Pollution Evaluation of a Phosphorus-Rich Area of Zhongxiang City

摘要

An extensive survey was carried out to understand the spatial distribution and possible sources of soil heavy metals in a phosphorus-rich area. A total of 615 topsoil samples were gathered, utilizing a regular sampling grid of 1×1 km squares, and the contents of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), vanadium (V) and zinc (Zn) were analysed to investigate the spatial distribution of these heavy metals, identify their sources, and assess levels of pollution. The results showed that the enrichment factor (EF) of the studied metals decreased in the order Cd > As > Pb > Co > Ni > Cr = Cu > Zn, and the mean contents of Cd, As and Pb were significantly higher than the background values. According to potential ecological risk (RI), 11.2% of the study areas had considerable potential ecological risk and the other areas had low to moderate potential ecological risk. The results of multivariate and geostatistical analyses indicated that Co, Cr, Ni and V, and to a lesser extent Cu and Zn, mostly originated from natural sources; while As and Pb, and to a lesser extent Cd, Cu and Zn, mainly originated from phosphorus-related industrial activities. The results also showed that Cd was affected by water with Cd pollution from the Hanjiang River. These results are useful for establishing policies for protecting local soil quality.