A Review of Atmospheric Mercury in the Polar Environment

Abstract

This paper is an overview of Hg measurements made in the Arctic and Antarctic regions, with an emphasis on the evaluation of the methodological approaches employed in both sampling and analysis between different Hg species as well as the fundamental aspects of their behavior. There have been numerous efforts to measure the concentrations of different Hg species, including gaseous elemental mercury (GEM), reactive gaseous mercury (RGM), and particulate mercury (Hg(p)) in polar environments. The mean concentration value for GEM, if evaluated on the basis of numerous studies conducted previously, was moderately higher in the Arctic region (1.56 ng m−3) than the Antarctic counterpart with the limited data sets (1.08 ng m−3). The mean GEM concentration in the Arctic environment varied moderately between different locations so that the highest mean values occurred in sub-Arctic locations with a complicated climatology (e.g., Kuujjuarapik, Quebec: 1.80 ng m−3), while the lowest one was recorded in Pallas, Finland (1.26 ng m−3). A comparison of temporal patterns between different studies also indicates that rather dynamic variations occur due to the effects of certain phenomenon, known as atmospheric mercury depletion events (AMDE). During such depletion events, the GEM concentrations frequently dropped below 1.0 ng m−3, while the RGM and Hg(p) exhibited oposing trends. The distribution of GEM in polar environments is, however, fairly comparable in spatial scale, while those of RGM and Hg(p) vary fairly dynamically in such respects. Evidence suggests that the distribution of Hg species at each measurement site in the polar environments is affected more effectively by site-specific meteorological conditions.