Studies on the sorption of elemental mercury vapor by soils.

Mercury vapor sorption by soil increased curvilinearly with the increase of soil moisture content until a maximum was reached. A further increase of moisture content caused a decline in mercury sorption. The percent moisture contents which gave maximal increase of 203Hg vapor sorption in these soils coincide quite closely with their water-holding capacity values at 1/3 bar. Soil microorganisms may play a part in moist soil for the increase of elemental mercury vapor sorption and subsequent transformation to mercuric form. Mercury vapor diffused into both dry and moist soil columns and the diffusion profile can be described by an exponential function of the form, y = ae-bx, where "a" is the adsorption characteristics of the soil, "b" is the diffusivity coefficient and x is the depth of soil. The diffusivity coefficient for mercury vapor varied with the soil type and its moisture content.