Measurements of atmospheric mercury, gaseous elemental mercury, and evasional fluxes in the Amundsen Gulf: the role of the sea-ice environment

Abstract

Mercury (Hg) has been recognized as a contaminant of global concern due to its high toxicity, as well as its ability to mobilize over long distances and biomagnify up through the food chain. The discovery of polar springtime atmospheric mercury depletion events (AMDEs) in the 1990s provides a new mechanism for enhanced atmospheric Hg deposition to the surface environment in the Arctic, yet questions remain on the process leading to AMDEs and the net contribution of AMDEs to Hg loadings to the Arctic marine ecosystem. Here we report the first systematic study of AMDEs over the open ocean conducted in the Amundsen Gulf flaw lead system from February to July 2008. A total of 31 AMDEs were observed which showed clear dependence on local sea ice environment and meteorological conditions. Enhanced concentrations of dissolved gaseous mercury were also measured in both under ice and open water conditions. Our results confirm that the sea ice environment plays a large role in Hg dynamics in the Arctic Ocean.