Abstract
Abstract. This paper presents the first gaseous elemental mercury (GEM) air-surface exchange measurements obtained over naturally enriched and background (<0.1 μg g−1 Hg) terrestrial landscapes in Australia. Two pilot field studies were carried out during the Australian autumn and winter periods at a copper-gold-cobalt-arsenic-mercury mineral field near Pulganbar, NSW. GEM fluxes using a dynamic flux chamber approach were measured, along with controlling environmental parameters over three naturally enriched and three background substrates. The enriched sites results showed net emission to the atmosphere and a strong correlation between flux and substrate Hg concentration, with average fluxes ranging from 14 ± 1 ng m−2 h−1 to 113 ± 6 ng m−2 h−1. Measurements at background sites showed both emission and deposition. The average Hg flux from all background sites showed an overall net emission of 0.36 ± 0.06 ng m−2 h−1. Fluxes show strong relationships with temperature, radiation, and substrate parameters. A compensation point of 2.48, representative of bare soils was determined. For periods of deposition, dry deposition velocities ranged from 0.00025 cm s−1 to 0.0083 cm s−1 with an average of 0.0041 ± 0.00018 cm s−1, representing bare soil, nighttime conditions. Comparison of the Australian data to North American data suggests the need for Australian-specific mercury air-surface exchange data representative of Australia's unique climatic conditions, vegetation types, land use patterns and soils.
Highlights
Background sitesB1 and B3 were bare soil sites, whereas site B2 was a sparsely vegetated site with mostly Oi horizon leaf litter, twigs, and grass
This paper presents the first Australian-specific gaseous ele- Introduction mental mercury (GEM) airsurface exchange measurements along with controlling climatic and substrate variables
Prior to undertaking the GEM air-surface exchange measurements presented here, there were no direct measurements of Hg exchange available for Australian landscapes
Summary
B1 and B3 were bare soil sites, whereas site B2 was a sparsely vegetated site with mostly Oi horizon leaf litter, twigs, and grass. Samples of these materials were collected and separated into two categories for analysis: (1) leaf litter and (2) grass and twigs. The samples were homogenized using a stainless steel coffee mill and analyzed using a DMA-80 (EPA method 7473). Results of this analysis showed THg for leaf litter as 0.041 ± 0.001 μg g−1 and 0.044 ± 0.005 μg g−1 for grass & twigs.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
