Whole-watershed mercury balance at Sagehen Creek, Sierra Nevada, CA

X Faïn, D Obrist, A Pierce, C Barth, MS Gustin… - … et Cosmochimica Acta, 2011 - Elsevier
X Faïn, D Obrist, A Pierce, C Barth, MS Gustin, DP Boyle
Geochimica et Cosmochimica Acta, 2011Elsevier
Few data are available on mercury (Hg) dynamics at high-elevation mountain sites. In this
project, a whole-watershed approach was used to quantify major fluxes and pools of Hg in
Sagehen basin, a closed basin in the Sierra Nevada mountains in California. Over a period
spanning 9months (January–September 2009), we estimated wet deposition inputs to the
watershed at 3.8 μgm− 2. Dry deposition added additional Hg in the range of 0.30–2.45
μgm− 2 during this time period, and was the dominant deposition process during summer …
Few data are available on mercury (Hg) dynamics at high-elevation mountain sites. In this project, a whole-watershed approach was used to quantify major fluxes and pools of Hg in Sagehen basin, a closed basin in the Sierra Nevada mountains in California. Over a period spanning 9months (January–September 2009), we estimated wet deposition inputs to the watershed at 3.8μgm−2. Dry deposition added additional Hg in the range of 0.30–2.45μgm−2 during this time period, and was the dominant deposition process during summer time. Seasonal snowpack accounted for only half of the Hg deposited by wet deposition. We suggest that photo-induced reduction of Hg(II) in snow and subsequent volatilization was responsible for this loss. Thus, snowpacks in the Sierra Nevada mountains likely reduce the effective atmospheric mercury flux via wet deposition due to significant emission fluxes prior to snowmelt. As such, wet Hg deposition could be of lesser importance as a Hg source in snow-dominated systems. Finally, stream runoff collected at the outlet of the watershed could account for only 4% of total Hg wet deposition suggesting that a large fraction of mercury deposition was sequestered in the ecosystem, specifically in the soils.
Elsevier
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