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Sakai M, Ohira M, Gomi T. Spatiotemporal patterns in differences between the 137Cs concentrations of forest and stream litters: effect of leaching. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2023; 25:1385-1390. [PMID: 37522302 DOI: 10.1039/d3em00236e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
Forest-stream ecotones possess prominent detritus-based food webs, and 137Cs-contaminated litter can influence the contamination levels of animals inhabiting such ecosystems. The effects of leaching on contaminated litter induce greater absolute differences between the 137Cs concentrations of forest and stream litter in more contaminated sites. Because 137Cs concentrations in litter can be attenuated temporally, spatiotemporal patterns in the differences in 137Cs concentrations between forest and stream litter may vary depending on both the amount of 137Cs deposition and the passage of time. To test this hypothesis, we sampled coniferous needle and broad-leaved deciduous litter in forests and streams at seven forested headwater sites affected by the Fukushima nuclear accident 3.24 and 11.24 years after the accident. We found that 137Cs concentrations in the two litter types were one order of magnitude lower 11.24 years after the accident than 3.24 years afterwards. The absolute difference in 137Cs activity concentrations of litter between forest and stream ecosystems was higher at more contaminated sites both 3.24 and 11.24 years after the accident. The spatiotemporal changes in litter contamination provide insight into 137Cs dynamics and complex transfer in the detritus-based food webs of forest-stream ecotones.
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Affiliation(s)
- Masaru Sakai
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, 10-2 Fukasaku, Miharu, Fukushima 963-7700, Japan.
| | - Mitsuru Ohira
- Institute of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Sauwau-cho, Fuchu, Tokyo 183-8509, Japan
- Field Science Center for Northern Biosphere, Hokkaido University, 131 Toikanbetu, Horonobe-cho, Teshio-gun, Hokkaido 098-2943, Japan.
| | - Takashi Gomi
- Institute of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Sauwau-cho, Fuchu, Tokyo 183-8509, Japan
- Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nogoya, Aichi 464-8601, Japan.
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Wada T, Hinata A, Furuta Y, Sasaki K, Konoplev A, Nanba K. Factors affecting 137Cs radioactivity and water-to-body concentration ratios of fish in river and pond environments near the Fukushima Dai-ichi Nuclear Power Plant. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2023; 258:107103. [PMID: 36599216 DOI: 10.1016/j.jenvrad.2022.107103] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 12/17/2022] [Accepted: 12/21/2022] [Indexed: 06/17/2023]
Abstract
To elucidate 137Cs contamination levels and mechanisms of fish inhabiting river and pond environments near the Fukushima Dai-ichi Nuclear Power Plant, 137Cs activity concentrations in fish (15 species, n = 164) and water collected from Maeda River (3.3-8.9 km from the plant) and Shimofukazawa Pond (2.9 km) in 2017 were analyzed. Also, an 8-week rearing experiment using Japanese dace Pseudaspius hakonensis fed on non-contaminated pellets and the pond water (mean 137Cs concentration of 2.0 Bq/L) was conducted to evaluate 137Cs accumulation from water to fish. The 137Cs concentrations in Japanese dace, the only species collected throughout five sampling sites from estuarine to upstream areas in Maeda River, were found to be correlated with ambient air dose rates and fish size, exhibiting large variations (16.5-2.6×103 Bq/kg-wet). By contrast, dissolved 137Cs in river waters increased from the upper to lower course (0.025-0.28 Bq/L), which caused large variations of the water-to-body concentration ratio (CR) in Japanese dace (60.0-35700 L/kg-wet). These CRs (geometric mean of 3670 L/kg-wet) were much higher than the steady-state CR of reared fish (9.7 L/kg-wet), indicating that river fish uptake 137Cs mainly from prey items from aquatic and riparian zones, rather than from water. Statistically significant negative correlations between K+ concentrations in water and river fish CRs were detected, resulting in the decreasing trend of CRs from upstream to estuarine areas. These results suggest that the large heterogeneity of air dose rates, K+ concentration, and estuarine processes in brackish water habitats, in association with the feeding habit and size effect in fish, can engender wide variation of 137Cs concentrations and CRs of river fish along a river course. In contrast, 137Cs concentrations in pond fish (4.3-14.6 kBq/kg-wet) were higher than in river fish. The CRs of pond fish were constantly high but the range was smaller (1010-3440 L/kg-wet) with larger values in fish of higher trophic levels. These findings suggest that biomagnification within a pond was inferred as the main cause of 137Cs contamination of pond fish.
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Affiliation(s)
- Toshihiro Wada
- Institute of Environmental Radioactivity, Fukushima University, Fukushima, Fukushima, 960-1296, Japan.
| | - Akinori Hinata
- Faculty of Symbiotic Systems Science, Fukushima University, Fukushima, Fukushima, 960-1296, Japan
| | - Yuma Furuta
- Faculty of Symbiotic Systems Science, Fukushima University, Fukushima, Fukushima, 960-1296, Japan
| | - Keiichi Sasaki
- Fukushima Prefectural Inland Water Fisheries Experiment Station, Inawashiro, Fukushima, 969-3283, Japan
| | - Alexei Konoplev
- Institute of Environmental Radioactivity, Fukushima University, Fukushima, Fukushima, 960-1296, Japan
| | - Kenji Nanba
- Institute of Environmental Radioactivity, Fukushima University, Fukushima, Fukushima, 960-1296, Japan; Faculty of Symbiotic Systems Science, Fukushima University, Fukushima, Fukushima, 960-1296, Japan
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Sakai M, Ishii Y, Tsuji H, Tanaka A, Jo J, Negishi JN, Hayashi S. Contrasting seasonality of 137Cs concentrations in two stream animals that share a trophic niche. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 315:120474. [PMID: 36270568 DOI: 10.1016/j.envpol.2022.120474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 09/28/2022] [Accepted: 10/15/2022] [Indexed: 06/16/2023]
Abstract
Understanding the seasonality of 137Cs concentrations in aquatic animals is crucial for reviving local inland fisheries. The seasonality of 137Cs concentrations in animals is expected to vary, even if focal species consume similarly contaminated foods because the 137Cs excretion rate is species-specific, and 137Cs uptake by foraging autochthonous food resources also vary among seasons. Here, we conducted a seasonal monitoring survey of dissolved 137Cs concentrations as an indicator of the contamination level of food resources and measured 137Cs concentrations in two carnivorous aquatic animals (Palaemon paucidens and Rhinogobius sp.) that share a trophic niche in a stream connected to a dam reservoir. The dissolved 137Cs concentration had clear seasonality-high in summer and low in winter. The 137Cs concentrations in the animals revealed a different seasonal pattern-it peaked in October in P. paucidens and peaked in February in Rhinogobius. Overall, the 137Cs concentration was relatively higher in P. paucidens than in Rhinogobius, suggesting that P. paucidens has a lower excretion rate than Rhinogobius. Consequently, the seasonality of the 137Cs concentration in P. paucidens showed temporal changes similar to those of the dissolved 137Cs concentration, which were likely affected by 137Cs uptake through foraging, whereas that in Rhinogobius was controlled by 137Cs excretion. This study shows that the seasonality of 137Cs concentration can differ between sympatric animals that share a trophic niche. Accumulating knowledge and comparing the seasonality of 137Cs concentrations in fisheries species based on the balance between uptake and excretion will be valuable to determine the appropriate seasons to obtain less-contaminated products.
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Affiliation(s)
- Masaru Sakai
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, Tamura District, 963-7700, Japan.
| | - Yumiko Ishii
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, Tamura District, 963-7700, Japan
| | - Hideki Tsuji
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, Tamura District, 963-7700, Japan
| | - Asuka Tanaka
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, Tamura District, 963-7700, Japan
| | - Jaeick Jo
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, Tamura District, 963-7700, Japan
| | - Junjiro N Negishi
- Faculty of Environmental Earth Science, Hokkaido University, Kita 10, Nishi 5, Kita-ku, Sapporo, Hokkaido, 060-0810, Japan
| | - Seiji Hayashi
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, Tamura District, 963-7700, Japan
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Urabe J. Ecological responses to the direct and indirect disturbances by the Great East Japan Earthquake, 2011. Ecol Res 2021. [DOI: 10.1111/1440-1703.12267] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Jotaro Urabe
- Graduate School of Life Sciences Tohoku University Sendai Japan
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