MERCURY ACCUMULATION IN TRANSPLANTED HYPOGYMNIA PHYSODES LICHENS DOWNWIND OF WISCONSIN CHLORALKALI PLANT

Emissions of mercury from a chlor-alkali plant in central Wisconsin ha ve raised concern about possible effects on biota in the area. Samples of the lichen Hypogymnia physodes, which no longer grows in the area, were transplanted from a site in northeastern Wisconsin and positione d on plastic stands at varying distances up to 1250 m from the plant a nd sampled for Hg quarterly for one year to test the hypothesis that H g would be taken up by the lichens and would decline with distance. Av erage tissue concentrations were elevated when first sampled at three months and continued to increase at the nearest sites until the study ended after one year. Average concentrations after a year of exposure ranged from 4418 ppb at 250 m from the plant to 403 ppb at 1250 m from the plant. The decrease over distance followed a negative exponential pattern. Background concentrations at a control site in northern Wisc onsin averaged 155 ppb.