Climatic and biogeochemical controls on the remobilization and reservoirs of persistent organic pollutants in Antarctica.

After decades of primary emissions, reservoirs of persistent organic pollutants (POPs) have accumulated in soils and snow/ice in polar regions. These reservoirs can be remobilized due to decreasing primary emissions or due to climate change-driven warmer conditions. Results from a sampling campaign carried out at Livingston Island (Antarctica) focusing on field measurements of air-soil exchange of POPs show that there is a close coupling of the polychlorinated biphenyls (PCBs) in the atmosphere and snow/ice and soils with a status close to air-surface equilibrium to a net volatilization from Antarctic reservoirs. This remobilization of PCBs is driven by changes in temperature and soil organic matter (SOM) content, and it provides strong evidence that the current and future remobilization and sinks of POPs are a strong function of the close coupling of climate change and carbon cycling in the Antarctic region and this is not only due to warming. Whereas an increase of 1 °C in ambient temperature due to climate change would increase current Antarctic atmospheric inventories of PCBs by 21-45%, a concurrent increase of 0.5% SOM would counteract the influence of warming by reducing the POP fugacity in soil. A 1 °C increase in Antarctic temperatures will induce an increase of the soil-vegetation organic carbon and associated POPs pools by 25%, becoming a net sink of POPs, and trapping up to 70 times more POPs than the amount remobilized to the atmosphere. Therefore, changes in soil biogeochemistry driven by perturbations of climate may increase to a larger degree the soil fugacity capacity than the decrease in air and soil fugacity capacity due to higher temperatures. Future research should focus on quantifying these remobilization fluxes and sinks for the Antarctic region.