Gaseous oxidised mercury compounds captured by membrane technologies at two Australian sites

Mercury (Hg) is a significant environmental pollutant, due its detrimental effects on both humans and ecosystems. The atmosphere is the largest natural pathway for global mercury distribution, and so understanding atmospheric mercury transport is of primary importance. Both the physical and chemical properties of gaseous oxidised mercury (GOM) in the atmosphere are poorly understood. Nylon and cation-exchange membranes have recently been pioneered as measurement tools for GOM. This study measured GOM using nylon and cation-exchange membranes at 2 sites in South Eastern Australia. One site, the Macquarie University campus, is located within an urban and industrial zone. The other, Cape Grim, is a rural site located far from urban or industrial environments. The ambient concentrations of GOM were analysed at both sites, and speciation data was analysed at Cape Grim. Values from both sites were examined for correlations with a variety of meteorological conditions. Higher average concentrations were observed at the Macquarie University site (20.2pg m-3, σ=5.4) than at Cape Grim (15.7pg m-3, σ=4.7) (P = 00348). A possible negative correlation was observed at both sites with relative humidity, in line with previous observations. Initial GOM speciation at Cape Grim using nylon membranes indicated the presence of Hg(NO3)2 and Hg(SO)4, with little evidence of HgCl2, HgBr2 or HgO.