Assessment of error in sediment core sampling in lakes using radiocesium derived from the Fukushima Nuclear Accident

Abstract

Radiocesium from the Fukushima Nuclear Accident that had been deposited on a lake sediment surface was used for an error evaluation of sediment core sampling through disturbance and loss of surface sediments. Sampling was performed in two lakes ( Kasumigaura and Nakanuma lakes ) with different sediment properties using two different methods: the HR-type core sampler and scuba diving. Radiocesium concentrations in the sediment cores changed greatly over the approximate range of depth of 0 to 20 cm, suggesting that radiocesium was usable for an evaluation of sediment sampling. The vertical profiles and inventories of radiocesium taken by the core sampler were similar to those taken by scuba divers, indicating that the disturbance and loss of surface sediments by the core sampler were less pronounced than with collection by divers. These results suggest the successful sampling of undisturbed sediment samples by the HR-type core sampler and the applicability of radiocesium to the assessment of error in sediment core sampling.