Abstract
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.
Highlights
Mercury (Hg) is a pollutant of concern due to its health effects and elevated concentrations in aquatic food webs
Limited studies suggest that TGM measurements consist of gaseous elemental mercury (GEM) and reactive gaseous mercury (RGM) [71,72]; it is possible that under certain environmental conditions and sample inlet configurations, the RGM is removed
A synthesis of all available Hg measurements from Canadian air and precipitation monitoring sites is presented, including diel and seasonal cycles and long-term trends
Summary
Mercury (Hg) is a pollutant of concern due to its health effects and elevated concentrations in aquatic food webs. Conversion of Hg between these three inorganic forms can take place on various timescales and media and influence deposition and surface emissions. Short-term temporal changes in atmospheric concentrations of Hg, such as diel and seasonal patterns, arise from changes in meteorology (e.g., temperature, winds, sunlight, precipitation) that lead to changes in emissions, mixing, chemistry and deposition. These patterns may yield information about the chemistry and air-surface exchange of Hg at a particular location, whereas long-term trends are reflective of multi-year changes in the Hg budget on local, regional and global scales [6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
