Automated Measurements of Environmental Mercury Speciation and Fluxes
Reactive gaseous mercury (RGM) refers to one or more oxidized (Hg2+) forms of airborne mercury. Reliable measurement of these RGM species is a critical need in understanding the biogeochemical mercury cycle, because the speciation of atmospheric mercury controls its deposition. Measurement of RGM is a difficult challenge because of its low concentration (in the pg/m3 range) and inherent instability and reactivity. We developed a method for collection and analysis of RGM in air using refluxing mist chambers (MC) combined with a Tekran automated field mercury analyzer. The MC method efficiently extracts water soluble gases from short-term ambient air samples and exhibits excellent precision and blanks. Our data show that RGM represents a few percent of Hg in air, exhibits a strong daytime maximum, and is strongly removed by wet and dry deposition.