EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Assessing the atmosphere-surface exchange of gaseous elemental mercury using passive air samplers

Meng Si1, Michelle Feigis1, Isabel Quant1, Shreya Mistry1, Melanie Snow1, Knut Breivik2, Melissa Lafreniere3, Scott Lamoureux3, Derek Muir4, Alexandra Steffen4, Geoff Stupple4, Ying Duan Lei1, Carl Mitchell1, and Frank Wania1
Meng Si et al.
  • 1Department of Physical and Environmental Sciences, University of Toronto, Scarborough, Canada
  • 2Atmosphere and Climate Department, University of Oslo, Oslo, Norway
  • 3Department of Geography and Planning, Queen's University, Kingston, Canada
  • 4Air Quality Research Division, Environment and Climate Change Canada, Toronto, Canada

The specific properties of gaseous elemental mercury (GEM) allow it to undergo bidirectional exchange between the atmosphere and the Earth’s surface. Determining the direction and the magnitude of GEM’s atmosphere-surface flux is possible and has been accomplished using micrometeorological and chamber techniques, but (i) is complex and labor-intensive, and (ii) often only yields fluxes over relatively short time scales. A recently developed passive air sampler for GEM has the precision required for identifying and quantifying vertical concentration gradients above the Earth’s surface. The feasibility and performance of this approach is currently being tested in a number of field studies aimed at the: (i) measurement of GEM concentration gradients above both mercury-contaminated and background forest soils, (ii) quantification of vertical concentration gradients on a tower through a temperate deciduous forest canopy, and (iii) measurement of mercury concentration gradients over stable and thawing permafrost to determine the effect of permafrost degradation on GEM evasion. Contrasting with earlier flux studies, these investigations cover long time periods (up to 1.5 years) and have coarse temporal resolution (monthly to seasonally). Significant gradients of GEM air concentrations, both increasing and decreasing with height above ground, were observed, implying that at a minimum, the method is able to identify the flux direction of GEM. Under the right circumstances, this method can also be used to estimate the approximate magnitude of the GEM air-surface exchange flux. The measured gradients also reveal the impact of factors such as temperature, solar irradiance, and snow cover on air-surface exchange. The method holds promise for establishing the direction and size of exchange fluxes at long time scales of months to a year, especially in study areas where access, effort and cost are prohibitive to longer duration studies with existing approaches.

How to cite: Si, M., Feigis, M., Quant, I., Mistry, S., Snow, M., Breivik, K., Lafreniere, M., Lamoureux, S., Muir, D., Steffen, A., Stupple, G., Lei, Y. D., Mitchell, C., and Wania, F.: Assessing the atmosphere-surface exchange of gaseous elemental mercury using passive air samplers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11905,, 2020

This abstract will not be presented.