ABSTRACTStudy of the Formation of Lead and Cadmium in the Soils lrrigated withSewage.
Li Zongli et al.(Research Center for Eco-Environmental Science,Chinese Acadenmy of Sciences,Beijing 100085),
AbstractThe formation and distribution of Pb and Cd using sequential extrac-tion method and the factors affecting them in some soils irrigated with sew-age were studied. In the layer of 0 -20cm of calcareous soils Pb and Cdexisted mainly in carbonate and sulfide forms,the organically bound formyarked second,and the exchangeable and adsorbed forms came third.Theexchangeable form of Cd was greater than the adsorbed but that of Pb wasiust on the contrary. The major factors affecting the distribution of Pb andCd were pH,organic matter,humic acid and CaCO_3. The total content of Cdin the soil of the Xi'an sewage irrigation zone increased significantly,andit existed mainly in organically bound form,mean while its carbonate formdeceased.But the same results were not found for Pb.