Distribution, fractionation and mobility assessment of heavy metals in a spiked soil using a multi-species soil system

Abstract

The concentration, distribution and fractionation of metals in a metal spiked soils were studied using a Multi-Species-Soil-System (MS·3), a terrestrial microcosms that allows a combined assessment of the chemical fate and effects on terrestrial organisms. Samples of a natural soil were spiked with a mixture of the metals Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn and placed on the top of soil columns simulating the heavy metal concentration due to an agricultural organic amendment (manure, sewage sludge) equivalent to 2, 5 and 10 times the original background of soil metal concentration. After 21 days exposure, metal mobility was assessed using three complementary approaches the metal concentrations at four depths in the soil profiles (I, II, III and IV), the metal fractionation in the top soil and the percent metal detected in leachates. The upper soil profile had the highest metal concentration for the majority of the metals. For Cd, Mn and Co highest concentrations were in the bottom profile. Maximum metal mobility in leachates was for Cd (24.67%) > Co (3.65%) > Mn (3.18%) > Zn (0.55%) > and Cu (0.012%). Nickel and Cr percentages were < 0.001%. Cobalt, in all leachates, control and treated, was > 0.1%. Lead mobility from soil to water was 0.004% and 0.008% for the lowest and highest treatments, respectively.