Carbaryl residue concentrations, degradation, and major sinks in the Seto Inland Sea, Japan.

Abstract

The fate of carbaryl in the Seto Inland Sea (west Japan) was predicted using a mass distribution model using carbaryl concentrations in river and sea water samples, degradation data, and published data. The predicted carbaryl concentrations in water in Kurose River and the Seto Inland Sea were 4.320 and 0.2134μg/L, respectively, and the predicted concentrations in plankton, fish, and sediment were 0.4140, 2.436, and 1.851μg/g dry weight, respectively. The carbaryl photodegradation and biodegradation rates were higher for river water (0.330 and 0.029day-1, respectively) than sea water (0.23 and 0.001day-1, respectively). The carbaryl photodegradation rates for river and sea water (0.33 and 0.23day-1, respectively) were higher than the biodegradation rates (0.029 and 0.001day-1, respectively). The hydrolysis degradation rate for carbaryl in sea water was 0.003day-1, and the half-life was 231days. Land (via rivers) was the main source of carbaryl to the Seto Inland Sea. The model confirmed carbaryl is distributed between sediment, plankton, and fish in the Seto Inland Sea. Degradation, loss to the Open Ocean, and sedimentation are the main carbaryl sinks in the Seto Inland Sea, accounting for 43.81, 27.90, and 17.68%, respectively, of total carbaryl inputs. Carbaryl source and sink data produced by the model could help in the management of the negative impacts of carbaryl on aquatic systems and human health.