MERCURY TRANSLOCATION IN AND EVAPORATION FROM SOIL .3. QUANTIFICATIONOF EVAPORATION OF MERCURY FROM PODZOLIZED SOIL PROFILES TREATED WITH HGCL

Mercury evaporation from undisturbed iron-humus podzol lysimeters was measured over 3 months after treatment with HgCl2 spiked with radioact ive Hg-203. Th, relative evaporation rate from HgCl2 treated soils fol lowed the sum of two exponential functions. Because evaporation asympt otically approaches zero with time, the integral of the fit curve repr esents the evaporative loss in percent of atmospheric deposition. For the soil investigated, about 5% of atmospheric Hg deposition was reemi tted into the atmosphere. It is hypothesized that mercury evaporation can decrease the leaching of mercury in and from soil significantly; t his effect is probably increasing with decreasing rain acidity or soil acidity. Mercury deposited as soluble salt remains susceptible to ree mission to air for 300 d after incorporation into the soil matrix. Ind ications are found that Hg evaporation from soils in geological backgr ound areas predominantly derives from recent atmospheric Hg deposition and not from geological sources.