Speciation Of Heavy Metals In The Sediments Of Jiulong River Estuary And Pb Isotopic Implication

The content level, distribution, speciation, pollution situation and history of heavymetals in the sediment from Jiulong river estuary were systematically studied in thisthesis. The lead isotope tracing technique was applied to discriminate the sources oflead pollution. The main conclusions of the research were summarized as follow:The average content of heavy metals in surface sediments were listed as following:Fe＞Mn＞Zn＞Cr＞Sc＞Pb＞Cu＞Co＞Ni＞Sr＞V＞Li＞Bi＞Y＞Tl＞Cd＞Sb＞Mo＞Hg. The results indicated that most of surface sediments were polluted bydifferent kind of heavy metals to some extent in comparison with the backgroundvalues of Fujian coastal soil. The fluctuating reduction of the heavy metals contentwas present in study area from the upstream to the estuary of Jiulong river in general.The research on the speciation of heavy metals in some surface sediment showedthat the highest percentages Fe, Ni, Cr, Cu and Zn were found in the residual fractions,while Mn was present at comparatively higher percentages in the acid extractablefractions and Pb was present relatively higher in the reductive fractions. The heavymetal pollution in surface sediments were carried out based on both total content andmorphological analysis. According to the results of assessment based on total content,the sediments were seriously polluted by Cd and to some extent contaminated by Cr,Cu, Ni and Pb. The conclusions based on the morphological analysis were that Mnshowed serious pollution, while the pollution of Cr and Cu couldn’t be ignored.The dating analysis result of the core sediment indicated that sedimentary andheavy metal reserves information from1909to2011were recorded in the core P109.The content of heavy metals in core sediments showed a rising trend from the bottomto the surface, meaning that the core sediments were polluted by heavy metals tovarying degrees. The study on the speciation of heavy metals in core sediments indicated that Cr, Feand Zn were present mainly in the reductive fractions in both two core sediment,while Pb, Cu, Mn and Ni showed different speciation in different core sediment. Thepollution assessment was also made in core sediment. The conclusion obtained fromgeoaccumulation index and potential ecological risk index indicated that the coresediments were relatively seriously polluted by Cd based on total content. The resultsof ratio of secondary to protogenic indicated that Mn appeared highest pollution tothe core P108, and that of Ni and Pb relatively higher in core P112.The sources of lead pollution in sediments were traced using lead isotope tracingtechnique. The results indicated that the sediments were mainly polluted by vehicleexhaust, industrial activities and sewage discharge. The lead isotopic compositions ofdifferent sources showed large difference to each other. Basing on the distinctionbetween²⁰⁶Pb/²⁰⁷Pb and²⁰⁸Pb/(^{（206+207）})Pb in the known sources, the sources of leadpollution in sediments from Jiulong river estuary could been traced distinctly.