外源铅化合物在土壤中的转化

Transformation of the external source lead compounds in soil

通过培养试验,研究外源铅化合物在黑土、棕壤和草甸土中的转化.结果表明,Pb(NO3)2、PbO、Pb3(CO3)2(OH)2和PbSO4处理的土壤溶解态Pb含量在试验开始时较高,随后迅速降低,逐渐达到平衡状态.PbS处理下,溶解性变化异常可能与PbS氧化有关.不同铅化合物在黑土、棕壤和草甸土中的溶解性大小一致,Pb(NO3)2>PbO,Pb3(CO3)2(OH)2>PbSO4>PbS,PbO和Pb3(CO3)2(OH)2处理下土壤溶解态Pb含量没有显著性差异(P>0.01).与土壤混合90d后,大部分PbSO4和PbS仍未溶解.pH值和PbS氧化是控制PbS溶解的主导因素.Pb(NO3)2、PbO和Pb3(CO3)2(OH)2溶解性表现为棕壤>黑土>草甸土(P<0.01).Pb(NO3)2处理下Pb2+所占比例显著高于其他Pb处理(P<0.01).与土壤混合90d后,Pb(NO3)2和PbO处理下Pb2+所占比例可高达75.23%,这可能与土壤溶液pH值和DOC含量降低有关.

The transformation of the external source in black soil, brown soil and meadow was studied through culture test. With the treatment of Pb （NO3）2, PbO, Pb3（CO3）2（OH）2 and PbSO4, the disabled Pb content of soil was high relatively at beginning of test, then lower quickly and reached equilibrium state gradually. With the treatment of PbS, the abnormal change of dissolve property might be related to the PbS oxidation. The dissolve properties of different lead compounds in black soil, brown soil and meadow were the same, which was： Pb（NO3）2〉PbO, Pb3（CO3）2（OH）2〉PbSO4〉PbS. The dissoluted Pb content did not have marked difference between PbO and Pb3（CO3）2（OH）2 （P〈0.01）. After mixing with soil 90d, large parts of PbSO4 and PbS were not dissolved, pH value and PbS oxidation were the main factors controlling the dissolubility of PbS. The dissolution properties of Pb（NO3）2, PbO, and Pb3（CO3）2（OH）2, were expressed as： brown soil〉black soil〉meadow soil （P〈0.01）. With treatment of Pb（NO3）2, the proportion occupred by Pb^2＋ was higher markedly than the other Pb treatments （P〈0.01）. After 90d mixing with soil, with treatment of Pb（NO3）2 and PbO, the proportion occupied by Pb^2＋ could be high reaching 75.23%, and related with lowering of pH value and DOC content of the soil solution.