Distribution characteristics of volatile methylsiloxanes in Tokyo Bay watershed in Japan: Analysis of surface waters by purge and trap method

- A sensitive purge and trap method was developed to determine cyclic and linear VMSs in water.
- Distribution of VMSs in Tokyo Bay watershed was studied for the first time.
- Annual emission of total VMSs through sewage treatment plants into Tokyo Bay watershed was 2300 kg.
- Distribution of cyclic VMS in river water was significantly correlated with TOC.

Surface waters including river water and effluent from sewage treatment plants (STPs) were collected from Tokyo Bay watershed, Japan, and analyzed for seven cyclic and linear volatile methylsiloxanes (VMSs), i.e., D3, D4, D5, D6, L3, L4, and L5 by an optimized purge and trap extraction method. The total concentrations of seven VMSs (ΣVMS) in river water ranged from < 4.9 to 1700 ng/L (mean: 220 ng/L). The individual mean concentrations of cyclic VMSs in surface waters were; 10 ng/L for D3, 13 ng/L for D4, 180 ng/L for D5, and 18 ng/L for D6. The concentrations of ΣVMS determined in STP effluents varied widely from 99 to 2500 ng/L and the individual mean concentrations were 21 ng/L for D3, 27 ng/L for D4, 540 ng/L for D5, and 45 ng/L for D6. D5, which is widely used in personal-care products, was found to be the most abundant compound in both river water and STP effluent. Linear VMSs were detected at much lower frequency and concentrations than those of cyclic VMSs. The measured concentrations of D4 were below the no-observed effect concentration (NOEC). The annual emission of ΣVMS through STPs into Tokyo Bay watershed was estimated at 2300 kg. Our results indicate widespread distribution of VMSs in Tokyo Bay watershed and the influence of domestic wastewater discharges as a source of VMSs in the aquatic environment.

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