Distribution and Risk Assessment of Heavy Metals in Surface Sediments of the Qingchuangan Section of the Upper Yellow River
In this study,we characterized the distribution of heavy metals in surface sediments of the Qin-gchuangan section of the upper Yellow River,assessed potential ecological risks,and identified potential sources.Our objective was to provide information supporting conservation of that ecologically sensitive ar-ea.In September 2020,surface sediment samples were collected from 18 sampling sites in the mainstream and primary tributaries(Baihe River,Heihe River,Taohe River and Huangshui River)of the upper Yellow River.The spatial distribution and pollution sources of chromium(Cr),arsenic(As),mercury(Hg),nickel(Ni),copper(Cu),zinc(Zn),cadmium(Cd)and lead(Pb)were analyzed,and the ecological risk of the eight heavy metals was assessed using the Nemero comprehensive pollution index,geo-accumulation in-dex and potential ecological hazard index.Results show that the average sediment concentrations of As and Hg were 11.74 mg/kg and 0.034 mg/kg,1.3 and 1.0 times the national background values.Concentra-tions of the other six heavy metals were below the background values for sediments in Chinese rivers.Among the eight heavy metals,the accumulation level and Nemero comprehensive pollution index of As was highest.Arsenic pollution was assessed as moderate,but its potential ecological risk was much lower than for Hg and Cd.The potential ecological risk index of Hg was highest(40.29)and at a medium level,followed by Cd,also at a medium level in Heihe River.Principal component analysis and Pearson correla-tion analysis show that high pollution degree and ecological risk of As,Hg and Cd in some sites,including the outlet of Longyangxia reservoir on the mainstream,Xizhai bridge in Taohe River,and Dashui in Heihe River,were primarily affected by human activities.Heavy metals in these sites should be closely moni-tored and controlled more strictly.
sedimentheavy metalupper reach of the Yellow River
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