中文摘要：

采集南京市居住和商业区内的河道沉积物,研究重金属元素的形态分布及Pb稳定同位素组成,探讨城市河道沉积物中重金属的迁移潜力和推断污染特征.沉积物中重金属改良的BCR三步顺序提取研究表明,沉积物中Cd和Zn主要分布于酸溶态;Pb和Cu主要分布于可氧化态;Ni和Cr主要分布于残渣态.Cd和Zn的环境效应最值得关注,而Ni和Cr环境影响最小.沉积物中m（208Pb）/m（206Pb）和m（206Pb）/m（207Pb）分别为2.102 4～2.123 9和1.159 3～1.184 5.居住和商业区内的河道沉积物Pb稳定同位素组成相近,具有相似污染源.居住和商业区内沉积物的Pb稳定同位素比率与文献中南京大气、城市土壤Pb稳定比率相似,因而河道沉积物重金属富集与城市重金属污染密切相关.

英文摘要：

In order to investigate the mobile potentiality and the characteristics of heavy metal contamination sources in urban channel sediments, samples were collected from urban channels in residential areas and shopping centers in Nanjing. Speciation of heavy metals was performed by the modified BCR sequential extraction （three- step） procedure, and Pb stable isotope ratios were determined using Inductively Coupled Plasma Mass Spectrometry. Results showed that Cd and Zn were predominantly associated with the acid extractable metal fraction, Pb and Cu with the oxidizable metal fraction, and Ni and Cr with residual metal fractions. Cd and Zn had the greatest environmental effects, while Ni and Cr had the smallest. The range was 2.1024-2. 1239 for ^204Pb/^206Pb and 1.1593-1.1845 for ^206Pb/^207Pb. The ratios of Pb stable isotopes in the residential area and the shopping center were similar and consistent with those in samples from atmosphere and soils in literature in Nanjing, suggesting that they may have similar Pb contamination sources.