Nationwide levels and distribution of endosulfan in air, soil, water, and sediment in South Korea

We investigated the levels and distribution patterns of α- and β-endosulfan and endosulfan sulfate in air, soil, water, and sediment samples collected from the South Korean persistent organic pollutants (POPs) monitoring networks. In the air samples, the highest concentrations of the total (Σ₃) endosulfan (50.3–611 pg/m³, mean: 274 pg/m³) were observed during summer. Spearman analysis revealed a good correlation between agricultural land area and atmospheric concentrations of Σ₃ endosulfan except during winter. Regardless of the season, the ratio of the two isomers (α/β) was 3.6–4.9 in the air samples, higher than that observed in technical mixtures (2.0–2.3), possibly due to the higher volatility of α-endosulfan, compared to β-endosulfan. Concentrations of Σ₃ endosulfan in the soil samples (n.d.−13.4 ng/g, mean: 0.8 ng/g) were not significantly different except at some stations adjacent to large areas of farmland. The average levels of Σ₃ endosulfan in the water and sediment samples were 2.1 ng/L and 0.1 ng/g dw, respectively. In analyzing the four largest rivers, it was observed that a few water stations during spring and fall and sediment stations in fall had high concentrations of the two isomers and endosulfan sulfate, particularly around the Yeoungsan and Nakdong Rivers near large areas of agricultural land. Endosulfan sulfate was dominant at most water and sediment sampling stations. This study demonstrates that the endosulfan found in most environmental compartments most probably derives from agricultural areas despite its ban as a pesticide. On the other hand, given that it was also detected in industrial and urban areas, in which pesticide application does not occur, it can be conjectured that endosulfan is aerially transported at higher temperatures and continuously circulates within the environment.