Mercury and major ions in rainfall, throughfall, and foliage from the Florida Everglades

Abstract

The deposition of Hg to the Everglades has been investigated using monthly integrated bulk and wet-only tower based precipitation samples, tower based aerosol Hg samples, and ground based throughfall samples. A small set of foliage samples was collected and analyzed for `reactive' and total Hg. There are large differences in the major ion chemistry of the wet and throughfall samples. Dry deposition of seasalt aerosols (Na and Cl) and foliar leaching of Ca and K contribute significantly to the throughfall fluxes. The concentrations and fluxes of total Hg in bulk deposition, wet deposition, and throughfall are not significantly different. These data demonstrate that dry deposited Hg is not `washed off' of, or leached from foliage by rainfall. Results from the chemical reactivity experiments suggest that the leaves accumulate Hg as they mature. The calculated litterfall Hg fluxes are similar to the measured rates of rainfall Hg deposition.