SORPTION OF INORGANIC MERCURY AND MONOMETHYL MERCURY IN AN IRON-HUMUSPODZOL SOIL OF SOUTHERN NORWAY STUDIED BY BATCH EXPERIMENTS

Considerable fractions of the Hg content of lake and river systems in Scandinavia are discharged from the soil of the catchments. An importa nt soil type in Scandinavia is the iron-humus podzol. The sorption cha racteristics of this soil type for inorganic Hg(II) and monomethyl mer cury were investigated by batch experiments. The solubility of Hg2+ an d CH3Hg+ in the soil horizons containing organic matter increases with increasing pH of the soil solution by favoring the formation of solut e organic matter-mercury complexes. While the solubility of Hg2+ is st rongly dependent on complexation to dissolved organic matter, the solu bility of CH3Hg+ is more dependent on ion exchange. The concentration of solute inorganic Hg(II) increased with increasing temperature proba bly because of an increase in the concentration of dissolved organic c arbon. There was no effect of temperature on the concentration of solu te CH2Hg+. A pH values were inorganic mercury-hydroxo complexes are fo rmed, inorganic Hg(II) is efficiently sorbed to the metal oxides of th e mineral soil. The soil-water distributions of inorganic Hg(II) in th e different soil horizons were described by Freundlich isotherms or li near isotherms for common and contaminated mercury contents in the soi ls.