A Survey of Mercury in Air and Precipitation across Canada: Patterns and Trends

Atmospheric mercury (Hg) measurements from across Canada were compiled and analysed as part of a national Hg science assessment. Here we update long-term trends of Hg in air and precipitation, and present more extensive measurements on patterns and trends in speciated Hg species (gaseous elemental m...

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Bibliographic Details
Published in:Atmosphere
Main Authors: Amanda S. Cole, Alexandra Steffen, Chris S. Eckley, Julie Narayan, Martin Pilote, Rob Tordon, Jennifer A. Graydon, Vincent L. St. Louis, Xiaohong Xu, Brian A. Branfireun
Format: Article in Journal/Newspaper
Language:English
Published: MDPI AG 2014
Subjects:
elemental mercury
total gaseous mercury
reactive mercury
gaseous oxidized mercury
particulate mercury
cycling of atmospheric mercury
mercury in precipitation
mercury trends
Meteorology. Climatology
QC851-999
Arctic
Canada
Online Access:https://doi.org/10.3390/atmos5030635
https://doaj.org/article/93c01caa3a51428a84b7a33deb483202
Description
Summary:Atmospheric mercury (Hg) measurements from across Canada were compiled and analysed as part of a national Hg science assessment. Here we update long-term trends of Hg in air and precipitation, and present more extensive measurements on patterns and trends in speciated Hg species (gaseous elemental mercury—GEM, reactive gaseous mercury—RGM, and total particulate mercury on particles <2.5 μm—TPM2.5) at several sites. A spatial analysis across Canada revealed higher air concentrations and wet deposition of Hg in the vicinity of local and regional emission sources, and lower air concentrations of Hg at mid-latitude maritime sites compared to continental sites. Diel and seasonal patterns in atmospheric GEM, RGM and TPM2.5 concentrations reflected differences in patterns of anthropogenic emissions, photo-induced surface emissions, chemistry, deposition and mixing. Concentrations of GEM decreased at rates ranging from −0.9% to −3.3% per year at all sites where measurements began in the 1990s. Concentrations of total Hg in precipitation declined up to 3.7% yr−1. Trends in RGM and TPM2.5 were less clear due to shorter measurement periods and low concentrations, however, in spring at the high Arctic site (Alert) when RGM and TPM2.5 concentrations were high, concentrations of both increased by 7%–10% per year.

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