Regarding the Possible Impact of Forest Fires on the Radioactive Pollution of Groundwater in the Chornobyl Exclusion Zone

Regarding the Possible Impact of Forest Fires on the Radioactive Pollution of Groundwater in the Chornobyl Exclusion Zone | 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 Regarding the Possible Impact of Forest Fires on the Radioactive Pollution of Groundwater in the Chornobyl Exclusion Zone Mykola Panasiuk, Mykhailo Buzynnyi, Serhii Kirieiev, Natalia Sosonna, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5926363/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 22 Apr, 2025 Read the published version in Scientific Reports → Version 1 posted 10 You are reading this latest preprint version Abstract Wood in the Chornobyl Exclusion Zone (CEZ) is contaminated with 137 Cs and 90 Sr. The 90 Sr activity concentration in the wood reaches tens of kBq/kg. According to laboratory experiments, complete combustion of 1 kg of dry pinewood generates about 2.8 g of ash, resulting in a 90 Sr concentration in the ash that is approximately 360 times higher. The specific activity of 90 Sr in the ash from six wood samples ranged from 0.16 to 3.4 kBq/g. In filtrate samples, the specific activity of 90 Sr, under consistent experimental conditions, reached 0.5 to 0.72 kBq/l. The fraction of 90 Sr washed out during the experiment was 12–33% for wood ash and 10.8–13.2% for forest litter ash. The high concentrations of potassium, sodium, calcium, and phosphate ions in the wood ash are readily leached, which increases groundwater mineralization and its ionic strength. This, in turn, contributes to a decrease in the sorption capacity of soils and an increase in the migration capacity of 90 Sr in the aquifer. The largest fires in the CEZ occurred in 2020 at the Temporary Radioactive Waste Location Point (PTLRW) “Red Forest” site, where the 90 Sr activity in wood peaked. The concentration of 90 Sr activity in groundwater samples from observation wells in this section of the CEZ shows an increase of 2 to 60 times, climbing from approximately 2 to about 180 Bq/l, beginning at the end of 2022. Radioactivity concentrated in ash on the soil surface in the burned area is vulnerable to rapid leaching by atmospheric precipitation; as a result, it can become a significant local source of radioactive contamination of surface and groundwater, necessitating updates to the regulations for monitoring radioactivity in the relevant CEZ observation wells. Earth and environmental sciences/Biogeochemistry Earth and environmental sciences/Ecology Earth and environmental sciences/Environmental sciences Earth and environmental sciences/Hydrology Earth and environmental sciences/Natural hazards forest fires wood forest litter ash groundwater 90Sr pollution sources mineralization ionic strength of the solution Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Introduction As trees grow, the forests in the Chornobyl Exclusion Zone accumulate significant levels of 90 Sr activity in their wood. Fires are common due to the limited control over the forested areas of the Chornobyl Exclusion Zone. The largest fires (Fig. 1 ) occurred over an area of 554 km² in 2020 (Hu J. et al., 2023; Hu J. et al., 2024) [ 1 , 2 ]. It is known that fires accompanied the military occupation of the CEZ by Russian troops in 2022. When wood burns, ash forms and the concentration of radionuclides in the ash significantly increases compared to the wood. Radionuclides in ash become available for leaching through atmospheric precipitation and intense migration with water, including infiltration into groundwater. Therefore, recent fires in the Chornobyl NPP area have heightened the secondary redistribution of radioactivity and its transfer, resulting in additional surface and groundwater contamination. The authors (Igarashi et al., 2024) [ 3 ] demonstrated that emissions of 137 Cs and 90 Sr during burning experiments at the Chornobyl fire site reached up to 4.2% of the 137 Cs and 2.9% of the 90 Sr stocks. This suggests that most 137 Cs and 90 Sr remained in the charred residues on the ground after the fire. An analysis of results from a systematic study conducted in the fire-affected zone of the Chornobyl NPP revealed that the water-soluble fractions of 137 Cs and 90 Sr in charred residues were significantly higher than those in the soil, which indicates their increased mobility (Igarashi et al., 2024) [ 3 ]. The geometric means of the water-soluble and exchangeable forms of 137 Cs in the charred residues were 2.2% and 17.4%, respectively. The geometric means for the water-soluble and exchangeable forms of 90 Sr in the charred residues were 5.4% and 27.5%, respectively. However, the extent of burnout of the charred residues used in this study is unknown. Therefore, the water-soluble fraction of 90 Sr content could be significantly higher for ashes with more incredible burnout. However, no significant increase in the concentration of 137 Cs in the river catchment area of Chornobyl was observed after the forest fires. However, 90 Sr concentrations increased significantly, periodically exceeding the permissible levels for drinking water (2 Bq/l) in Ukraine (DSanPiN, 2010) [4]. Thus, in the surface water of the Sakhan River, the concentrations of dissolved 90 Sr before the 2020 fire ranged mainly from 0.22 to 3.61 Bq/l, increasing from 0.35 to 11.0 Bq/l after the forest fires. The authors explain this increase by hydrologically driven transport processes of soluble 90 Sr from charred remains and the soil surface into the river during snowmelt and precipitation. Studies of the forest ecosystem conducted in Bavaria (F. Bruchertseifer et al., 2002) [ 5 ], where most of the 90 Sr is attributed to nuclear test fallouts, demonstrated that the majority remains in the forest's organic horizons, indicating a very low migration rate for an extended period after the fallout. A study of young trees planted in the "Red Forest" area (Buzinny et al., 2000) evidenced the high contamination of 137 Cs and 90 Sr, with a significant contrast in the distribution in the cross-section [ 6 ]. The authors (Holiaka et al., 2019) [7] calibrated a simulation model for the distribution of 90 Sr in elements of the forest ecological system ( Pinus sylvestris L.) based on the results of their recent experimental studies. According to the 2025 forecast generated from the model, wood contains 20% of the forest litter, and 14% of the 90 Sr activity is concentrated in the forest bio-system. Subsequent studies of the wood of the “Red Forest” conducted between 2005 and 2018 showed (Yoschenko et al., 2024) [ 8 ] that with a general decrease in the specific activity of 90 Sr in all compartments of the tree biomass, its total reserves in wood increased from 18 to 23 GBq/ha, respectively. Corresponding estimates based on the results of studies of trees planted in the trenches of the "Red Forest" wood burials show that the 90 Sr reserves here increased almost 6-fold, reaching approximately 560 GBq/ha, which is about (19 ± 9)% of the total reserve in the trench zone. The aim of the study (Alicja, K., Grzegorz, C., 2024) [ 9 ] was to determine the content and leaching capacity of strontium (Sr) in ash obtained from the combustion of household waste in domestic furnaces. For ash derived from various materials, the authors assessed the total Sr content, considering the strontium fractions in terms of their leaching with water—specifically, phyto-available and ion-exchange capacities. The study revealed that the concentration of Sr in ash produced from the combustion of traditional fuels, alternative fuels, and household waste ranges from 0.1 to 1.0 g/kg. The most mobile fraction leached with water ranged from 1.3% to nearly 91% of the total Sr content. After a forest fire, a layer of ash and charred material quickly forms on the ground. This layer will gradually diminish and be redistributed by precipitation, wind, or animals through partial dissolution and incorporation into the soil. Ash can either increase or decrease water runoff on the surface after a fire, depending on the ash and soil properties, as well as the thickness of the ash layer. The study's authors (Body et al., 2011) [10] focused significantly on the wettability of ash, which varies from low to extremely high, determined by the burning temperature and depth and the organic carbon content. The interaction within the water-ash-soil system largely depends on soil properties. The study's authors (Sánchez-García, 2023) [ 11 ] argue that forest fire ash can pose significant risks to society because of the concentration of potentially harmful chemical components. After examining 148 samples (42 types) of ash, the authors found that most samples exhibited an alkaline reaction (mean pH 8.8, range 6 to 11.2). Their main components were organic carbon (mean value: 204 g/kg), calcium, aluminum, and iron (mean values: 47.9, 17.9, and 17.1 g/kg, respectively). Based on ash samples from a pine forest fire in Portugal, (Pereira et al., 2014) [ 12 ] determined that the ash filtrate had a higher pH and conductivity and was enriched in Ca2+, Mg2+, Na+, K+, and Si4 + ions. Additionally, this study found that the solubility of potassium and calcium in charred residues was 1.7 times and 9.7 times higher, respectively than in unburned forest litter. In this regard, (Igarashi et al., 2024) stated that the fate of 137 Cs and 90 Sr in charred residues is currently unknown, but the dynamics of 137 Cs and 90 Sr in the environment are similar to those of K and Ca. The authors (Earl, S. R.; Blinn, D. W., 2003) [13] investigated the impact of fire ash on water quality in the Gila River drainage in southwestern New Mexico, USA, over a 5-year period. Following the introduction of fire ash, the water showed elevated concentrations of ammonium, nitrate, dissolved reactive phosphate (SRP), potassium, and alkalinity. Increased mineralization leads to a rise in groundwater's ionic strength. This diminishes soils' sorption properties, further contributing to augmented radionuclide migration (Kovalenko, I. O. et al., 2024) [ 14 ]. This study aimed to identify the characteristics of wood ash and forest litter ash, the corresponding activity concentrations of 137 Cs and 90 Sr, and the extent of their leaching from wood and forest litter ash due to two years of rainfall. The information above assessed the situation at the site of the fires in the CEZ and their impact on the radioactive contamination of groundwater. The activity concentrations of 137Cs and 90 Sr in wood, forest litter, ash, and filtrate were measured to achieve this goal. The degree of 137 Cs and 90 Sr leaching from wood and forest litter ash was determined, and the dynamics of 90 Sr in groundwater samples from some wells located within the burnt areas of the "Red Forest" TRW site were analyzed. Materials and methods Wood and forest litter samples For laboratory studies of wood ash and forest litter, we used the dry residue from samples collected in the Chornobyl Exclusion Zone in 1996, 2013, and 2021, which had been previously studied (Buzinny et al., 1997; Buzinny, 2006; Buzynnyi et al., 2023) [15, 16, 17]. Wood samples (Pinus sylvestris L.) were taken at two sites near the Yaniv railway station. Forest litter samples were gathered near the Prypiat oil base, site 96/36. They displayed characteristic morphological layers: A – a light upper layer of fresh litter, B – a thick layer with partial structural changes in the material, and C – a lower layer that has undergone severe decomposition. Given the long interval between wood samplings, we observed changes in the specific activity and ratio of radionuclides. Over time, the activity of 90 Sr increased while 137 Cs decreased, which is particularly significant in the most contaminated areas of the CEZ (Buzinny et al., 2000; Yoschenko et al., 2024) [ 6 , 8 ]. Wood samples I, II, and III were collected in 2013, while wood sample IV corresponded to one tree from 2021. Ashing of samples Wood samples I, II, and III represented chopped wood, while wood sample IV - chips. This determined the duration of the final combustion process - chips burned out faster in the conditions of the muffle furnace used. Ash samples were prepared in 2 stages - first, carbonization was carried out (little oxygen), then - ashing (more oxygen). The temperature in both cases was 600º C. Quantitative data on the ash preparation process are given in Table 1 . To control the variability of the process, sample I was repeated as I-A, and sample IV was prepared in three portions with the names of samples IV-A, IV-B, and IV-C. The quality of the ash was assessed as satisfactory: visually, it had a dark gray color or a shade of brown. The average ash content of wood (ash/dry material, g/kg) was 2.8 ± 0.37 (N = 7). The ash content coefficients for different layers of the forest litter were A – 29, B – 48, and C – 192 due to the increase in the proportion of mineral fraction in the litter from top (A) to bottom (C). The wide variety of ash content coefficients between samples of different litter layers allowed us to use them as is and not perform repeated samples. Laboratory experiment on leaching Sr with water from ash In preparation for the laboratory experiment, 0.3 to 1.1 g of ash was considered to have been obtained for the various wood samples described above. Disposable 2 ml and 5 ml medical syringes created a compact and economical experimental column (see Figs. 2 and 3), while successive portions of the filtrate were collected in 20 ml plastic vials. First experiment: 2 ml syringe (luer lock). For pre-wetting and subsequent filtration, an ash sample weighing approximately 0.2 g was placed between layers of cotton discs. The primary syringe containing the ash was positioned between two others to enhance the structure and create additional water volume that could be loaded simultaneously. The lower syringe held extra filter material. Overnight, all the water filtered through the ash. The second portion of water was not accepted because the water stopped flowing through the syringe due to the excessively thick layer of ash. The second experiment utilized a 5 ml syringe with an ash weight of about 0.2 g. A reinforced plastic tube with a specified diameter of 8 x 2.5 mm (Fig. 3) extended the column, which was positioned vertically in a laboratory stand. Although passing water in 5 portions of 5 ml was initially lengthy, with time, increasing the portion to 20 ml has no delay - water flow was more intense. The planned volume of 125 ml of water was passed within 3–4 hours. Before the following experiments, the ash loading per cross-sectional area of the experimental column was calculated (Table 2 , rows 1 and 2). In option 2, the cross-sectional area was nearly doubled compared to option 1. Then, in option 3, the ash portion was reduced by half. Consequently, the column's cross-sectional area was approximately 1.0 cm², with the ash loading per cross-sectional area capped at about 1.0 kg/m². Table 1 – Description of the change in mass of samples during the ashing process Sample Dry material, kg Total ash, g Ash/Dry, g/kg Ash code Wood II 0.36 0.98 2.72 II I 0.36 0.89 2.47 I I A 0.36 0.84 2.32 III III 0.36 1.11 3.08 IV IV A 0.10 0.30 3.0 V IV B 0.10 0.34 3.4 VI IV C 0.20 0.54 2.7 VII 2.80 ± 0.37 96/36 Forest litter A 0.033 0.9 28.6 96/36-A B 0.041 2.0 47.6 96/36-B C 0.025 4.8 192.3 96/36-C Table 2 – Ash loading parameters for different experimental conditions N Syringe volume Inner diameter, mm Syringe cross-sectional area, mm 2 Sample mass, g Conversion coefficient per m 2 Ash mass per unit surface area, g/m 2 1 2 ml 82 52.8 0.2154 18940 4080 2 5 ml 11.4 102.1 0.2154 9795 2110 3 5 ml 11.4 102.1 0.105 9794 1028 Based on option 3, ash studies were conducted for sample I, where the water flow was faster than in option 2. The subsequent experiments for samples II and III were carried out simultaneously—all subsequent experiments adhered to option 3, utilizing 5 ml syringes and approximately 0.1 g of ash. Since the task involved washing out a wide range of volumes, the first 5 ml portions were administered five times, followed by 20 ml portions also administered five times. After each experiment, water samples were collected in separate bottles, totaling ten. The first bottle in each set contained a slightly smaller volume because some water moistened the column material. Sampling data is provided in Table 3 , which presents the cumulative volume of filtered water obtained for each step (vial). Balance in the sample activity Filtrate samples were prepared to measure the 90 Sr content directly using a Quantulus 1220™ liquid scintillation spectrometer and the Cerenkov counting method to estimate the fraction of activity washed out of the sample due to the described experiment. To determine the residual 90 Sr activity after the filtration procedure, the ash (wood) sample residues were dissolved by adding 1M HNO 3 . If necessary, a few drops of H 2 O 2 were added to clarify the resulting solution. Measurement of Sr activity The measurement scenario indicated that the activity 90 Sr significantly exceeded that of 137 Cs. Based on a Quantulus 1220™ liquid scintillation spectrometer, the Cerenkov counting method accounts for the color quenching effect (Buzynnyi, 2023) [ 18 ]. To standardize the volume in the first five portions of each set, the filtrate was diluted to 20 ml using distilled water. Measurements of the filtrates conducted immediately after the experiment revealed a low counting rate; however, subsequent measurements, even after a day, showed a rapid increase in the counting rate. This increase is attributed to the accumulation of 90 Y, suggesting that primarily, only 90 Sr was supplied with water. After two days, we could assess the results more effectively, considering the accumulation and the final results were obtained later when the measurements were repeated after nearly two weeks, at which point 90 Sr and 90 Y were in equilibrium. Final estimates of 90 Sr in the vial indicated uncertainty below 10%. The activity of 90 Sr in residual ash samples from forest litter was evaluated using a solid-state beta spectrometer produced by Atom Komplex Prylad [19]. Due to the notable 90 Sr activity, the measurement uncertainty stayed below 20%. Measurement of 137 Cs activity An ORTEC semiconductor spectrometer (MCB 918 + HPG detector GMX-25200) featuring a lead protective housing was utilized for measurements. The measurement of 137 Cs content commenced with samples that had, as anticipated, the highest 137 Cs activity, specifically the litter (layer C). Due to the limited sample volume and low 137 Cs activity, it was necessary to study a combined cumulative sample. To accomplish this, 10 vials from each experiment were arranged in a 1-liter Marinelli vessel positioned in the lower part around the circumference. This method was justified because we were primarily interested in evaluating the total leaching of 137 Cs. Calibration was conducted using a certified Be-261 source. Results Table 3 shows each sample vial's cumulative water volume and 90 Sr activity results. Table 4 presents the cumulative values of 90 Sr and 137 Cs activity, specifically the cumulative leaching activity over 10 steps, the residual 90 Sr and 137 Cs activity, and the balance of 90 Sr and 137 Cs activity within the samples, as well as the calculated percentage of leached activity. The fraction of leached 90 Sr activity was calculated for each ash sample, whereas the leached 137 Cs activity was measured in ash samples obtained from forest litter. In wood ash samples, the fraction of 137 Cs activity was measured only in high-activity ash samples – S-VI and S-VII (89 ± 4%). The estimated leached fraction of 137 Cs for other wood ash samples was also approximately 89%. According to the data in Table 3 , Figs. 4 (wood) and 5 (forest litter) show the cumulative 90 Sr leaching with each portion of water for each ash sample studied. The leaching rate of 137 Cs was studied in just one sample set, specifically the litter and layer C, where the 137 Cs content was measured for each of the 10 portions of water washed from a distinct portion of ash. It is similar to the leaching rate 90 Sr, but near-complete saturation occurs during the initial five of the five ml samples. Using the data above, it can be concluded that burning wood and forest litter in the CEZ leads to ash becoming a significant secondary source of local environmental pollution, particularly affecting groundwater. According to estimates by Yoschenko et al. (2024) [ 8 ], the reserves of 90 Sr in wood outside the trenches containing buried radioactive waste in the PTLRW "Red Forest" area amounted to 23 GBq/ha. Even with the combustion (conversion to ash) of 10% of the wood and leaching from the ash, 10% of 90 Sr per year becomes available for water migration. On each hectare of burned area, (23×0.1×0.3 = 0.69) 0.69 GBq of 90 Sr is available for migration with water. The corresponding fraction of 90 Sr available for water migration over the entire burned area of 554 km² (55400 ha) in 2020 (Hu et al., 2023; Hu et al., 2024) [ 1 , 2 ] is (554×100×0.69 = 38226) GBq, which is approximately 17 times higher than the 90 Sr reserves in the water of the CNPP’s cooling pond before its decommissioning − 2200 GBq (cite this) [20]. Within the area of the burial trenches, the 90 Sr reserves in wood reach 560 GBq/ha (Yoschenko et al., 2024) [ 8 ], which is nearly 25 times higher than in the surrounding territory. The estimates provided above are solely for pinewood ashes. When considering the recent 90 Sr distribution forecast in the forest (Pinus sylvestris L.) ecosystem [7], refer to the introduction; forest litter constitutes a comparable portion, approximately 70%, compared to pinewood (14/20 = 0.7). Table 3 – Data on the leaching of 90 Sr activity from wood ash and forest litter with water Sample N 1 2 3 4 5 6 7 8 9 10 Wood samples S II V, ml 3.4 8.5 13.3 18.4 23.3 43.5 62.6 83.9 104.5 121.1 A, Bq 2.9 8.0 11.8 17.4 22.0 26.0 28.0 29.9 30.9 31.6 S III V, ml 3.8 8.0 12.9 17.9 22.9 43.1 62.6 83.2 103.5 124.4 A, Bq 2.7 7.4 12.6 14.4 15.1 17.0 17.8 18.4 18.9 19.4 S IV V, ml 3.76 8.79 13.8 18.7 23.7 43.3 62.6 82.1 103.4 124.7 A, Bq 0.6 1.0 1.4 1.5 1.7 2.3 2.9 3.4 3.8 4.2 S V V, ml 3.8 8.8 13.7 18.7 23.7 45.1 64.2 84.1 102.9 123.2 A, Bq 1.8 4.9 7.8 10.3 12.8 23.2 28.9 31.8 33.4 34.4 S VI V, ml 3.8 8.8 13.7 18.7 23.7 45.1 64.2 84.1 102.9 123.2 A, Bq 13.2 23.3 31.4 36.8 41.8 52.1 60.6 68.3 81.3 90.8 S VII V, ml 3.3 8.5 12.9 17.9 22.9 43.0 64.0 84.4 104.0 121.4 A, Bq 4.3 7.9 9.6 11.4 12.7 19.0 23.2 28.4 34.1 38.3 Forest litter 96/36 A V, ml 4.2 9.0 14.8 19.1 24.0 43.9 64.1 84.6 102.7 123.7 A, Bq 1.3 2.3 3.0 3.5 3.9 4.8 5.5 6.0 6.3 6.8 B V, ml 5.8 10.9 15.8 21.4 27.0 47.8 68.6 88.1 108.4 127.8 A, Bq 2.2 3.6 4.9 6.1 7.0 9.1 10.5 11.1 11.8 12.3 C V, ml 4.0 9.1 14.1 19.1 24.1 45.6 65.9 86.1 107.0 128.1 A, Bq 15.7 30.3 36.8 40.5 43.3 50.8 54.9 58.9 61.2 64.0 Table 4 – Cumulative leaching ( 90 Sr vs 137 Cs) from ash sample with water (V ≈ 125ml) Sample, code Ash code Weight of ash, g (~) Nuclide Washed, Bq Residue, Bq Total, Bq Washed up, % Wood I S-II 0.2 90 Sr 31.6 104.0 135.6 23.3% 137 Cs 0.36 < 0.05 ≈ 89% Wood I S-III 0.2 90 Sr 19.4 98.0 117.4 16.5% 137 Cs 0.41 < 0.05 ≈ 89% Wood II S-IV 0.1 90 Sr 4.2 12.0 16.2 25.9% 137 Cs 0.37 < 0.05 ≈ 89% Wood III S-V 0.1 90 Sr 34.4 70.0 104.4 33.0% 137 Cs 0.79 < 0.05 ≈ 89% Wood IV S-VI 0.1 90 Sr 90.8 251.0 341.8 26.6% 137 Cs 1.59 0.2 1.79 89 ± 4% Wood IV S-VII 0.1 90 Sr 38.3 280.0 318.3 12.0% 137 Cs 2.0 0.23 2.23 89 ± 3% 96/36 A A 0.1 90 Sr 6.8 55.9 62.7 10.8% 137 Cs 2.8 5.2 8.0 35.0 ± 2.5% 96/36 B B 0.1 90 Sr 12.3 78.8 91.8 13.5% 137 Cs 6.5 80 86.5 7.5 ± 1.5% 6/36 C C 0.17 90 Sr 64.0 494 558 11.5% 137 Cs 8.0 715 723 1.1 ± 0.5% Analysis of the dynamics of the Sr activity in the observation wells water A map of the fire spread area from 2020 within a 10 km zone is depicted in Fig. 6 (in color). Figure 6 illustrates the lines of equal pressure and the direction of groundwater movement, indicated by red arrows. As shown, groundwater movement in the fire area at the "Red Forest" PTLRW is directed northeast. Wells K-2/1 and K-2/2 are situated within the 2020 fire zone. The dynamics of changes in the specific activity of 90 Sr in groundwater samples from wells K-2/1 and K-2/2 are presented in Figs. 7 and 8 based on research data from the SSE Ecocentre. In groundwater samples from well K-2/1, an increase in 90 Sr concentrations is noted starting at the end of 2022, rising from 15 to 98 Bq/l, a 2–6 fold increase. In well K-2/2, the rise in the specific activity of 90 Sr began in October 2022, increasing from 2.9 to 180 Bq/l, equivalent to a 10-60-fold increase (Fig. 8 ). The rise in 90 Sr concentrations was likely caused by leaching with atmospheric precipitation that fell on ash and debris from wood and forest litter burned during the fire. Groundwater contamination occurs when atmospheric precipitation infiltrates the soils of the aeration zone. In this area, the aeration zone thickness is 3–4 m. The hypothesis regarding the effect of fires on groundwater contamination, observed in wells K-2/1 and K-2/2, is supported by previous predictive calculations carried out under similar conditions (Starikov et al., 2012) [21]. The thickness of the aeration zone in the modeling was 2 m. The inflow of 90 Sr from the active layer through the aeration zone was modeled to the aquifer. The distribution coefficient was determined at the level of 1 ml/h. According to calculations, the main predicted inflow of 90 Sr to the groundwater level occurs after 200 days. About 97% of the total inflow into the aquifer falls during 200–365 days. Considering the difference in the power of the aeration zone, the assumption about the impact of burns on groundwater contamination observed in the wells, as mentioned above, seems realistic. Conclusions Laboratory experiments demonstrated that burning 1 kg of pinewood from the Chornobyl zone (N = 6) results in an ash residue of 2.80 ± 0.37 g. This yields a 90 Sr concentration in the ash approximately 357 times, with its specific activity ranging from 0.16 to 3.4 kBq/g. When burning one kg of forest litter (morphological layers A, B, and C), approximately 29 g, 48 g, and 192 g of ash were produced. This resulted in a corresponding 90 Sr specific activity approximately 35, 21, and 5 times higher than the input material; the specific activity in the respective layers A, B, and C ash was 0.63, 0.92, and 3.3 kBq/g. According to data, 12 to 33% of the 90 Sr activity in wood ash is washed out with water, and 10.8 to 13.2% of the 90 Sr activity in forest litter ash is washed out. Experiments unveiled that 90 Y leaching is invisible, unlike the studied 90 Sr leaching. The leaching of 137 Cs from wood ash with water was 89 ± 4%, and from the ash of forest litter corresponding morphological layers: A, B, C − 35.0 ± 2.5%, 7.5 ± 1.5%, 1.1 ± 0.5%. Recently, researchers observed an increase in the specific activity of 90 Sr in the water of observation wells drilled at the Chornobyl NPP, located downstream of the groundwater flow from the fire centers and within them. This increase varied from 2 to 60 times, reaching values of 180 Bq/l, which can be attributed to the local impact of recent fires. The interval required to achieve the maximum specific activity of 90 Sr in water was between 200 and 365 days, consistent with the previously projected duration of over 200 days from earlier predictive calculations (Starikov et al., 2012) [21]. The estimates obtained during the laboratory experiment indicate that fires in radionuclide-contaminated territories should be considered a notable source of 90 Sr entering surface and groundwater. This requires appropriate amendments to the regulations for the radioecological monitoring of waters. Declarations Author Contribution MP - idea, curation of research, writing the manuscript; MB - experimental research, LSC measurements, data curation, preparing and writing the manuscript; SK- presenting data on 90Sr in water, discussing results and the manuscript;NS- discussion results and a draft of the manuscript; IK- discussion results and a draft of the manuscript; LM- gamma-spectroscopy research, discussing results and the manuscript Acknowledgement The authors thank Khan V. Ye-I., Chikur L. B., and Palamar L. A. for determining the concentrations of 90Sr in individual ash and wood samples. Data Availability All data generated or analysed during this study are included in this published article [and its supplementary information files]. References Hu, J. et al. Application of a Tuning-Free Burned Area Detection Algorithm to the Chornobyl Wildfires in 2022. Sci. Rep. 13, 5236. doi:10.1038/s41598-023-32300-5 (2023). Hu, J. et al. Tuning-Free Moderate-Scale Burned Area Detection Algorithm A Case Study in Chornobyl-Contaminated Region. Int. J. Remote Sens. 45, 2444−2461. doi:10.1080/01431161.2024.2331976 (2024). Igarashi, Y. et al. Effects of Large-Scale Wildfires on the Redistribution of Radionuclides in the Chornobyl River System. Environmental Science & Technology . 58, 20630−20641. doi:10.1021/acs.est.4c07019 (2024). Hygienic requirements for drinking water intended for human consumption: state health and safety standards and rules DSanPiN 2.2.4-171-10, Кyiv, 2010, 32. URL: https://zakon.rada.gov.ua/laws/show/z0452-10#Text. Bruchertseifer, F., Steiner, M., Hiersche, L., Savkin, B., Poppitz-Spuhler ,A., Wirth, E. Dynamics of strontium-90 in forest ecosystems. Radioprotection, 37(Cl), 409- 413. doi:10.1051/radiopro/2002077 (2002). Buzinny, M., Los, I., Shepelevich, K. The distribution of 137 Cs and 90 Sr in the biomass of pine trees planted in 1987–1988 in the near zone of the Chernobyl nuclear power plant. Applied Radiation and Isotopes . 52 ( 4 ) , 905-910. doi:10.1016/S0969-8043(99)00142-6 (2000). Holiaka, D. M., Levchuk, S. E., Yoschenko, V. I., Yoschenko, L. V., Holiaka, M. A. The model of biogenic fluxes and depots of 90 Sr in contaminated pine stands. Scientific Bulletin of UNFU . 29 (9), 81-86. doi:10.36930/40290914 (2019). Yoschenko, V., Thiry, Y., Holiaka, D., Levchuk, S., Kashparov, V., Nanba, K. Long-term changes in 90 Sr pools of Scots pine biomass in the Chornobyl Red Forest. Journal of Environmental Radioactivity . 273, 107366. doi:10.1016/j.jenvrad.2023.107366 (2024). Alicja, K., Grzegorz, C. Strontium leaching from municipal waste subjected to incineration. Environ Geochem Health. 46 , 220. doi:10.1007/s10653-024-01998-1 (2024). Bodí, M. B., Mataix-Solera, J., Doerr, S. H., Cerdà, A. The Wettability of Ash from Burned Vegetation and Its Relationship to Mediterranean Plant Species Type, Burn Severity and Total Organic Carbon Content. Geoderma. 160, 599−607. doi:10.1016/j.geoderma.2010.11.009 (2011). Sánchez-García, C. et al. Chemical Characteristics of Wildfire Ash across the Globe and Their Environmental and Socioeconomic Implications. Environ. Int. 178, 108065. doi:10.1016/j.envint.2023.108065 (2023). Pereira, P., Úbeda, X., Martin, D., Mataix-Solera, J., Cerdà, A., Burguet, M. Wildfire Effects on Extractable Elements in Ash from a Pinus pinaster Forest in Portugal. Hydrol. Process. 28, 3681- 3690. doi:10.1002/hyp.9907 (2014). Earl, S. R., Blinn, D. W. Effects of Wildfire Ash on Water Chemistry and Biota in South-Western U.S.A. streams. Freshwater Biology. 48, 1015-1030. doi:10.1046/j.1365-2427.2003.01066.x (2003). Kovalenko, I. O. et al. Factors influencing the increased 90 Sr radioisotope migration in highly alkaline groundwater at Chornobyl NPP site. Journal of Environmental Radioactivity . 275, 107431. doi:10.1016/j.jenvrad.2024.107431 (2024). Buzinny, M., Likhtarev, I., Los, I., Talerko, N., Tsigankov, N. 14 C Analysis of Annual Tree Rings from the Vicinity of the Chernobyl NPP. Radiocarbon . 40 (1) , 373-379. doi:10.1017/S0033822200018257 (1997). Buzinny, M. Radioactive Graphite Dispersion in the Environment in the Vicinity of the Chernobyl Nuclear Power Plant. Radiocarbon . 48(3) , 451-458. doi:10.1017/S003382220003887X (2006). Buzynnyi, M., Romanenko, O., Mykhailova, L., Lytvynko, A., Panasiuk, M. Traces of 14 C emissions for the operation period of two Ukrainian NPPS: Rivne and Chornobyl. Radiocarbon . 65(2) , 335-342. doi:10.1017/RDC.2023.3 (2023). Buzynnyi M. Practical aspects of the application of cherenkov counting method with the correction of sample’s color quenching. Environment & Health. 2(107),40-46. doi:10.32402/dovkil2023.02.040 (2023) Beta spectrometer SEB-01. Operation manual. RPE "ATOM KOMPLEX PRYLAD". http://www.akp.com.ua/index.php?option=com_content&view=article&id=119&Itemid=106 Dzhepo, S.P., Skal’skii, A. S. Radioaсtive Contamination of Groundwater within the Chernobyl Exclusion Zone in Chernobyl Disaster and Groundwater (ed. Shestopalov, V.) 25-71 (A.A. Balkema Publisher, 2002). https://books.google.com.ua/books?id=MUl16_H8MksC Starikov, N. B., Alfyorov, A. M., Panasyuk, М. I., Lytvyn, I. A., Liushnya E. P. Simulation of migration of radionuclides in the zone of aeration at the industrial site of the “Ukryttya” object. Safety Issues of Nuclear Power Plants and Chernobyl . 18, 96-102 http://dspace.nbuv.gov.ua/handle/123456789/113337 (2012). Additional Declarations No competing interests reported. Supplementary Files SuplementaryFile.docx Cite Share Download PDF Status: Published Journal Publication published 22 Apr, 2025 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 06 Feb, 2025 Reviews received at journal 05 Feb, 2025 Reviewers agreed at journal 03 Feb, 2025 Reviews received at journal 02 Feb, 2025 Reviewers agreed at journal 02 Feb, 2025 Reviewers invited by journal 02 Feb, 2025 Editor assigned by journal 02 Feb, 2025 Editor invited by journal 02 Feb, 2025 Submission checks completed at journal 30 Jan, 2025 First submitted to journal 29 Jan, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-5926363","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":410212402,"identity":"e1a2656d-d68d-42d3-a658-afa0b77be4d2","order_by":0,"name":"Mykola Panasiuk","email":"","orcid":"","institution":"Institute for Safety Problems of Nuclear Power Plants, National Academy of Sciences of Ukraine","correspondingAuthor":false,"prefix":"","firstName":"Mykola","middleName":"","lastName":"Panasiuk","suffix":""},{"id":410212405,"identity":"a1a7c896-621c-4c21-861b-fd5b04378cdf","order_by":1,"name":"Mykhailo Buzynnyi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABAElEQVRIiWNgGAWjYDACZgY2IGnBYAAkDwCxHEjwwAPCWiTgWozBWhLw24PQAgKJDSASnxbdduZnD35USDCYS6Q/PFy443D6/LDDD4G22MnpNmDXYnaYzdyw54wEg+WMhITDM88czt14O80AqCXZ2OwALi08bBK8bUCH3Ug4cJi3DahldgJIy4HEbXi0SP79B9KS2ADSkm44O/0DQS3SvA0gLckMIC0J8tI5hGxhM5OWOSbBY9nzDKQl3XCDdE7BgQQDPH45f/iZ5JsaGzlz9vTHn3nbrOXlZ6dv/vChwk4OlxYY4IHSzQwGYJUGuJWigzoG+QbiVY+CUTAKRsHIAABw6l9Xb+bybQAAAABJRU5ErkJggg==","orcid":"","institution":"State Institution O.M. Marzieiev Institute of Public Health of National Academy of Medical Sciences of Ukraine","correspondingAuthor":true,"prefix":"","firstName":"Mykhailo","middleName":"","lastName":"Buzynnyi","suffix":""},{"id":410212407,"identity":"315bd470-f95f-47a7-b152-9e8762e7d046","order_by":2,"name":"Serhii Kirieiev","email":"","orcid":"","institution":"State Specialized Enterprise Ecocentre","correspondingAuthor":false,"prefix":"","firstName":"Serhii","middleName":"","lastName":"Kirieiev","suffix":""},{"id":410212408,"identity":"9b201b87-6632-47c0-9aa9-660bf2c419f5","order_by":3,"name":"Natalia Sosonna","email":"","orcid":"","institution":"Institute for Safety Problems of Nuclear Power Plants, National Academy of Sciences of Ukraine","correspondingAuthor":false,"prefix":"","firstName":"Natalia","middleName":"","lastName":"Sosonna","suffix":""},{"id":410212410,"identity":"00139850-a2d7-4652-a9b6-49c71d272d28","order_by":4,"name":"Ihor Kovalenko","email":"","orcid":"","institution":"Institute for Safety Problems of Nuclear Power Plants, National Academy of Sciences of Ukraine","correspondingAuthor":false,"prefix":"","firstName":"Ihor","middleName":"","lastName":"Kovalenko","suffix":""},{"id":410212412,"identity":"f41111e6-aabe-4deb-803f-4208c101e03d","order_by":5,"name":"Liubov Mykhailova","email":"","orcid":"","institution":"State Institution O.M. Marzieiev Institute of Public Health of National Academy of Medical Sciences of Ukraine","correspondingAuthor":false,"prefix":"","firstName":"Liubov","middleName":"","lastName":"Mykhailova","suffix":""}],"badges":[],"createdAt":"2025-01-29 19:53:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5926363/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5926363/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-025-99095-5","type":"published","date":"2025-04-22T15:57:49+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":75291623,"identity":"b9b0db0c-ccc1-40cf-9fd5-89d4f347ef55","added_by":"auto","created_at":"2025-02-03 06:02:55","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":72578,"visible":true,"origin":"","legend":"\u003cp\u003eBurns after the 2020 fires at the “Red Forest” PTLRW site\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5926363/v1/f985305be32f59d52cde7863.jpg"},{"id":75291634,"identity":"8e34e91b-1ca6-4ba2-b4d4-9d5124a50a3b","added_by":"auto","created_at":"2025-02-03 06:02:57","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":14938,"visible":true,"origin":"","legend":"\u003cp\u003eSyringe column (2 ml)\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5926363/v1/d6dee4c71d901b6bddbb5d31.jpg"},{"id":75291637,"identity":"0ce513b6-e967-4c4b-b469-0ede7af8154e","added_by":"auto","created_at":"2025-02-03 06:02:57","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":11258,"visible":true,"origin":"","legend":"\u003cp\u003eSyringe column (5 ml)\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5926363/v1/b3c822eaea111fd06eda1e10.jpg"},{"id":75291643,"identity":"e0e6efca-6c9c-4d62-b39b-f95584f250c6","added_by":"auto","created_at":"2025-02-03 06:02:58","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":84043,"visible":true,"origin":"","legend":"\u003cp\u003eCumulative \u003csup\u003e90\u003c/sup\u003eSr activity leached from a pinewood ash sample with water, Bq\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5926363/v1/e59633af2f341e29f490801d.jpg"},{"id":75291629,"identity":"bf5dcb8b-5a71-4469-9f8b-af360890c69f","added_by":"auto","created_at":"2025-02-03 06:02:56","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":64192,"visible":true,"origin":"","legend":"\u003cp\u003eCumulative \u003csup\u003e90\u003c/sup\u003eSr activity leached from a forest litter ash sample with water, Bq\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5926363/v1/936772366cae53ca61e1a6f6.jpg"},{"id":75291630,"identity":"cdf3c92f-1a57-433d-989f-1cb3f14bde9f","added_by":"auto","created_at":"2025-02-03 06:02:57","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":135810,"visible":true,"origin":"","legend":"\u003cp\u003eDirection of the spread of contaminated groundwater from fires in 2020 in the “Red Forest” PTLRW area on the Landsat satellite image dated September 20, 2020.\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5926363/v1/022c7c88522ecefe8f4363c3.jpg"},{"id":75292704,"identity":"83efd69e-cd7f-41d2-911f-91ceb031fbc7","added_by":"auto","created_at":"2025-02-03 06:10:55","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":70794,"visible":true,"origin":"","legend":"\u003cp\u003eDynamics of change in specific activity of \u003csup\u003e90\u003c/sup\u003eSr in drilled well K-2/1, located downstream of groundwater flow from the burn site in 2020 (according to data from the SSE Ecocentre)\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5926363/v1/155ad1fb2944c01d3f35616c.jpg"},{"id":75291618,"identity":"c5a57682-043b-47d9-a242-cd38dcf88d4a","added_by":"auto","created_at":"2025-02-03 06:02:55","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":77168,"visible":true,"origin":"","legend":"\u003cp\u003eDynamics of change in specific activity of \u003csup\u003e90\u003c/sup\u003eSr in drilled well K-2/2, located downstream of groundwater flow from the burn site in 2020 (according to data from the SSE Ecocentre)\u003c/p\u003e","description":"","filename":"8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5926363/v1/d94ee9acdfaff7ae98da8863.jpg"},{"id":81570265,"identity":"8320cc8a-c18b-4a83-ad77-dcb62af20309","added_by":"auto","created_at":"2025-04-28 16:13:01","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1580453,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5926363/v1/9eeea030-f0c2-4938-8f29-3dcdd56adaa6.pdf"},{"id":75291626,"identity":"bb393a91-4fcc-457a-85f9-d6af80f9ee40","added_by":"auto","created_at":"2025-02-03 06:02:56","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":89430,"visible":true,"origin":"","legend":"","description":"","filename":"SuplementaryFile.docx","url":"https://assets-eu.researchsquare.com/files/rs-5926363/v1/a89e5f53537fc4ea48c14696.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eRegarding the Possible Impact of Forest Fires on the Radioactive Pollution of Groundwater in the Chornobyl Exclusion Zone\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAs trees grow, the forests in the Chornobyl Exclusion Zone accumulate significant levels of \u003csup\u003e90\u003c/sup\u003eSr activity in their wood. Fires are common due to the limited control over the forested areas of the Chornobyl Exclusion Zone. The largest fires (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) occurred over an area of 554 km\u0026sup2; in 2020 (Hu J. et al., 2023; Hu J. et al., 2024) [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. It is known that fires accompanied the military occupation of the CEZ by Russian troops in 2022.\u003c/p\u003e \u003cp\u003eWhen wood burns, ash forms and the concentration of radionuclides in the ash significantly increases compared to the wood. Radionuclides in ash become available for leaching through atmospheric precipitation and intense migration with water, including infiltration into groundwater. Therefore, recent fires in the Chornobyl NPP area have heightened the secondary redistribution of radioactivity and its transfer, resulting in additional surface and groundwater contamination.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe authors (Igarashi et al., 2024) [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] demonstrated that emissions of \u003csup\u003e137\u003c/sup\u003eCs and \u003csup\u003e90\u003c/sup\u003eSr during burning experiments at the Chornobyl fire site reached up to 4.2% of the \u003csup\u003e137\u003c/sup\u003eCs and 2.9% of the \u003csup\u003e90\u003c/sup\u003eSr stocks. This suggests that most \u003csup\u003e137\u003c/sup\u003eCs and \u003csup\u003e90\u003c/sup\u003eSr remained in the charred residues on the ground after the fire. An analysis of results from a systematic study conducted in the fire-affected zone of the Chornobyl NPP revealed that the water-soluble fractions of \u003csup\u003e137\u003c/sup\u003eCs and \u003csup\u003e90\u003c/sup\u003eSr in charred residues were significantly higher than those in the soil, which indicates their increased mobility (Igarashi et al., 2024) [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The geometric means of the water-soluble and exchangeable forms of \u003csup\u003e137\u003c/sup\u003eCs in the charred residues were 2.2% and 17.4%, respectively. The geometric means for the water-soluble and exchangeable forms of \u003csup\u003e90\u003c/sup\u003eSr in the charred residues were 5.4% and 27.5%, respectively. However, the extent of burnout of the charred residues used in this study is unknown. Therefore, the water-soluble fraction of \u003csup\u003e90\u003c/sup\u003eSr content could be significantly higher for ashes with more incredible burnout.\u003c/p\u003e \u003cp\u003eHowever, no significant increase in the concentration of \u003csup\u003e137\u003c/sup\u003eCs in the river catchment area of Chornobyl was observed after the forest fires. However, \u003csup\u003e90\u003c/sup\u003eSr concentrations increased significantly, periodically exceeding the permissible levels for drinking water (2 Bq/l) in Ukraine (DSanPiN, 2010) [4]. Thus, in the surface water of the Sakhan River, the concentrations of dissolved \u003csup\u003e90\u003c/sup\u003eSr before the 2020 fire ranged mainly from 0.22 to 3.61 Bq/l, increasing from 0.35 to 11.0 Bq/l after the forest fires. The authors explain this increase by hydrologically driven transport processes of soluble \u003csup\u003e90\u003c/sup\u003eSr from charred remains and the soil surface into the river during snowmelt and precipitation.\u003c/p\u003e \u003cp\u003eStudies of the forest ecosystem conducted in Bavaria (F. Bruchertseifer et al., 2002) [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], where most of the \u003csup\u003e90\u003c/sup\u003eSr is attributed to nuclear test fallouts, demonstrated that the majority remains in the forest's organic horizons, indicating a very low migration rate for an extended period after the fallout.\u003c/p\u003e \u003cp\u003eA study of young trees planted in the \"Red Forest\" area (Buzinny et al., 2000) evidenced the high contamination of \u003csup\u003e137\u003c/sup\u003eCs and \u003csup\u003e90\u003c/sup\u003eSr, with a significant contrast in the distribution in the cross-section [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The authors (Holiaka et al., 2019) [7] calibrated a simulation model for the distribution of \u003csup\u003e90\u003c/sup\u003eSr in elements of the forest ecological system (\u003cem\u003ePinus sylvestris\u003c/em\u003e L.) based on the results of their recent experimental studies. According to the 2025 forecast generated from the model, wood contains 20% of the forest litter, and 14% of the \u003csup\u003e90\u003c/sup\u003eSr activity is concentrated in the forest bio-system. Subsequent studies of the wood of the \u0026ldquo;Red Forest\u0026rdquo; conducted between 2005 and 2018 showed (Yoschenko et al., 2024) [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e8\u003c/span\u003e] that with a general decrease in the specific activity of \u003csup\u003e90\u003c/sup\u003eSr in all compartments of the tree biomass, its total reserves in wood increased from 18 to 23 GBq/ha, respectively. Corresponding estimates based on the results of studies of trees planted in the trenches of the \"Red Forest\" wood burials show that the \u003csup\u003e90\u003c/sup\u003eSr reserves here increased almost 6-fold, reaching approximately 560 GBq/ha, which is about (19\u0026thinsp;\u0026plusmn;\u0026thinsp;9)% of the total reserve in the trench zone.\u003c/p\u003e \u003cp\u003eThe aim of the study (Alicja, K., Grzegorz, C., 2024) [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] was to determine the content and leaching capacity of strontium (Sr) in ash obtained from the combustion of household waste in domestic furnaces. For ash derived from various materials, the authors assessed the total Sr content, considering the strontium fractions in terms of their leaching with water\u0026mdash;specifically, phyto-available and ion-exchange capacities. The study revealed that the concentration of Sr in ash produced from the combustion of traditional fuels, alternative fuels, and household waste ranges from 0.1 to 1.0 g/kg. The most mobile fraction leached with water ranged from 1.3% to nearly 91% of the total Sr content.\u003c/p\u003e \u003cp\u003eAfter a forest fire, a layer of ash and charred material quickly forms on the ground. This layer will gradually diminish and be redistributed by precipitation, wind, or animals through partial dissolution and incorporation into the soil. Ash can either increase or decrease water runoff on the surface after a fire, depending on the ash and soil properties, as well as the thickness of the ash layer. The study's authors (Body et al., 2011) [10] focused significantly on the wettability of ash, which varies from low to extremely high, determined by the burning temperature and depth and the organic carbon content. The interaction within the water-ash-soil system largely depends on soil properties.\u003c/p\u003e \u003cp\u003eThe study's authors (S\u0026aacute;nchez-Garc\u0026iacute;a, 2023) [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e11\u003c/span\u003e] argue that forest fire ash can pose significant risks to society because of the concentration of potentially harmful chemical components. After examining 148 samples (42 types) of ash, the authors found that most samples exhibited an alkaline reaction (mean pH 8.8, range 6 to 11.2). Their main components were organic carbon (mean value: 204 g/kg), calcium, aluminum, and iron (mean values: 47.9, 17.9, and 17.1 g/kg, respectively).\u003c/p\u003e \u003cp\u003eBased on ash samples from a pine forest fire in Portugal, (Pereira et al., 2014) [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e12\u003c/span\u003e] determined that the ash filtrate had a higher pH and conductivity and was enriched in Ca2+, Mg2+, Na+, K+, and Si4\u0026thinsp;+\u0026thinsp;ions. Additionally, this study found that the solubility of potassium and calcium in charred residues was 1.7 times and 9.7 times higher, respectively than in unburned forest litter. In this regard, (Igarashi et al., 2024) stated that the fate of \u003csup\u003e137\u003c/sup\u003eCs and \u003csup\u003e90\u003c/sup\u003eSr in charred residues is currently unknown, but the dynamics of \u003csup\u003e137\u003c/sup\u003eCs and \u003csup\u003e90\u003c/sup\u003eSr in the environment are similar to those of K and Ca.\u003c/p\u003e \u003cp\u003eThe authors (Earl, S. R.; Blinn, D. W., 2003) [13] investigated the impact of fire ash on water quality in the Gila River drainage in southwestern New Mexico, USA, over a 5-year period. Following the introduction of fire ash, the water showed elevated concentrations of ammonium, nitrate, dissolved reactive phosphate (SRP), potassium, and alkalinity.\u003c/p\u003e \u003cp\u003eIncreased mineralization leads to a rise in groundwater's ionic strength. This diminishes soils' sorption properties, further contributing to augmented radionuclide migration (Kovalenko, I. O. et al., 2024) [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThis study aimed to identify the characteristics of wood ash and forest litter ash, the corresponding activity concentrations of \u003csup\u003e137\u003c/sup\u003eCs and \u003csup\u003e90\u003c/sup\u003eSr, and the extent of their leaching from wood and forest litter ash due to two years of rainfall.\u003c/p\u003e \u003cp\u003eThe information above assessed the situation at the site of the fires in the CEZ and their impact on the radioactive contamination of groundwater. The activity concentrations of 137Cs and \u003csup\u003e90\u003c/sup\u003eSr in wood, forest litter, ash, and filtrate were measured to achieve this goal. The degree of \u003csup\u003e137\u003c/sup\u003eCs and \u003csup\u003e90\u003c/sup\u003eSr leaching from wood and forest litter ash was determined, and the dynamics of \u003csup\u003e90\u003c/sup\u003eSr in groundwater samples from some wells located within the burnt areas of the \"Red Forest\" TRW site were analyzed.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eWood and forest litter samples\u003c/h2\u003e \u003cp\u003eFor laboratory studies of wood ash and forest litter, we used the dry residue from samples collected in the Chornobyl Exclusion Zone in 1996, 2013, and 2021, which had been previously studied (Buzinny et al., 1997; Buzinny, 2006; Buzynnyi et al., 2023) [15, 16, 17]. Wood samples (Pinus sylvestris L.) were taken at two sites near the Yaniv railway station. Forest litter samples were gathered near the Prypiat oil base, site 96/36. They displayed characteristic morphological layers: A \u0026ndash; a light upper layer of fresh litter, B \u0026ndash; a thick layer with partial structural changes in the material, and C \u0026ndash; a lower layer that has undergone severe decomposition. Given the long interval between wood samplings, we observed changes in the specific activity and ratio of radionuclides. Over time, the activity of \u003csup\u003e90\u003c/sup\u003eSr increased while \u003csup\u003e137\u003c/sup\u003eCs decreased, which is particularly significant in the most contaminated areas of the CEZ (Buzinny et al., 2000; Yoschenko et al., 2024) [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Wood samples I, II, and III were collected in 2013, while wood sample IV corresponded to one tree from 2021.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eAshing of samples\u003c/h3\u003e\n\u003cp\u003eWood samples I, II, and III represented chopped wood, while wood sample IV - chips. This determined the duration of the final combustion process - chips burned out faster in the conditions of the muffle furnace used. Ash samples were prepared in 2 stages - first, carbonization was carried out (little oxygen), then - ashing (more oxygen). The temperature in both cases was 600\u0026ordm; C. Quantitative data on the ash preparation process are given in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. To control the variability of the process, sample I was repeated as I-A, and sample IV was prepared in three portions with the names of samples IV-A, IV-B, and IV-C. The quality of the ash was assessed as satisfactory: visually, it had a dark gray color or a shade of brown. The average ash content of wood (ash/dry material, g/kg) was 2.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37 (N\u0026thinsp;=\u0026thinsp;7). The ash content coefficients for different layers of the forest litter were A \u0026ndash; 29, B \u0026ndash; 48, and C \u0026ndash; 192 due to the increase in the proportion of mineral fraction in the litter from top (A) to bottom (C). The wide variety of ash content coefficients between samples of different litter layers allowed us to use them as is and not perform repeated samples.\u003c/p\u003e\n\u003ch3\u003eLaboratory experiment on leaching Sr with water from ash\u003c/h3\u003e\n\u003cp\u003eIn preparation for the laboratory experiment, 0.3 to 1.1 g of ash was considered to have been obtained for the various wood samples described above. Disposable 2 ml and 5 ml medical syringes created a compact and economical experimental column (see Figs.\u0026nbsp;2 and 3), while successive portions of the filtrate were collected in 20 ml plastic vials.\u003c/p\u003e\u003cp\u003eFirst experiment: 2 ml syringe (luer lock). For pre-wetting and subsequent filtration, an ash sample weighing approximately 0.2 g was placed between layers of cotton discs. The primary syringe containing the ash was positioned between two others to enhance the structure and create additional water volume that could be loaded simultaneously. The lower syringe held extra filter material. Overnight, all the water filtered through the ash. The second portion of water was not accepted because the water stopped flowing through the syringe due to the excessively thick layer of ash.\u003c/p\u003e \u003cp\u003eThe second experiment utilized a 5 ml syringe with an ash weight of about 0.2 g. A reinforced plastic tube with a specified diameter of 8 x 2.5 mm (Fig.\u0026nbsp;3) extended the column, which was positioned vertically in a laboratory stand.\u003c/p\u003e \u003cp\u003eAlthough passing water in 5 portions of 5 ml was initially lengthy, with time, increasing the portion to 20 ml has no delay - water flow was more intense. The planned volume of 125 ml of water was passed within 3\u0026ndash;4 hours. Before the following experiments, the ash loading per cross-sectional area of the experimental column was calculated (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, rows 1 and 2). In option 2, the cross-sectional area was nearly doubled compared to option 1. Then, in option 3, the ash portion was reduced by half. Consequently, the column's cross-sectional area was approximately 1.0 cm\u0026sup2;, with the ash loading per cross-sectional area capped at about 1.0 kg/m\u0026sup2;.\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\u003e\u0026ndash; Description of the change in mass of samples during the ashing process\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry material, kg\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTotal ash, g\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAsh/Dry, g/kg\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAsh code\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWood\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eII\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eI A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eIII\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eIV\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIV A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eV\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIV B\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eVI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIV C\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eVII\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.80\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e96/36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eForest litter\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.033\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e28.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e96/36-A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.041\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e47.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e96/36-B\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.025\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e192.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e96/36-C\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \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\u003e\u0026ndash; Ash loading parameters for different experimental conditions\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSyringe volume\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eInner diameter, mm\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSyringe cross-sectional area, mm\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSample mass, g\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eConversion coefficient per m\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eAsh mass per unit surface area, g/m\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e52.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.2154\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e18940\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e4080\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5 ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e102.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.2154\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9795\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e2110\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5 ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e102.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.105\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9794\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1028\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\u003eBased on option 3, ash studies were conducted for sample I, where the water flow was faster than in option 2. The subsequent experiments for samples II and III were carried out simultaneously\u0026mdash;all subsequent experiments adhered to option 3, utilizing 5 ml syringes and approximately 0.1 g of ash.\u003c/p\u003e \u003cp\u003eSince the task involved washing out a wide range of volumes, the first 5 ml portions were administered five times, followed by 20 ml portions also administered five times. After each experiment, water samples were collected in separate bottles, totaling ten. The first bottle in each set contained a slightly smaller volume because some water moistened the column material. Sampling data is provided in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, which presents the cumulative volume of filtered water obtained for each step (vial).\u003c/p\u003e\n\u003ch3\u003eBalance in the sample activity\u003c/h3\u003e\n\u003cp\u003eFiltrate samples were prepared to measure the \u003csup\u003e90\u003c/sup\u003eSr content directly using a Quantulus 1220\u0026trade; liquid scintillation spectrometer and the Cerenkov counting method to estimate the fraction of activity washed out of the sample due to the described experiment. To determine the residual \u003csup\u003e90\u003c/sup\u003eSr activity after the filtration procedure, the ash (wood) sample residues were dissolved by adding 1M HNO\u003csub\u003e3\u003c/sub\u003e. If necessary, a few drops of H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e were added to clarify the resulting solution.\u003c/p\u003e\n\u003ch3\u003eMeasurement of Sr activity\u003c/h3\u003e\n\u003cp\u003eThe measurement scenario indicated that the activity \u003csup\u003e90\u003c/sup\u003eSr significantly exceeded that of \u003csup\u003e137\u003c/sup\u003eCs. Based on a Quantulus 1220\u0026trade; liquid scintillation spectrometer, the Cerenkov counting method accounts for the color quenching effect (Buzynnyi, 2023) [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. To standardize the volume in the first five portions of each set, the filtrate was diluted to 20 ml using distilled water. Measurements of the filtrates conducted immediately after the experiment revealed a low counting rate; however, subsequent measurements, even after a day, showed a rapid increase in the counting rate. This increase is attributed to the accumulation of \u003csup\u003e90\u003c/sup\u003eY, suggesting that primarily, only \u003csup\u003e90\u003c/sup\u003eSr was supplied with water. After two days, we could assess the results more effectively, considering the accumulation and the final results were obtained later when the measurements were repeated after nearly two weeks, at which point \u003csup\u003e90\u003c/sup\u003eSr and \u003csup\u003e90\u003c/sup\u003eY were in equilibrium. Final estimates of \u003csup\u003e90\u003c/sup\u003eSr in the vial indicated uncertainty below 10%.\u003c/p\u003e \u003cp\u003eThe activity of \u003csup\u003e90\u003c/sup\u003eSr in residual ash samples from forest litter was evaluated using a solid-state beta spectrometer produced by Atom Komplex Prylad [19]. Due to the notable \u003csup\u003e90\u003c/sup\u003eSr activity, the measurement uncertainty stayed below 20%.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eMeasurement of \u003csup\u003e137\u003c/sup\u003eCs activity\u003c/h2\u003e \u003cp\u003eAn ORTEC semiconductor spectrometer (MCB 918\u0026thinsp;+\u0026thinsp;HPG detector GMX-25200) featuring a lead protective housing was utilized for measurements. The measurement of \u003csup\u003e137\u003c/sup\u003eCs content commenced with samples that had, as anticipated, the highest \u003csup\u003e137\u003c/sup\u003eCs activity, specifically the litter (layer C). Due to the limited sample volume and low \u003csup\u003e137\u003c/sup\u003eCs activity, it was necessary to study a combined cumulative sample. To accomplish this, 10 vials from each experiment were arranged in a 1-liter Marinelli vessel positioned in the lower part around the circumference. This method was justified because we were primarily interested in evaluating the total leaching of \u003csup\u003e137\u003c/sup\u003eCs. Calibration was conducted using a certified Be-261 source.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e shows each sample vial's cumulative water volume and \u003csup\u003e90\u003c/sup\u003eSr activity results. Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e presents the cumulative values of \u003csup\u003e90\u003c/sup\u003eSr and \u003csup\u003e137\u003c/sup\u003eCs activity, specifically the cumulative leaching activity over 10 steps, the residual \u003csup\u003e90\u003c/sup\u003eSr and \u003csup\u003e137\u003c/sup\u003eCs activity, and the balance of \u003csup\u003e90\u003c/sup\u003eSr and \u003csup\u003e137\u003c/sup\u003eCs activity within the samples, as well as the calculated percentage of leached activity. The fraction of leached \u003csup\u003e90\u003c/sup\u003eSr activity was calculated for each ash sample, whereas the leached \u003csup\u003e137\u003c/sup\u003eCs activity was measured in ash samples obtained from forest litter. In wood ash samples, the fraction of \u003csup\u003e137\u003c/sup\u003eCs activity was measured only in high-activity ash samples \u0026ndash; S-VI and S-VII (89\u0026thinsp;\u0026plusmn;\u0026thinsp;4%). The estimated leached fraction of \u003csup\u003e137\u003c/sup\u003eCs for other wood ash samples was also approximately 89%.\u003c/p\u003e \u003cp\u003eAccording to the data in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e4\u003c/span\u003e (wood) and 5 (forest litter) show the cumulative \u003csup\u003e90\u003c/sup\u003eSr leaching with each portion of water for each ash sample studied.\u003c/p\u003e \u003cp\u003eThe leaching rate of \u003csup\u003e137\u003c/sup\u003eCs was studied in just one sample set, specifically the litter and layer C, where the \u003csup\u003e137\u003c/sup\u003eCs content was measured for each of the 10 portions of water washed from a distinct portion of ash. It is similar to the leaching rate \u003csup\u003e90\u003c/sup\u003eSr, but near-complete saturation occurs during the initial five of the five ml samples.\u003c/p\u003e \u003cp\u003eUsing the data above, it can be concluded that burning wood and forest litter in the CEZ leads to ash becoming a significant secondary source of local environmental pollution, particularly affecting groundwater. According to estimates by Yoschenko et al. (2024) [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e8\u003c/span\u003e], the reserves of \u003csup\u003e90\u003c/sup\u003eSr in wood outside the trenches containing buried radioactive waste in the PTLRW \"Red Forest\" area amounted to 23 GBq/ha. Even with the combustion (conversion to ash) of 10% of the wood and leaching from the ash, 10% of \u003csup\u003e90\u003c/sup\u003eSr per year becomes available for water migration. On each hectare of burned area, (23\u0026times;0.1\u0026times;0.3\u0026thinsp;=\u0026thinsp;0.69) 0.69 GBq of \u003csup\u003e90\u003c/sup\u003eSr is available for migration with water. The corresponding fraction of \u003csup\u003e90\u003c/sup\u003eSr available for water migration over the entire burned area of 554 km\u0026sup2; (55400 ha) in 2020 (Hu et al., 2023; Hu et al., 2024) [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] is (554\u0026times;100\u0026times;0.69\u0026thinsp;=\u0026thinsp;38226) GBq, which is approximately 17 times higher than the \u003csup\u003e90\u003c/sup\u003eSr reserves in the water of the CNPP\u0026rsquo;s cooling pond before its decommissioning \u0026minus;\u0026thinsp;2200 GBq (cite this) [20]. Within the area of the burial trenches, the \u003csup\u003e90\u003c/sup\u003eSr reserves in wood reach 560 GBq/ha (Yoschenko et al., 2024) [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e8\u003c/span\u003e], which is nearly 25 times higher than in the surrounding territory. The estimates provided above are solely for pinewood ashes.\u003c/p\u003e \u003cp\u003eWhen considering the recent \u003csup\u003e90\u003c/sup\u003eSr distribution forecast in the forest (Pinus sylvestris L.) ecosystem [7], refer to the introduction; forest litter constitutes a comparable portion, approximately 70%, compared to pinewood (14/20\u0026thinsp;=\u0026thinsp;0.7).\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\u003e\u0026ndash; Data on the leaching of \u003csup\u003e90\u003c/sup\u003eSr activity from wood ash and forest litter with water\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"12\"\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=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"11\" nameend=\"c12\" namest=\"c2\"\u003e \u003cp\u003eWood samples\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS II\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eV, ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e18.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e23.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e43.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e62.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e83.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e104.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e121.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA, Bq\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e11.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e17.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e22.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e26.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e28.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e29.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e30.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e31.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS III\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eV, ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e12.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e17.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e22.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e43.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e62.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e83.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e103.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e124.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA, Bq\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e12.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e14.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e15.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e17.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e17.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e18.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e18.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e19.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS IV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eV, ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e18.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e23.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e43.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e62.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e82.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e103.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e124.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA, Bq\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e3.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e3.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e4.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS V\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eV, ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e18.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e23.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e45.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e64.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e84.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e102.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e123.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA, Bq\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e12.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e23.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e28.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e31.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e33.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e34.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS VI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eV, ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e18.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e23.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e45.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e64.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e84.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e102.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e123.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA, Bq\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e23.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e31.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e36.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e41.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e52.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e60.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e68.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e81.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e90.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS VII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eV, ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e12.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e17.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e22.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e43.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e64.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e84.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e104.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e121.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA, Bq\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e11.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e12.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e19.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e23.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e28.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e34.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e38.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"10\" nameend=\"c12\" namest=\"c3\"\u003e \u003cp\u003eForest litter 96/36\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eV, ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e14.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e19.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e24.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e43.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e64.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e84.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e102.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e123.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA, Bq\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e3.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e4.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e5.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e6.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e6.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e6.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eV, ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e15.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e21.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e27.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e47.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e68.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e88.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e108.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e127.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA, Bq\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e6.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e7.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e9.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e10.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e11.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e11.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e12.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eV, ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e14.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e19.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e24.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e45.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e65.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e86.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e107.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e128.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA, Bq\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e36.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e40.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e43.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e50.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e54.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e58.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e61.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e64.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \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\u003e\u0026ndash; Cumulative leaching (\u003csup\u003e90\u003c/sup\u003eSr vs \u003csup\u003e137\u003c/sup\u003eCs) from ash sample with water (V\u0026thinsp;\u0026asymp;\u0026thinsp;125ml)\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=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample, code\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAsh\u003c/p\u003e \u003cp\u003ecode\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWeight\u003c/p\u003e \u003cp\u003eof ash, g (~)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNuclide\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eWashed,\u003c/p\u003e \u003cp\u003eBq\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eResidue,\u003c/p\u003e \u003cp\u003eBq\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eTotal,\u003c/p\u003e \u003cp\u003eBq\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eWashed\u003c/p\u003e \u003cp\u003eup, %\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eWood I\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eS-II\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e90\u003c/sup\u003eSr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e31.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e104.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e135.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e23.3%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e137\u003c/sup\u003eCs\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026asymp;\u0026thinsp;89%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eWood I\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eS-III\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e90\u003c/sup\u003eSr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e19.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e98.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e117.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e16.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e137\u003c/sup\u003eCs\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026asymp;\u0026thinsp;89%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eWood II\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eS-IV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e90\u003c/sup\u003eSr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e12.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e16.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e25.9%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e137\u003c/sup\u003eCs\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026asymp;\u0026thinsp;89%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eWood III\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eS-V\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e90\u003c/sup\u003eSr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e34.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e70.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e104.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e33.0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e137\u003c/sup\u003eCs\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026asymp;\u0026thinsp;89%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eWood IV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eS-VI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e90\u003c/sup\u003eSr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e90.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e251.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e341.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e26.6%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e137\u003c/sup\u003eCs\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e89\u0026thinsp;\u0026plusmn;\u0026thinsp;4%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eWood IV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eS-VII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e90\u003c/sup\u003eSr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e38.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e280.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e318.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e12.0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e137\u003c/sup\u003eCs\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e2.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e89\u0026thinsp;\u0026plusmn;\u0026thinsp;3%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e96/36 A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e90\u003c/sup\u003eSr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e55.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e62.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e10.8%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e137\u003c/sup\u003eCs\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e8.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e35.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e96/36 B\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e90\u003c/sup\u003eSr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e12.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e78.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e91.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e13.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e137\u003c/sup\u003eCs\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e86.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e7.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e6/36 C\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e90\u003c/sup\u003eSr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e64.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e494\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e558\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e11.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e137\u003c/sup\u003eCs\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e715\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e723\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eAnalysis of the dynamics of the Sr activity in the observation wells water\u003c/h3\u003e\n\u003cp\u003eA map of the fire spread area from 2020 within a 10 km zone is depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e6\u003c/span\u003e (in color). Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e6\u003c/span\u003e illustrates the lines of equal pressure and the direction of groundwater movement, indicated by red arrows. As shown, groundwater movement in the fire area at the \"Red Forest\" PTLRW is directed northeast. Wells K-2/1 and K-2/2 are situated within the 2020 fire zone. The dynamics of changes in the specific activity of \u003csup\u003e90\u003c/sup\u003eSr in groundwater samples from wells K-2/1 and K-2/2 are presented in Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e7\u003c/span\u003e and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e8\u003c/span\u003e based on research data from the SSE Ecocentre. In groundwater samples from well K-2/1, an increase in \u003csup\u003e90\u003c/sup\u003eSr concentrations is noted starting at the end of 2022, rising from 15 to 98 Bq/l, a 2\u0026ndash;6 fold increase. In well K-2/2, the rise in the specific activity of \u003csup\u003e90\u003c/sup\u003eSr began in October 2022, increasing from 2.9 to 180 Bq/l, equivalent to a 10-60-fold increase (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe rise in \u003csup\u003e90\u003c/sup\u003eSr concentrations was likely caused by leaching with atmospheric precipitation that fell on ash and debris from wood and forest litter burned during the fire. Groundwater contamination occurs when atmospheric precipitation infiltrates the soils of the aeration zone. In this area, the aeration zone thickness is 3\u0026ndash;4 m. The hypothesis regarding the effect of fires on groundwater contamination, observed in wells K-2/1 and K-2/2, is supported by previous predictive calculations carried out under similar conditions (Starikov et al., 2012) [21].\u003c/p\u003e\u003cp\u003eThe thickness of the aeration zone in the modeling was 2 m. The inflow of \u003csup\u003e90\u003c/sup\u003eSr from the active layer through the aeration zone was modeled to the aquifer. The distribution coefficient was determined at the level of 1 ml/h. According to calculations, the main predicted inflow of \u003csup\u003e90\u003c/sup\u003eSr to the groundwater level occurs after 200 days. About 97% of the total inflow into the aquifer falls during 200\u0026ndash;365 days. Considering the difference in the power of the aeration zone, the assumption about the impact of burns on groundwater contamination observed in the wells, as mentioned above, seems realistic.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eLaboratory experiments demonstrated that burning 1 kg of pinewood from the Chornobyl zone (N\u0026thinsp;=\u0026thinsp;6) results in an ash residue of 2.80\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37 g. This yields a \u003csup\u003e90\u003c/sup\u003eSr concentration in the ash approximately 357 times, with its specific activity ranging from 0.16 to 3.4 kBq/g.\u003c/p\u003e \u003cp\u003eWhen burning one kg of forest litter (morphological layers A, B, and C), approximately 29 g, 48 g, and 192 g of ash were produced. This resulted in a corresponding \u003csup\u003e90\u003c/sup\u003eSr specific activity approximately 35, 21, and 5 times higher than the input material; the specific activity in the respective layers A, B, and C ash was 0.63, 0.92, and 3.3 kBq/g.\u003c/p\u003e \u003cp\u003eAccording to data, 12 to 33% of the \u003csup\u003e90\u003c/sup\u003eSr activity in wood ash is washed out with water, and 10.8 to 13.2% of the \u003csup\u003e90\u003c/sup\u003eSr activity in forest litter ash is washed out.\u003c/p\u003e \u003cp\u003eExperiments unveiled that \u003csup\u003e90\u003c/sup\u003eY leaching is invisible, unlike the studied \u003csup\u003e90\u003c/sup\u003eSr leaching.\u003c/p\u003e \u003cp\u003eThe leaching of \u003csup\u003e137\u003c/sup\u003eCs from wood ash with water was 89\u0026thinsp;\u0026plusmn;\u0026thinsp;4%, and from the ash of forest litter corresponding morphological layers: A, B, C \u0026minus;\u0026thinsp;35.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5%, 7.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5%, 1.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5%.\u003c/p\u003e \u003cp\u003eRecently, researchers observed an increase in the specific activity of \u003csup\u003e90\u003c/sup\u003eSr in the water of observation wells drilled at the Chornobyl NPP, located downstream of the groundwater flow from the fire centers and within them. This increase varied from 2 to 60 times, reaching values of 180 Bq/l, which can be attributed to the local impact of recent fires.\u003c/p\u003e \u003cp\u003eThe interval required to achieve the maximum specific activity of \u003csup\u003e90\u003c/sup\u003eSr in water was between 200 and 365 days, consistent with the previously projected duration of over 200 days from earlier predictive calculations (Starikov et al., 2012) [21].\u003c/p\u003e \u003cp\u003eThe estimates obtained during the laboratory experiment indicate that fires in radionuclide-contaminated territories should be considered a notable source of \u003csup\u003e90\u003c/sup\u003eSr entering surface and groundwater. This requires appropriate amendments to the regulations for the radioecological monitoring of waters.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eMP - idea, curation of research, writing the manuscript; MB - experimental research, LSC measurements, data curation, preparing and writing the manuscript; SK- presenting data on 90Sr in water, discussing results and the manuscript;NS- discussion results and a draft of the manuscript; IK- discussion results and a draft of the manuscript; LM- gamma-spectroscopy research, discussing results and the manuscript\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThe authors thank Khan V. Ye-I., Chikur L. B., and Palamar L. A. for determining the concentrations of 90Sr in individual ash and wood samples.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eAll data generated or analysed during this study are included in this published article [and its supplementary information files].\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eHu, J. et al. Application of a Tuning-Free Burned Area Detection Algorithm to the Chornobyl Wildfires in 2022. \u003cem\u003eSci. Rep.\u003c/em\u003e\u003cstrong\u003e13,\u003c/strong\u003e 5236. doi:10.1038/s41598-023-32300-5 (2023).\u003c/li\u003e\n\u003cli\u003eHu, J. et al. Tuning-Free Moderate-Scale Burned Area Detection Algorithm A Case Study in Chornobyl-Contaminated Region. \u003cem\u003eInt. J. Remote Sens.\u003c/em\u003e\u003cstrong\u003e45,\u003c/strong\u003e 2444\u0026minus;2461. doi:10.1080/01431161.2024.2331976 (2024).\u003c/li\u003e\n\u003cli\u003eIgarashi, Y. et al. Effects of Large-Scale Wildfires on the Redistribution of Radionuclides in the Chornobyl River System. \u003cem\u003eEnvironmental Science \u0026amp; Technology\u003c/em\u003e. \u003cstrong\u003e58,\u003c/strong\u003e 20630\u0026minus;20641. doi:10.1021/acs.est.4c07019 (2024). \u003c/li\u003e\n\u003cli\u003eHygienic requirements for drinking water intended for human consumption: state health and safety standards and rules DSanPiN 2.2.4-171-10, Кyiv, 2010, 32. URL: https://zakon.rada.gov.ua/laws/show/z0452-10#Text.\u003c/li\u003e\n\u003cli\u003eBruchertseifer, F., Steiner, M., Hiersche, L., Savkin, B., Poppitz-Spuhler ,A., Wirth, E. Dynamics of strontium-90 in forest ecosystems. \u003cem\u003eRadioprotection, \u003c/em\u003e\u003cstrong\u003e37(Cl),\u003c/strong\u003e 409- 413. doi:10.1051/radiopro/2002077 (2002). \u003c/li\u003e\n\u003cli\u003eBuzinny, M., Los, I., Shepelevich, K. The distribution of \u003csup\u003e137\u003c/sup\u003eCs and \u003csup\u003e90\u003c/sup\u003eSr in the biomass of pine trees planted in 1987\u0026ndash;1988 in the near zone of the Chernobyl nuclear power plant. \u003cem\u003eApplied Radiation and Isotopes\u003c/em\u003e. \u003cstrong\u003e52\u003c/strong\u003e\u003cstrong\u003e (\u003c/strong\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003cstrong\u003e)\u003c/strong\u003e\u003cstrong\u003e,\u003c/strong\u003e 905-910. doi:10.1016/S0969-8043(99)00142-6 (2000).\u003c/li\u003e\n\u003cli\u003eHoliaka, D. M., Levchuk, S. E., Yoschenko, V. I., Yoschenko, L. V., Holiaka, M. A. The model of biogenic fluxes and depots of \u003csup\u003e90\u003c/sup\u003eSr in contaminated pine stands. \u003cem\u003eScientific Bulletin of\u003c/em\u003e\u003cem\u003e UNFU\u003c/em\u003e. \u003cstrong\u003e\u003cem\u003e29\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u003cem\u003e \u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e(9),\u003c/strong\u003e 81-86. doi:10.36930/40290914 (2019).\u003c/li\u003e\n\u003cli\u003eYoschenko, V., Thiry, Y., Holiaka, D., Levchuk, S., Kashparov, V., Nanba, K. Long-term changes in \u003csup\u003e90\u003c/sup\u003eSr pools of Scots pine biomass in the Chornobyl Red Forest. \u003cem\u003eJournal of Environmental Radioactivity\u003c/em\u003e. \u003cstrong\u003e273,\u003c/strong\u003e 107366. doi:10.1016/j.jenvrad.2023.107366 (2024).\u003c/li\u003e\n\u003cli\u003eAlicja, K., Grzegorz, C. Strontium leaching from municipal waste subjected to incineration. \u003cem\u003eEnviron Geochem Health.\u003c/em\u003e\u003cstrong\u003e46\u003c/strong\u003e, 220. doi:10.1007/s10653-024-01998-1 (2024).\u003c/li\u003e\n\u003cli\u003eBod\u0026iacute;, M. B., Mataix-Solera, J., Doerr, S. H., Cerdà, A. The Wettability of Ash from Burned Vegetation and Its Relationship to Mediterranean Plant Species Type, Burn Severity and Total Organic Carbon Content. \u003cem\u003eGeoderma.\u003c/em\u003e\u003cstrong\u003e160,\u003c/strong\u003e 599\u0026minus;607. doi:10.1016/j.geoderma.2010.11.009 (2011).\u003c/li\u003e\n\u003cli\u003eS\u0026aacute;nchez-Garc\u0026iacute;a, C. et al. Chemical Characteristics of Wildfire Ash across the Globe and Their Environmental and Socioeconomic Implications. \u003cem\u003eEnviron. Int.\u003c/em\u003e\u003cstrong\u003e178,\u003c/strong\u003e 108065. doi:10.1016/j.envint.2023.108065 (2023).\u003c/li\u003e\n\u003cli\u003ePereira, P., Úbeda, X., Martin, D., Mataix-Solera, J., Cerd\u0026agrave;, A., Burguet, M. Wildfire Effects on Extractable Elements in Ash from a Pinus pinaster Forest in Portugal. \u003cem\u003eHydrol. Process.\u003c/em\u003e\u003cstrong\u003e28,\u003c/strong\u003e 3681- 3690. doi:10.1002/hyp.9907 (2014).\u003c/li\u003e\n\u003cli\u003eEarl, S. R., Blinn, D. W. Effects of Wildfire Ash on Water Chemistry and Biota in South-Western U.S.A. streams. \u003cem\u003eFreshwater Biology.\u003c/em\u003e\u003cstrong\u003e48,\u003c/strong\u003e 1015-1030. doi:10.1046/j.1365-2427.2003.01066.x (2003).\u003c/li\u003e\n\u003cli\u003eKovalenko, I. O. et al. Factors influencing the increased \u003csup\u003e90\u003c/sup\u003eSr radioisotope migration in highly alkaline groundwater at Chornobyl NPP site. \u003cem\u003eJournal of Environmental Radioactivity\u003c/em\u003e. 275, 107431. doi:10.1016/j.jenvrad.2024.107431 (2024).\u003c/li\u003e\n\u003cli\u003eBuzinny, M., Likhtarev, I., Los, I., Talerko, N., Tsigankov, N. \u003csup\u003e14\u003c/sup\u003eC Analysis of Annual Tree Rings from the Vicinity of the Chernobyl NPP. \u003cem\u003eRadiocarbon\u003c/em\u003e. \u003cstrong\u003e40\u003c/strong\u003e\u003cstrong\u003e(1)\u003c/strong\u003e\u003cstrong\u003e,\u003c/strong\u003e 373-379. doi:10.1017/S0033822200018257 (1997).\u003c/li\u003e\n\u003cli\u003eBuzinny, M. Radioactive Graphite Dispersion in the Environment in the Vicinity of the Chernobyl Nuclear Power Plant. \u003cem\u003eRadiocarbon\u003c/em\u003e. \u003cstrong\u003e48(3)\u003c/strong\u003e\u003cstrong\u003e,\u003c/strong\u003e 451-458. doi:10.1017/S003382220003887X (2006).\u003c/li\u003e\n\u003cli\u003eBuzynnyi, M., Romanenko, O., Mykhailova, L., Lytvynko, A., Panasiuk, M. Traces of \u003csup\u003e14\u003c/sup\u003eC emissions for the operation period of two Ukrainian NPPS: Rivne and Chornobyl. \u003cem\u003eRadiocarbon\u003c/em\u003e. \u003cstrong\u003e65(2)\u003c/strong\u003e\u003cstrong\u003e,\u003c/strong\u003e 335-342. doi:10.1017/RDC.2023.3 (2023).\u003c/li\u003e\n\u003cli\u003eBuzynnyi M. Practical aspects of the application of cherenkov counting method with the correction of sample\u0026rsquo;s color quenching. Environment \u0026amp; Health. 2(107),40-46. doi:10.32402/dovkil2023.02.040 (2023)\u003c/li\u003e\n\u003cli\u003eBeta spectrometer SEB-01. Operation manual. RPE \u0026quot;ATOM KOMPLEX PRYLAD\u0026quot;. http://www.akp.com.ua/index.php?option=com_content\u0026amp;view=article\u0026amp;id=119\u0026amp;Itemid=106 \u003c/li\u003e\n\u003cli\u003eDzhepo, S.P., Skal\u0026rsquo;skii, A. S.\u003cem\u003e \u003c/em\u003eRadioaсtive Contamination of Groundwater within the Chernobyl Exclusion Zone in \u003cem\u003eChernobyl Disaster and Groundwater\u003c/em\u003e (ed. Shestopalov, V.) 25-71 (A.A. Balkema Publisher, 2002). https://books.google.com.ua/books?id=MUl16_H8MksC\u003c/li\u003e\n\u003cli\u003eStarikov, N. B., Alfyorov, A. M., Panasyuk, М. I., Lytvyn, I. A., Liushnya E. P. Simulation of migration of radionuclides in the zone of aeration at the industrial site of the \u0026ldquo;Ukryttya\u0026rdquo; object. \u003cem\u003eSafety Issues of Nuclear Power Plants and Chernobyl\u003c/em\u003e. \u003cstrong\u003e18,\u003c/strong\u003e 96-102 http://dspace.nbuv.gov.ua/handle/123456789/113337 (2012).\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":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"forest fires, wood, forest litter, ash, groundwater, 90Sr, pollution sources, mineralization, ionic strength of the solution","lastPublishedDoi":"10.21203/rs.3.rs-5926363/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5926363/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eWood in the Chornobyl Exclusion Zone (CEZ) is contaminated with \u003csup\u003e137\u003c/sup\u003eCs and \u003csup\u003e90\u003c/sup\u003eSr. The \u003csup\u003e90\u003c/sup\u003eSr activity concentration in the wood reaches tens of kBq/kg. According to laboratory experiments, complete combustion of 1 kg of dry pinewood generates about 2.8 g of ash, resulting in a \u003csup\u003e90\u003c/sup\u003eSr concentration in the ash that is approximately 360 times higher. The specific activity of \u003csup\u003e90\u003c/sup\u003eSr in the ash from six wood samples ranged from 0.16 to 3.4 kBq/g. In filtrate samples, the specific activity of \u003csup\u003e90\u003c/sup\u003eSr, under consistent experimental conditions, reached 0.5 to 0.72 kBq/l. The fraction of \u003csup\u003e90\u003c/sup\u003eSr washed out during the experiment was 12\u0026ndash;33% for wood ash and 10.8\u0026ndash;13.2% for forest litter ash. The high concentrations of potassium, sodium, calcium, and phosphate ions in the wood ash are readily leached, which increases groundwater mineralization and its ionic strength. This, in turn, contributes to a decrease in the sorption capacity of soils and an increase in the migration capacity of \u003csup\u003e90\u003c/sup\u003eSr in the aquifer.\u003c/p\u003e \u003cp\u003eThe largest fires in the CEZ occurred in 2020 at the Temporary Radioactive Waste Location Point (PTLRW) \u0026ldquo;Red Forest\u0026rdquo; site, where the \u003csup\u003e90\u003c/sup\u003eSr activity in wood peaked. The concentration of \u003csup\u003e90\u003c/sup\u003eSr activity in groundwater samples from observation wells in this section of the CEZ shows an increase of 2 to 60 times, climbing from approximately 2 to about 180 Bq/l, beginning at the end of 2022. Radioactivity concentrated in ash on the soil surface in the burned area is vulnerable to rapid leaching by atmospheric precipitation; as a result, it can become a significant local source of radioactive contamination of surface and groundwater, necessitating updates to the regulations for monitoring radioactivity in the relevant CEZ observation wells.\u003c/p\u003e","manuscriptTitle":"Regarding the Possible Impact of Forest Fires on the Radioactive Pollution of Groundwater in the Chornobyl Exclusion Zone","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-02-03 06:02:48","doi":"10.21203/rs.3.rs-5926363/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-02-06T08:23:16+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-02-05T17:59:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"226382292127476511110118861022821381272","date":"2025-02-03T17:24:16+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-02-02T22:10:51+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"249921018062613969719265807066124989423","date":"2025-02-02T21:00:51+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-02-02T12:34:18+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-02-02T12:16:58+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-02-02T09:47:01+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-01-30T12:01:37+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-01-29T19:40:39+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"559a69fb-988b-47e5-8488-a008943644e0","owner":[],"postedDate":"February 3rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":43743986,"name":"Earth and environmental sciences/Biogeochemistry"},{"id":43743987,"name":"Earth and environmental sciences/Ecology"},{"id":43743988,"name":"Earth and environmental sciences/Environmental sciences"},{"id":43743989,"name":"Earth and environmental sciences/Hydrology"},{"id":43743990,"name":"Earth and environmental sciences/Natural hazards"}],"tags":[],"updatedAt":"2025-04-28T16:09:42+00:00","versionOfRecord":{"articleIdentity":"rs-5926363","link":"https://doi.org/10.1038/s41598-025-99095-5","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2025-04-22 15:57:49","publishedOnDateReadable":"April 22nd, 2025"},"versionCreatedAt":"2025-02-03 06:02:48","video":"","vorDoi":"10.1038/s41598-025-99095-5","vorDoiUrl":"https://doi.org/10.1038/s41598-025-99095-5","workflowStages":[]},"version":"v1","identity":"rs-5926363","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5926363","identity":"rs-5926363","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}