Application of chemometric methods to analyze the distribution and chemical fraction patterns of metals in sediment from a metropolitan river

摘要

Rivers in metropolitan areas are often highly polluted with materials that pose a threat to a large number of residents. Human influences lead to contaminants in metropolitan rivers having more complex sources than those in rural rivers. This complexity results in contamination that is unstable and rapidly changing. Here, the contents and chemical fractionation patterns of eleven toxic elements (As, Cd, Co, Cu, Cr, Mn, Ni, Pb, Zn, Y, and Hg) were evaluated in 13 samples collected from along the Beiyunhe River in Beijing, China. The results revealed that the metal contents were unevenly distributed along the river, with higher levels being observed in the downriver sites and the rendezvous sites. Additionally, more than 80% of the metals were found to be in the residual phase. The organic and sulfide phases were the most important extractable phases of most metals, with Ni, Co, Cu, and Cr primarily being associated with these phases and As, Cd, and Zn having a strong association with the iron/manganese oxide and hydroxide phases. Additionally, Mn was associated with the exchangeable and carbonate phases, with the lowest concentrations being observed in the organic and sulfide phases. Conversely, the metal exchangeable and carbonate phases were uniformly distributed throughout the river. Analysis of the metal sources revealed that particles input from the atmosphere comprised a considerable amount of the metals in the Beiyunhe River. However, these metals likely do not enter the sediment via atmospheric deposition directly, but rather through rainwater runoff into the river. The methods used in the present study will be useful in other studies that require analysis of complex data.