Trophic transfer of cyclic methyl siloxanes in the marine food web in the Bohai Sea, China

Trophic transfer of cyclic methyl siloxanes (CMS) in aquatic ecosystems is an important criterion for assessing its environmental risks. This study researched the trophic transfer of four CMS (octamethylcyclotetrasiloxane (D-4), decamethylcyclopentasiloxane (D-5), dodecamethylcyclohexasiloxane (D-6), and tetradecamethylcycloheptasiloxane (D-7)) in marine food web from zooplankton up to seabirds in the Chinese Bohai Sea. In the zooplankton-invertebrate-fish-seabird based food web, the significant trophic magnifications were found for D-4 to D-6 (D-4: R-2 = 0.040, p < 0.05, D-5: R-2 = 0.26, p < 0.0001, D-6: R-2 = 0.071, p < 0.001), and the significant trophic dilution was found for D-7 (R-2 = 0.026 and p < 0.05). The trophic magnification factors (TMF) for D-4 to D-7 were 1.7 (95% confidence interval: 1.1-2.6), 3.5 (2.5-5.0), 1.8 (1.3-2.6), and 0.63 (95% CI: 0.40-0.99) respectively. In the zooplankton-invertebrate-fish based food web, both significant trophic magnification for D-5 (R-2 = 0.16, p < 0.0001, TMF = 3.0) and significant trophic dilution for D-7 (R-2 = 0.073, p < 0.01, TMF = 0.4) were found, but for D-4 and D-6, the trophic magnifications were not significant (D-4: R-2 = 0.010, p = 0.23, D-6: R-2 = 0.010, p = 0.23). The trophic transfer of the legacy contaminant BDE-47 and BDE-99 were also conducted as the benchmark chemicals and significant positive correlation was found. As far as we know, this is the first research on the trophic transfer of CMS in the zooplankton-invertebrate-fish-bird food chain which provided new insight of these compounds in the area.