Mercury throughout polar sunrise 2002

Abstract. Mercury depletion events (MDEs) are now a well-known phenomenon occurring in Polar Regions during the springtime. During these MDEs gaseous elemental mercury (GEM) is chemically transformed to less volatile mercury species (operationally defrned as reactive gaseous mercury (RGM) and mercury associated with particles (PM)). Various measurement techniques have been employed to measure these different mercury species. However, it is still to be established what species of mercury are being measured in the Arctic air during depletion events. A study was undertaken in the spring of 2002 at Alert, Canada to investigate several techniques for the measurement of these reactive mercury species under Arctic conditions during polar sunrise. This study compared automated GEM, manual and automated RGM and PM measurement techniques as well as a method for total atmospheric mercury. Results showed that manual and automated sampling techniques compared reasonably well. Relative différences in RGM and PM concentrations over land and over the ocean were investigated. PM concentrations were consistent higher than RGM, with the same relative abundance at both sample sites. Additionally, flux measurements were undertaken, including chamber and micrometeorological methods. Mercury depletion events (MDEs) were first discovered in 1995 at Alert, Canada [1]. This discovery bas led to a better understanding of atmospheric cycling of mercury in Polar Regions. Gaseous elemental mercury (GEM), known for its long residence time in the atmosphere (6-24 months) [2], has been found to convert quit