the equivalent circuit model shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003eA-\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, whereas the QMC specimen employed the equivalent circuit depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003eA-\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003csup\u003e\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e\u003c/sup\u003e Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e presents the fitted parameters of the EIS measurements, where R\u003csub\u003es\u003c/sub\u003e, R\u003csub\u003ef\u003c/sub\u003e, R\u003csub\u003ect\u003c/sub\u003e, and W correspond to solution resistance, corrosion product resistance, charge transfer resistance, and diffusion impedance, respectively. The constant phase elements (CPEs) include CPE\u003csub\u003ef\u003c/sub\u003e, which represents the capacitance (C\u003csub\u003ef\u003c/sub\u003e) of the corrosion products and the dispersion factor (n\u003csub\u003ef\u003c/sub\u003e), and CPE\u003csub\u003edl\u003c/sub\u003e, which denotes the double-layer capacitance (C\u003csub\u003edl\u003c/sub\u003e) and its dispersion factor (n\u003csub\u003ed\u003c/sub\u003e). The impedance of a CPE is calculated using the following formula:\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e\n$$\\:{Z}_{CPE}={C}^{-1}{\\left(j\\omega\\:\\right)}^{-n}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003cem\u003eZ\u003c/em\u003e \u003csub\u003e \u003cem\u003eCPE\u003c/em\u003e \u003c/sub\u003e\u0026mdash; Impedance of the CPE (Ω), \u003cem\u003eC\u003c/em\u003e\u0026mdash; Capacitance value (Ω\u003csup\u003e\u0026minus;1\u003c/sup\u003e\u0026middot;cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e\u0026middot;s\u003csup\u003en\u003c/sup\u003e), ω\u0026mdash; Angular frequency (rad\u0026middot;s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), \u003cem\u003en\u003c/em\u003e\u0026mdash; Diffusion index\u003c/p\u003e \u003cp\u003eThe resistance R\u003csub\u003ef\u003c/sub\u003e is closely related to the structure and porosity of corrosion products. The R\u003csub\u003ef\u003c/sub\u003e value of the mussel-adhesion group reached 830.7 Ω\u0026middot;cm\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e, fairly exceeding that of the control group (264.8 Ω\u0026middot;cm\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e). This result corresponded to Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, which demonstrates that the corrosion products in the QL group exhibited a denser morphology compared to those in the QC group. During the electrochemical corrosion process, when charges (electrons and electrolyte ions) traverse the double electric layer at the material's surface, charge transfer resistance (R\u003csub\u003ect\u003c/sub\u003e) may arise. This resistance reflects the electrochemical reaction occurring within the solution. The sum of R\u003csub\u003ef\u003c/sub\u003e + R\u003csub\u003ect\u003c/sub\u003e typically provides insights into the compactness of the rust film, which is strongly correlated with the corrosion rate: higher values indicate lower corrosion rates.\u003csup\u003e\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e\u003c/sup\u003e Conversely, parameters associated with the constant phase element (CPE), such as CPE\u003csub\u003edl\u0026minus;n\u003c/sub\u003e and CPE\u003csub\u003ef\u0026minus;n\u003c/sub\u003e, are less significantly influenced. Depending on the value of n, CPE may represent a resistor (n\u0026thinsp;=\u0026thinsp;0), a Warburg impedance (n\u0026thinsp;=\u0026thinsp;1/2), or a capacitor (n\u0026thinsp;=\u0026thinsp;1).\u003csup\u003e58\u003c/sup\u003e The n value is determined by the roughness of the electrode surface and the non-uniform distribution of corrosion current density. For all data sets, R\u003csub\u003ect\u003c/sub\u003e consistently exceeds R\u003csub\u003ef\u003c/sub\u003e, indicating that charge transfer resistance plays a dominant role in corrosion protection compared to film resistance. A larger R\u003csub\u003ect\u003c/sub\u003e suggests that the corrosive medium cannot penetrate further into the inner layers; in the absence of direct contact with the corrosive medium, dissolution cannot be activated, thereby enhancing corrosion resistance. Conversely, a smaller R\u003csub\u003ect\u003c/sub\u003e value in the electrochemical parameters indicates reduced resistance to the electrochemical process and a higher susceptibility of the material to corrosion. As shown in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, the R\u003csub\u003ect\u003c/sub\u003e values for the three samples, in descending order, are: 12040 Ω\u0026middot;cm\u0026sup2; (QMC)\u0026thinsp;\u0026gt;\u0026thinsp;4053 Ω\u0026middot;cm\u0026sup2; (QMR)\u0026thinsp;\u0026gt;\u0026thinsp;2265 Ω\u0026middot;cm\u0026sup2; (QNC). Among these, QMC exhibits the best corrosion resistance in 0.1 M NaCl solution. Although, in real-world environments, the presence of crevices between mussels and substrates may trigger autocatalytic mechanisms that lead to the accumulation of anions such as SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e, Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e and NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e, thereby enhancing the solution's corrosivity and reducing R\u003csub\u003ect\u003c/sub\u003e, the concentration of anions in freshwater systems is significantly lower than in marine environments. Consequently, under short-term experimental conditions, the increased corrosion rate caused by mussel adhesion is not pronounced.\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\u003eDerived values of R\u003csub\u003es\u003c/sub\u003e, CPE\u003csub\u003ef\u003c/sub\u003e, R\u003csub\u003ef\u003c/sub\u003e, CPE\u003csub\u003edl\u003c/sub\u003e and R\u003csub\u003ect\u003c/sub\u003e of the Nyquist diagrams.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\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=\"\u0026times;\" 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=\"\u0026times;\" 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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eSpecimen\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eR\u003csub\u003es\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e(Ω\u0026middot;cm\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eCPE\u003csub\u003ef\u003c/sub\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eR\u003csub\u003ef\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e(Ω\u0026middot;cm\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003eCPE\u003csub\u003edl\u003c/sub\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eR\u003csub\u003ect\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e(Ω\u0026middot;cm\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eC\u003csub\u003ef\u003c/sub\u003e (Ω\u003csup\u003e\u0026minus;1\u003c/sup\u003e\u0026middot;cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e\u0026middot;s\u003csup\u003en\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003en\u003csub\u003ef\u003c/sub\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eC\u003csub\u003edl\u003c/sub\u003e (Ω\u003csup\u003e\u0026minus;1\u003c/sup\u003e\u0026middot;cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e\u0026middot;s\u003csup\u003en\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003en\u003csub\u003edl\u003c/sub\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNot covered\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e136.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026times;\" colname=\"c3\"\u003e \u003cp\u003e1.35\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.754\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e264.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026times;\" colname=\"c6\"\u003e \u003cp\u003e6.80\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.854\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e2265\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMussel covered\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e134.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026times;\" colname=\"c3\"\u003e \u003cp\u003e3.92\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.713\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e830.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026times;\" colname=\"c6\"\u003e \u003cp\u003e3.28\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.841\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e12040\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMussel removed\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e72.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026times;\" colname=\"c3\"\u003e \u003cp\u003e1.15\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.785\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e339.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026times;\" colname=\"c6\"\u003e \u003cp\u003e3.20\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.906\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4053\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Corrosion mechanism of the steel with and without \u003cem\u003eL. fortunei\u003c/em\u003e\u003c/h2\u003e \u003cp\u003eTo further investigate the corrosion mechanisms on substrate surfaces, MD simulations were employed to analyze the adsorption of liquid layers and the distribution of ions within the liquid for two different systems (Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e). The absence of significant fluctuations during the final 5 ps of the simulation indicates that the system reached equilibrium (Fig. S2). In both systems, water molecules form a compact hydration layer on the Fe (110) surface, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003eA. According to Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003eB, the strongest peak in the water density profile appears at a distance of 10.30 \u0026Aring; from the Fe (110) surface. In the system without Lffp, the maximum water density is 31.33 g/mL, whereas in the system with Lffp, the water density is slightly lower at 30.17 g/mL. Figure\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003eC illustrates the distribution of ions on the Fe (110) surface for the two systems. The ion density profiles reveal their strongest peaks at 10.04 \u0026Aring; from the surface, corresponding to the hydration layer. In the system without Lffp, the maximum ion density is 26.32 g/mL, whereas in the presence of Lffp, the ion density fairly increases to 36.22 g/mL. Considering the water density in the hydration layer for both systems, it is evident that the presence of Lffp facilitates ion accumulation on the Fe (110) surface. Under real-world conditions, however, the distribution of \u003cem\u003eL. fortunei\u003c/em\u003e is uneven, suggesting that mussel adhesion accelerates localized corrosion on the substrate surface.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe mechanisms by which \u003cem\u003eL. fortunei\u003c/em\u003e coverage affects the corrosion behavior of steel surfaces can be discussed from several perspectives. Firstly, the form and rate of steel corrosion are directly linked to the concentration of dissolved oxygen. Oxygen levels have been identified as one of the critical parameters influencing the temporal variation of corrosion-induced weight loss.\u003csup\u003e\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e\u003c/sup\u003e For steel covered by mussels in natural environments, the weak adhesion of mussels transforms the corrosion system from an open riverwater environment to a closed or semi-closed system. Due to the oxygen concentration gradient between the area beneath the mussel shell and the external environment, the oxygen-rich external region serves as the cathode in an oxygen concentration cell, reducing the overall corrosion rate. In contrast, the oxygen-depleted region beneath the shell acts as the anode, promoting localized anodic corrosion and exacerbating corrosion severity. Secondly, the accumulation of ions such as SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e, NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e, and Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e plays a crucial role in the process. The synergistic action of SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e and Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e significantly accelerates corrosion.\u003csup\u003e\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e\u003c/sup\u003e In freshwater environments, the ion concentration is much lower than in marine environments, making ion accumulation less apparent. Nevertheless, simplified molecular dynamics simulations with increased ion concentrations have demonstrated that \u003cem\u003eL. fortunei\u003c/em\u003e-secreted foot proteins lead to the enrichment of ions on the substrate surface in simulated river water systems. Furthermore, the presence of oxygen in pitting corrosion cavities facilitates continuous autocatalytic reactions within the pits. This causes the accumulation of metal cations inside the pits and drives the inward migration of Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e and SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e from outside the pits to maintain charge balance, thereby worsening the growth of corrosion pits. Thirdly, microbially influenced corrosion (MIC) contributes to the development of macrofouling and the corrosion process at the carbon steel interface. On surfaces covered by mussels, oxygen is partially blocked, resulting in low oxygen concentrations and limited replenishment, creating ideal conditions for the growth of anaerobic bacteria.\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e The proliferation of anaerobic bacteria such as sulfate-reducing bacteria (SRB) intensifies localized corrosion, leading to the formation of FeS. Previous SEM and microbial analyses confirmed the growth of anaerobic bacteria on mussel-attached substrates, while XRD and Raman spectroscopy validated the presence of FeS. Lastly, the adhesion process of mussels involves redox reactions that accelerate the consumption of dissolved oxygen around the foot. Additionally, cysteine thiols in the proteins secreted by mussels strongly deplete oxygen levels.\u003csup\u003e\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e\u003c/sup\u003e These processes collectively accelerate the corrosion of the steel substrate and promote the proliferation of anaerobic bacteria. On the other hand, the secretions can infiltrate the porous rust layer structure, altering its state to become more compact and enhancing its adhesion. Changes in the physicochemical properties of the rust layer also influence oxygen diffusion and microbial growth.\u003c/p\u003e \u003cp\u003eAccording to the aforementioned discussion, the corrosion process on the carbon steel surface can be illustrated as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e. Initially, the primary corrosion product of carbon steel in river water is Fe(OH)\u003csub\u003e2\u003c/sub\u003e. Owing to its inherent instability, Fe(OH)\u003csub\u003e2\u003c/sub\u003e readily undergoes dehydration and decomposition to form protective layers of FeOOH和Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e.\u003csup\u003e\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e\u003c/sup\u003e Over prolonged immersion, FeOOH may further react with Fe\u003csup\u003e2+\u003c/sup\u003e to produce Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e,\u003csup\u003e\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e\u003c/sup\u003e as described by the following reaction equations:\u003c/p\u003e \u003cp\u003eFe\u0026rarr;Fe\u003csup\u003e2+\u003c/sup\u003e+2e\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eO\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;2H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;+\u0026thinsp;4e\u003csup\u003e\u0026minus;\u003c/sup\u003e\u0026rarr;4OH\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eFe\u003csup\u003e2+\u003c/sup\u003e+ 2OH\u003csup\u003e\u0026minus;\u003c/sup\u003e\u0026rarr;Fe(OH)\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003e2Fe(OH)+O→2FeOOH + 2HO; 3Fe(OH)+O→FeO + 3HO\u003c/h3\u003e\n\n\u003ch3\u003e2FeOOH + Fe→FeO + 2H\u003c/h3\u003e\n\u003cp\u003eSince the substrate with mussel attachment has the propagation of SRB and other microorganisms, the corrosion products will also contain FeS, and the equations are as follows:\u003c/p\u003e \u003cp\u003eFe\u0026rarr;Fe\u003csup\u003e2+\u003c/sup\u003e+2e\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u0026rarr;OH\u003csup\u003e\u0026minus;\u003c/sup\u003e +H\u003csup\u003e+\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eH\u003csup\u003e+\u003c/sup\u003e +e\u003csup\u003e\u0026minus;\u003c/sup\u003e\u0026rarr;[H]\u003c/p\u003e \u003cp\u003eSO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e+8[H]\u0026rarr;S\u003csup\u003e2\u0026minus;\u003c/sup\u003e+4H\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003cp\u003eFe\u003csup\u003e2+\u003c/sup\u003e+S\u003csup\u003e2\u0026minus;\u003c/sup\u003e\u0026rarr;FeS\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThis study demonstrates that the prolonged adhesion of \u003cem\u003eL. fortunei\u003c/em\u003e reduced the overall corrosion rate of carbon steel but exacerbatec localized corrosion. The corrosion products common to both sample groups include goethite (α-FeOOH), lepidocrocite (γ-FeOOH), and magnetite (Fe₃O₄). However, the presence of mussels fosters the growth of sulfate-reducing bacteria (SRB), resulting in FeS formation in the innermost corrosion layer. The corrosion mechanism of Q345 steel in a simulated river water environment influenced by \u003cem\u003eL. fortunei\u003c/em\u003e can be attributed to factors such as the enclosed microenvironment created by mussel shells, bacterial proliferation, anion accumulation, and mussel secretions. Formostly, the mussel coverage altered the corrosion environment by creating oxygen concentration cells, where the oxygen-depleted region beneath the mussel shell acted as an anode, exacerbating localized corrosion, while the external oxygen-rich area served as a cathode, reducing overall corrosion rates. Furthermore, the accumulation of ions like Cl⁻ and SO₄\u0026sup2;⁻, driven by mussel-secreted proteins, facilitated ion enrichment on the substrate surface, promoting pitting corrosion. In addition, the low-oxygen conditions beneath mussels supported the growth of anaerobic bacteria, such as sulfate-reducing bacteria (SRB), which intensified localized corrosion through the formation of FeS. The secreted proteins further altered the rust layer's compactness and adhesion, influencing corrosion dynamics and microbial activity. Over time, in real freshwater environments, the uneven attachment of mussels causes severe corrosion, such localized corrosion can compromise the structural integrity of materials, leading to premature failure and increased maintenance costs, highlighting the necessity of effective mitigation strategies.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eData availability\u003c/p\u003e\n\u003cp\u003eData will be made available on request.\u003c/p\u003e\n\u003cp\u003eCRediT authorship contribution statement\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design. The idea of the article was proposed by Yuhan Liu and Xiuqin Bai. The Investigation and data analysis were performed by Xiaoyan He and Xianfu Yuan. The first draft of the manuscript was written by Yuhan Liu. The work was critically revised by Ying Yang, Ziquan Zhou and Chengqing Yuan. The research activity was supervised by Ying Yang and Xiuqin Bai. All authors review the manuscript.\u003c/p\u003e\n\u003cp\u003eDeclaration of Competing Interest\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003eAcknowledgements\u003c/p\u003e\n\u003cp\u003eThis work was financially supported by Innovation and Development Joint Fund Key Project of Hubei Provincial Natural Science Foundation (2022CFD029) and National Natural Science Foundation of China (52475212).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eVuong P, McKinley A, Kaur P. 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An electrochemical study of phase-transitions in rust layers. \u003cem\u003eCorrosion Science\u003c/em\u003e \u003cstrong\u003e23\u003c/strong\u003e, 969-985 (1983).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"npj-materials-degradation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"npjmatdeg","sideBox":"Learn more about [npj Materials Degradation](http://www.nature.com/npjmatdeg/)","snPcode":"41529","submissionUrl":"https://submission.springernature.com/new-submission/41529/3","title":"npj Materials Degradation","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"NPJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Macrobiologically influenced corrosion, Fouled steel surface, Limnoperna fortunei, Freshwater environments, Pitting corrosion","lastPublishedDoi":"10.21203/rs.3.rs-5751902/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5751902/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cem\u003eLimnoperna fortunei (L. fortune)\u003c/em\u003e, a representative macrofouling organism in freshwater environments, causes significant degradation to the surfaces of hydraulic engineering materials through prolonged adhesion. The corrosion behavior of \u003cem\u003eL. fortunei\u003c/em\u003e on Q345 carbon steel in river water environments was investigated employing topography detection, rust layer identification, corrosion rate analysis, electrochemical measurements, and molecular dynamics (MD) simulation. The results demonstrated that the attachment of mussels decreased the overall corrosion rate of the steel surface, but significantly aggravated pitting corrosion, a localized and highly destructive form of material degradation. The corrosion behavior of Q345 steel in a freshwater environment influenced by \u003cem\u003eL. fortunei\u003c/em\u003e was primarily driven by the formation of a restricted microenvironment beneath the mussel shells, which promoted localized anion enrichment, bacterial colonization, and the accumulation of aggressive secretions. These factors collectively intensified electrochemical heterogeneity, accelerating pitting initiation and propagation. These findings emphasize the critical need for mitigation strategies to address localized corrosion caused by biofouling in hydraulic engineering applications.\u003c/p\u003e","manuscriptTitle":"Corrosion behavior of Limnoperna fortunei on carbon steel in freshwater environments","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-01-08 06:11:25","doi":"10.21203/rs.3.rs-5751902/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-01-25T05:01:48+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-01-24T15:14:08+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"147194320665235044369168582755267773231","date":"2025-01-20T07:21:59+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-01-16T10:02:53+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-01-14T17:29:14+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-01-14T07:43:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"12672648121129234641269218464866844984","date":"2025-01-08T15:41:40+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"249114926493929839628445080988389631874","date":"2025-01-08T15:05:41+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"247402698413532368740895598732786944982","date":"2025-01-07T15:32:20+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-01-07T13:30:20+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-01-06T15:23:31+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-01-06T12:53:31+00:00","index":"","fulltext":""},{"type":"submitted","content":"npj Materials Degradation","date":"2025-01-02T12:50:28+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"npj-materials-degradation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"npjmatdeg","sideBox":"Learn more about [npj Materials Degradation](http://www.nature.com/npjmatdeg/)","snPcode":"41529","submissionUrl":"https://submission.springernature.com/new-submission/41529/3","title":"npj Materials Degradation","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"NPJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5ac0c0a2-e461-4f1d-9bb7-ed29adfb3616","owner":[],"postedDate":"January 8th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":42508995,"name":"Physical sciences/Materials science"},{"id":42508996,"name":"Earth and environmental sciences/Environmental sciences"}],"tags":[],"updatedAt":"2025-06-16T16:07:58+00:00","versionOfRecord":{"articleIdentity":"rs-5751902","link":"https://doi.org/10.1038/s41529-025-00618-2","journal":{"identity":"npj-materials-degradation","isVorOnly":false,"title":"npj Materials Degradation"},"publishedOn":"2025-06-14 15:57:07","publishedOnDateReadable":"June 14th, 2025"},"versionCreatedAt":"2025-01-08 06:11:25","video":"","vorDoi":"10.1038/s41529-025-00618-2","vorDoiUrl":"https://doi.org/10.1038/s41529-025-00618-2","workflowStages":[]},"version":"v1","identity":"rs-5751902","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5751902","identity":"rs-5751902","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}