Heavy metal pollution in the Baotou section of the Yellow River, China

Baotou City is a representative heavy industrial city in the drainage basin of the Yellow River. This paper studies the pollution of a contaminated section (Baotou section) of the Yellow River, China, with a known anthropogenic heavy metal input from the industrial discharge. The distribution of heavy metals (Cu, Pb, Zn and Cd) in the overlying water, filtered water (overlying water filtered through a 0.45-mu m filter membrane) and sediments was determined in the Baotou section of the Yellow River. The results of this research indicate that heavy metal pollutants transport mostly through the carriers of suspended particulates and sediments in the fluvial environment. Baotou City's industrial discharge draining into the Yellow River from the tributaries (the Kundulun River and the Sidaosha River) increases the concentrations of Cu, Pb, Zn and Cd in the mainstream and influences heavy metals speciation. Speciation analyses show that the Cd is easily enriched in the secondary phase (bioavailable form), followed by Pb. Furthermore, based on the acute water quality criteria (WQC-Acute) and chronic water quality criteria (WQC-Chronic) set by the United States Environmental Protection Agency, the acute sediment quality criteria (SQC-Acute) and the chronic sediment quality criteria (SQC-Chronic) are calculated respectively using the developed equilibrium partitioning approach (EqP). By comparing heavy metal contents in sediments with SQC-Acute and SQC-Chronic respectively, we note that Pb and Cd have posed a high risk to the quality of water environment and to the aquatic ecosystem health of Baotou section of the Yellow River.