Tracking Long-range Atmospheric Transport of Contaminants in Arctic Regions Using Lake Sediments

Abstract

Due to the nature of global atmospheric circulation patterns, numerous contaminants of concern, including mercury (Hg) and persistent organic pollutants (POPs), undergo long-range transport to the Arctic where they can be deposited to landscapes and water bodies. As a result, both mercury and POPs have recently reached levels in Arctic mammals and fishes that are high enough to pose health risks to Northern peoples consuming these animals as traditional country foods. Dated lake sediment cores provide a valuable tool for examining temporal trends in atmospheric contaminant deposition. In addition, the recent application of novel multi-proxy approaches is allowing atmospheric contaminant deposition to be examined within the context of numerous climate-induced alterations to contaminant cycling, such as increased catchment contaminant inputs driven by climate-induced erosion. Here, we review current information on the use of dated sediment cores to examine post-industrial (post-~ 1850) changes to atmospheric mercury and POPs deposition, including atmospheric contaminant transport and deposition processes, the impacts of climate-induced changes on these processes, and the application of novel lake sediment core analyses to untangle trends in contaminant deposition due to multiple sources and environmental stressors. Hg and POPs are compared and contrasted throughout the chapter, as, although these contaminants are both of great concern in the Arctic, their differing physical-chemical properties and emission sources result in differing transport and deposition pathways. Finally, we make suggestions for future research that will allow dated lake sediment cores to continue to provide valuable information on contaminant deposition in the face of a changing Arctic climate.