Effect of Compost on the Distribution of Copper in Heavy Metal Contaminated Soil

Abstract

Pot experiments were carried out to study the effect of compost application amount on the distribution of copper in heavy metal contaminated soil. The results showed that the total Cu content reduced 11.54%, 11.60%, 22.02%, 25.27%, 7.08% and 3.65% after the amendment of 0, 20, 40, 60, 80, 100 g/kg compost to soil with Brassica juncea, respectively. The amount of water-soluble fraction had no correlation with the compost application amount. However, compost amendment decreased the proportion of Cu in the exchangeable and residual fractions, and increased the percentage of Cu in the carbonate bound, Fe-Mn oxide bound and organic-bound Cu. Furthermore, though the mobility factor of Cu decreased slightly only from 16.64% to 16.27-16.52% due to the addition of compost, the addition of compost to soil can immobilize the heavy metal through bound to organic matter and therefore, lowered their mobility and their phytotoxicity.