Cyclic volatile methylsiloxanes in sediment, soil, and surface water from Dongting Lake, China

Previous reports have shown that some cyclic volatile methylsiloxanes (cVMS) are characterized as persistent, toxic, and potentially harmful to ecology. In the present work, concentrations of three widely used cVMS, namely, octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) were investigated in surface water, sediment, and soil from Dongting Lake in China. Solid-liquid extraction and liquid-liquid extraction were used for solid and aqueous samples. Gas chromatography-mass spectrometry (GC-MS) was used to analyze cVMS concentrations in the samples. The relationship between total organic matter in the samples and cVMS concentrations was also measured. The total concentrations of cVMS ranged from 64.89 to 489.07 ng L-1, < LOD 163.00 ng g(-1) dry weight (dw), and 26.63-996.95 ng g(-1) dw in surface water, soil, and sediment, respectively. There was a significant correlation between cVMS concentrations and total organic carbon in the sediment samples, suggesting that sediment was the main source of cVMS in the lake area investigated. A very strong geographic gradient in concentrations of total cVMS was found in that sediments from samples collected downstream contained higher concentrations of cVMS than those from upstream. According to the concentrations measured in surface waters, sediments, and soils compared with the criterion for the maximum no observed effected concentrations (NOEC) and LC50 values, cVMS posed low environmental risks to aquatic, sediment-dwelling and terrestrial organisms.