Research On The Environmental Quality Of River Sediments In Northern Anhui Province

Wanbei rivers refer to the rivers located in the north of mainstream of Huaihe River in Anhui Province, including twenty-two tributaries such as Shaying River, Wohe River, Tuohe River and so on. Due to the excessive growth of economy, population explotion, industrialization and urbanization, resulting in a decline of the water quality. Sediment is an important source and sink of polluants, therefore, study on the characteristics of river sediments in northern Anhui province has important practical significance.In this paper, the physicochemical properties, heavy metals concentration and bacterial community of 135 river sediments in Anhui province (including the mainstream of Huaihe River and twenty-two tributaries) were studied. Then combining the indicator features of three contents to comprehensive evalute the sediment environmental quality. The results indicated that:(1)The pH of sediments in different rivers has small range, and silt is the main grain composition. Due to the impact of terrigenous input the organic matter is in high level. Ammonia nitrogen is the main form of exchangeable nitrogen in sediments. The content of TP is greatly influenced by IP, and show the characteristics that the content of HC1-P is higher than NaOH-P.(2)The average content of eight heavy metal As、Cd、Cr、Cu、Ni、Pb、Zn and Hg in sediment was lower than the secondary soil standard limits, in addition to As. The spatial distribution of heavy metals is that content in westward and eastward is much higer than central section. Heavy meals derived from either weathering of rock and soil or domestic sweage and industrial waste water. The ecological risk status of heavy metals in river sediments of northern Anhui province is in medium level, and Cd and Hg were significance contribution factor. The severe polluted rivers were Tuohe River, Quanhe River and Youhe River based on the assessment results of the geoaccumulation index, pollution load index and ecological risk index.(3)The bacteria community of river sediments in Anhui province is mainly contain twenty dominant algaes, with a high bacterial diversity and good evenness. The aboundance of three important genes which participate in denitrification function was decline from nirS、nirK to nosZ, with a significance positive correlation between them. Correlation analysis indicated that OM、NO3-N (nitrate nitrogen) and TN are the main factors which affect the denitrification function.(4)According to the analysis by canonical correlation analysis, the sediments environment factors pH、OM (organic material)、TN (total nitrogen、NaOH-P、Ni、 Zn and Cd had an significance level influence to the bacteria community in sediments. Meanwhile Cd, Zn have a siginificant positive correlation with OM, TN, NaOH-P and Ni has a siginificant positive correlation with OM, NaOH-P.(5)The average of SQCI (sediment quality comprehensive index) is 58.04 of river sediments in northern Anhui province, belong to moderate pollution level. The sediment quality status of Guhe River, Tuohe River and Xinsuihe River is severe than other rivers in northern Anhui river. The spatial distribution characteristics of sediment environmental quality are sampling sites in south are more serious.(6)The results of physiochemical indexes such as nitrogen and phosphorus, ecological risk assessment of heavy metals and sediment environmental quality evalution shows that Tuohe River is the most polluted rivers of all, especially the sampling sites of T3 which located in the surrounding of mining area and city performance particularly prominent.