| More than 30 heavy metals content level,distribution,speciation,and pollution status in the sediment of Shanghai Huangpu River and Dianshan Lake were systematically investigated in this thesis.The heavy metals sources in sediments were explored by combination of multivariate statistical and Zn isotopic analysis.Meanwhile,the pollution potential of Huangpu River from upstream to downstream was evaluated according to the gradient of urbanization in Shanghai.The main conclusions of the research were summarized as follow.(1)Heavy metals of Cr,Pb,Zn,Cu,Cd,Sb and Mn in Huangpu River sediments were highly polluted while the pollution of Dianshan Lake was relatively light.The pollution of Cd and Bi elements in Dianshan Lake sediments was the most serious.The results showed fluctuating increase of all heavy metals content in Huangpu River sediments from the upstream to the downstream.Zn,Mn,Li,As,Cr have a relatively large range of changes and were mainly concentrated in the midstream and the downstream reaches of the central commercial area.The change of heavy metals in sediments of Dianshan Lake was no obvious regularity,and the main fluctuations occurred at residential areas,highways,and northern areas of the lake.(2)The research on the speciation of heavy metals in sediments of Huangpu River and Dianshan Lake indicated that the highest percentages of Fe,Cd,Ni,Cr,and Cu were found in the residual fractions,while Mn and Pb was present at comparatively higher percentage in the acid extractable fractions and reductive fractions,respectively.It should be noticed that the proportion of non-steady states of Zn is relatively high.The bioavailability and ecological risk of Pb,Zn,and Cu needed to pay attention.(3)The evaluation of heavy metal pollution in sediments was carried out based on total content and heavy metal speciations.According to the total heavy metal content,Cd and Bi were the most polluted elements in Huangpu River sediments,followed by Pb,Sb,Zn,and Co.The results based on the heavy metal speciations implying that Mn showed the most serious pollution,followed by Cd,Zn,and Cu.(4)The gradient of urbanization in different administrative regions had a significant impact on the heavy metal content in Huangpu River sediments.Zn,Pb,Cu,and Cr were positively affected by urbanization.It was found that the heavy metal content gradually increased from agriculture area to central urban area.The content was higher in the central urban area and Minhang District owing to the reason of most significant urbanization area and the main industrial area,respectively.Cd was less affected by regional differences.As and Bi were greatly affected by agriculture and industry in the upper and middle reaches.Additionally,the pollution was also serious in high population,business,and traffic developed areas.(5)Multivariate statistics analysis displayed that the probably source of Mn?Co?Sr?Sb?V in Huangpu River sediments were mainly from nature.P,Cu,Pb,Zn,Cd,B,and Ni may be highly affected by anthropogenic activities and were mainly from the mixed sources of industrial,agricultural and traffic.Besides,As,Sb,Bi,and Zn may be classified by shipping and transport activities on Huangpu River.The pollution of Dianshan Lake was relatively light.V,Ni,Co,Cr,and Bi were probably affected by the polluted upstream water.Fe,Pb,and Cd were mainly from traffic pollution,and Zn,Cu,P,As were probably from agricultural activities.Mn and Sr content were more contributed by natural sources.(6)Zn isotopic analysis indicated that Zn in sediments of the Huangpu River is directly affected by traffic sources.The vehicle exhaust gas and tire-wear particles could enter into the river via atmospheric deposition or surface runoff.Furthermore,the transportation of shipping on Huangpu River is also an important source of Zn pollution. |
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