title: Atmospheric mercury in the Canadian Arctic. Part II: insight from modeling.
abstract: A review of mercury in the Canadian Arctic with a focus on field measurements is presented in part I (see Steffen et al., this issue). Here we provide insights into the dynamics of mercury in the Canadian Arctic from new and published mercury modeling studies using Environment Canada's mercury model. The model simulations presented in this study use global anthropogenic emissions of mercury for the period 1995-2005. The most recent modeling estimate of the net gain of mercury from the atmosphere to the Arctic Ocean is 75 Mg year(-1) and the net gain to the terrestrial ecosystems north of 66.5° is 42 Mg year(-1). Model based annual export of riverine mercury from North American, Russian and all Arctic watersheds to the Arctic Ocean are in the range of 2.8-5.6, 12.7-25.4 and 15.5-31.0 Mg year(-1), respectively. Analysis of long-range transport events of Hg at Alert and Little Fox Lake monitoring sites indicates that Asia contributes the most ambient Hg to the Canadian Arctic followed by contributions from North America, Russia, and Europe. The largest anthropogenic Hg deposition to the Canadian Arctic is from East Asia followed by Europe (and Russia), North America, and South Asia. An examination of temporal trends of Hg using the model suggests that changes in meteorology and changes in anthropogenic emissions equally contribute to the decrease in surface air elemental mercury concentrations in the Canadian Arctic with an overall decline of ~12% from 1990 to 2005. A slow increase in net deposition of Hg is found in the Canadian Arctic in response to changes in meteorology. Changes in snowpack and sea-ice characteristics and increase in precipitation in the Arctic related with climate change are found to be primary causes for the meteorology-related changes in air concentrations and deposition of Hg in the region. The model estimates that under the emissions reduction scenario of worldwide implementation of the best emission control technologies by 2020, mercury deposition could potentially be reduced by 18-20% in the Canadian Arctic.
authors.affiliation: Air Quality Research Division, Environment Canada, 2121 TransCanada Highway, Dorval, QC H9P 1J3, Canada. Electronic address: Ashu.Dastoor@ec.gc.ca.
authors.forename: Ashu
authors.initials: A
authors.lastname: Dastoor
authors.affiliation: Air Quality Research Division, Environment Canada, 2121 TransCanada Highway, Dorval, QC H9P 1J3, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Ryzhkov
authors.affiliation: Meteorological Service of Canada, Environment Canada, 2121 TransCanada Highway, Dorval, QC H9P 1J3, Canada.
authors.forename: Dorothy
authors.initials: D
authors.lastname: Durnford
authors.affiliation: University of Waterloo, Department of Earth and Environmental SciencesWaterloo, Ontario N2L 3G1, Canada.
authors.forename: Igor
authors.initials: I
authors.lastname: Lehnherr
authors.affiliation: Environment Canada, Air Quality Research Division, Toronto, Ontario M3H 5T4, Canada.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Steffen
authors.affiliation: Environment Canada, Air Quality Research Division, Toronto, Ontario M3H 5T4, Canada.
authors.forename: Heather
authors.initials: H
authors.lastname: Morrison
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D001110:Arctic Regions; D001272:Atmosphere / Q000737:chemistry*; D002170:Canada; D004784:Environmental Monitoring; D008628:Mercury / Q000032:analysis*; D008956:Models, Chemical
chemical_list: D000393:Air Pollutants; D008628:Mercury
keywords: Arctic; Concentration; Deposition; Mercury; Model; Source attribution