Abstract:

In the Shunde Area of Foshan, Pearl River Delta Economic Zone, 208 topsoil samples were collected from vegetable fields to measure the contents of copper, nickel, chromium, arsenic, lead, zinc, cadmium, and mercury. The results showed that the average concentration of all these eight heavy metals were higher than their background values of Guangdong Province. Coefficients of variation of Cd and Hg reached as high as 115％ and 151％ respectively, coupling with high concentrations, which suggested anthropogenic sources of these elements. Cr, Ni and Cu displayed low coefficients of variation, thus suggesting a major natural source. The combination of multivariate statistical and Fourier spectral analysis methods successfully identified the elements Pb, Zn, As, Cd and Hg from anthropogenic sources and Cr, Ni and Cu from natural source. Furthermore, Fourier spectral analysis not only interpreted the double sources of Zn and Cu, but also inferred that atmosphere deposition could be an important source of Hg enrichment in soil. According to the pollution evaluation, 217 percent of the study area is suffered from moderate and severe pollution, indicating the requirement of modifications in agricultural cultivation practices in these areas.

Key words: heavy metal, multivariate statistics, Fourier spectral analysis, Pearl River Delta Economic Zone