Calculation of soil-water and benthic sediment partition coefficients for mercury

To accurately model mercury transport to water bodies, an assessment of this pollutantʹs behavior in the watershed is critical. Partition coefficients, defined as an estimate of the ratio of the pollutant concentration sorbed onto soil/sediment particles to the pollutant concentration dissolved in pore water at equilibrium, is an important term in multimedia models. In this paper, partition coefficients are calculated for two broad species of mercury: inorganic mercuric mercury (Hg-II) and methylmercury (MHg). Although there is considerable variability in the calculated values, the approximate mean values for the soil-water partition coefficients range from 3.3x103 to 6.0x104 L/kg for Hg-II and 2.0x101 to 6.7x103 L/kg for MHg. For the benthic sediment partition coefficients, the values range from 5.7x103 to 9.9x105 L/kg for Hg-II, and 6.5x102 to 1.1x105 L/kg for MHg.