A Study on Pesticide Distribution Characteristics and Environmental Risk Assessment in the Saemangeum Watershed

Pesticides have been widely used to enhance agricultural productivity and protect crops. However, their extensive use has raised concerns about potential environmental impacts. This study aimed to assess the spatial and temporal distribution of 21 pesticides and their environmental hazard indices in the Mangyeong and Dongjin Rivers, which are representative rivers in the active agricultural region of Saemangeum watershed. The results of this study revealed significant variations in pesticide concentrations depending on the regional and seasonal variations. Pesticide concentrations in the Dongjin River, for instance, showed a notable increase in June, aligning with the peak of agricultural activities. Conversely, the Mangyeong River exhibited elevated pesticide levels even in October, reflecting the continued pesticide use during the harvesting season. Environmental hazard assessment identified specific pesticides with environmental risks, such as Ethion, Sulfotep, Fenamiphos, and Phosalone, which posed substantial risks. Diazinon and Phenthoate also raised concerns, particularly Diazinon showed significant cumulative risk. Furthermore, the study applied a dose/concentration addition approach to evaluate pesticide mixture risks, demonstrated its utility in early screening of pesticide mixture hazards. This approach proved to be an efficient tool for risk comparison among various sampling points and prioritizing initial risk assessments.