Volatile Methyl Siloxanes in Polar Regions

Abstract

This chapter reviews volatile methyl siloxanes (VMS) in polar regions (i.e., at latitudes above the polar circles), including their sources, measured concentrations, and the effect of polar environmental conditions on behavior of VMS. Knowledge about VMS in polar regions has been centered on cyclic VMS (cVMS) due to their widespread use and presence in the environment. Due to their high volatility, cVMS are mainly emitted to and remain in the atmosphere, where they eventually degrade. cVMS are present in Arctic air due to both long-range atmospheric transport and local sources within the Arctic. There is no evidence that cVMS deposit to surface media to a significant extent, not even under polar environmental conditions. However, cVMS are emitted via wastewater, and many Arctic communities have limited wastewater treatment where low removal efficiency of cVMS from wastewater can result in high emissions. cVMS concentrations in sediments and aquatic biota close to wastewater outlets in the Norwegian Arctic are comparable to those at temperate latitudes. Sporadic detections of cVMS in biota and surface media in remote Arctic and Antarctic regions need further investigation to be confirmed. Very few measurements are reported for linear VMS (lVMS) in polar regions, with a majority of studies reporting findings below detection limits. The understanding of how Arctic conditions, including low temperatures and strong seasonality, affect the environmental behavior and bioaccumulation of VMS has been expanded through modelling studies. However, important knowledge gaps remain regarding temperature dependence of partitioning behavior in aquatic environments, biotransformation rates in polar biota, and the influence of physiological and behavioral adaptations of polar biota on bioaccumulation of VMS.