Research On The Pollution Characteristics Of Heavy Metals In Sediments From The Tuohe River, Suzhou City,Anhui Province

The sediment was sources and sinks of the river heavy metal pollution, and heavy metal pollution in sediments could reflect the overall pollution of heavy metals in river water environment. Tuohe River in Suzhou City, a major tributary of the Huaihe River, was one of the most important rivers in the Northern Areas of Anhui Province and related to economic and social development of Huaibei City and Suzhou City which were both coal cities. However, the pollutants discharged in the processes of coal mining, industrial and agricultural production, urban transportation and life had some impact on the contents of heavy metals in Tuohe River but few scholars at home and abroad concerned it. In order to fill the blank of research on heavy metal contamination characteristics in the area and provide reference information on pollution prevention of heavy metals in Suzhou City, the research on the pollution characteristics of heavy metals in sediments from Tuohe River was carried out.In this thesis, V, Mn, Ni, Zn, Cu, Pb, Cr, As, K, Ca, and Fe contents of35sampling points from Tuohe River and12sampling points from the moat in Suzhou City were determined by X-ray atomic fluorescence spectrometry (XRF). Based on the above, the distribution and variation of the contents along the river, pollution assessment, possible sources and geochemical baseline of heavy metals in sediment from Tuohe River were discussed. In addition, the contents distribution and pollution assessment of heavy metals in sediment from Delta Park to Cuiyuan Village segment and moat which were the major inland rivers of Suzhou City were compared and analyzed. The main conclusions were as follows:(1) In the sediment of Tuohe River Delta Park to Cuiyuan Village segment, the average contents of Cr, Mn, Cu, Zn, As and Pb were more than the soil background values in Anhui Province. In the sediment of Tuohe River sluice to Songqiao Village segment, for8heavy metals elements, only the average content of V was less than the soil background values in Anhui Province, but the average contents of Cr, Mn, Ni Cu and Pb respectively exceeded20%,27%,22%,50%and17%of background values, and the average contents of Zn and As were one times more than background values. In the sediment from Luling mine subsidence area section of Tuohe River, the average contents of Mn, Ni, Zn, Cu, Cr, and As except V and Pb were more than the soil background values in Anhui Province while the content of As in each sampling point was more than background value of As in Anhui Province. The contents of heavy metal in sediment from Boqiao Village to Tuohu Lake segment was less than the other three sections’, because only the average contents of As Cr and Mn was higher than the background values in Anhui Province. The contents of heavy metals in sediment from Suzhou moat except V and Mn were more than the soil background values in Anhui Province. The average contents of Zn, Cu, As and Pb were2-5times more than the background value while the average content of Ni exceeded50%or more of the background value and the average content of Cr was slightly higher than the background value.(2) The orderes of the stability for the content changes of8kinds of heavy metals in the sediment along the way is:As<Cu<Ni<Zn<Cr<Mn<Pb<V, in Tuohe River Delta Park to Cuiyuan Village segment; Ni<Zn<Mn<As<Cu<Pb<V<Cr, in Tuohe River sluice to Songqiao Village segment; Ni<Zn<As<Mn<Cr<Cu<V<Pb, in Luling mine subsidence area section of Tuohe River; Ni<As<Mn<Cr<Cu<Zn<V<Pb, Boqiao Village to Tuohu Lake segment.(3) In Suzhou City, the average contents of Cr, Zn, Cu, Ni and Pb in sediment from the moat are higher than Tuohe River Delta Park to Cuiyuan Village segment’s but where the average contents of Mn, V and As were lower than the moat’s.(4) The Igeo of8kinds of heavy metals in sediment from Tuohe River showed:In sediment from Tuohe River, V, Cr and Mn were less pollution but As is in the mild to partial moderately polluted state; The pollution of Ni in sediment from Luling mine subsidence area section is higher than the other three sections; Zn and Cu of the sampling points near the urban and Economic-Technological Development Zone in Suzhou City were enriched to a certain extent; The Igeo of Pb except T10in all the sampling points were less than zero, which showed the pollution level of Pb in the area is zero and kept a pollution-free status.(5) The Pollution Load Index of8kinds of heavy metals in sediment from Thuohe River displayed:The descending order of integrated pollution levels for8kinds of heavy metal was Tuohe River sluice to Songqiao Village segment> Tuohe River Delta Park to Cuiyuan Village segment> Luling mine subsidence area section of Tuohe River> Boqiao Village to Tuohu Lake segment; The IPL of all the sampling points covered a wide range of0.87to1.62and the sampling point of the highest integrated pollution level was T10near the Economic and Technological Development Zone in Suzhou City.(6) The four main sources of heavy metals in sediment from Tuohe River were: agricultural production activities, the waste water of power plant and industrial production in Suzhou City, natural pedogenic and coal mining whose contribution rates were as follows:28.16%,23.49%,18.24%and12.99%, respectively. The descending order of heavy metal migration ability in sediment from Tuohe River was:Cu>V> Zn> Pb>As>Cr>Mn>Ni.(7) The geochemical baseline values of V, Cr, Mn, Ni, Cu, Zn, As, and Pb in sediment from Tuohe River obtained by the standardized methods and the relative cumulative frequency were88.15mg/kg,74.73mg/kg,604.84mg/kg,20.65mg/kg,25.14mg/kg,72.17mg/kg,20.58mg/kg and22.43mg/kg.