Cesium radioisotope content of wild edible fungi, mineral soil, and surface litter in western North America after the Fukushima nuclear accident

Abstract

We measured activity levels of radioisotopes cesium-134 (134Cs) and cesium-137 (137Cs) in wild edible fungi, mineral soil, and surface litter of the west coast of North America from southern California to northern Vancouver Island after the Fukushima nuclear accident. All activity measurements were below United States governmental limits for human health.137Cs activity increased to the north in mineral soils and fungal samples, whereas134Cs activity increased to the south in surface litter samples. Chanterelles (Cantharellus spp.) did not significantly bioconcentrate either radioisotope, but chanterelle activity levels were correlated with those of mineral soil. Activity levels demonstrated a high degree of variability, even in samples from the same site. In most cases, the level of137Cs activity was substantially higher than that of134Cs, suggesting that137Cs was present in the environment prior to the Fukushima release.