Mercury dynamics within natural and experimental sea ice
Beattie, Sarah Anne
This work presents the first comprehensive study of Hg dynamics within Arctic multiyear sea ice, followed by a mechanistic study of Hg behaviour in new and growing experimental sea ice. Multiyear sea ice taken from the eastern Beaufort Sea and McClure Strait showed total Hg concentrations ranging from 0.12 to 12.2 ng L-1. Both vertical distribution patterns and regional differences can be explained by the sources and dynamics of particulate matter in sea ice. Methylated mercury was measured in Arctic sea ice: ratios of methylated to total Hg reached 0.4 within bottom ice, suggesting the potential occurrence of in situ methylation in sea ice. The dominant role of particulate dynamics in controlling Hg distribution in sea ice was supported by a mesocosm-scale study at the Sea-ice Environmental Research Facility. This suggests that melting multiyear sea ice represents a considerable loading of total and methylated Hg into the Arctic Ocean.