Risk Assessment And Source Apportionment Of Heavy Metals In Jiangdong Reservoir Of Jiulong River

Since 21 century,with the acceleration of urbanization process,in order to meet the needs of large-scale development of industrial and agricultural production,the development and utilization of metal mineral resources by human beings are increasing,there are many serious environmental problems,such as heavy metal pollution,which seriously endanger the ecological environment and human health.Sediment is an important component of water environment,which provides habitat and nutrients for aquatic animals and plants,sediments have stored a lot of heavy metal pollutants,which significantly affect the migration and transformation of heavy metals and their biological effects.Reservoir plays a very important role in the development of economy and society,the pollution of reservoir will threaten the safety of water supply,the North Jiulong River water diversion project is the largest water control project in Fujian province,more than 80%Xiamen water supply comes from it,in order to protect drinking water resources and maintain the ecological safety of water environment,it is very important to study heavy metals in water and sediment in reservoir area.Therefore,this study selected Jiangdong Reservoir as the study object,analyzed the characteristics of water quality and the basic physicochemical properties of the sediments;Water Quality Index and Nemerow Pollution Index are used to evaluate the risk of water heavy metal pollution;Geo-accumulation Index,Pollution Load Index,Potential Ecological Risk Index and Secondary Phase and Primary Phase Ratio are used to evaluate the risk of sediments heavy metal pollution;the sources of heavy metals in water and sediments were analyzed by factor analysis and UNMIX model.The main conclusions are as follows:(1)The total heavy metals,dissolved and granular content of heavy metals in water are lower than that of the guideline Class III of national standard of surface water,the water quality of heavy metals in the study area was good.The evaluation results of Water Quality Index and Nemerow Pollution Index in the Jiangdong Reservoir were similar,this result showed that the water quality of the study area was good,and the water body was free from pollution.(2)The variation coefficient of V,Cu,Zn,Se,Cr,Pb,Ni,T1,Ba and Ga dispersed in the surface sediments were small,and the spatial distribution were uniform,the variation coefficient of Cd,Mo,Co,Ag and Sr were relatively large,the spatial distribution is nonuniform.The bioavailability of Cu,Zn,Se,Cd,Pb,Co and Ni were relatively high,and the range was 58.92?97.35%,it needs to enhance real-time monitoring and control of bioactivity and heavy metal elements.(3)The results of the risk of sediments heavy metals as follows:in Geo-accumulation Index,Cd showed strong pollution,and Zn showed moderate pollution to strong pollution.In Pollution Load Index,Cd and Zn showed strong pollution,while Pb,Ag,Co,Mo and Cu showed moderate pollution.In Potential Ecological Risk Index,MYX was at strong risk and the remaining points were at very strong risks,Cd plays a leading role in the potential ecological risk of surface sediments heavy metals,with a contribution rate of 89.21%.in Secondary Phase and Primary Phase Ratio,Se and Cd showed strong pollution level.Pb,Co,Cu and Zn showed moderate pollution level.The four risk assessment results were different,but they all pointed out that the Cd pollution level was high,and the Cd should be the best sediment control pollutant.(4)The source of heavy metals mainly comes from endogenous release,natural sources and anthropogenic sources.Factor analysis showed that endogenous release was the main source,the contribution rate was 40.76%,the UNMIX model showed that natural resources was the main source,the cumulative contribution rate was 47.21%.In the source apportionment of sediments heavy metals,human source are the main sources of heavy metals in sediments.The cumulative contribution rates of factor analysis and UNMIX model were 46.63%and 58.87%,the cumulative contribution rate of natural resources were 40.32%and 41.13%.