Snow Amplification of Persistent Organic Pollutants at Coastal Antarctica

Abstract

Many legacy and emerging persistent organic pollutants (POPs) have been reported in polar regions, and act as sentinels of global pollution. Maritime Antarctica is recipient of abundant snow precipitation. Snow scavenges air pollutants, and after snow melting, it can induce an unquantified and poorly understood amplification of concentrations of POPs. Air, snow, the fugacity in soils and snow, seawater and plankton were sampled concurrently from late spring to late summer at Livingston Island (Antarctica). Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) concentrations in snow and air were close to equilibrium. POPs in soils showed concentrations close to soil–air equilibrium or net volatilization depending on chemical volatility. Seawater–air fugacity ratios were highly correlated with the product of the snow–air partition coefficient and the Henry’s law constant (K SA H’), a measure of snow amplification of fugacity. Therefore, coastal seawater mirrored the PCB congener profile and increased concentrations in snowmelt due to snowpack releasing POPs to seawater. The influence of snowpack and glacier inputs was further evidenced by the correlation between net volatilization fluxes of PCBs and seawater salinity. A meta-analysis of K SA, estimated as the ratio of POP concentrations in snow and air from previously reported simultaneous field measurements, showed that snow amplification is relevant for diverse families of POPs, independent of their volatility. We claim that the potential impact of atmospheric pollution on aquatic ecosystems has been under-predicted by only considering air–water partitioning, as snow amplification influences, and may even control, the POP occurrence in cold environments.

Global Drivers on Southern Ocean Ecosystems: Changing Physical Environments and Anthropogenic Pressures in an Earth System

“…In contrast to some previous studies, there was no indication of local sources for this pollution, e.g., from research stations (Wild et al, 2015), rather that the pollution was highly likely to have come from atmospheric sources (Krasnobaev et al, 2020). This atmospheric origin is supported by the highest concentration of POPs being recorded in the surface phytoplankton, early in the summer, soon after the sea ice, and any snow cover has melted (Casal et al, 2018(Casal et al, , 2019Krasnobaev et al, 2020). With changes in the cryosphere, particularly the reduction in sea ice duration, and the associated changes in phytoplankton bloom dynamics, the seasonal pattern of POPs is projected to become less pronounced (high confidence).…”

Rain Amplification of Persistent Organic Pollutants

“…This together with the high specific surface area of snow, makes this deposition process crucial to understand the occurrence of a large variety of POPs in polar regions. [17][18][19]26,27,29 A meta-analysis of the snow−air partition constants (K SA ), estimated as the ratio of POP concentrations in snow and air, from previously reported simultaneous field measurements, showed that snow amplification was relevant for diverse families of POPs, independent of their volatility. 18 The same work showed that seawater−air fugacity ratios of polychlorinated biphenyls (PCBs) were highly correlated with the product of K SA and the dimensionless Henry's law constant (H′), a measure of snow amplification of fugacity.…”

Large Enrichment of Anthropogenic Organic Matter Degrading Bacteria in the Sea-Surface Microlayer at Coastal Livingston Island (Antarctica)

“…The SML is also a direct recipient of atmospherically deposited aerosols, which have been shown to trigger community dissimilarities between SML and SSL bacterial populations in other regions, due to effects of nutrient inputs (Vila-Costa et al, 2013;Astrahan et al, 2016;Marín-Beltrán et al, 2019) and pollination events (Södergren, 1987) on bacterioneuston. The diffusive atmosphere-ocean exchange and snow deposition are the main sources of not only semivolatile OP, such as Polycyclic Aromatic Hydrocarbons (PAH) and polychlorinated biphenyls (Galbán-Malagón et al, 2013;Casal et al, 2018Casal et al, , 2019, but also other hydrophobic and surfactant-like OPs such as perfluoroalkylsubstances (Casal et al, 2017). All these OP become part of the anthropogenic dissolved organic carbon (ADOC) (Vila-Costa et al, 2020) pool, which due to its hydrophobic and surfactant-like properties is enriched in the SML (Cincinelli et al, 2005;Stortini et al, 2009;Casas et al, 2020).…”