Characteristics of 137Cs Concentration and Radioactivity Transfer in Large Aquatic Insect Species

Characteristics of 137Cs concentration and radioactivity transfer in two large aquatic insect species, caddisfly Stenopsyche marmorata Navas (Trichoptera) and dobsonfly Protohermes grandis (Megaloptera) of four rivers were compared. The order of concentration factors, CF_water and CF_sediment of each species have not significantly changed for 8 years. The magnitudes of the concentration factors of both species of each river were independent from the individual weight. Due to natural flashing, resuspension, and retention of suspended particulate matter of streams, concentration factors were temporarily affected on 137Cs contamination in S. marmorata. Accumulation of 137Cs in S. marmorata was negligible and the concentration decreased below the detection limit from larvae to pupae and adults.