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Vertical Distribution of Major Pollution in the Sediments from Three Polluted Seriously Rivers in Guangzhou

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Tutor: PanWeiBin
School: South China University of Technology
Course: Environmental Engineering
Keywords: sediment,organic matter,petroleum hydrocarbons,heavy metals,verticaldistribution
CLC: X832
Type: Master's thesis
Year:  2012
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Abstract:
In recent years, the rivers were cleaned in Guangzhou. However, because thepollutants that discharged into rivers were different in different Time, this resulted themain pollutants in different depth were different, therefore, if contamination ofpollutants in sediments was not known well, blind dredging may results that thepollutant in deep mud was exposed to mud-water interface after surface sludge wascleaned up, and then bring about internal contamination pollutants were secondarilyreleased, therefore, it is necessary to study vertical distribution of pollutants in riversediments. Vertical distribution of organic matter, petroleum hydrocarbons, Cd, Cr,Cu, Ni, Pb, Zn, were studied in three rivers sediments of Guangzhou, The mainconclusions were as follows.1¡¢ variational trends of OM and Phs were similar in vertical direction in sediments,the variety characteristics were presented by ¡°low in upper layer and high in the lowerlayer¡± in Zeng Bian river, reduced with depth in Nan Cun river sediments, reducedfirstly and then risen with depth in Hui Jiang river.2¡¢ The vertical distribution of heavy metals in sediments was different, vertical ofdistribution of Cd was gentle, the content of Zn was declined with depth in Zengbianriver and Nancun river sediments; the contents of Cr¡¢Ni¡¢Pb was low in upper layer,high in middle layer, low in lower layer, the content of Cu was high in upper layer andlow in lower layer; the contents of Cr¡¢Ni¡¢Pb¡¢Zn were declined with depth in surfacesediments, there was not obvious regularity.3¡¢ There were not obvious diversity about chemical form of heavy metals indifferent river sediments, in the sediments of three rivers, the form of Cd was mainlyresidual, Cu was mainly reducible and oxidizable, Pb was mainly residual andreducible, Zn was mainly reducible and acid-soluble, however, the form of Ni wasresidual in Zengbian and Nancun river sediments, the form of Ni was mainlyacid-soluble and reducible. There was not obvious regularity on the form of heavymetals in vertical sediments.4¡¢ Pollution degree of Cd in different depth in three rivers sediments showed heavy pollution. Pollution degree of Cr¡¢Cu¡¢Pb showed clean, pollution degree of Znshowed partial moderate pollution in0-24centimeter, and declined to clean under24centimeter; pollution degree of Cr¡¢Cu¡¢Ni showed clean or mild contamination,pollutants degree of Pb was increased with depth, showed mild contamination in0-12centimeter, showed partial moderate pollution or moderate pollution; there wereobvious difference between stream stretch in Huijiang river, pollution degree of Cr¡¢Pb was increased with depth in sampling A, pollution degree of Cu showed heavypollution in0-6centimeter.5¡¢ Harm level of Cd on ecosystem was very strong in Zengbian river, Nancun riverand Huijiang river sediments, mean value was4.89times,3.30times,7.78times asmuch as supper pair of ecological risk factors.6¡¢ The vertical distribution of pollutants in sediments from different rivers weredifferent, and vertical distribution of different pollutants in sediments from same river;so, When water quality was improved with use of dredging, consideration should begiven to history of river pollution, and the vertical distribution of pollutants insediment should be investigated.
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