| In recent years,with the accelerated urbanization and industrialization,more and more heavy metals and other pollutants have been remitted to urban rivers as a result of the increase of urban domestic waste,unreasonable discharge of industrial wastewater and the use of chemical fertilizers and pesticides,making the pollution of urban river water bodies increasingly serious.This paper takes three typical urban rivers in Wuhu(Central City river,Huicheng river and Zhongshan South Road river)as the research objects,tests the content,distribution pattern and physicochemical properties of heavy metals in the water bodies of the rivers,and evaluates the water bodies of the three urban rivers in Wuhu by using the comprehensive pollution index and water environment health risk evaluation model,meanwhile,the ground accumulation index and potential ecological hazard index are used to evaluate the heavy metals in the sediments of the rivers.The degree of heavy metal pollution and potential ecological risk were evaluated.Through the study,the main conclusions are as follows:(1)The water bodies of the three rivers are weakly alkaline in general.Comparing with China’s surface water environmental quality standard(GB3838-2002),the contents of TN,TP and NH3-N in the three rivers exceed the water quality standard of class Ⅳ The distribution trend of the four heavy metals in the water body was Zhongshan South Road river>Central City river>Huicheng river,the content of heavy metals Pb and Cr exceeded the Ⅲ water quality standard,Cu and Zn contained less than the Ⅲ water quality standard;correlation analysis and clustering found that NH3-N,TP,Cr,CODcr,TN may be related to anthropogenic sources such as residential sewage discharge;Pb,Cu,Zn may be related to the river Auto repair,electroplating industry and other anthropogenic sources;BOD5 may be related to natural sources.(2)The sediments of the three rivers were weakly alkaline in general,and the pH and TN in the sediments were evenly distributed,but the spatial distribution of organic matter and TP in the sediments varied greatly,and the organic matter and TP in the sediments had the highest content in the Central City river,and the TN content was the highest in the Huicheng river;comparing with the grading index of the Second National Pollution Source Census Regulations,the organic matter,TN and TP in the sediments all exceeded the secondary standard and were abundant.The overall distribution of heavy metals in the three rivers is Central City river>Huicheng river>Zhongshan South Road river,and the average contents of Pb,Cr,Cu and Zn in sediment are 28.61 mg/kg,99.18 mg/kg,38.34 mg/kg and 82.41 mg/kg,which are 1.08,1.50,1.88 and 1.33 times of the background value of Anhui soil,respectively.1.33 times,and 1.10,1.63,1.70,and 1.11 times of the background values of Chinese soils,respectively;correlation and principal component analysis showed that Cu,Zn,Pb,and TP may be related to agricultural sources such as greening and fertilization and traffic sources such as automobile tire wear and exhaust emissions;organic matter is related to domestic sources such as residential wastewater;Cr and TP are related to anthropogenic sources in industries such as electroplating.(3)The overall distribution of the effective states of Pb,Cr,Cu,and Zn in the sediments of the three rivers was Central City river>South Zhongshan Road river>Huicheng river,and the effective state of heavy metal Zn was significantly higher compared with other heavy metals,and the effective state of Cr was the lowest;correlation analysis showed that pH was significantly and positively correlated with the effective states of heavy metals Cr and Zn,and organic matter and TP were significantly and positively correlated with the effective states of heavy metals Pb,Cu,and Zn.The correlation analysis shows that pH is significantly and positively correlated with the effective states of heavy metals Cr and Zn,and organic matter and TP are significantly and positively correlated with the effective states of heavy metals Pb,Cu and Zn;in the three rivers,the Pb,Cr,Cu and Zn forms generally appear in the residue state,among which,Pb,Cr and Cu in the Central City river are mainly in the residue state,and Zn is mainly in the Fe-Mn combined state;Pb,Cr,Cu and Zn in the Huicheng river and the Zhongshan South Road river are mainly in the residue state.(4)Health risk evaluation found that the three river water bodies noncarcinogenic elements health risk is low,almost no health risk;Cr is the main carcinogenic factor,its health risk value exceeds the ICRP recommended maximum acceptable level of 5.0×10-5 a-1,should be Cr as a priority control index;Comprehensive pollution index method found that when referring to the IV water quality standard,61.1%of the sampling points comprehensive pollution index is high,Zhongshan South Road river comprehensive pollution index is relatively the highest;ground cumulative index method evaluation shows that the degree of pollution of four heavy metals in the river sediment size of Cu>Pb>Cr>Zn,the overall reached a light pollution level.The analysis of potential ecological hazard index method shows that the order of heavy metal pollution is Cu>Pb>Cr>Zn,and the ecological hazard index of all sampling points of four heavy metals in river sediment is less than 40,which is a low risk level;the RI value of the upstream section of Zhongshan South Road river is relatively high,in which Cu and Pb pollution is the highest,while Zn and Cr pollution and potential ecological hazard risk are low.Figure[14]table[20]reference[131]... |
