磷矿粉和腐熟水稻秸秆对土壤铅污染的钝化

Effects of Phosphate Rock and Decomposed Rice Straw Application on Lead Immobilization in a Contaminated Soil

通过室内培养试验研究了磷矿粉和草酸活化磷矿粉与腐熟水稻秸秆配施及不同水分处理对土壤基本性质和铅形态变化的影响.结果表明,施用3种钝化材料都能提高土壤p H值、有效磷、交换性钙、阳离子交换量,其中活化磷矿粉效果最佳;与保持70%田间持水量相比,淹水处理增加p H、提高交换性钙效果更好,但有效磷较低.施用3种钝化材料能使可交换态铅减少,促进其向生物难利用态转变,活化磷矿粉对铅的钝化效果优于未活化的磷矿粉,两者最高分别可使交换态与对照相比降低40.3%和24.2%,且钝化效果与施用量呈正相关;腐熟水稻秸秆能增加土壤有机结合态铅;淹水处理可促使交换态铅向铁锰氧化物和残渣态转化.

The soils treated with phosphate rock( PR) and oxalic acid activated phosphate rock( APR) mixed with decomposed rice straw were incubated in different moisture conditions for 60 days to study the effect on the basic property of the soil and on the speciation variation of Pb. The results showed that all these three types of immobilizing materials increased the p H,the Olsen-P,the exchangeable Ca and the soil cation exchange capacity,and APR showed more obvious effect; the p H and the exchangeable Ca of soil in the flooding treatment were higher than those in normal water treatment( 70%),but the Olsen-P of soil in normal water treatment was a little bit more. These materials reduced exchangeable Pb fraction,and converted it into unavailable fraction. But the APR was better than raw PR in immobilizing lead,and the exchangeable Pb fraction was reduced by 40. 3% and 24. 2%,compared with the control,respectively,and the immobilization effect was positively correlated with the dosage. Decomposed rice straw could transform the exchangeable Pb fraction in soil into organic-bound fraction,while the flooding treatment changed it into the Fe-Mn oxide-bound and residue fractions.