Multi-matrix contamination by cyclic and linear siloxanes in a highly industrialized estuarine environment of Korea: source identification, seasonal variation, and bioaccumulation potential

Cyclic and linear siloxanes are widely used in personal care, industrial, and consumer products. To better understand their fate and ecological risks in estuarine environments, this study investigated spatial distribution, seasonal variations, and the bioaccumulation potential of siloxanes in surface water, sediment, and in benthic organisms in an industrialized bay of Korea. Cyclic siloxanes exhibited higher concentrations than linear siloxanes across multiple environmental matrices, indicating their predominance and persistence. Water and sediment had distinct spatial distributions of siloxanes, which were influenced by local sources and hydrodynamic conditions. Industrial activities and power plant effluents were identified as major contributors to siloxane contamination in the coastal environment. Overall, the concentration of siloxanes in surface water was highest in winter. In particular, cyclic siloxanes showed a greater sensitivity to seasonal variation than linear siloxanes, with concentrations fluctuating significantly across sampling periods. The spatial distribution of siloxanes in sediment was strongly associated with organic carbon. Benthic invertebrates exhibited a strong potential for bioaccumulation of D5 and L9, with the highest bioaccumulation factors and biota-sediment accumulation factors among the detected compounds. These findings highlight the need for continued monitoring and management of siloxane contamination in industrialized estuarine environments.