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Title: Micrometeorological gradient approach for quantifying air/surface exchange of mercury vapor: Tests over contaminated soils

Journal Article · · Environmental Science and Technology; (United States)
DOI:https://doi.org/10.1021/es00001a016· OSTI ID:6594546
; ;  [1];  [2]
  1. Oak Ridge National Lab., TN (United States)
  2. National Oceanic and Atmospheric Administration, Oak Ridge, TN (United States)

The micrometerological modified Bowen ratio method was used for the first time to quantify fluxes of elemental mercury vapor (Hg[sup 0]) over contaminated soils during the spring and fall of 1993. We determined fluxes using relationships among the concentration gradients and fluxes of water vapor (measured with fast-response sensors and eddy correlation) and measured gradients in Hg[sup 0] (sampled with a multi-replicate, high-precision device). The contaminated soils consistently exhibited significant emission of Hg[sup 0] to the atmosphere. Fluxes associated with winds from the primary source area ranged from [approximately]10 to [approximately]200 ng m[sup [minus]2] h[sup [minus]1], up to several orders of magnitude above background. Fluxes increased exponentially with soil temperature, yielding a temperature coefficient similar to nitrogen oxide (exp[<(0.065 [+-] 0.011)> T[sub soil]], for T[sub soil] = 7-29[degrees]C). These results provided confidence in the method for Hg[sup 0] because the gradients and fluxes behaved predictably. Fluxes appear to be controlled by volatilization of existing contaminant elemental Hg plus reduction of Hg[sup 2+] to Hg[sup 0] in soil solution. We modeled the emission from an area of contaminated soils within approximately 20-50 m of our site using the flux/soil temperature relationship and annual temperature data. 55 refs., 8 figs., 1 tab.

OSTI ID:
6594546
Journal Information:
Environmental Science and Technology; (United States), Vol. 29:1; ISSN 0013-936X
Country of Publication:
United States
Language:
English