Heavy Metal Concentration, Speciation And Ecological Risk Assessment Of Surface Sediments In Songhua River

The Songhua River is one of the seven major rivers in China.The water resources in the basin are not only the drinking water source for the surrounding residents,but also the industrial development and agricultural irrigation water sources.Most heavy metals discharged into water can be absorbed by river sediment with a strong accumulative effect presented,which may seriously threat human beings and ecosystems.Therefore,the study of the distribution characteristics and ecological risk assessment of heavy metals in the surface sediments of the Songhua River Basin was of great significance to the health and ecological environment protection of surrounding residents.The concentration distribution characteristics,speciation and ecological risk of heavy metal in the surface sediments of the Songhua River whole basin in the different river sections and flow periods were respectively studied.The concentration characteristics and speciations of Cr?Ni?Zn?Cu?As?Cd?Pb?V?Co?Sn and Sb of 11 heavy metals were studied using inductively coupled plasma mass spectrometry?ICP-MS?method.The heavy metal pollution sources were also analyzed by the Pearson correlation coefficient and principal component analysis method.In addition,the ecological risk of heavy metals in surface sediment was also assessed by geo-accumulation,potential ecological risk index and risk assessment code method.The main results were shown as follows:The heavy metal concentration of 27 surface sediments in the Songhua River Basin during the September normal period was 101.16-486.03 mg/kg,and the average content was313.54mg/kg.The heavy metal concentration of 14 surface sediments in the Songhua River Basin during the June flood season was 141.2-291.33mg/kg,and the average content was222.61mg/kg.The heavy metal concentration of 17 surface sediments in the Songhua River Basin during the March dry season was 132.21-253.57 mg/kg,and the average content was185.26mg/kg.By comparison,it was found that the total change of heavy metals in the sediments of the Songhua River is in the period of normal river flow>flood season>dry season.The chemical forms of heavy metals such as Cr,Ni,Cu,Cd,Sn and Sb in the Songhua River sediments in the September normal river flow period and June flood season 2017 were mainly in the residual form,Zn and Co were mainly weak acid extracted and reducible,As proportions of the four forms are relatively uniform,Pb is mainly in the reducible form and the residual form,V is mainly in the oxidizable and the residual form.The chemical forms of heavy metals such as Cr,Ni,Cu,Cd,Sn and Sb in the Songhua River sediments in the March dry season were mainly in the residual form,Co were mainly weak acid extracted and reducible,Zn proportions of the four forms are relatively uniform,As and V is mainly in the oxidizable form,Pb is mainly in the reducible form and the residual form.Three main components were extracted by principal component analysis.It was concluded that the heavy metals of Cr?Ni?Zn?Cu?V and Co were mainly derived from natural sources,Pb?Sn and Sb are mainly composed of traffic sources and industrial sources,Cd pollution is mainly caused by agricultural sources in the Songhua River Basin during September normal river flow period and June flood season.It was concluded that Cr?Ni?Zn?Cu?Pb?V and Co pollution mainly came from natural sources,As?Sn and Sb pollution were mainly composed of industrial sources,Cd pollution is mainly caused by agricultural sources during March dry season.According to the ecological risk assessment method,the I_geoeo pollution index of the Songhua River sediments in the September normal river flow period is Sb>As>Sn>Cd>Pb>V>Cr>Cu>Zn>Co>Ni.The order of heavy metal pollutionE_rⁱ index is Cd>As>Pb>Cu>Ni>Co>Cr>V>Zn.The I_geoeo pollution index of the Songhua River sediments in the September June flood season is:Sb>Cd>As>Sn>Pb>Cu>V>Cr>Zn>Ni>Co.The order of heavy metal pollutionE_rⁱ index is Cd>As>Pb>Cu>Ni>Co>Cr>V>Zn.The Igeo pollution index of the Songhua River sediments in the September March dry season is:Sb>Cd>As>Sn>Pb>Cu>V>Cr>Zn>Ni>Co.The order of heavy metal pollutionE_rⁱ index is Cd>As>Pb>Cu>Ni>Co>Cr>V>Zn.