Combined Pollution Behavior And Control Technology Of Soil Contaminated With Heavy Metals

In this dissertation, the fractionation and bioavailability of heavy metals Cd, Pb, and Cu were studied using pot experiments under the greenhouse conditions. The results indicate that â‘ The exchangeable Cd and carbonate-bound Cd (B1) became the predominant species, and the residual Cd significantly decreased at the higher Cd concentration. These results demonstrate that the residual species of Cd transformed to exchangeable and carbonate-bound species with Cd pollution enhancing. The predominant species of Pb were the organic-bound (B3) and Fe-Mn oxide-bound (B2). The predominant species of Cu were Fe-Mn oxide-bound (B2). With the increase of Cu concentration, the exchangeable Cu and carbonate-bound Cu (Bl) and the organic-bound Cu (B3) significantly increased, and the Fe-Mn oxide-bound (B2) decreased. â‘¡The ternary combination of Cd+Pb+Cu decreased the Bl Cd, and enhanced the B2, B3, and the residual Cd. The combination effects enhanced the Bl Pb and the residual Pb, while decreased the B2 and B3 Pb. However, the B3 Cu significantly increased and the B2 and the residual Cu decreased in the presence of Cd and Pb, and there were little change in the Bl Cu.â‘¢Ternary combination of Cd+Pb+Cu produced two responses for the growth of plant, synergistic and antagonistic responses. Bioaccumulation of Cd, Pb, and Cu were observed in plant and the bioaccumulation of one metal was influenced by the presence of other metals in metal mixtures.The pot experiments were conducted to elucidate the possible mechanism and effects that plants absorbed heavy metals (Cd, Pb, and Cu) in soil after adding compost and mesoporous molecular sieves (MCM-41). Different kinds of chemical additives and application levels had different effects on phyto-availability of heavy metals in soil. The results showed as follows: â‘ In this experiment, compost could reduce or obviously reduce phyto-availability of Cd and Pb. Compost enhanced the phyto-availability of Cu. â‘¡The effect of MCM-41 treatment on Cd, Pb, and Cu uptake by plants were different with application levels. It had obvious effect upon the contents of heavy metals, especially for Pb. â‘¢Different kinds of chemical additives could affect plant absorption of heavy metals through changing the speciation distribution of heavy metals in soil and effect plant absorption. In a word, introduction of amendments to soil does interrupt the heavy metals balance in the environment and worth comprehensive investigation.