Equilibrium partitioning of heavy metals in dutch field soils. I. Relationship between metal partition coefficients and soil characteristics

Twenty Dutch soils were sampled at sites that were expected to have elevated levels of heavy metals compared to background values. Field-based partition coefficients (Kp) for As, Cd, Cr, Cu, Ni, Pb, and Zn were determined by calculating the ratio of the amount of metal extracted by concentrated HNO3 to the metal concentration in the pore water. Kp values varied widely with metal and soil type and correlated well with soil pH. To a lesser extent amorphous Fe-content and dissolved organic carbon (DOC) also explained part of the variation in Kp values. Thereupon, regression equations based on easily obtainable soil characteristics were derived. External validation of the regression equations showed that predicted log Kp values were in agreement with measured values.