Air-surface exchange measurements of gaseous elemental mercury over naturally enriched and background terrestrial landscapes in Australia
This paper presents the first gaseous elemental mercury (GEM) air-surface exchange measurements obtained over naturally enriched and background (<0.1 μg g<sup>−1</sup> Hg) terrestrial landscapes in Australia. Two pilot field studies were carried out during the Australian autumn and wi...
Main Authors: | , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2013-05-01
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Series: | Atmospheric Chemistry and Physics |
Online Access: | http://www.atmos-chem-phys.net/13/5325/2013/acp-13-5325-2013.pdf |
Summary: | This paper presents the first gaseous elemental mercury (GEM) air-surface exchange measurements obtained over naturally enriched and background (<0.1 μg g<sup>−1</sup> 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<sup>−2</sup> h<sup>−1</sup> to 113 ± 6 ng m<sup>−2</sup> h<sup>−1</sup>. 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<sup>−2</sup> h<sup>−1</sup>. 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<sup>−1</sup> to 0.0083 cm s<sup>−1</sup> with an average of 0.0041 ± 0.00018 cm s<sup>−1</sup>, 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. |
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ISSN: | 1680-7316 1680-7324 |