Monitoring And Evaluation Of Heavy Metal Pollution In The Sediment Of Qing River And Fan River Basin

Qing River and Fan River are important rivers in Northeast China,as the main tributaries of Liao River system.Water resources in the basin not only provide drinking water for the surrounding residents,but also support industrial development and agricultural irrigation.Therefore,water health is not only related to the national economy and people’s livelihood,but also affects health of people.Sediments are the source and sink of heavy metal pollution in the river,After entering the water,most of heavy metals in the pollutants will be absorbed by the sediment in the river and show a strong aggregation effect.Once great changes have taken place in the external environment,the heavy metals in the sediment will be released and enter the water again,so the characteristics of heavy metal pollution in sediments can reflect the overall pollution status of heavy metal in water environment.Therefore,it is of great practical significance to study the monitoring and evaluation of heavy metal pollution in the sediment of Qing River and Fan River.In order to access comprehensively and fully the content,distribution characteristics,correlation,principal components and pollution risk of heavy metals in the sediment of Qing River and Fan River,sediment samples were collected in April,July and October 2019.The contents of Cu,Pb,Zn,Cd,Ni,Cr,As and Hg were determined and the accumulation condition of heavy metals in the sediment was discussed.And the correlation of eight heavy metals and principal component were analyzed.Then the pollution of heavy metal pollution was evaluated by the index of geo-accumulation,the potential ecological risk index and pollution load index to evaluate.The results are shown as following:The contents of eight heavy metals were different in every point and season in Qing River and Fan River.The order of average contents is as following:Zn>Cr>Ni>Cu>Pb>As>Hg>Cd.The average contents of Cu,Zn,Ni and Cr were higher than the environmental background value,and the average contents of Pd,Cd,As and Hg were lower than the environmental background values.The order of the total contents during different period is as following:Dry season>Normal period>Wet season.Zn,Cu,Ni and Cr in Qing River showed high positive correlation.The correlation between Zn and Cu is the highest,and Pd and Cd also showed high positive correlation.The contents of Zn,Ni and Cr in Fan River showed high positive correlation.However,the correlations of As and other heavy metals were very low.The first major components of the Qing River are the main pollution source of Cu,Ni,Zn and Cr,the second were the main pollution source of Pd and Cd,and the third is the main pollution source of As.According to the analysis results,it is found that the pollution order of the eight heavy metals of in Fan River is as following:Zn>Ni>Cu>Cr>Pb>Hg>Cd>As.The average geo-accumulation index of each element was 0,which indicated that it belonged to the clean state.The evaluation results obtained by using the potential ecological risk index shows that the pollution extent of every heavy metals as following:Hg>Cd>Ni>Cu>Pb>Cr>Zn>As,which were of slight ecological risk.The level of the potential ecological risk was low in every sampling points.According to the comprehensive RI value of all sampling points,the risk value of the dry season is higher than that of the normal period and the high water period.By using the pollution load index method and referring to the average value of the highest pollution coefficient of each sampling point,the results of eight kinds of heavy metal pollution in Qing River and Fan River are respectively as follows:Zn>Ni>Cu>Cr>Pb>Hg=Cd>As,Ni>Zn>Cu>Cr>Pb>Hg>Cd>As.And the pollution degree is all pollution-free.In conclusion,the pollution risk of heavy metal in sediment of Qing River and Fan river is low.