Affiliations: Guangdong Institute of Eco-Environment and Soil
Sciences, Guangdong Key Laboratory of Integrated Control of Agro-environment,
Guangzhou 510650, China
Abstract: Distribution and speciation of heavy metals of agricultural soils (85
surface soil samples and 4 soil profiles) in Dongguan were investigated, while
total Cr, Cu, Ni, Pb, Zn (abbreviated as Cr, Cu, Ni, Pb, Zn) and available Cu,
Zn (Av-Cu, Av-Zn) were analyzed by a flame absorption spectrophotometer (AAS),
and total Cd (Cd) was analyzed using graphite furnace AAS. The content of Cd, Cu
and Ni was partially much more than the second grade of GB15618-1995 even
though the mean contents of all heavy metal were less than the threshold value
of the second grade and only the mean content of Pb was more than the value of
national background. Results of descriptive statistic showed that the mean
content of heavy metals should depend on land utilization and spatial location
at some extent. The heavy metal contents were higher in the Southwest and
Northwest than in the Central. In addition, the mean contents of Zn and Pb in
Dongguan paddy soils were significantly higher than those of Pearl River
Delta (PRD) and Taihu Lake region (TLR). Correlation analyses indicated that
there existed significant correlation between Cr and Ni in orchard soils, and
among Zn, Cd and Cu, between Av-Cu and Cu, between Av-Zn and Cr, Ni, pH value
in vegetable soils, and a weak relationship between Cd, Cu and Pb, between
Av-Zn and Zn. Principal component analyses (PCA) showed that the order of
importance should be Zn> Pb> Cr> Ni> Cu.
Keywords: heavy metal, spatial distribution, agricultural soil, Dongguan
