Particle-size distribution characteristics and pollution of heavy metals in the surface sediments of Kuitun River in Xinjiang, China

On the basis of analyzing particle composition of the surface sediments of Kuitun River in Xinjiang, heavy metal concentrations of Co, Cr, Pb, Ni, Mn, Cu and Zn in different particle-size fraction of the surface sediments were measured. The enrichment and contamination levels of heavy metals in the surface sediments of different size were assessed based on both the single factor index method and Nemerow integrated pollution index method. The results showed that the surface sediments of the Kuitun River were dominated by the particles with sizes lower than 250 mu m. Co, Cr, Mn, Cu and Pb have a peak concentration in the range of <4 mu m. The five heavy metals concentrations were 0.81, 7.96, 1.98, 3.42 and 3.50 times their local soil background values, respectively. While Ni and Zn have a peak concentration in the range of 4-63 and 125-250 mu m, respectively, they were 2.13 and 1.49 times their local soil background values. The results of evaluation showed that the heavy metals of the surface sediments in the range of <4 mu m were moderately polluted, and the heavy metals of the surface sediments in the range of 4-63, 63-125 and 125-250 mu m belonged to the category of low polluted.