(P253) Solid-solution partitioning of Cd, Cu, Ni, Pb and Zn in the organic horizons of a forest soil.
Sauvé, Sébastien*,1, Manna, Sylvie2, Turmel, Marie-Claude2, Courchesne, François2, Roy, André2, 1 Université de Montréal - Department of Chemistry, Montréal, QC, Canada2 Université de Montréal - Department of Geography, Montréal, QC, Canada
ABSTRACT- We report the solid-liquid partitioning of Cd, Cu, Ni, Pb and Zn in 60 organic horizons samples from forest soils from the Hermine watershed (St-Hippolyte, QC, Canada). The mean Kd coeffcients are, in the same order, 1132, 966, 802, 3337 and 561. Comparison of those Kd coefficients to published compilation values show that the Kd values are lower in acidic organic soil horizons relative to the overall mean Kd values compiled for mineral soils. But, given normalization to a mean pH of 4.4, the Kd coefficients in organic soil horizons demonstrate the high sorption affinity of organic matter which is either as good as or up to 30 times better than mineral soils for sorbing trace metals. Regression analysis shows that, within our dataset, pH and total metal contents are not consistent predictors of metal partitioning. Metal sorption by the solid phase must be studied in relation to complexation by dissolved organic ligands and both processes may sometime counteract one another.
Key words: partitioning, trace elements, soil organic matter, Kd