ABSTRACT

Understanding the pathways of ¹³⁷Cs transfer to spiders as generalist predators is useful to assess the long-term recycling of ¹³⁷Cs through the food chain in forest ecosystems. Approximately 6.5 years after the Fukushima Dai-ichi Nuclear Power Plant accident, we collected spider samples at two different habitats (in a forest interior and along a river) in a forest and determined their ¹³⁷Cs activity concentrations and stable carbon and nitrogen isotope ratio values (δ¹³C and δ¹⁵N). Across the locations, ¹³⁷Cs was detected in all spiders, indicating that a significant fraction of the deposited ¹³⁷Cs is still bioavailable. The geometric means of the transfer factor (T_ag) values were 1.3 × 10⁻³ m² kg⁻¹ and 0.8 × 10⁻³ m² kg⁻¹ for the spiders in the forest interior and along the river, respectively. There were no significant differences in the ¹³⁷Cs activity concentration and T_ag value between the locations. In contrast, the δ¹³C and δ¹⁵N for the spiders were significantly different between the locations, indicating different food resources of the spiders. The preliminary results indicate that the transfer of ¹³⁷Cs to spiders can be a useful indicator of ¹³⁷Cs recycling in forest ecosystems, but the transfer pathways remain difficult to identify because of high variability.

摘要

了解¹³⁷ Cs作为通配捕食者转移至蜘蛛的途径对于评估森林生态系统中整个食物链中¹³⁷ Cs的长期回收很有用。福岛第一核电站事故发生约6.5年后，我们在森林中两个不同的生境（森林内部和沿河）收集了蜘蛛样本，并确定了它们的¹³⁷ Cs活性浓度和稳定的碳氮同位素比值（δ ¹³ C和δ ¹⁵ N）。在所有位置上，所有蜘蛛中都检测到了¹³⁷ Cs，这表明在沉积的¹³⁷ Cs中有很大一部分Cs仍然是生物可利用的。对于森林内部和沿河的蜘蛛，转移因子（T _ag）值的几何平均值分别为1.3×10 ^-3 m ² kg ^-1和0.8×10 ^-3 m ² kg ^-1。位置之间的¹³⁷ Cs活性浓度和T _ag值之间无显着差异。与此相反，δ ¹³ C和δ ¹⁵ N代表蜘蛛人的位置之间显著不同，表示蜘蛛不同食物资源。初步结果表明，转让¹³⁷Cs转化为蜘蛛可能是森林生态系统中¹³⁷ Cs回收的有用指标，但是由于变异性高，转移途径仍然难以确定。