Department of Urban and Environmental Engineering (Environmental Science and Engineering )Siloxanes have been used as chemical additives in various consumer and industrial products since the 1940s. Based on their extensive usage, cyclic siloxanes are categorized as high production volume chemicals. However, siloxanes are known to cause potential toxic effects and result in environmental persistence and bioaccumulation. Furthermore, previous studies have detected the high levels of siloxanes in various environmental matrices, which can lead to negative effects on the ecosystem. Therefore, siloxanes are an emerging concern as contaminants in the environment.
In this study, 6 cyclic siloxanes (D4???D9) and 13 linear siloxanes (L3???L15) were analyzed in coastal sediment collected from southeastern industrial bays in Ulsan, Busan, Jinhae, and Gwangyang, South Korea (March???April 2016). The four bays are heavily industrialized and designated as special management sea areas by the Korean government, because of severe coastal pollution originating from industrial complexes and commercial ports. A total of 69 surface sediment samples were collected using grab samplers and were extracted by shaking with organic solvents and then analyzed using gas chromatography mass spectrometry (GC/MS). From the results, contamination levels, spatial distribution, and correlationship of siloxanes in coastal sediment was investigated. Additionally, the hazard quotients (HQs) for siloxanes were evaluated using Monte Carlo simulation.
The total concentrations of siloxanes were in the range of 10.1 to 3,877.2 (mean: 304.2) ng/g dry weight (dw) for all studied samples. The relative composition of D5 (28%) and D6 (33%) were the highest, followed by L11 (5.9%) and L10 (5.2%). The highest concentration of total siloxanes was found in Busan (579.4 ng/g dw), followed by Ulsan (315.8 ng/g dw), Jinhae (266.2 ng/g dw), and Gwangyang (31.1 ng/g dw). The total concentration levels of siloxanes in South Korea are similar to other countries. Significant correlations exist among the concentrations of siloxanes, the concentrations of persistent organic pollutants (POPs), and TOC content in sediment. The hazard quotients (HQs) for siloxanes in coastal sediment were less than 1, indicating that there is no risk to organisms of the exposure of siloxanes in coastal sediment.clos
