EFFECT, IMMOBILIZATION AND COOPERATIVITY OF AMENDMENTS ON REMEDIATION OF PB-CONTAMINATED SOIL

In our study, zeolite, sepiolite, vermiculite and biochar were added to high -concentration lead-contaminated soils, respectively, and the metal fractions, toxicity leaching amount and leaching characteristics of lead (Pb) in soils were studied after 30 d. Besides, the feasibility of chemical immobilization to reduce Pb was investigated.In the soil immobilization experiments, compared with the control, the toxicity leaching amount of soils added zeolite, sepiolite, vermiculite and biochar decreased.The decreasing ratios were 40.12%, 41.28%, 25.50%, and 16.04%, respectively.It is clear that the treatment of zeolite showed the best effect.And the group matching curing agents (GMCAs) with a mass ratio of 2:1 for zeolite and sepiolite was the best, of which the Pb content in soil leaching solutions decreased by 41.4%.Meanwhile, through soil column leaching experiment, compared with the control, the pH of leachates generally increased, and the electrical conductivity (EC) of leachates presented a falling trend .The Pb content of accumulated leachates from treatments decreased, and the best effect treatment was at a mass ratio of 1:2 for zeolite andsepiolite with the highest decrease rate at 93.35%.And the immobilization effect was further verified.Therefore, the addition of curing agents could decrease the bioavailability and migration of Pb.