In order to determine the key influencing factors, risk areas, and source pathways of heavy metals in the sediment of the Yellow River, 37 samples were collected in the surface sediment (0–5 cm) of the Inner Mongolia section of the Yellow River main stream for the determination of heavy metals copper (Cu), nickel (Ni), zinc (Zn), chromium (Cr), lead (Pb), and cadmium (Cd). Based on the geographical detector model (GDM) and ArcGIS 10.2 software, this paper selected 6 heavy metals and 15 influencing factors, including 8 natural factors and 7 anthropogenic factors, to detect key influencing factors, risk areas, and sources of heavy metals. The results showed that: (1) The average contents of heavy metals Cr and Cd in the sediments exceeded the average value in soil, the world average concentration in the shales, and the first-level standard of soil environmental quality in China, and they were the main risk metals; (2) Vegetation coverage (VC) was the largest influencing factor for the spatial distribution of heavy metals in the sediment, followed by per capita income (PI), and land use type (LUT) and road network density (RD) were smaller influencing factors. The interactions of the factors were enhanced; (3) The Wuhai section for a risk area was mainly polluted by Cd and Pb, which were caused by atmospheric deposition and industrial emission. The Baotou section for a risk area was mainly polluted by Cr, which mainly originated from river transportation and industrial discharge. The conclusions can provide a scientific basis for the environmental protection and management of the different areas in the Inner Mongolia section of the Yellow River.
Heavy metals such as Cu, Fe, Mn, Ni, Zn, Cd, Cr and Pb in surface sediments from the Lanzhou Section of the Yellow River were investigated to analyze chemical speciation by a sequential extraction and to evaluate their pollution level. The metal contents in the sediments were found to be in the range of (mg/kg) Cu 15.
Recently, the water quality of the second longest River in China (the Yellow river) is deteriorating severely. To investigate the heavy metals contaminated degrees, potential risks and pollution sources of heavy metals in the river, we measured the concentrations of 8 heavy metals (Fe, Mn, Cu, Ni, Zn, Cr, Pb and Cd) from 122 surface sediment samples collected along the upstream Yellow River. According to the results of enrichment factor (EF) analysis and the geoaccumulation index (I geo) evaluation, we found Cd accumulated significantly for moderately contaminated level and the other heavy metals existed at uncontaminated levels. We conducted risk assessment by using calculation of the sediment quality guidelines (TEC-PEC SQGs) and potential ecological risk index (RI), and the results implied that the concentrations of Ni, Cr and Cd had potential harm for aquatic organisms and the upstream Yellow River had integral no toxic. Moreover, the results of multivariate analysis (principle component analysis, hierarchical cluster analysis and correlation analysis) indicated that Fe, Mn, Cu, Zn, Cr and Cd in the river primarily originated from natural sources, while Ni and Pb mainly derived from different human activities. In addition, partial Cu and Cd come from anthropogenic sources of Ni discharge.
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