Mercury pollution in the Arctic from wildfires: Source attribution for the 2000s

Document Type

Article

Publication Date

9-3-2019

Department

Department of Geological and Mining Engineering and Sciences

Abstract

Atmospheric mercury (Hg) is a global environmental pollutant, with wildfire emissions being an important source. There have been growing concerns on Hg contamination in the Arctic region, which is largely attributed to long-range transport from lower latitude regions. In this work, we estimate the contributions of wildfire emissions from various source regions to Hg pollution in the Arctic (66° N to 90° N) using a newly developed global Hg wildfire emissions inventory and an atmospheric chemical transport model (GEOS-Chem). Our results show that global wildfires contribute to about 10% (15 Mg year–1) of the total annual Hg deposition to the Arctic, with the most important source region being Eurasia, which contribute to 5.3% of the total annual Hg deposition followed by Africa (2.5%) and North America (1%). The substantial contributions from the Eurasia region are driven by the strong wildfire activity in the boreal forests. The total wildfire-induced Hg deposition to the Arctic amounts to about one-third of the deposition caused by present-day anthropogenic emissions. We also find that wildfires result in significant Hg deposition to the Arctic across all seasons (winter: 8.3%, spring: 7%, summer: 11%, and fall: 14.6%) with the largest deposition occurring during the boreal fire season. These findings indicate that wildfire is a significant source for Arctic Hg contamination and also demonstrate the importance of boreal forest in the global and regional Hg cycle through the mobilization of sequestered Hg reservoir.

Publisher's Statement

Copyright © 2019 American Chemical Society. Publisher’s version of record: https://doi.org/10.1021/acs.est.9b01773

Publication Title

Environmental science & technology

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