title: Estimation of dry deposition of atmospheric mercury in Nevada by direct and indirect methods.
abstract: Atmospheric models and limited measurements indicate that dry deposition of atmospheric mercury is an important process by which mercury is input to ecosystems. To begin to fill the measurement data gap, multiple methods were used simultaneously during seasonal campaigns conducted in 2005 and 2006 to estimate dry deposition of atmospheric mercury at two Mercury Deposition Network (MDN) sites in rural Nevada and in Reno, Nevada. Gaseous elemental mercury (Hg0), reactive gaseous mercury (RGM), and particulate-bound mercury (Hgp) concentrations were measured using Tekran 2537A/1130/ 1135 systems. These speciated measurements were combined with on-site meteorological measurements to estimate depositional fluxes of RGM and Hgp using dry deposition models. Modeled fluxes were compared with more direct measurements obtained using polysulfone cation-exchange membranes and foliar surfaces. Dynamic flux chambers were used to measure soil mercury exchange. RGM concentrations were higher during warmer months at all sites, leading to seasonal variation in the modeled importance of RGM as a component of total depositional load. The ratio of dry to wet deposition was between 10 and 90%, and varied with season and with the methods used for dry deposition approximations. This work illustrates the variability of mercury dry deposition with location and time and highlights the need for direct dry deposition measurements.
authors.affiliation: Department of Natural Resources and Environmental Science/MS 370, University of Nevada, Reno 89557, USA.
authors.forename: Seth N
authors.initials: SN
authors.lastname: Lyman
authors.forename: Mae Sexauer
authors.initials: MS
authors.lastname: Gustin
authors.forename: Eric M
authors.initials: EM
authors.lastname: Prestbo
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Marsik
mesh_terms: D001272:Atmosphere / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods* / Q000706:statistics & numerical data*; D004785:Environmental Pollutants / Q000032:analysis*; D008567:Membranes, Artificial; D008628:Mercury / Q000032:analysis*; D008962:Models, Theoretical; D009505:Nevada; D018515:Plant Leaves / Q000737:chemistry; D012621:Seasons
chemical_list: D004785:Environmental Pollutants; D008567:Membranes, Artificial; D008628:Mercury