Research On Group Matching Curing Agents And Their Effects On Stabilization Of Soil Heavy Metals

In order to understand heavy metal pollution of planting soils, sampling and surveys of soil samples were conducted in someplace in Hengyang, someplace in Chenzhou, someplace in Zhuzhou. Single curing agents and group matching curing agents with a concertration of6g·kg-1were added to the soils of heavy metal contaminated in Hengyang and Chenzhou in the laboratory. Research on effects of single curing agents and group matching curing agents addition on the leaching contents of soil Pb, Cd, Cu and Zn, evaluation the effects of two types of curing agents on stabilization of soil heavy metals, selection of curing agents which had the best curing effect, conduction of concentration gradient test were conducted through extraction procedure for leaching toxicity (TCLP). A runoff field was established in Zhuzhou, in which curing agents were added to the soils with a concentration of6g·kg-1, rainfall was simulated in the way of artificial splashing, surface runoff water and seepage water were collected and analyzed for the contents of heavy metals. The primary results of the experiments were as follows:(1) In the farming soil samples collected from Hengyang, Pb, Cd and Zn contents were higher than the third level of soil environmental quality standard (SEQS). In the soils from Shihupu village in Chenzhou, Pb and Cd content were higher than the third level of SEQS,.Zn contents higher than the first level of SEQS. Cd content was higher than the third level of SEQS in the soils from Zhuzhou, and Pb and Zn contents exceeded the first level of SEQS.(2) Compared to the control, limestone was the best curing agent to stabilize soil heavy metals among six single curing agents, and decreased the leaching contents of Pb, Cd, Cu and Zn from the soils by29.5%,100%,68.6%, and49.6%, respectively. For group matching curing agents, the best curing effects for soil heavy metals showed for curing agent II with a ratio of1:2for diatomite and limestone. Compared to the control, this curing agent reduced the leaching contents of Pb, Cd, Cu and Zn by54.3%,100%,27.3%, and63.8%from the soils in Hengyang, and by100%,48.4%, 64.8%, and71.2%from the soils in Chenzhou, respectively.(3) As a result of concentration gradient test for curing agent II with a ratio of1:2for diatomite and limestone, the best curing effects for stabilization of soil heavy metals were showed for the addition of this curing agent with the concentration of6g-kg-1compared to the control, and the leaching contents of Pb, Cd, Cu and Zn from the soils were decreased by54.3%,100%,27.3%and63.8%, respecti vely.(4) Heavy metals were not detected either for the surface runoff waters or for the seepage waters from the runoff field in Zhuzhou no matter the soils treated with single curing agents or not.