Mercury accumulation and exchange associated with grass, forb, and tree species

Plants have been shown to accumulate mercury (Hg) in foliage and exhibit bi-directional foliar fluxes. However, our understanding is limited to a few plant species and the mechanism of uptake is not known. The work presented in Chapter 1 was to assess the relative influence of air and soil Hg concentrations on foliar Hg content of four tallgrass prairie species, using air CO 2 exposures as a possible way to differentiate between air and soil influence. The work presented in Chapter 2 focused on the influence of air and soil Hg concentrations on foliar Hg content of three tree species. Mercury gas-exchange was quantified for two of the three tree species as a means to investigate conditions of foliar Hg uptake and emission. The studies were conducted using replicated environmentally, closed-system growth chambers, which provided for precise control of air Hg and CO2, and soil Hg concentration exposures.