> Research Highlight: Mercury Measurement Inter-comparison Study
Research Highlight:
Mercury Measurement Inter-comparison Study
ARL scientists participated in a mercury dry deposition measurement inter-
comparison study from August 4-13 near Ann Arbor, Michigan. The study was
hosted by the University of Michigan with funds from the Great Lakes Air
Deposition (GLAD) program. The study involved an inter-comparison of various
techniques to measure mercury compounds in ambient air and dry deposition. ARL
used a technique it pioneered called a modified Bowen ratio micro-meteorological
measurement method of gaseous elemental and reactive gaseous mercury. This
technique measures the mercury flux to a real ecosystem. Other participants in
the study included scientists from Environment Canada, U.S. EPA, University of
Michigan, Clarkson University, and the University of Nevada, Reno. With the
exception of ARL and Environment Canada, the participants used surrogate surface
techniques, which measure the mercury flux to an artificial surface. The
outcome of this inter-comparison study will assist the GLAD with its atmospheric
deposition monitoring program priority.
Scientists have a good handle on quantifying mercury in rainfall, but
measuring dry deposition (particles and gases which deposit without the
assistance of precipitation) remains a challenge. Methods to measure mercury in
air and dry deposition are actively under development. Yet, little is known
regarding the uncertainty and comparability of various measurement approaches.
Through a competitive research initiative, the GLAD program works with leading
scientists to better understand the sources of toxic pollutants, their transport
in the environment, their deposition to the Great Lakes basin and the resulting
impacts on human health and the Great Lakes ecosystem.
The greatest input of mercury to aquatic and terrestrial ecosystems is
atmospheric deposition from mercury emissions. While surrogate surfaces
potentially offer a less expensive and simpler technique to estimate mercury
fluxes, the relationship between mercury collected by an artificial surface and
a real ecosystem flux is uncertain. ARL, as a recognized leader in the field of
mercury measurement research, is providing critical information of mercury
fluxes to a real ecosystem.
