Assessing the Influence of Different Atmospheric and Soil Mercury Concentrations on Foliar Mercury Concentrations in a Controlled Environment

Abstract

This study investigated the influence of soil and air mercury (Hg) concentrations on Hg accumula- tion in plant components for three plant species, Robinia pseudoacacia (Black locust), Juniperous scopulorum (Juniper), and Artemisia tridentata (Sage- brush), grown in environmentally controlled growth chambers. Exposures included ambient and elevated air (3.1±0.4 and 30.1±3.5 ng m −3 ) and soil (0.06±0.02 and 27.7±6.3 μ gg −1 ) Hg concentrations. In addition, foliar Hg fluxes were measured, as was Hg accumu- lated directly on the leaf surface. Air Hg concentrations were found to be the dominant factor associated with foliar Hg concentrations. Foliar MeHg concentrations of deciduous plant species were greater than evergreen species. Trunk Hg concentrations were influenced by air and soil Hg concentrations. Root Hg concentrations were directly correlated with soil Hg concentrations. Foliar Hg fluxes for R. pseudoacacia were predomi- nantly deposition. For A. tridentata foliar Hg fluxes were bi-directional, and foliar fluxes measured for J. scopulorum were not statistically different from the blank chamber fluxes. Measured fluxes did not correspond well with predicted uptake based on foliar Hg concentrations.