Different factors determine ~(137)Cs concentration factors of freshwater fish and aquatic organisms in lake and river ecosystems

摘要

Determination of radionuclide concentration factor (CF) allows estimating the transfer of environmental radionuclides and potential risks of consuming fish contaminated with radionuclides. Although it is known that biotic and abiotic factors affect fish CF, only a few studies have examined whether these factors differ among ecosystems. We estimated radiocesium (Cs-137) CF of 30 different fish species and other aquatic organisms by monitoring three lakes and five rivers in Fukushima, 2-4 y after the Fukushima Dai-ichi Nuclear Power Plant accident. The relative effects of biotic and abiotic factors on Cs-137 CF in freshwater organisms were compared between river and lake ecosystems using generalized linear models. Our analysis demonstrated the following. (1) The factors critically affecting fish CF differed between rivers and lakes. The negative effects of suspended solid concentration (SS), total organic carbon (TOC), and salinity were significant for rivers, but not for lakes. Biomagnification of Cs-137 in piscivore fish was significant only in the lakes. (2) Fish size significantly affected the CF in both rivers and lakes. Nevertheless, the correlation between Cs-137 concentration and piscivore fish size was stronger in lakes than in rivers. (3) The SS, TOC, and salinity simultaneously influenced the CF at every trophic level. However, feeding habit was a stronger determinant of Cs-137 bioaccumulation than water chemistry in organisms at higher trophic levels, such as aquatic insects, amphibians, and fish. Our findings indicate that Cs-137 accumulation in aquatic organisms is ecosystem-dependent due to different environmental factors and food web structure.