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Time Dependence of the 137Cs Concentration in Particles Discharged from Rice Paddies to Freshwater Bodies after the Fukushima Daiichi NPP Accident
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† Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Sahei Building 8F 1-29, Okitama-cho, Fukushima-shi, Fukushima 960-8034, Japan
‡ Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
§ Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, 3-5-8, Saiwai-cho, Fuchu, Tokyo 183-8509, Japan
*Phone: +81-24-529-5560; e-mail: [email protected]
Copyright © 2016 American Chemical Society
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Abstract
The concentration of particulate 137Cs in paddy fields, which can be a major source of 137Cs entering the water system, was studied following the Fukushima Daiichi Nuclear Power Plant accident. To parametrize the concentration and to estimate the time dependence, paddy fields covering various levels of 137Cs deposition were investigated over the period 2011–2013 (n = 121). The particulate 137Cs concentration (kBq kg–SS–1) showed a significant correlation with the initial surface deposition density (kBq m–2). This suggests that the entrainment coefficient (m2 kg–SS–1), defined as the ratio between the particulate 137Cs concentration and the initial surface deposition density, is an important parameter when modeling 137Cs wash-off from paddy fields. The entrainment coefficient decreased with time following a double exponential function. The decrease rate constant of the entrainment coefficient was clearly higher than that reported for other land uses and for river water. The difference in the decrease rates of the entrainment coefficient suggests that paddy fields play a major role in radiocesium migration through the water system. An understanding of the decrease rate of the entrainment coefficient of paddy fields is therefore crucial to understand the migration of radiocesium in the water system.
1 Introduction
ARTICLE SECTIONS
Large amounts of radiocesium, especially 137Cs, were released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident and deposited on the ground over the North Kanto and the South Tohoku regions of Japan.(1-3) Most of the 137Cs deposited over ground bound tightly to soil particles,(4, 5) and a part of this 137Cs subsequently migrates to the water system through physical processes such as soil erosion. It was then mainly transported in particulate form through the river system.(6-9) The migration of particulate 137Cs from terrestrial fields to the water system is a serious issue when predicting changes in environmental contamination levels and for evaluating the effect on water utilization in downstream region.
Paddy fields for growing rice are a major land use in South, East, and Southeast Asia. In Fukushima prefecture, paddy fields cover an area of 1053 km2, accounting for 70% of agricultural capacity.(10) Large areas of the paddy in Fukushima prefecture have been affected by 137Cs deposition following the FDNPP accident (Figure 1). While the contamination levels of the rice have been confirmed to be within safety margins, a major proportion of the radiocesium inventory in paddy fields might still be in place.(11) Paddy fields have been shown to be one of the most sensitive land uses to soil erosion in the region.(9, 11-13) Accordingly, they constitute the main source of particle-bound radiocesium entering the rivers. The typical paddy cultivation cycle in Japan and the corresponding field conditions are as follows. In spring, the dry field is flooded with irrigation water, followed by soil puddling, which mixes the paddy soil to a depth of around 15 cm. This produces a muddy soil surface covered by highly turbid water with a 5–10 cm depth. The field is then left fallow for 2–5 days as to allow the water level to adjust to 0–5 cm and for soil compaction appropriate for rice planting to take place. The rice seedlings are then planted. The paddy field is kept flooded throughout the irrigation period at a water depth varying approximately 0–10 cm. The irrigation water is drained off in early autumn, followed by harvesting. There is then a period from the end of autumn to early spring in which the fields are not irrigated. The major causes of soil wash-off from paddy fields are runoff of turbid paddy water during puddling, enforced drainage after puddling, runoff of paddy water during heavy rainfall, and soil erosion during the nonirrigation period. Many studies have used monitoring and modeling to evaluate the soil wash-off from paddy field.(11, 13-17) However, to estimate the particulate 137Cs wash-off from paddy fields, parametrization of the particulate 137Cs concentration in the discharged suspended solid (SS) is essential.
The 137Cs concentration in river water has been normalized by the surface deposition density in the catchment area to model the rate of 137Cs transfer in the river.(18, 19) Significant correlations between the particulate 137Cs concentration in the SS in river water and the surface deposition density in the catchment area have been reported.(9, 20) An entrainment coefficient (m2 kg–SS–1), defined as the ratio of 137Cs concentration in the eroded soil (kBq kg–SS–1) and the initial surface deposition density (kBq m–2), has been used to model the concentration of 137Cs in eroded soil.(21-23) These studies suggest that the relationship between the 137Cs concentration and the initial surface deposition density can be used to estimate the particulate 137Cs concentration discharged from paddy fields into the water system. Entrainment coefficients were investigated from experimental runoff plots in land uses such as farmland, grassland, bare ground, and forests, following the Chernobyl Nuclear Power Plant accident(21-23) and the FDNPP accident,(24) but the coefficient has never been established for paddy fields. A decrease in 137Cs concentrations in river and lake waters was reported in the period following the Chernobyl Nuclear Power Plant accident,(18, 19, 25, 26) suggesting that the entrainment coefficient decreases with time. This decrease is thought to reflect factors affecting radiocesium wash-off, such as susceptibility to soil erosion, the chemical/physical properties of the soil (i.e., adsorption and desorption of radiocesium), and progressive vertical migration of radiocesium. These factors in turn depended on the uses to which the land is put. It is therefore important to evaluate the entrainment coefficient of paddy fields.
The entrainment coefficient should vary with the particle size of the matrix, such as soil and SS, because the specific surface area of the matrix directly affects the 137Cs adsorption capacity. The fine fractions of soil and SS in river water and the sediment in river beds show higher 137Cs concentrations than those of coarser fractions.(7, 8, 27-30) The entrainment coefficient has also been shown to vary depending on the particle size of SS in the river water.(24) These findings suggest that particle size needs to be considered to parametrize the entrainment coefficient.
This study monitored particulate 137Cs concentration in paddy fields extensively in the area covering various deposition levels in the Fukushima prefecture. The aim of the study was to provide a parameter that can be used to model the wash-off of 137Cs from paddy fields and to improve our understanding of the migration of 137Cs from agricultural fields into the water system.
Figure 1
Figure 1. Distributions of 137Cs inventory and paddy fields in Fukushima prefecture. This map was generated by ArcGIS 10 software. The prefectural border and shore-lines were obtained from Geospatial Information Authority of Japan. The 137Cs distribution was derived from the Third Airborne Monitoring Survey by Ministry of Education, Culture, Sports, Science and Technology, Japan.(37) The distribution of paddy field in 2009 was based on the National Land Numerical Information service of the Ministry of Land, Infrastructure, Transport, and Tourism.(39)
2 Materials and Methods
ARTICLE SECTIONS
2-1 Study sites and Sampling
To estimate the entrainment coefficient in paddy fields at various deposition levels of 137Cs, turbid paddy water was collected 0–2 days after puddling from 14 sites between May 6 and June 22, 2012, and from 27 sites between April 29 and May 23, 2013, including 12 of the sites selected in 2012 (Figure 2). At all sites, cultivation had been carried out continuously, including 2011. Sampling was carried out before seedling planting and while sedimentation of SS was in progress. Coarse soil fractions, which are sedimented within 0–2 days of puddling, were not sampled. Although puddling causes vertical and horizontal mixing of the paddy soil, the 137Cs concentration and inventory have been found to be heterogeneous.(31, 32) In this study, we therefore collected turbid paddy water at four points in a paddy field and combined these samples.
In addition to the extensive sampling of turbid paddy water, particulate 137Cs concentrations in the discharged SS due to puddling or rainfall were monitored at six experimental paddy fields to evaluate the sequential decrease in the entrainment coefficient (Figure 2). Monitoring at site 1 was conducted between September 1 and October 24, 2011 and from May 14, 2012 to September 14, 2013. Monitoring at sites 2–6 was carried out from August 19, 2012 to September 23, 2013. The monitoring at site 1 was a continuation of a previous study,(11) which monitored two paddy fields, one of which had been decontaminated, while the other one was not. In this study, we analyzed only the data from the undecontaminated paddy field. The SS discharged from paddy fields by heavy rainfall and puddling was trapped using a time-integrated SS sampler(33) installed at an outlet of the paddy field, as shown in Figure 3. The trapped SS was collected in suspension at intervals of 2–4 weeks. The monitoring system was based on the previous study of in site 1.(11) Samples of turbid paddy water and the suspension were kept still for 2–3 days, and the supernatant was removed. Next, the residue was dried at 105 °C for 24 h for analysis.
Figure 2
Figure 2. Sites where turbid paddy water was collected after puddling (open circles and double circles) and SS discharge from paddy fields was monitored (open squares). A double circle indicates that the site was used to collect turbid paddy water in both 2012 and 2013, while an open circle denotes a site used only once in either 2012 or 2013. This map was generated by ArcGIS 10 software. The prefectural border and shore-lines were obtained from Geospatial Information Authority of Japan. The 137Cs distribution was derived from the Third Airborne Monitoring Survey by Ministry of Education, Culture, Sports, Science and Technology, Japan.(37)
Figure 3
Figure 3. Cross-section of paddy field and location of the time-integrated SS sampler. The water level ranged approximately 0–10 cm because of evaporation, weeping, and withdrawal of irrigation water during the irrigation period.
2-2 Analysis of 137Cs
The particulate 137Cs concentration (kBq m2 kg–SS–1) was measured using a high-purity germanium gamma-ray well detector (GCW2022S, Canberra–Eurisys, Meriden) equipped with an amplifier (PSC822, Canberra, Meriden), and a multichannel analyzer (DSA1000, Canberra, Meriden). Gamma-ray emissions were measured at an energy of 662 keV. Analytical accuracy was certified by the World-Wide Proficiency Test using standard soil samples from IAEA.(34) Measurement was continued until the counting error in the measurement of 137Cs activity was less than 10%. This required a measurement period of 1–24 h, depending on the sample weight.
There were time lags in the date of sampling of turbid irrigation water after puddling in the 2012 and 2013 samples. Therefore, the particulate 137Cs concentration was decay-corrected from the first date of each sampling period. The 137Cs concentration in the SS samples from the six experimental paddy fields was also decay-corrected from the first date of sampling for each period.
2-3 Correction of Particle Size Dependency
The particle size dependency of the 137Cs concentration was corrected using a particle-size correction factor (P) based on specific surface area.(9, 35, 36) We measured the particle size distribution using a laser diffraction particle size analyzer (SALD-3100, Shimadzu Co., Ltd., Kyoto, Japan), and the specific surface area was estimated using a spherical approximation of particles in each size class. To normalize the particle size dependency of the 137Cs concentration in the SS, the concentration was divided by P, which was calculated as follows:
(1)where Ss is the specific surface area of the criterial sample. In this study, Ss was 0.386 m2 g-dry–1, determined from the SS discharge from the experimental paddy field during puddling at site 1 on June 13, 2011. Sr denotes the specific surface area of each soil sample (Tables S1–S2), and v is a constant coefficient with the value 0.65.(9, 30)
(1)where Ss is the specific surface area of the criterial sample. In this study, Ss was 0.386 m2 g-dry–1, determined from the SS discharge from the experimental paddy field during puddling at site 1 on June 13, 2011. Sr denotes the specific surface area of each soil sample (Tables S1–S2), and v is a constant coefficient with the value 0.65.(9, 30)To ensure valid correction, a typical Ss should be applied. The average P obtained in this study was 1.0 (standard deviation (SD) = 0.41, n = 121), indicating that the Ss value applied was typical for correcting the 137Cs concentration in the SS discharged from the paddy fields.
2-4 Entrainment Coefficient
The entrainment coefficient (Sc, m2 kg–SS–1) of 137Cs was calculated as follows:
(2)where Ct is the particulate 137Cs concentration with or without correction for particle size dependency at time t (kBq m2 kg–SS–1), and A0 is the initial surface deposition density of 137Cs (kBq m–2). The initial surface deposition densities were based on the results of the Third Airborne Monitoring Survey(37) as the value on July 2, 2011. These were calibrated using a proportional relationship between air dose rates estimated by the survey and the deposition density of 137Cs on the ground surface measured from soil core samples taken at 2200 points. The initial surface deposition density ranged 13–415 kBq m–2 in the paddy fields used to collect turbid paddy water and 61–391 kBq m–2 in the six experimental paddy fields.
(2)where Ct is the particulate 137Cs concentration with or without correction for particle size dependency at time t (kBq m2 kg–SS–1), and A0 is the initial surface deposition density of 137Cs (kBq m–2). The initial surface deposition densities were based on the results of the Third Airborne Monitoring Survey(37) as the value on July 2, 2011. These were calibrated using a proportional relationship between air dose rates estimated by the survey and the deposition density of 137Cs on the ground surface measured from soil core samples taken at 2200 points. The initial surface deposition density ranged 13–415 kBq m–2 in the paddy fields used to collect turbid paddy water and 61–391 kBq m–2 in the six experimental paddy fields.3 Results and Discussion
ARTICLE SECTIONS
3-1 Variation in Particulate 137Cs Concentrations
Figure 4 shows the variations in particulate 137Cs concentration in the turbid paddy waters in 2012 and 2013 with the initial surface deposition density. The increase in uncorrected particulate 137Cs concentrations showed a statistically significant relationship with the initial surface deposition density in both the 2012 and 2013 samples. This suggests that the initial surface deposition density is an important factor in the particulate 137Cs concentration in paddy fields, and that the entrainment coefficient is an appropriate metric for estimating the particulate 137Cs concentration in the discharged SS. This is in line with reports of the particulate 137Cs concentration of SS in river water.(9, 20)
Figure 4
Figure 4. Relationship between initial surface deposition densities of 137Cs obtained from the Third Airborne Monitoring Survey(37) and the particulate 137Cs concentrations found in the SS of turbid paddy water in 2012 and 2013. The particulate 137Cs concentration uncorrected for the particle size dependency is shown by the closed circles with a solid regression line, and the corrected data is shown by the open circles with a dashed regression line. The particulate 137Cs concentrations collected from May 6 to June 22, 2012 and from April 29 to May 23, 2013 were corrected for decay from the first date of each sampling period.
The particle size dependency of particulate 137Cs concentration of eroded soil, SS in river water, and sediments in riverbeds have been well documented.(7, 8, 27-30) Particle size varies depending on the location, processes and intensity of soil erosion. Difference in particulate size distribution between the samples were therefore assumed to be reflected in variation in the entrainment coefficient. The particulate size dependency of the particulate 137Cs concentration was corrected and compared with the initial surface deposition density (shown by the open circles in Figure 4). The corrected particulate 137Cs concentration also significantly correlated with the initial surface deposition density. The determination coefficients were higher than those of uncorrected data. The average entrainment coefficient and its standard deviation are given in Table 1. The standard deviation decreased after correcting for the particle size dependency, which has also been reported to improve the correlation between particulate 137Cs concentration of SS in river water and the initial surface deposition density in the catchment area.(9) This suggests that the particulate size dependency of the particulate 137Cs concentration is an important factor that should be considered in the parametrization of the entrainment coefficient in terrestrial environments.
The averaged entrainment coefficients calculated for the eroded soil samples from the six experimental paddy fields are given in Table 2. The entrainment coefficient of the samples collected at site 1 in the 2011 study(11) was also calculated. The particulate 137Cs concentration,(11) corrected for particle size dependency using the particle size distribution reanalyzed in this study, and the initial surface deposition density (310 kBq m–2) estimated by the Third Airborne Monitoring Survey(37) were used for the calculation. The entrainment coefficients obtained in this study (after September 23, 2011) varied by almost the same order of magnitude.
3-2 Temporal Decrease in Entrainment Coefficient
Figure 5 shows the distributions of the entrainment coefficient measured from turbid paddy water in 2012 and 2013. The entrainment coefficient from the previous study, measured at site 1 on June 13, 2011 (0.184), is also plotted. The range, median, and averaged values decreased between 2012 and 2013. The entrainment coefficient in 2011 was higher than those in 2012 and 2013. These results demonstrate a temporal decrease in the entrainment coefficient.
Figure 5
Figure 5. Boxplot of entrainment coefficients calculated from particulate 137Cs concentrations in turbid paddy water corrected for particle size dependency. The box and the error bars show the ranges from the first to third quartiles and from the minimum to the maximum values, respectively. The line identified the median value, and the averaged entrainment coefficient is represented by the closed circle. The entrainment coefficient calculated for the turbid paddy water sample collected on June 13, 2013 in previous study(11) is shown as an open circle.
Figure 6 shows the temporal decrease in entrainment coefficient taken from Tables 1 and 2. The decrease occurred in two phases: a steep decrease in the first half year after the FDNPP accident, followed by a slower decrease. Although the data 2011 data covered only site 1, the decrease in the entrainment coefficient of 137Cs over time was derived by fitting a double exponential function as follows:
(3)where Sct is the entrainment coefficient at time t (yr), and A0 and B0 (m2 kg–SS–1) are constants denoting the initial fractions of the entrainment coefficient that decreased steeply and slowly over time with decrease rate constants of −k1 and −k2 (yr–1), respectively. The decrease rate constants include the decay constant of 137Cs (0.023 yr–1). The data used to calculate A0 and −k1 came from only site 1, and the coefficients may be biased by the first one data of June 13, 2011. This adds large uncertainties to the coefficient. The data were included in the analysis, however, because the initial period after the accident is crucially important, and data on this period is scarce. Assuming that the decrease half a year after the accident was represented by the −k2 obtained using the results of this study, the parameters of the paddy field were calculated as an A0 of 1.7 m2 kg–SS–1 (σ range from 0.19 to 15 m2 kg–SS–1), a B0 of 0.051 m2 kg–SS–1 (σ range from 0.041 to 0.065 m2 kg–SS–1), a −k1 of −14 yr–1 (σ range from −20 to −7.5 yr–1), and a −k2 of −0.48 yr–1 (σ range from −0.60 to −0.35 yr–1).
(3)where Sct is the entrainment coefficient at time t (yr), and A0 and B0 (m2 kg–SS–1) are constants denoting the initial fractions of the entrainment coefficient that decreased steeply and slowly over time with decrease rate constants of −k1 and −k2 (yr–1), respectively. The decrease rate constants include the decay constant of 137Cs (0.023 yr–1). The data used to calculate A0 and −k1 came from only site 1, and the coefficients may be biased by the first one data of June 13, 2011. This adds large uncertainties to the coefficient. The data were included in the analysis, however, because the initial period after the accident is crucially important, and data on this period is scarce. Assuming that the decrease half a year after the accident was represented by the −k2 obtained using the results of this study, the parameters of the paddy field were calculated as an A0 of 1.7 m2 kg–SS–1 (σ range from 0.19 to 15 m2 kg–SS–1), a B0 of 0.051 m2 kg–SS–1 (σ range from 0.041 to 0.065 m2 kg–SS–1), a −k1 of −14 yr–1 (σ range from −20 to −7.5 yr–1), and a −k2 of −0.48 yr–1 (σ range from −0.60 to −0.35 yr–1).The decreases in the 137Cs concentrations in European and Asian river waters were also represented using a double or triple exponential function.(19, 25, 26) The results suggest that the decrease in 137Cs concentration in a water system is characterized by both fast and slow phases. Smith and co-workers used the triple exponential function to represent the decrease based on data from the long-term monitoring over a period of 10 years following the Chernobyl Nuclear Power Plant accident.(19) The third decrease rate (i.e., −k3 in their report) was 1 order of magnitude lower than the −k2 values in our study and in their own report, suggesting that the radiocesium wash-off from paddy field will decrease with time. Therefore, long-term monitoring data is needed to evaluate the rate of decrease in the entrainment coefficient in paddy fields and to predict the migration of 137Cs through paddy fields.
Figure 6
Figure 6. Temporal decrease in entrainment coefficients obtained from the particulate 137Cs concentration corrected for the particle size dependency. Closed and open circles show the averaged entrainment coefficients obtained from the turbid paddy water after puddling and from the SS discharged from the six experimental paddy fields, respectively. Error bars represents standard deviations. Gray circles and crosses represent the entrainment coefficient obtained at site 1 from June to July 2012 and from the previous 2011 study.(11) The double exponential function fitted to the data is shown as a solid line.
While the temporal trends in the concentration of dissolved and total (dissolved and particulate) 137Cs in river and lake waters were well documented after the Chernobyl Nuclear Power Plant accident,(18, 19, 25, 26) the decrease in particulate 137Cs concentrations were less precisely evaluated. Furthermore, the decreasing rate constant of the 137Cs concentration depends strongly on the time span over which the constant is calculated.(26) As a result, only limited information is available to compare with our results. Temporal variation in the entrainment coefficient has been reported for the eroded soil from experimental plots of farmland, grassland, and forest in the two years after the FDNPP accident.(24) The results showed no temporal decrease in the entrainment coefficient, while the coefficient of the paddy fields decreased by approximately 1 order of magnitude over the same period. The decrease in 137Cs concentration in river water has been observed after the FDNPP accident.(7) The entrainment coefficient of SS in water from the Abukuma River, which is the largest river in Fukushima prefecture, has been evaluated from the ratio between the particulate 137Cs concentration and the initial surface deposition density in the catchment.(38) The rate of decrease in the entrainment coefficient of SS observed from one to three years after the accident was 0.27 yr–1, or 56% of that obtained for paddy fields. These results suggest a rapid decrease in particulate 137Cs concentrations in SS discharged from paddy fields, compared with those in land under other uses and in river water.
SS in river water is derived from a diversity of land uses. The entrainment coefficient of SS in the river water decreased with time, while the decrease in the entrainment coefficient has only been observed for paddy fields. This suggests that the paddy field is an important source of SS and particulate radiocesium in river water, accounting for the decrease in the entrainment coefficient of SS in river water. This large contribution by paddy fields to SS migration in the water system is consistent with the results of studies monitoring the SS flux from paddy fields.(11-13) An understanding of the time dependence of the entrainment coefficient of paddy fields is therefore crucial for understanding the migration of radiocesium through the water system.
The paddy fields studied, with the exception of site 1, are located outside the evacuation zone, and all the sites, including site 1, have been cultivated, every year including 2011. The countermeasures used against radiocesium contamination of the paddy fields mainly comprised fertilizer management and deep tillage to inhibit the migration of radiocesium into the rice plants. The role of decontamination in the decrease in the entrainment coefficient has therefore been limited. As the paddy fields were kept flooded for several days after puddling, the fine soil fractions, which settle slowly, are assumed to form the surface layer and to be discharged preferentially. Fine soil is well-known to contain higher concentrations of 137Cs than coarse soil.(7, 8, 27-30) Highly contaminated fine soil was therefore assumed to have been removed from the paddy fields preferentially during the period immediately after the FDNPP accident. Annual puddling would lead to mixing with deeper and less-contaminated soil, further decreasing the particulate 137Cs concentration of the surface soil.(31, 32) Although additional research is necessary, the preferential discharge of highly contaminated fine soil, and the physical mixing with deeper and less-contaminated soil, can explain the faster rate of decrease in the particulate 137Cs concentration of paddy fields than that recorded for other land uses.
Table 1. Averaged Entrainment Coefficient Obtained from Turbid Paddy Water and Their Standard Deviation (SD)a
| entrainment coefficient (uncorrected) m2 kg–SS–1 | entrainment coefficient (corrected) m2 kg–SS–1 | |||
|---|---|---|---|---|
| sampling dates | ave | SD | ave | SD |
| May 6, 2012 | 0.062 | 0.050 | 0.037 | 0.023 |
| April 29, 2013 | 0.026 | 0.020 | 0.023 | 0.013 |
a
Both of the uncorrected and corrected data for the particle size dependency are shown.
Table 2. Entrainment Coefficients Obtained from Ss Discharged from Paddy Fields and Their Standard Deviation (SD)a
| entrainment coefficient (uncorrected) m2 kg–SS–1 | entrainment coefficient (corrected) m2 kg–SS–1 | |||
|---|---|---|---|---|
| sampling dates | ave | SD | ave | SD |
| June 13, 2011 | 0.184 | 0.184 | – | |
| June 20, 2011 | 0.036 | 0.069 | – | |
| July 3, 2011 | 0.046 | 0.062 | – | |
| July 4, 2011 | 0.058 | 0.074 | – | |
| July15, 2011 | 0.041 | 0.057 | – | |
| July 22, 2011 | 0.030 | 0.047 | – | |
| July 31, 2011 | 0.044 | 0.062 | – | |
| August 6, 2011 | 0.034 | 0.056 | – | |
| August 9, 2011 | 0.031 | 0.043 | – | |
| August18, 2011 | 0.024 | 0.041 | – | |
| August. 19, 2011 | 0.039 | 0.057 | – | |
| August Twenty-eight 2011 | 0.029 | 0.038 | – | |
| September 23, 2011 | 0.030 | 0.050 | – | |
| October 24, 2011 | 0.021 | 0.038 | – | |
| June 1, 2012 | 0.011 | – | 0.017 | – |
| June 22, 2012 | 0.023 | – | 0.028 | – |
| July 6, 2012 | 0.017 | – | 0.021 | – |
| July 18, 2012 | 0.017 | – | 0.021 | – |
| July 27, 2012 | 0.004 | – | 0.008 | – |
| September 4, 2012 | 0.027 | 0.017 | 0.028 | 0.016 |
| September 17, 2012 | 0.029 | 0.019 | 0.031 | 0.019 |
| September 30, 2012 | 0.037 | 0.027 | 0.036 | 0.023 |
| October 15, 2012 | 0.029 | 0.021 | 0.029 | 0.022 |
| November 10, 2012 | 0.026 | 0.018 | 0.027 | 0.021 |
| December 9, 2012 | 0.025 | 0.016 | 0.022 | 0.014 |
| January 1, 2013 | 0.034 | 0.022 | 0.027 | 0.014 |
| February 5, 2013 | 0.033 | 0.016 | 0.025 | 0.008 |
| May 9, 2013 | 0.029 | 0.025 | 0.029 | 0.018 |
| June 12, 2013 | 0.022 | 0.012 | 0.021 | 0.010 |
| July 14, 2013 | 0.022 | 0.013 | 0.022 | 0.013 |
| August 20, 2013 | 0.015 | 0.012 | 0.016 | 0.010 |
| September 14, 2013 | 0.015 | 0.012 | 0.014 | 0.011 |
a
Both of the uncorrected and corrected data for the particle size dependency are shown. The data from June 13, 2011 to July 27, 2012 was obtained from site 1 only. Italics indicate the data calculated for the 137Cs concentration obtained in previous campaign at site 1.
ARTICLE SECTIONS
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.est.5b05513.
Table S1. Specific surface area of SS in the turbid paddy water collected after puddling. Table S2. Specific surface area of SS discharged from six monitoring paddy fields (PDF)
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Acknowledgment
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This work was conducted as a part of project entitled the Establishment of grasp method of long-term effects caused by radioactive materials from the Fukushima Daiichi Nuclear Power Plant accident, financially supported by the Ministry of Education, Culture, Sports, Science and Technology and by the Nuclear Regulation Authority, Japan. We are grateful to reviewers for their valuable comments to improve this article.
References
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This article references 39 other publications.
- 1Morino, Y.; Ohara, T.; Watanabe, M.; Hayashi, S.; Nishizawa, M. Episode Analysis of Deposition of Radiocesium from the Fukushima Daiichi Nuclear Power Plant Accident Environ. Sci. Technol. 2013, 47 (5) 2314– 2322 DOI: 10.1021/es304620x
- 2Saito, K.; Tanihata, I.; Fujiwara, M.; Saito, T.; Shimoura, S.; Otsuka, T.; Onda, Y.; Hoshi, M.; Ikeuchi, Y.; Takahashi, F. Detailed deposition density maps constructed by large-scale soil sampling for gamma-ray emitting radioactive nuclides from the Fukushima Daiichi Nuclear Power Plant accident J. Environ. Radioact. 2015, 139, 308– 19 DOI: 10.1016/j.jenvrad.2014.02.014
- 3Mikami, S.; Maeyama, T.; Hoshide, Y.; Sakamoto, R.; Sato, S.; Okuda, N.; Demongeot, S.; Gurriaran, R.; Uwamino, Y.; Kato, H. Spatial distributions of radionuclides deposited onto ground soil around the Fukushima Dai-ichi Nuclear Power Plant and their temporal change until December 2012 J. Environ. Radioact. 2015, 139, 320– 343 DOI: 10.1016/j.jenvrad.2014.09.010
- 4Qin, H. B.; Yokoyama, Y.; Fan, Q. H.; Iwatani, H.; Tanaka, K.; Sakaguchi, A.; Kanai, Y.; Zhu, J. M.; Onda, Y.; Takahashi, Y. Investigation of cesium adsorption on soil and sediment samples from Fukushima Prefecture by sequential extraction and EXAFS technique Geochem. J. 2012, 46 (4) 297– 302 DOI: 10.2343/geochemj.2.0214[Crossref], [CAS], Google Scholar4https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhsleqsL3O&md5=640d06d8983456911cb8c67261ce6729Investigation of cesium adsorption on soil and sediment samples from Fukushima prefecture by sequential extraction and EXAFS techniqueQin, Haibo; Yokoyama, Yuka; Fan, Qiaohui; Iwatani, Hokuto; Tanaka, Kazuya; Sakaguchi, Aya; Kanai, Yutaka; Zhu, Jianming; Onda, Yuichi; Takahashi, YoshioGeochemical Journal (2012), 46 (4), 297-302CODEN: GEJOBE; ISSN:0016-7002. (Geochemical Society of Japan)Previous studies have shown that radiocesium (mainly 137Cs) was retained at the very surface of soils in Fukushima Prefecture, Japan. Clay minerals and micas are assumed as the main sorbents for Cs in Fukushima, but direct evidence is lacking for this hypothesis. Radiocesium in the natural sample (soil and sediment) from Fukushima Prefecture was studied through sequential extn. expt. (modified BCR method), which showed that >94% of 137Cs was fixed in the residual phase. The results indicated that most of Cs occurred in the interlayer of phyllosilicate minerals. Cs LIII-edge extended x-ray absorption fine structure (EXAFS) showed that the Cs species adsorbed on the natural samples were very similar to those adsorbed on clay minerals and micas. This finding provided the direct evidence on the significant contribution of clay minerals or micas to Cs retention in soils from Fukushima Prefecture.
- 5Tanaka, K.; Sakaguchi, A.; Kanai, Y.; Tsuruta, H.; Shinohara, A.; Takahashi, Y. Heterogeneous distribution of radiocesium in aerosols, soil and particulate matters emitted by the Fukushima Daiichi Nuclear Power Plant accident: retention of micro-scale heterogeneity during the migration of radiocesium from the air into ground and river systems J. Radioanal. Nucl. Chem. 2013, 295 (3) 1927– 1937 DOI: 10.1007/s10967-012-2160-9[Crossref], [CAS], Google Scholar5https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXisF2jurc%253D&md5=7498fa4be18f1e0ea82aaa7490544fe7Heterogeneous distribution of radiocesium in aerosols, soil and particulate matters emitted by the Fukushima Daiichi Nuclear Power Plant accident: retention of micro-scale heterogeneity during the migration of radiocesium from the air into ground and river systemsTanaka, Kazuya; Sakaguchi, Aya; Kanai, Yutaka; Tsuruta, Haruo; Shinohara, Atsushi; Takahashi, YoshioJournal of Radioanalytical and Nuclear Chemistry (2013), 295 (3), 1927-1937CODEN: JRNCDM; ISSN:0236-5731. (Springer)This work analyzed 137Cs in aerosol, rock, soil, and river suspended sediment collected after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. Based on the results, radiocesium post-event behavior and transport in the environment from the air into groundwater and river water systems are discussed. Radionuclides were emitted from FDNPP as airborne hot particles which contained water-sol. radiocesium fractions. Radiocesium was still present in a water-sol. fraction after deposition on the ground. Subsequent interaction of hot particles with water (e.g., rainfall) dissolved and strongly fixed the radiocesium on rock and soil particles, changing it into insol. forms. Hot spot distribution was possibly controlled by the initial deposition position on the ground. Consequently, hot spots were studded on the rock surface rather than being uniformly distributed. Radiocesium distribution in river suspended particles was not homogeneous during water transport, reflecting the radiocesium heterogeneity in rock and soil. Leaching expts. demonstrated radiocesium in rock, soil, and river suspended sediment was fairly insol., showing the adsorption reaction is irreversible. Radiocesium micro-scale heterogeneous distribution in aerosol, soil and suspended particles was due to the presence of hot particles in aerosols. Radiocesium dissoln. in hot particles in aerosol and subsequent irreversible adsorption on soil particle complex was responsible for the preservation of heterogeneity in soil and in river suspended particles.
- 6Yamashiki, Y.; Onda, Y.; Smith, H. G.; Blake, W. H.; Wakahara, T.; Igarashi, Y.; Matsuura, Y.; Yoshimura, K. Initial Flux of Sediment-associated Radiocesium to the Ocean from the Largest River Impacted by Fukushima Daiichi Nuclear Power Plant Sci. Rep. 2014, 4, 3714 DOI: 10.1038/srep03714[Crossref], [PubMed], [CAS], Google Scholar6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXlsVCisL0%253D&md5=e237b05b28fa4fd3f808aef5e93a8ba0Initial flux of sediment-associated radiocesium to the ocean from the largest river impacted by Fukushima Daiichi Nuclear Power PlantYamashiki, Yosuke; Onda, Yuichi; Smith, Hugh G.; Blake, William H.; Wakahara, Taeko; Igarashi, Yasuhito; Matsuura, Yuki; Yoshimura, KazuyaScientific Reports (2014), 4 (), 3714/1-3714/7CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)This study aimed to quantify the flux of radiocesium in the Abukuma Basin (5,172 km2), the largest river system affected by fallout from the Fukushima Daiichi Nuclear Power Plant (FDNPP) event. In the period from 10 August 2011 to 11 May 2012 an estd. 84 to 92% of the total radiocesium transported in the basin's fluvial system was carried in particulate form. During this monitoring period Typhoon Roke (Sept. 2011) was obsd. to induce a significant and temporally punctuated redistribution of radiocesium. The storm-mobilised radiocesium was an estd. 6.18 Terabecquerels corresponding to 61.4% of the total load delivered to the coastal zone during the observation period. The total flux of radiocesium into the Pacific Ocean estd. at the outlet station (basin area 5,172 km2) was 5.34 TBq for 137Cs, and 4.74 TBq for 134Cs, corresponding to 1.13% of the total estd. radiocesium fallout over the basin catchment (890 TBq). This was equiv. to the estd. amt. of direct leakage from FDNPP to the ocean during June 2011 to Sept. 2012 of 17 TBq and the Level 3 Scale Leakage on 21August 2013 (24 TBq).
- 7Sakaguchi, A.; Tanaka, K.; Iwatani, H.; Chiga, H.; Fan, Q.; Onda, Y.; Takahashi, Y. Size distribution studies of 137Cs in river water in the Abukuma riverine system following the Fukushima Dai-ichi Nuclear Power Plant accident J. Environ. Radioact. 2015, 139, 379– 389 DOI: 10.1016/j.jenvrad.2014.05.011[Crossref], [PubMed], [CAS], Google Scholar7https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXpvVWqtbo%253D&md5=9445c6f76d7cccf765e0f1246e6cededSize distribution studies of 137Cs in river water in the Abukuma Riverine system following the Fukushima Dai-ichi Nuclear Power Plant accidentSakaguchi, Aya; Tanaka, Kazuya; Iwatani, Hokuto; Chiga, Haruka; Fan, Qiaohui; Onda, Yuichi; Takahashi, YoshioJournal of Environmental Radioactivity (2015), 139 (), 379-389CODEN: JERAEE; ISSN:0265-931X. (Elsevier Ltd.)The occurrence of 137Cs in size fractionated samples in river water from the Abukuma River system, (the Kuchibuto and Abukuma Rivers, five sampling events for three sites) was studied from June 2011 - approx. some three months after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident until Dec. 2012. The total concn. of 137Cs (mBq/L) in river water was generally high at the upper stream site in the Yamakiya District within the evacuation/off-limits zone. The 137Cs concn. was about 1 Bq/L for the first sampling campaign (June 2011) at all sites, but then decreased substantially to about one-tenth of that by the time of a second sampling campaign (Nov. or Dec. 2011). The 137Cs in the <0.45 μm fraction was present exclusively as a dissolved species rather than as a species adsorbed on suspended solids or complexed with org. materials. The contribution of the dissolved fraction ranged from 1.2 to 48.9% (averaged 20%) of the total concn. of 137Cs throughout the observation period. The max. contribution of 137Cs was found in the silt size fraction (3-63 μm), which can be explained by the relatively large Kd values and the suspended solids (SS) concn. of this size fraction. Although the concn. (Bq/g) of 137Cs ineach size fraction did not show any significant trends and/or variations for any of the sampling campaign, Kd values for each site increased with time. Furthermore, it was found that the Kd values decreased with distance from the headstream in the off-limits zone. Thus, the data acquired in this study give an overview of the radiol. situation for Fukushima including temporal and spatial variation of radiocaesium in a natural riverine system, within a few years after the accident.
- 8Tanaka, K.; Iwatani, H.; Sakaguchi, A.; Takahashi, Y.; Fan, Q. Size-dependent distribution of radiocesium in riverbed sediments and its relevance to the migration of radiocesium in river systems after the Fukushima Daiichi Nuclear Power Plant accident J. Environ. Radioact. 2015, 139, 390– 397 DOI: 10.1016/j.jenvrad.2014.05.002
- 9Yoshimura, K.; Onda, Y.; Sakaguchi, A.; Yamamoto, M.; Matsuura, Y. An extensive study of the concentrations of particulate/dissolved radiocaesium derived from the Fukushima Dai-ichi Nuclear Power Plant accident in various river systems and their relationship with catchment inventory J. Environ. Radioact. 2015, 139, 370– 378 DOI: 10.1016/j.jenvrad.2014.08.021
- 10Japan Statistical Yearbook 2015; Ch. 7; Statistics Bureau, Ministry of Internal Affairs and Communications Japan, Tokyo, 2015; www.stat.go.jp/english/data/nenkan/back61/1431-07.htm (accessed October 28, 2015).Google ScholarThere is no corresponding record for this reference.
- 11Wakahara, T.; Onda, Y.; Kato, H.; Sakaguchi, A.; Yoshimura, K. Radiocesium discharge from paddy fields with different initial scrapings for decontamination after the Fukushima Dai-ichi Nuclear Power Plant accident Environ. Sci. Process. Impacts 2014, 16 (11) 2580– 2591 DOI: 10.1039/C4EM00262H[Crossref], [PubMed], [CAS], Google Scholar11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhsVWqsLnF&md5=75f8f9c7297ca1bf13ba47ce838b81fdRadiocesium discharge from paddy fields with different initial scrapings for decontamination after the Fukushima Dai-ichi Nuclear Power Plant accidentWakahara, Taeko; Onda, Yuich; Kato, Hiroaki; Sakaguchi, Aya; Yoshimura, KazuyaEnvironmental Science: Processes & Impacts (2014), 16 (11), 2580-2591CODEN: ESPICZ; ISSN:2050-7895. (Royal Society of Chemistry)To explore the behavior of radionuclides released after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011, and the distribution of radiocesium in paddy fields, we monitored radiocesium (Cs) and suspended sediment (SS) discharge from paddy fields. We proposed a rating scale for measuring the effectiveness of surface soil removal. Our exptl. plots in paddy fields were located ∼40 km from the FDNPP. Two plots were established: one in a paddy field where surface soil was not removed (the "normally cultivated paddy field") and the second in a paddy field where the top 5-10 cm of soil was removed before cultivation (the "surface-removed paddy field"). The amts. of Cs and SS discharge from the paddy fields were continuously measured from June to August 2011. The Cs soil inventory measured 3 mo after the FDNPP accident was approx. 200 kBq m-2. However, after removing the surface soil, the concn. of Cs-137 decreased to 5 kBq m-2. SS discharged from the normally cultivated and surface-removed paddy fields after puddling (mixing of soil and water before planting rice) was 11.0 kg and 3.1 kg, resp., and Cs-137 discharge was 630 000 Bq (1240 Bq m-2) and 24 800 Bq (47.8 Bq m-2), resp. The total amt. of SS discharge after irrigation (natural rainfall-runoff) was 5.5 kg for the normally cultivated field and 70 kg for the surface-removed field, and the total amts. of Cs-137 discharge were 51 900 Bq (102 Bq m-2) and 165 000 Bq (317 Bq m-2), resp. During the irrigation period, discharge from the surface-removed plot showed a twofold greater inflow than that from the normally cultivated plot. Thus, Cs inflow may originate from the upper canal. The topsoil removal process eliminated at least approx. 95% of the Cs-137, but upstream water contaminated with Cs-137 flowed into the paddy field. Therefore, to accurately det. the Cs discharge, it is important to examine Cs inflow from the upper channel. Furthermore, puddling and irrigation processes inhibit the discharge of radiocesium downstream. This indicates that water control in paddy fields is an important process in the prevention of river pollution and radionuclide transfer.
- 12Harada, H.; Ota, T.; Shindo, H.; Kobayashi, H.; Ito, C. Estimations and Characteristics of Water Pollutant Load from Large Scale Paddy Fields in Hachirogata Polder Jpn. J. Soil Sci. Plant Nutr. 2008, 79, 53– 60
(in Japanese).
Google ScholarThere is no corresponding record for this reference. - 13Sudo, M.; Miki, T.; Masuda, Y. Research on Characteristics of Turbid Water Effluent from Paddy Fields during the Paddling and the Transplanting Period: Based on a study of paddy watershed in Uso river basin, Japan Transactions of the Jpn Soc. Irrigation, Drainage Rural Eng. 2009, 77 (2) 113– 119
(in Japanese).
Google ScholarThere is no corresponding record for this reference. - 14Yamada, Y.; Igeta, A.; Nakashima, S.; Mito, Y.; Ogasahara, T.; Wada, S.; Ohno, T.; Ueda, A.; Hyodo, F.; Imada, M. The runoff of suspended, substances, nitrogen, and phosphorus by enforced draining during the ploughing season; Experiments in paddy fields Rikusuigaku Zasshi 2006, 67, 105– 112DOI: 10.3739/rikusui.67.105
(in Japanese).
[Crossref], [CAS], Google Scholar14https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XhtFSktrjK&md5=cfa6fbb9dbfa145317fc803ff0356e8aThe runoff of suspended substances, nitrogen, and phosphorus by enforced draining during the ploughing season experiments in paddy fieldsYamada, Yoshihiro; Igeta, Akitake; Nakashima, Sachi; Mito, Yugo; Ogasahara, Takako; Wada, Sayaka; Ohno, Tomohiko; Ueda, Atsushi; Hyodo, Fujio; Imada, Miho; Yachi, Shigeo; Tayasu, Ichiro; Fukuhara, Syoichi; Tanaka, Takuya; Wada, EitaroRikusuigaku Zasshi (2006), 67 (2), 105-112CODEN: RIZAAU; ISSN:0021-5104. (Nippon Rikusui Gakkai)The runoff of suspended substances (SS), nitrogen, and phosphorus by enforced draining during the ploughing season was calcd. from expts. in two paddy fields. The area of a paddy field was 3000 m2. The total fluxes were 33 kg (SS), 85 g (total-N), and 46 g (total-P) in Field A, with a small decrease in water levels (8 mm), 110 kg (SS), 589 g (total-N), and 146 g (total-P) in Field B with a major decrease in water levels (72 mm). Furthermore, the nitrogen/phosphorus ratios (mol ratios) of the wastewater by the enforced draining were 4.1 (Field A) and 8.8 (Field B). In comparison with N/P of the phytoplankton (16), it was found that the phosphorus flowed out efficiently with the enforced draining. Increasing the supply of the phosphorus to Lake Biwa is not desirable in view of the current problems of eutrophication. The careless water management of paddy fields was a crucial factor in any plan to improve the water quality of Lake Biwa. - 15Matsui, H.; Fukunaga, R.; Shimizu, S.; Noda, K. Suspended sediment runoff from paddy fields in rainfall-runoff events and applicability of USLE Pro. Hydraul. Eng., JSCE 2009, 53, 673– 678
(in Japanese).
Google ScholarThere is no corresponding record for this reference. - 16Chen, S. K.; Liu, C. W.; Chen, Y. R. Assessing soil erosion in a terraced paddy field using experimental measurements and universal soil loss equation Catena 2012, 95, 131– 141 DOI: 10.1016/j.catena.2012.02.013
- 17Chen, S. K.; Chen, Y. R.; Peng, Y. H. Experimental study on soil erosion characteristics in flooded terraced paddy fields Paddy Water Environ. 2013, 11 (1–4) 433– 444 DOI: 10.1007/s10333-012-0334-2
- 18Santschi, P. H.; Bollhader, S.; Zingg, S.; Luck, A.; Farbenkothen, K. The self-cleaning capacity of surface waters after radioactive fallout. Evidence from European waters after Chernobyl, 1986–1988 Environ. Sci. Technol. 1990, 24 (4) 519– 527 DOI: 10.1021/es00074a009
- 19Smith, J. T.; Wright, S. M.; Cross, M. A.; Monte, L.; Kudelsky, A. V.; Saxén, R.; Vakulovsky, S.; Timms, D. N. Global Analysis of the Riverine Transport of 90Sr and 137Cs Environ. Sci. Technol. 2004, 38 (3) 850– 857 DOI: 10.1021/es0300463
- 20Tsuji, H.; Yasutaka, T.; Kawabe, Y.; Onishi, T.; Komai, T. Distribution of dissolved and particulate radiocesium concentrations along rivers and the relations between radiocesium concentration and deposition after the nuclear power plant accident in Fukushima Water Res. 2014, 60, 15– 27 DOI: 10.1016/j.watres.2014.04.024[Crossref], [PubMed], [CAS], Google Scholar20https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXps12hsb0%253D&md5=1b8eca6d5a67d2cc08993b2de05eff98Distribution of dissolved and particulate radiocesium concentrations along rivers and the relations between radiocesium concentration and deposition after the nuclear power plant accident in FukushimaTsuji, Hideki; Yasutaka, Tetsuo; Kawabe, Yoshishige; Onishi, Takeo; Komai, TakeshiWater Research (2014), 60 (), 15-27CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)This study involved measurement of concns. of dissolved and particulate radiocesium (134Cs and 137Cs) in river water, and detn. of the quant. relations between the amt. of deposited 137Cs and 137Cs concns. in river waters after the Fukushima Daiichi nuclear power plant accident. First, the current concns. of dissolved and particulate 134Cs·137Cs were detd. in a river watershed from 20 sampling locations in four contaminated rivers (Abukuma, Kuchibuto, Shakado, and Ota). Distribution characteristics of different 137Cs forms varied with rivers. Moreover, a higher dissolved 137Cs concn. was obsd. at the sampling location where the 137Cs deposition occurred much more heavily. In contrast, particulate 137Cs concn. along the river was quite irregular, because fluctuations in suspended solids concns. occur easily from disturbance and heavy pptn. A similar tendency with dissolved 137Cs distribution was obsd. for the 137Cs concn. per unit wt. of suspended solids. Regression anal. between deposited 137Cs and dissolved/particulate 137Cs concns. was performed for the four rivers. The results showed a strong correlation between deposited 137Cs and dissolved 137Cs, and a relatively weak correlation between deposited 137Cs and particulate 137Cs concn. for each river. However, if the particulate 137Cs concn. was converted to 137Cs concn. per unit wt. of suspended solid, the values showed a strong correlation with deposited 137Cs.
- 21Konoplev, A. V.; Bulgakov, A. A.; Popov, V. E.; Bobovnikova, Ts. I. Behaviour of long-lived Chernobyl radionuclides in a soil-water system Analyst 1992, 117 (6) 1041– 1047 DOI: 10.1039/AN9921701041
- 22Garcia-Sanchez, L.; Konoplev, A. V.; Bulgakov, A. Radionuclide entrainment coefficients by wash-off derived from plot experiments near Chernobyl Radioprotection 2005, 40, S519– S524 DOI: 10.1051/radiopro:2005s1-076
- 23Garcia-Sanchez, L.; Konoplev, A. V. Watershed wash-off of atmospherically deposited radionuclides: a review of normalized entrainment coefficients J. Environ. Radioact. 2009, 100 (9) 774– 778 DOI: 10.1016/j.jenvrad.2008.08.005
- 24Yoshimura, K.; Onda, Y.; Kato, H. Evaluation of radiocaesium wash-off by soil erosion from various land uses using USLE plots J. Environ. Radioact. 2015, 139, 362– 369 DOI: 10.1016/j.jenvrad.2014.07.019
- 25Smith, J. T.; Fesenko, S. V.; Howard, B. J.; Horrill, A. D.; Sanzharova, N. I.; Alexakhin, R. M.; Elder, D. G.; Naylor, C. Temporal Change in Fallout 137Cs in Terrestrial and Aquatic Systems: A Whole Ecosystem Approach Environ. Sci. Technol. 1999, 33 (1) 49– 54 DOI: 10.1021/es980670t
- 26Smith, J. T.; Clarke, R. T.; Saxén, R. Time-dependent behaviour of radiocaesium: A new method to compare the mobility of weapons test and Chernobyl derived fallout J. Environ. Radioact. 2000, 49, 65– 83 DOI: 10.1016/S0265-931X(99)00088-0
- 27Livens, F. R.; Baxter, M. S. Particle size and radionuclide levels in some west Cumbrian soils Sci. Total Environ. 1988, 70, 1– 17 DOI: 10.1016/0048-9697(88)90248-3
- 28Walling, D. E.; Quine, T. A. Use of 137Cs measurements to investigate soil erosion on arable fields in the UK: potential applications and limitations J. Soil Sci. 1991, 42, 147– 165 DOI: 10.1111/j.1365-2389.1991.tb00099.x
- 29Walling, D. E.; Woodward, J. C. Use of radiometric fingerprints to derive information on suspended sediment sources. In Erosion and Sediment Transport Monitoring Programmes in River Basins; Bogen, J.; Walling, D. E.; Day, T., Eds.; International Association of Hydrological Sciences Publications: Wallingford, 1992; pp 153– 164.Google ScholarThere is no corresponding record for this reference.
- 30He, Q.; Walling, D. E. Interpreting particle size effects in the adsorption of 137Cs and unsupported 210Pb by mineral soils and sediments J. Environ. Radioact. 1996, 30 (2) 117– 137 DOI: 10.1016/0265-931X(96)89275-7
- 31Harada, N.; Nonaka, M. Soil radiocesium distribution in rice fields disturbed by farming process after the Fukushima Dai-ichi Nuclear Power Plant accident Sci. Total Environ. 2012, 438, 242– 247 DOI: 10.1016/j.scitotenv.2012.05.032
- 32Tanaka, K.; Iwatani, H.; Sakaguchi, A.; Takahashi, Y.; Onda, Y. Investigation of Spatial Distribution of Radiocesium in a Paddy Field as a Potential Sink PLoS One 2013, 8 (11) e80794 DOI: 10.1371/journal.pone.0080794
- 33Phillips, J. M.; Russell, M. A.; Walling, D. E. Time-integrated sampling of fluvial suspended sediment: a simple methodology for small catchments Hydrol. Processes 2000, 14 (14) 2589– 2602 DOI: 10.1002/1099-1085(20001015)14:14<2589::AID-HYP94>3.0.CO;2-D
- 34Report on the IAEA-CU-2006–03 World-wide Proficiency Test on the Determination of Gamma Emitting Radionuclides (IAEA/AL/171); International Atomic Energy Agency: Vienna, 2007; https://nucleus.iaea.org/rpst/Documents/iaea_al_171.pdf. (accessed October 28, 2015).Google ScholarThere is no corresponding record for this reference.
- 35Mizugaki, S.; Onda, Y.; Fukuyama, T.; Koga, S.; Asai, H.; Hiramatsu, S. Estimation of suspended sediment sources using 137Cs and 210Pbex in unmanaged Japanese cypress plantation watersheds in southern Japan Hydrol. Processes 2008, 22 (23) 4519– 4531 DOI: 10.1002/hyp.7053[Crossref], [CAS], Google Scholar35https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhsFCrsr%252FO&md5=71b2337419edd0c7b4ee728865be8a27Estimation of suspended sediment sources using 137Cs and 210Pbex in unmanaged Japanese cypress plantation watersheds in southern JapanMizugaki, Shigeru; Onda, Yuichi; Fukuyama, Taijiro; Koga, Satoko; Asai, Hiroki; Hiramatsu, ShinyaHydrological Processes (2008), 22 (23), 4519-4531CODEN: HYPRE3; ISSN:0885-6087. (John Wiley & Sons Ltd.)To analyze suspended sediment sources in unmanaged Japanese cypress plantation watersheds, field measurements and fingerprinting of the suspended sediment was conducted in the Shimanto River basin in southern Japan. For sediment fingerprinting, 137Cs and 210Pbex were detected by means of gamma-ray spectrometry in the surface soil of the forest floor, stream bank and truck trail and mobilized sediment by interrill erosion. The 137Cs and 210Pbex activities assocd. with the forest floor materials were considerably higher than those of the stream bank and truck trail. The 137Cs and 210Pbex activities assocd. with the suspended sediment were found to vary with the sampling period. Evidently, the suspended sediment can comprise materials generated from the forest floor by interrill erosion and those from the truck trail and/or stream bank. The multivariate sediment-mixing model using 137Cs and 210Pbex showed that the contribution of the forest floor varied periodically, ranging from 23-56% in the Hinoki 156 subwatershed and from 18-85% in the Hinoki 155 subwatershed. The difference in the av. contribution of the forest floor between Hinoki 156 (46%) and Hinoki 155 (69%) may relate to the presence of truck trail networks in the watershed. The truck trail network can play roles of sediment source and pathway for sediment from forest floor to stream channel due to the concd. overland flow on the truck trail during heavy rainfall events. These results indicate that the forest floor should be recognized as a major source of suspended sediment in unmanaged Japanese cypress plantation watersheds.
- 36Yoshimura, K.; Onda, Y.; Fukushima, T. Sediment particle size and initial radiocesium accumulation in ponds following the Fukushima DNPP accident Sci. Rep. 2014, 4, 4514 DOI: 10.1038/srep04514[Crossref], [PubMed], [CAS], Google Scholar36https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXovVOis7g%253D&md5=bf6e80994928b0ae347474e9ef86272aSediment particle size and initial radiocesium accumulation in ponds following the Fukushima DNPP accidentYoshimura, Kazuya; Onda, Yuichi; Fukushima, TakehikoScientific Reports (2014), 4 (), 4514/1-4514/6CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)This study used particle size anal. to investigate the initial accumulation and trap efficiency of radiocesium (137Cs) in four irrigation ponds, ∼4-5 mo after the Fukushima Dai-ichi nuclear power plant (DNPP) accident. Trap efficiency, represented by the inventory of 137Cs in pond sediment to the inventory of radiocesium in soil surrounding the pond (i.e., total 137Cs inventory), was less than 100% for all but one pond. Trap efficiency decreased as sediment particle size increased, indicating that sediments with a smaller particle size accumulate more 137Cs. In ponds showing low trap efficiency, fine sediment contg. high concns. of 137Cs appeared to be removed from the system by hydraulic flushing, leaving behind mostly coarse sediment. The results of this study suggest that sediment particle size can be used to est. the initial accumulation and trap efficiency of 137Cs in pond sediment, as well as the amt. lost through hydraulic flushing.
- 37Corrections of the Results of Airborne Monitoring Surveys by MEXT and Ibaraki Prefecture; Ministry of Education, Culture, Sports, Science and Technology: Tokyo, 2012; http://radioactivity.nsr.go.jp/en/contents/4000/3171/24/1270_083114.pdf. (accessed January 7, 2016).Google ScholarThere is no corresponding record for this reference.
- 38Report for the project of Nuclear Regulation Authority entitled Establishment of Grasp Method of Long-Term Effects Caused by Radioactive Materials from the Fukushima Daiichi Nuclear Power Plant Accident (In 2013); Japan Atomic Energy Agency: Ibaraki, 2015; http://fukushima.jaea.go.jp/initiatives/cat03/entry06.html (accessed October 28, 2015) (in Japanese).Google ScholarThere is no corresponding record for this reference.
- 39Ministry of Land, Infrastructure, National Land Numerical Information. http://nlftp.mlit.go.jp/ksj-e/index.html (accessed October 28, 2015) .Google ScholarThere is no corresponding record for this reference.
Cited By
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- . Introduction. 2019,,, 5-49. https://doi.org/10.1017/9781108574273.003
- , , , . Environmental Contamination from the Fukushima Nuclear Disaster. 2019,,https://doi.org/10.1017/9781108574273
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Abstract
Figure 1
Figure 1. Distributions of 137Cs inventory and paddy fields in Fukushima prefecture. This map was generated by ArcGIS 10 software. The prefectural border and shore-lines were obtained from Geospatial Information Authority of Japan. The 137Cs distribution was derived from the Third Airborne Monitoring Survey by Ministry of Education, Culture, Sports, Science and Technology, Japan.(37) The distribution of paddy field in 2009 was based on the National Land Numerical Information service of the Ministry of Land, Infrastructure, Transport, and Tourism.(39)
Figure 2
Figure 2. Sites where turbid paddy water was collected after puddling (open circles and double circles) and SS discharge from paddy fields was monitored (open squares). A double circle indicates that the site was used to collect turbid paddy water in both 2012 and 2013, while an open circle denotes a site used only once in either 2012 or 2013. This map was generated by ArcGIS 10 software. The prefectural border and shore-lines were obtained from Geospatial Information Authority of Japan. The 137Cs distribution was derived from the Third Airborne Monitoring Survey by Ministry of Education, Culture, Sports, Science and Technology, Japan.(37)
Figure 3
Figure 3. Cross-section of paddy field and location of the time-integrated SS sampler. The water level ranged approximately 0–10 cm because of evaporation, weeping, and withdrawal of irrigation water during the irrigation period.
Figure 4
Figure 4. Relationship between initial surface deposition densities of 137Cs obtained from the Third Airborne Monitoring Survey(37) and the particulate 137Cs concentrations found in the SS of turbid paddy water in 2012 and 2013. The particulate 137Cs concentration uncorrected for the particle size dependency is shown by the closed circles with a solid regression line, and the corrected data is shown by the open circles with a dashed regression line. The particulate 137Cs concentrations collected from May 6 to June 22, 2012 and from April 29 to May 23, 2013 were corrected for decay from the first date of each sampling period.
Figure 5
Figure 5. Boxplot of entrainment coefficients calculated from particulate 137Cs concentrations in turbid paddy water corrected for particle size dependency. The box and the error bars show the ranges from the first to third quartiles and from the minimum to the maximum values, respectively. The line identified the median value, and the averaged entrainment coefficient is represented by the closed circle. The entrainment coefficient calculated for the turbid paddy water sample collected on June 13, 2013 in previous study(11) is shown as an open circle.
Figure 6
Figure 6. Temporal decrease in entrainment coefficients obtained from the particulate 137Cs concentration corrected for the particle size dependency. Closed and open circles show the averaged entrainment coefficients obtained from the turbid paddy water after puddling and from the SS discharged from the six experimental paddy fields, respectively. Error bars represents standard deviations. Gray circles and crosses represent the entrainment coefficient obtained at site 1 from June to July 2012 and from the previous 2011 study.(11) The double exponential function fitted to the data is shown as a solid line.
References
ARTICLE SECTIONSThis article references 39 other publications.
- 1Morino, Y.; Ohara, T.; Watanabe, M.; Hayashi, S.; Nishizawa, M. Episode Analysis of Deposition of Radiocesium from the Fukushima Daiichi Nuclear Power Plant Accident Environ. Sci. Technol. 2013, 47 (5) 2314– 2322 DOI: 10.1021/es304620x
- 2Saito, K.; Tanihata, I.; Fujiwara, M.; Saito, T.; Shimoura, S.; Otsuka, T.; Onda, Y.; Hoshi, M.; Ikeuchi, Y.; Takahashi, F. Detailed deposition density maps constructed by large-scale soil sampling for gamma-ray emitting radioactive nuclides from the Fukushima Daiichi Nuclear Power Plant accident J. Environ. Radioact. 2015, 139, 308– 19 DOI: 10.1016/j.jenvrad.2014.02.014
- 3Mikami, S.; Maeyama, T.; Hoshide, Y.; Sakamoto, R.; Sato, S.; Okuda, N.; Demongeot, S.; Gurriaran, R.; Uwamino, Y.; Kato, H. Spatial distributions of radionuclides deposited onto ground soil around the Fukushima Dai-ichi Nuclear Power Plant and their temporal change until December 2012 J. Environ. Radioact. 2015, 139, 320– 343 DOI: 10.1016/j.jenvrad.2014.09.010
- 4Qin, H. B.; Yokoyama, Y.; Fan, Q. H.; Iwatani, H.; Tanaka, K.; Sakaguchi, A.; Kanai, Y.; Zhu, J. M.; Onda, Y.; Takahashi, Y. Investigation of cesium adsorption on soil and sediment samples from Fukushima Prefecture by sequential extraction and EXAFS technique Geochem. J. 2012, 46 (4) 297– 302 DOI: 10.2343/geochemj.2.0214[Crossref], [CAS], Google Scholar4https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhsleqsL3O&md5=640d06d8983456911cb8c67261ce6729Investigation of cesium adsorption on soil and sediment samples from Fukushima prefecture by sequential extraction and EXAFS techniqueQin, Haibo; Yokoyama, Yuka; Fan, Qiaohui; Iwatani, Hokuto; Tanaka, Kazuya; Sakaguchi, Aya; Kanai, Yutaka; Zhu, Jianming; Onda, Yuichi; Takahashi, YoshioGeochemical Journal (2012), 46 (4), 297-302CODEN: GEJOBE; ISSN:0016-7002. (Geochemical Society of Japan)Previous studies have shown that radiocesium (mainly 137Cs) was retained at the very surface of soils in Fukushima Prefecture, Japan. Clay minerals and micas are assumed as the main sorbents for Cs in Fukushima, but direct evidence is lacking for this hypothesis. Radiocesium in the natural sample (soil and sediment) from Fukushima Prefecture was studied through sequential extn. expt. (modified BCR method), which showed that >94% of 137Cs was fixed in the residual phase. The results indicated that most of Cs occurred in the interlayer of phyllosilicate minerals. Cs LIII-edge extended x-ray absorption fine structure (EXAFS) showed that the Cs species adsorbed on the natural samples were very similar to those adsorbed on clay minerals and micas. This finding provided the direct evidence on the significant contribution of clay minerals or micas to Cs retention in soils from Fukushima Prefecture.
- 5Tanaka, K.; Sakaguchi, A.; Kanai, Y.; Tsuruta, H.; Shinohara, A.; Takahashi, Y. Heterogeneous distribution of radiocesium in aerosols, soil and particulate matters emitted by the Fukushima Daiichi Nuclear Power Plant accident: retention of micro-scale heterogeneity during the migration of radiocesium from the air into ground and river systems J. Radioanal. Nucl. Chem. 2013, 295 (3) 1927– 1937 DOI: 10.1007/s10967-012-2160-9[Crossref], [CAS], Google Scholar5https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXisF2jurc%253D&md5=7498fa4be18f1e0ea82aaa7490544fe7Heterogeneous distribution of radiocesium in aerosols, soil and particulate matters emitted by the Fukushima Daiichi Nuclear Power Plant accident: retention of micro-scale heterogeneity during the migration of radiocesium from the air into ground and river systemsTanaka, Kazuya; Sakaguchi, Aya; Kanai, Yutaka; Tsuruta, Haruo; Shinohara, Atsushi; Takahashi, YoshioJournal of Radioanalytical and Nuclear Chemistry (2013), 295 (3), 1927-1937CODEN: JRNCDM; ISSN:0236-5731. (Springer)This work analyzed 137Cs in aerosol, rock, soil, and river suspended sediment collected after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. Based on the results, radiocesium post-event behavior and transport in the environment from the air into groundwater and river water systems are discussed. Radionuclides were emitted from FDNPP as airborne hot particles which contained water-sol. radiocesium fractions. Radiocesium was still present in a water-sol. fraction after deposition on the ground. Subsequent interaction of hot particles with water (e.g., rainfall) dissolved and strongly fixed the radiocesium on rock and soil particles, changing it into insol. forms. Hot spot distribution was possibly controlled by the initial deposition position on the ground. Consequently, hot spots were studded on the rock surface rather than being uniformly distributed. Radiocesium distribution in river suspended particles was not homogeneous during water transport, reflecting the radiocesium heterogeneity in rock and soil. Leaching expts. demonstrated radiocesium in rock, soil, and river suspended sediment was fairly insol., showing the adsorption reaction is irreversible. Radiocesium micro-scale heterogeneous distribution in aerosol, soil and suspended particles was due to the presence of hot particles in aerosols. Radiocesium dissoln. in hot particles in aerosol and subsequent irreversible adsorption on soil particle complex was responsible for the preservation of heterogeneity in soil and in river suspended particles.
- 6Yamashiki, Y.; Onda, Y.; Smith, H. G.; Blake, W. H.; Wakahara, T.; Igarashi, Y.; Matsuura, Y.; Yoshimura, K. Initial Flux of Sediment-associated Radiocesium to the Ocean from the Largest River Impacted by Fukushima Daiichi Nuclear Power Plant Sci. Rep. 2014, 4, 3714 DOI: 10.1038/srep03714[Crossref], [PubMed], [CAS], Google Scholar6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXlsVCisL0%253D&md5=e237b05b28fa4fd3f808aef5e93a8ba0Initial flux of sediment-associated radiocesium to the ocean from the largest river impacted by Fukushima Daiichi Nuclear Power PlantYamashiki, Yosuke; Onda, Yuichi; Smith, Hugh G.; Blake, William H.; Wakahara, Taeko; Igarashi, Yasuhito; Matsuura, Yuki; Yoshimura, KazuyaScientific Reports (2014), 4 (), 3714/1-3714/7CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)This study aimed to quantify the flux of radiocesium in the Abukuma Basin (5,172 km2), the largest river system affected by fallout from the Fukushima Daiichi Nuclear Power Plant (FDNPP) event. In the period from 10 August 2011 to 11 May 2012 an estd. 84 to 92% of the total radiocesium transported in the basin's fluvial system was carried in particulate form. During this monitoring period Typhoon Roke (Sept. 2011) was obsd. to induce a significant and temporally punctuated redistribution of radiocesium. The storm-mobilised radiocesium was an estd. 6.18 Terabecquerels corresponding to 61.4% of the total load delivered to the coastal zone during the observation period. The total flux of radiocesium into the Pacific Ocean estd. at the outlet station (basin area 5,172 km2) was 5.34 TBq for 137Cs, and 4.74 TBq for 134Cs, corresponding to 1.13% of the total estd. radiocesium fallout over the basin catchment (890 TBq). This was equiv. to the estd. amt. of direct leakage from FDNPP to the ocean during June 2011 to Sept. 2012 of 17 TBq and the Level 3 Scale Leakage on 21August 2013 (24 TBq).
- 7Sakaguchi, A.; Tanaka, K.; Iwatani, H.; Chiga, H.; Fan, Q.; Onda, Y.; Takahashi, Y. Size distribution studies of 137Cs in river water in the Abukuma riverine system following the Fukushima Dai-ichi Nuclear Power Plant accident J. Environ. Radioact. 2015, 139, 379– 389 DOI: 10.1016/j.jenvrad.2014.05.011[Crossref], [PubMed], [CAS], Google Scholar7https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXpvVWqtbo%253D&md5=9445c6f76d7cccf765e0f1246e6cededSize distribution studies of 137Cs in river water in the Abukuma Riverine system following the Fukushima Dai-ichi Nuclear Power Plant accidentSakaguchi, Aya; Tanaka, Kazuya; Iwatani, Hokuto; Chiga, Haruka; Fan, Qiaohui; Onda, Yuichi; Takahashi, YoshioJournal of Environmental Radioactivity (2015), 139 (), 379-389CODEN: JERAEE; ISSN:0265-931X. (Elsevier Ltd.)The occurrence of 137Cs in size fractionated samples in river water from the Abukuma River system, (the Kuchibuto and Abukuma Rivers, five sampling events for three sites) was studied from June 2011 - approx. some three months after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident until Dec. 2012. The total concn. of 137Cs (mBq/L) in river water was generally high at the upper stream site in the Yamakiya District within the evacuation/off-limits zone. The 137Cs concn. was about 1 Bq/L for the first sampling campaign (June 2011) at all sites, but then decreased substantially to about one-tenth of that by the time of a second sampling campaign (Nov. or Dec. 2011). The 137Cs in the <0.45 μm fraction was present exclusively as a dissolved species rather than as a species adsorbed on suspended solids or complexed with org. materials. The contribution of the dissolved fraction ranged from 1.2 to 48.9% (averaged 20%) of the total concn. of 137Cs throughout the observation period. The max. contribution of 137Cs was found in the silt size fraction (3-63 μm), which can be explained by the relatively large Kd values and the suspended solids (SS) concn. of this size fraction. Although the concn. (Bq/g) of 137Cs ineach size fraction did not show any significant trends and/or variations for any of the sampling campaign, Kd values for each site increased with time. Furthermore, it was found that the Kd values decreased with distance from the headstream in the off-limits zone. Thus, the data acquired in this study give an overview of the radiol. situation for Fukushima including temporal and spatial variation of radiocaesium in a natural riverine system, within a few years after the accident.
- 8Tanaka, K.; Iwatani, H.; Sakaguchi, A.; Takahashi, Y.; Fan, Q. Size-dependent distribution of radiocesium in riverbed sediments and its relevance to the migration of radiocesium in river systems after the Fukushima Daiichi Nuclear Power Plant accident J. Environ. Radioact. 2015, 139, 390– 397 DOI: 10.1016/j.jenvrad.2014.05.002
- 9Yoshimura, K.; Onda, Y.; Sakaguchi, A.; Yamamoto, M.; Matsuura, Y. An extensive study of the concentrations of particulate/dissolved radiocaesium derived from the Fukushima Dai-ichi Nuclear Power Plant accident in various river systems and their relationship with catchment inventory J. Environ. Radioact. 2015, 139, 370– 378 DOI: 10.1016/j.jenvrad.2014.08.021
- 10Japan Statistical Yearbook 2015; Ch. 7; Statistics Bureau, Ministry of Internal Affairs and Communications Japan, Tokyo, 2015; www.stat.go.jp/english/data/nenkan/back61/1431-07.htm (accessed October 28, 2015).Google ScholarThere is no corresponding record for this reference.
- 11Wakahara, T.; Onda, Y.; Kato, H.; Sakaguchi, A.; Yoshimura, K. Radiocesium discharge from paddy fields with different initial scrapings for decontamination after the Fukushima Dai-ichi Nuclear Power Plant accident Environ. Sci. Process. Impacts 2014, 16 (11) 2580– 2591 DOI: 10.1039/C4EM00262H[Crossref], [PubMed], [CAS], Google Scholar11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhsVWqsLnF&md5=75f8f9c7297ca1bf13ba47ce838b81fdRadiocesium discharge from paddy fields with different initial scrapings for decontamination after the Fukushima Dai-ichi Nuclear Power Plant accidentWakahara, Taeko; Onda, Yuich; Kato, Hiroaki; Sakaguchi, Aya; Yoshimura, KazuyaEnvironmental Science: Processes & Impacts (2014), 16 (11), 2580-2591CODEN: ESPICZ; ISSN:2050-7895. (Royal Society of Chemistry)To explore the behavior of radionuclides released after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011, and the distribution of radiocesium in paddy fields, we monitored radiocesium (Cs) and suspended sediment (SS) discharge from paddy fields. We proposed a rating scale for measuring the effectiveness of surface soil removal. Our exptl. plots in paddy fields were located ∼40 km from the FDNPP. Two plots were established: one in a paddy field where surface soil was not removed (the "normally cultivated paddy field") and the second in a paddy field where the top 5-10 cm of soil was removed before cultivation (the "surface-removed paddy field"). The amts. of Cs and SS discharge from the paddy fields were continuously measured from June to August 2011. The Cs soil inventory measured 3 mo after the FDNPP accident was approx. 200 kBq m-2. However, after removing the surface soil, the concn. of Cs-137 decreased to 5 kBq m-2. SS discharged from the normally cultivated and surface-removed paddy fields after puddling (mixing of soil and water before planting rice) was 11.0 kg and 3.1 kg, resp., and Cs-137 discharge was 630 000 Bq (1240 Bq m-2) and 24 800 Bq (47.8 Bq m-2), resp. The total amt. of SS discharge after irrigation (natural rainfall-runoff) was 5.5 kg for the normally cultivated field and 70 kg for the surface-removed field, and the total amts. of Cs-137 discharge were 51 900 Bq (102 Bq m-2) and 165 000 Bq (317 Bq m-2), resp. During the irrigation period, discharge from the surface-removed plot showed a twofold greater inflow than that from the normally cultivated plot. Thus, Cs inflow may originate from the upper canal. The topsoil removal process eliminated at least approx. 95% of the Cs-137, but upstream water contaminated with Cs-137 flowed into the paddy field. Therefore, to accurately det. the Cs discharge, it is important to examine Cs inflow from the upper channel. Furthermore, puddling and irrigation processes inhibit the discharge of radiocesium downstream. This indicates that water control in paddy fields is an important process in the prevention of river pollution and radionuclide transfer.
- 12Harada, H.; Ota, T.; Shindo, H.; Kobayashi, H.; Ito, C. Estimations and Characteristics of Water Pollutant Load from Large Scale Paddy Fields in Hachirogata Polder Jpn. J. Soil Sci. Plant Nutr. 2008, 79, 53– 60
(in Japanese).
Google ScholarThere is no corresponding record for this reference. - 13Sudo, M.; Miki, T.; Masuda, Y. Research on Characteristics of Turbid Water Effluent from Paddy Fields during the Paddling and the Transplanting Period: Based on a study of paddy watershed in Uso river basin, Japan Transactions of the Jpn Soc. Irrigation, Drainage Rural Eng. 2009, 77 (2) 113– 119
(in Japanese).
Google ScholarThere is no corresponding record for this reference. - 14Yamada, Y.; Igeta, A.; Nakashima, S.; Mito, Y.; Ogasahara, T.; Wada, S.; Ohno, T.; Ueda, A.; Hyodo, F.; Imada, M. The runoff of suspended, substances, nitrogen, and phosphorus by enforced draining during the ploughing season; Experiments in paddy fields Rikusuigaku Zasshi 2006, 67, 105– 112DOI: 10.3739/rikusui.67.105
(in Japanese).
[Crossref], [CAS], Google Scholar14https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XhtFSktrjK&md5=cfa6fbb9dbfa145317fc803ff0356e8aThe runoff of suspended substances, nitrogen, and phosphorus by enforced draining during the ploughing season experiments in paddy fieldsYamada, Yoshihiro; Igeta, Akitake; Nakashima, Sachi; Mito, Yugo; Ogasahara, Takako; Wada, Sayaka; Ohno, Tomohiko; Ueda, Atsushi; Hyodo, Fujio; Imada, Miho; Yachi, Shigeo; Tayasu, Ichiro; Fukuhara, Syoichi; Tanaka, Takuya; Wada, EitaroRikusuigaku Zasshi (2006), 67 (2), 105-112CODEN: RIZAAU; ISSN:0021-5104. (Nippon Rikusui Gakkai)The runoff of suspended substances (SS), nitrogen, and phosphorus by enforced draining during the ploughing season was calcd. from expts. in two paddy fields. The area of a paddy field was 3000 m2. The total fluxes were 33 kg (SS), 85 g (total-N), and 46 g (total-P) in Field A, with a small decrease in water levels (8 mm), 110 kg (SS), 589 g (total-N), and 146 g (total-P) in Field B with a major decrease in water levels (72 mm). Furthermore, the nitrogen/phosphorus ratios (mol ratios) of the wastewater by the enforced draining were 4.1 (Field A) and 8.8 (Field B). In comparison with N/P of the phytoplankton (16), it was found that the phosphorus flowed out efficiently with the enforced draining. Increasing the supply of the phosphorus to Lake Biwa is not desirable in view of the current problems of eutrophication. The careless water management of paddy fields was a crucial factor in any plan to improve the water quality of Lake Biwa. - 15Matsui, H.; Fukunaga, R.; Shimizu, S.; Noda, K. Suspended sediment runoff from paddy fields in rainfall-runoff events and applicability of USLE Pro. Hydraul. Eng., JSCE 2009, 53, 673– 678
(in Japanese).
Google ScholarThere is no corresponding record for this reference. - 16Chen, S. K.; Liu, C. W.; Chen, Y. R. Assessing soil erosion in a terraced paddy field using experimental measurements and universal soil loss equation Catena 2012, 95, 131– 141 DOI: 10.1016/j.catena.2012.02.013
- 17Chen, S. K.; Chen, Y. R.; Peng, Y. H. Experimental study on soil erosion characteristics in flooded terraced paddy fields Paddy Water Environ. 2013, 11 (1–4) 433– 444 DOI: 10.1007/s10333-012-0334-2
- 18Santschi, P. H.; Bollhader, S.; Zingg, S.; Luck, A.; Farbenkothen, K. The self-cleaning capacity of surface waters after radioactive fallout. Evidence from European waters after Chernobyl, 1986–1988 Environ. Sci. Technol. 1990, 24 (4) 519– 527 DOI: 10.1021/es00074a009
- 19Smith, J. T.; Wright, S. M.; Cross, M. A.; Monte, L.; Kudelsky, A. V.; Saxén, R.; Vakulovsky, S.; Timms, D. N. Global Analysis of the Riverine Transport of 90Sr and 137Cs Environ. Sci. Technol. 2004, 38 (3) 850– 857 DOI: 10.1021/es0300463
- 20Tsuji, H.; Yasutaka, T.; Kawabe, Y.; Onishi, T.; Komai, T. Distribution of dissolved and particulate radiocesium concentrations along rivers and the relations between radiocesium concentration and deposition after the nuclear power plant accident in Fukushima Water Res. 2014, 60, 15– 27 DOI: 10.1016/j.watres.2014.04.024[Crossref], [PubMed], [CAS], Google Scholar20https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXps12hsb0%253D&md5=1b8eca6d5a67d2cc08993b2de05eff98Distribution of dissolved and particulate radiocesium concentrations along rivers and the relations between radiocesium concentration and deposition after the nuclear power plant accident in FukushimaTsuji, Hideki; Yasutaka, Tetsuo; Kawabe, Yoshishige; Onishi, Takeo; Komai, TakeshiWater Research (2014), 60 (), 15-27CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)This study involved measurement of concns. of dissolved and particulate radiocesium (134Cs and 137Cs) in river water, and detn. of the quant. relations between the amt. of deposited 137Cs and 137Cs concns. in river waters after the Fukushima Daiichi nuclear power plant accident. First, the current concns. of dissolved and particulate 134Cs·137Cs were detd. in a river watershed from 20 sampling locations in four contaminated rivers (Abukuma, Kuchibuto, Shakado, and Ota). Distribution characteristics of different 137Cs forms varied with rivers. Moreover, a higher dissolved 137Cs concn. was obsd. at the sampling location where the 137Cs deposition occurred much more heavily. In contrast, particulate 137Cs concn. along the river was quite irregular, because fluctuations in suspended solids concns. occur easily from disturbance and heavy pptn. A similar tendency with dissolved 137Cs distribution was obsd. for the 137Cs concn. per unit wt. of suspended solids. Regression anal. between deposited 137Cs and dissolved/particulate 137Cs concns. was performed for the four rivers. The results showed a strong correlation between deposited 137Cs and dissolved 137Cs, and a relatively weak correlation between deposited 137Cs and particulate 137Cs concn. for each river. However, if the particulate 137Cs concn. was converted to 137Cs concn. per unit wt. of suspended solid, the values showed a strong correlation with deposited 137Cs.
- 21Konoplev, A. V.; Bulgakov, A. A.; Popov, V. E.; Bobovnikova, Ts. I. Behaviour of long-lived Chernobyl radionuclides in a soil-water system Analyst 1992, 117 (6) 1041– 1047 DOI: 10.1039/AN9921701041
- 22Garcia-Sanchez, L.; Konoplev, A. V.; Bulgakov, A. Radionuclide entrainment coefficients by wash-off derived from plot experiments near Chernobyl Radioprotection 2005, 40, S519– S524 DOI: 10.1051/radiopro:2005s1-076
- 23Garcia-Sanchez, L.; Konoplev, A. V. Watershed wash-off of atmospherically deposited radionuclides: a review of normalized entrainment coefficients J. Environ. Radioact. 2009, 100 (9) 774– 778 DOI: 10.1016/j.jenvrad.2008.08.005
- 24Yoshimura, K.; Onda, Y.; Kato, H. Evaluation of radiocaesium wash-off by soil erosion from various land uses using USLE plots J. Environ. Radioact. 2015, 139, 362– 369 DOI: 10.1016/j.jenvrad.2014.07.019
- 25Smith, J. T.; Fesenko, S. V.; Howard, B. J.; Horrill, A. D.; Sanzharova, N. I.; Alexakhin, R. M.; Elder, D. G.; Naylor, C. Temporal Change in Fallout 137Cs in Terrestrial and Aquatic Systems: A Whole Ecosystem Approach Environ. Sci. Technol. 1999, 33 (1) 49– 54 DOI: 10.1021/es980670t
- 26Smith, J. T.; Clarke, R. T.; Saxén, R. Time-dependent behaviour of radiocaesium: A new method to compare the mobility of weapons test and Chernobyl derived fallout J. Environ. Radioact. 2000, 49, 65– 83 DOI: 10.1016/S0265-931X(99)00088-0
- 27Livens, F. R.; Baxter, M. S. Particle size and radionuclide levels in some west Cumbrian soils Sci. Total Environ. 1988, 70, 1– 17 DOI: 10.1016/0048-9697(88)90248-3
- 28Walling, D. E.; Quine, T. A. Use of 137Cs measurements to investigate soil erosion on arable fields in the UK: potential applications and limitations J. Soil Sci. 1991, 42, 147– 165 DOI: 10.1111/j.1365-2389.1991.tb00099.x
- 29Walling, D. E.; Woodward, J. C. Use of radiometric fingerprints to derive information on suspended sediment sources. In Erosion and Sediment Transport Monitoring Programmes in River Basins; Bogen, J.; Walling, D. E.; Day, T., Eds.; International Association of Hydrological Sciences Publications: Wallingford, 1992; pp 153– 164.Google ScholarThere is no corresponding record for this reference.
- 30He, Q.; Walling, D. E. Interpreting particle size effects in the adsorption of 137Cs and unsupported 210Pb by mineral soils and sediments J. Environ. Radioact. 1996, 30 (2) 117– 137 DOI: 10.1016/0265-931X(96)89275-7
- 31Harada, N.; Nonaka, M. Soil radiocesium distribution in rice fields disturbed by farming process after the Fukushima Dai-ichi Nuclear Power Plant accident Sci. Total Environ. 2012, 438, 242– 247 DOI: 10.1016/j.scitotenv.2012.05.032
- 32Tanaka, K.; Iwatani, H.; Sakaguchi, A.; Takahashi, Y.; Onda, Y. Investigation of Spatial Distribution of Radiocesium in a Paddy Field as a Potential Sink PLoS One 2013, 8 (11) e80794 DOI: 10.1371/journal.pone.0080794
- 33Phillips, J. M.; Russell, M. A.; Walling, D. E. Time-integrated sampling of fluvial suspended sediment: a simple methodology for small catchments Hydrol. Processes 2000, 14 (14) 2589– 2602 DOI: 10.1002/1099-1085(20001015)14:14<2589::AID-HYP94>3.0.CO;2-D
- 34Report on the IAEA-CU-2006–03 World-wide Proficiency Test on the Determination of Gamma Emitting Radionuclides (IAEA/AL/171); International Atomic Energy Agency: Vienna, 2007; https://nucleus.iaea.org/rpst/Documents/iaea_al_171.pdf. (accessed October 28, 2015).Google ScholarThere is no corresponding record for this reference.
- 35Mizugaki, S.; Onda, Y.; Fukuyama, T.; Koga, S.; Asai, H.; Hiramatsu, S. Estimation of suspended sediment sources using 137Cs and 210Pbex in unmanaged Japanese cypress plantation watersheds in southern Japan Hydrol. Processes 2008, 22 (23) 4519– 4531 DOI: 10.1002/hyp.7053[Crossref], [CAS], Google Scholar35https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhsFCrsr%252FO&md5=71b2337419edd0c7b4ee728865be8a27Estimation of suspended sediment sources using 137Cs and 210Pbex in unmanaged Japanese cypress plantation watersheds in southern JapanMizugaki, Shigeru; Onda, Yuichi; Fukuyama, Taijiro; Koga, Satoko; Asai, Hiroki; Hiramatsu, ShinyaHydrological Processes (2008), 22 (23), 4519-4531CODEN: HYPRE3; ISSN:0885-6087. (John Wiley & Sons Ltd.)To analyze suspended sediment sources in unmanaged Japanese cypress plantation watersheds, field measurements and fingerprinting of the suspended sediment was conducted in the Shimanto River basin in southern Japan. For sediment fingerprinting, 137Cs and 210Pbex were detected by means of gamma-ray spectrometry in the surface soil of the forest floor, stream bank and truck trail and mobilized sediment by interrill erosion. The 137Cs and 210Pbex activities assocd. with the forest floor materials were considerably higher than those of the stream bank and truck trail. The 137Cs and 210Pbex activities assocd. with the suspended sediment were found to vary with the sampling period. Evidently, the suspended sediment can comprise materials generated from the forest floor by interrill erosion and those from the truck trail and/or stream bank. The multivariate sediment-mixing model using 137Cs and 210Pbex showed that the contribution of the forest floor varied periodically, ranging from 23-56% in the Hinoki 156 subwatershed and from 18-85% in the Hinoki 155 subwatershed. The difference in the av. contribution of the forest floor between Hinoki 156 (46%) and Hinoki 155 (69%) may relate to the presence of truck trail networks in the watershed. The truck trail network can play roles of sediment source and pathway for sediment from forest floor to stream channel due to the concd. overland flow on the truck trail during heavy rainfall events. These results indicate that the forest floor should be recognized as a major source of suspended sediment in unmanaged Japanese cypress plantation watersheds.
- 36Yoshimura, K.; Onda, Y.; Fukushima, T. Sediment particle size and initial radiocesium accumulation in ponds following the Fukushima DNPP accident Sci. Rep. 2014, 4, 4514 DOI: 10.1038/srep04514[Crossref], [PubMed], [CAS], Google Scholar36https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXovVOis7g%253D&md5=bf6e80994928b0ae347474e9ef86272aSediment particle size and initial radiocesium accumulation in ponds following the Fukushima DNPP accidentYoshimura, Kazuya; Onda, Yuichi; Fukushima, TakehikoScientific Reports (2014), 4 (), 4514/1-4514/6CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)This study used particle size anal. to investigate the initial accumulation and trap efficiency of radiocesium (137Cs) in four irrigation ponds, ∼4-5 mo after the Fukushima Dai-ichi nuclear power plant (DNPP) accident. Trap efficiency, represented by the inventory of 137Cs in pond sediment to the inventory of radiocesium in soil surrounding the pond (i.e., total 137Cs inventory), was less than 100% for all but one pond. Trap efficiency decreased as sediment particle size increased, indicating that sediments with a smaller particle size accumulate more 137Cs. In ponds showing low trap efficiency, fine sediment contg. high concns. of 137Cs appeared to be removed from the system by hydraulic flushing, leaving behind mostly coarse sediment. The results of this study suggest that sediment particle size can be used to est. the initial accumulation and trap efficiency of 137Cs in pond sediment, as well as the amt. lost through hydraulic flushing.
- 37Corrections of the Results of Airborne Monitoring Surveys by MEXT and Ibaraki Prefecture; Ministry of Education, Culture, Sports, Science and Technology: Tokyo, 2012; http://radioactivity.nsr.go.jp/en/contents/4000/3171/24/1270_083114.pdf. (accessed January 7, 2016).Google ScholarThere is no corresponding record for this reference.
- 38Report for the project of Nuclear Regulation Authority entitled Establishment of Grasp Method of Long-Term Effects Caused by Radioactive Materials from the Fukushima Daiichi Nuclear Power Plant Accident (In 2013); Japan Atomic Energy Agency: Ibaraki, 2015; http://fukushima.jaea.go.jp/initiatives/cat03/entry06.html (accessed October 28, 2015) (in Japanese).Google ScholarThere is no corresponding record for this reference.
- 39Ministry of Land, Infrastructure, National Land Numerical Information. http://nlftp.mlit.go.jp/ksj-e/index.html (accessed October 28, 2015) .Google ScholarThere is no corresponding record for this reference.
Supporting Information
ARTICLE SECTIONSThe Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.est.5b05513.
Table S1. Specific surface area of SS in the turbid paddy water collected after puddling. Table S2. Specific surface area of SS discharged from six monitoring paddy fields (PDF)
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