CHEMISTRY AND SPECIATION OF SOIL-WATER FROM SERPENTINITIC SOILS - IMPORTANCE OF COLLOIDS IN THE TRANSPORT OF CR, FE, MG, AND NI

This study focused on the chemistry of soil water samples (SWS) obtain ed by tension-free lysimetry from serpentinitic, i.e., Cr- and Ni-rich , Dystric Eutrochrepts. Soil water samples from undisturbed soil profi les had total elemental concentrations (mumol/L) of 0.1-3.2 Cr, 0.2-3. 1 Ni, 3-154 Fe, and 55-401 Mg; however, dialysis revealed that on aver age, only 72% of total Mg, 39% Ni, 28% Cr and 15% Fe were present in d issolved form. Thus, in serpentinitic soils, colloids can be an import ant means of element translocation. Among metallic cations, Mg contrib uted generally more than 50% to the positive charge of SWS; also, ther e was a high linear correlation between dissolved (dialyzable) Mg and electrical conductivity.