Sources of variability in mercury flux measurements

Abstract

Abstract. Chamber and micrometeorological mercury flux data collected during the Nevada STORMS intercomparison study were used to identify natural and methodological factors controlling data variability. Micrometeorological and chamber measurements revealed that flux variability at a site is closely related to the Hg concentrations in the substrate, which were found to vary with mineral composition, grain size, and sampling depth. Environmental factors also influenced flux variability. Following two rainfall events, fluxes measured by chamber and micrometeorological methods increased substantially. The micrometeorological flux was enhanced five fold following the rain event. Fluxes measured by both methods were also influenced by net radiation and temperature as evidenced by their tendency to follow the diel cycle in these variables. Daytime fluxes were 6 times greater than nighttime fluxes. Data analysis revealed that interactions between environmental and geochemical variables complicate relationships between the flux and these variables. Understanding the variability at a flux monitoring site is important to establish relationships for scaling up and for the development of consistent sampling protocols that allow comparisons from one study to another and adequately quantify mercury fluxes from natural sites to provide representative emission data that can be used for scaling up to regional and global scales.

Air-surface exchange measurements of gaseous elemental mercury over naturally enriched and background terrestrial landscapes in Australia

“…M1 to M3) were obtained over a range of substrate concentrations, showing a clear relationship between flux and substrate concentration. This general relationship has been observed by others (Gustin et al, 1999a;Edwards et al, 2001;Rasmussen et al, 1998) and will be explored further in Sect. 3.4.…”

“…The dynamic flux method used aligns with current common practice (Eckley et al, 2010;Carpi et al, 2007;Zhang et al, 2002;Gillis and Miller, 2000;Edwards et al, 2001) and is described in detail in Rasmussen et al (2005). The semi-cylindrical chamber is low profile (i.e., 0.1 m) and has a footprint of 0.1 m 2 , and a volume of 0.008 m 3 .…”

“…Over the past decade a series of field studies over naturally enriched and background terrestrial landscapes were carried out in Canada and USA (Edwards et al, 2001(Edwards et al, , 2002Schroeder et al, 2005;Gustin et al, 1999a, b;Lindberg et al, 1999). Data from these studies showed a strong relationship between emission flux and substrate concentration for naturally enriched sites and highlighted relationships with environmental factors such as temperature, solar radiation, precipitation and soil moisture.…”

Global observations and modeling of atmosphere–surface exchange of elemental mercury: a critical review

“…Higher soil porosity and enhanced soil disturbance have been suggested to facilitate Hg II reduction and Hg 0 transfer from soil (Fu et al, 2012a;Bash and Miller, 2007). Small soil grain size, clay and silt occurrence with higher surface area and Hg content, showed higher Hg 0 flux (Edwards, et al, 2001;Gustin et al, 2002). Microbial-induced reduction can enhance Hg 0 evasion but to a lesser extent (Fritsche et al, 2008a;Choi and Holsen, 2009b).…”

Mercury vapor air–surface exchange measured by collocated micrometeorological and enclosure methods – Part I: Data comparability and method characteristics

“…The disparate results may largely stem from methodological issues (Fritsche et al, 2008b). In some previous studies using the AGM method to gauge various trace gas fluxes including Hg 0 (Edwards et al, 2001;Edwards et al, 2005;Simpson et al, 1997), normalization of Eq. (5) was introduced to mitigate for systematical failure of obtaining energy budget closures (Twine et al, 2000) by a factor of 1.3-1.35.…”