Metal Distribution Characteristics,Health Risks And Source Analysis Of Typical River Water In Liaohe River Basin

Heavy metals are a class of highly toxic,persistent and refractory environmental pollutants,which exist in aquatic environment and can be accumulated in organisms and food chains,posing a potential threat to aquatic organisms and human health.In the context of economic globalization,industrialization and urbanization accelerated development,water pollution of heavy metals has become one of the world environmental problems.In this study,the typical rivers in the Liaohe River basin(Liaohe River,Hunhe River and Taizihe river)under the background of heavy industry are selected as the study area,the contents of Zn,Cu,Pb,Hg,Cr and Cd in water at different water periods were analyzed by Inductively coupled plasma emission spectrometry(ICP-AES),the parameters of the health risk model were adjusted according to the drinking water data of local residents and the health risk of heavy metals in the water body of each river was evaluated,the source of heavy metals was analyzed by Principal Component Analysis(PCA).The main conclusions are as follows:(1)The average concentrations of six heavy metals in the Liaohe River basin were Hg > Pb > Zn > Cu > Cr > Cd,and Hg was the main heavy metal.The pollution characteristics of heavy metals in the three typical rivers are different.Zn is the highest heavy metal in Liaohe River,Hg is the highest heavy metal in Hunhe River and Taizihe river.The distribution characteristics of heavy metals were different in different water periods,most heavy metals were higher in Liaohe River in wet period,and higher in Taizihe River in dry period.The sections of the Hunhe River and the Taizihe River,Cd and Hg,are at the level of V in the national surface water.(2)The average health risk values of the six heavy metals in the Liaohe River basin were Cr>Cd>Hg>Pb>Cu>Zn.Cr and Cd in Liaohe River,Cr and Cd in Hunhe River and Cr in Taizihe River had the highest health risk values.The highest health risk heavy metals in Liaohe River and Hunhe River were Cr and Cd,and the highest health risk heavy metals in Taizihe River were Cr.The highest health risk values for non-carcinogens(Zn,Cu,Pb and Hg)in the Liao River basin were lower than the maximum acceptable risk levels recommended by the USEPA,and the healthrisks for carcinogens(Cr and Cd)in the three rivers were higher than those for noncarcinogens,among them,Cr and Cd have the highest health risk.(3)Most of the heavy metals in the three typical rivers in the Liaohe River basin have significant correlation with each other,the sources of the six heavy metals are similar in different periods,and the major sources are mainly industrial pollution,especially in the petrochemical,metal smelting and electroplating industries,the contribution rate of industrial pollution is especially significant in dry period.Most of heavy metals had no significant correlation with water quality indexes,which indicated that their pollution sources were different from those of water quality.The section with high heavy metal content is located in the middle and lower reaches of each city,which is related to the industrial enterprises around the cross-section.