Okada et al. 2021 を発表しました

福島第一原発事故由来セシウムが魚類に取り込まれ濃度が変動する機構を明らかにしました。論文へ

Title: Seasonal variations of ¹³⁷Cs concentration in freshwater charr through uptake and metabolism in 1–2 years after the Fukushima accident

Abstract: Understanding the factors influencing ¹³⁷Cs concentrations in freshwater salmonids is crucial for reviving inland fisheries in polluted regions. We studied seasonal variations of ¹³⁷Cs concentration in charr (Salvelinus leucomaenis) through uptake and metabolism in forested headwaters at Fukushima and Gunma sites. Charr consumed both terrestrial and aquatic animals, and terrestrial prey was predated more in summer at both sites. The ¹³⁷Cs concentrations in litter, which is a dominant basal food resource of both forest and stream ecosystems, differed between forest and stream due to ¹³⁷Cs leaching effect on litter submerged in streams. The concentration difference in both litter and prey was greater at Fukushima site than at Gunma site. The estimated prey ¹³⁷Cs concentration at Fukushima site peaked in summer when terrestrial preys are most available, whereas it remained relatively constant at Gunma site because of the small difference of ¹³⁷Cs concentrations in between terrestrial and aquatic preys. The specific metabolic rate of charr was commonly changed with stream water temperature, greatest in summer, and lowest in winter at both sites. Because both prey ¹³⁷Cs concentrations and specific metabolic rates peaked in summer, the combination of uptake and metabolism at Fukushima site largely negated seasonal ¹³⁷Cs fluctuations in charr, whereas specific metabolic rate fluctuations could be the major determinant of charr ¹³⁷Cs concentrations at Gunma site. Our results suggested that ¹³⁷Cs concentrations in prey items, whose seasonality are varied due to initial ¹³⁷Cs fallout volume, were expected to be an important determinant for ¹³⁷Cs concentrations in charr.