Investigation of radiocesium translation from contaminated sediment to benthic organisms

Abstract

We estimated the radiocesium translation from contaminated sediments to benthic organisms off the coast of Fukushima. We conducted field investigations and an experiment with a benthic polychaete (Perinereis aibuhitensis) reared on highly contaminated sediments collected from a station 1 km off the Fukushima Dai-ichi Nuclear Power Plant. Results of the field investigations revealed that radiocesium contamination in benthic organisms depended on their feeding habitat. The radiocesium concentration in carnivore or herbivore feeder polychaetes was higher than that in deposit feeders. Radiocesium concentrations of all benthic organism specimens were lower than that in sediments collected from the same sampling point. Results of the rearing experiment showed that the concentration ratio (CR) of 137 Cs for P. aibuhitensis and contaminated sediments (wet/wet) was less than 0.10. Moreover, 4 days after separation from the contaminated sediments, the 137 Cs concentrations in P. aibuhitensis rapidly decreased. Based on the results of our field investigations and rearing experiment, we conclude that the intake of radiocesium through the benthic food web is limited for benthic organisms, despite the high contamination of the surrounding sediments.