title: Foliar mercury accumulation and exchange for three tree species.
abstract: The goals of this study were to (1) investigate plant mercury (Hg) uptake using different air and soil Hg concentrations near natural background values for three tree species, and (2) test if measured foliar Hg fluxes could explain observed foliar Hg concentrations. Plants were exposed to three soil treatments (<0.01, 0.09 +/- 0.02, and 0.92 +/- 0.27 microg Hg g(-1)), and to three atmospheric exposure concentrations (5.9 +/- 2.3, 14.3 +/- 2.7, and 30.1 +/- 3.5 ng Hg m(-3)). Foliar Hg concentrations were found to be influenced primarily by atmospheric Hg concentrations and to a lesser extent by soil Hg exposures. Data indicated that deciduous species might play a more active role in ecosystem Hg cycling than evergreen trees. Foliar mercury fluxes quantified using a dynamic single-plant gas-exchange chamber for two species were variable and accumulation rates were lower than those predicted based on foliar Hg concentrations. A hypothesis to explain this discrepancy is that the plant gas-exchange chamber measures net flux which includes emission, deposition, adsorption, and reemission of Hg at the leaf surface, while total foliar accumulation represents only deposition and assimilation.
authors.affiliation: Department of Natural Resources and Environmental Sciences, University of Nevada-Reno, 89557, USA.
authors.forename: Allison G
authors.initials: AG
authors.lastname: Millhollen
authors.forename: Mae S
authors.initials: MS
authors.lastname: Gustin
authors.forename: Daniel
authors.initials: D
authors.lastname: Obrist
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring; D018653:Juniperus; D008628:Mercury / Q000032:analysis*; D041604:Pinus ponderosa; D018515:Plant Leaves / Q000737:chemistry*; D018517:Plant Roots / Q000737:chemistry*; D031301:Robinia; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D012989:Soil Pollutants; D008628:Mercury