Multivariate and geostatistical analyses of the spatial distribution and source of arsenic and heavy metals in the agricultural soils in Shunde, Southeast China

An extensive survey was conducted in the study to determine the spatial distribution and possible sources of As and heavy metals in the agricultural soils in the Shunde, a representative area in the Pearl River Delta, China. A total of 238 topsoil samples were collected (0-20 cm) from the study area. The levels of Cd, Co and Ni were then analyzed by inductively coupled plasma mass spectrometry, while the content of Cr was determined by inductively coupled plasma optical emission spectrometry, and As and Hg concentrations were analyzed by atomic fluorescence spectrophotometty. The results showed that the mean concentrations of As, Cd, Co, Cr, Hg and Ni are 16.08, 0.60, 16.76, 78.87, 0.38 and 33.45 mg/kg, respectively. The concentrations of Cd and Hg were far higher than their background values of Pearl River Delta topsoil, and in the study area, 2.10%, 90.86%, 43.27% and 18.07% samples for As, Cd, Hg and Ni were higher than the guideline values of the Chinese Environmental Quality Standard for Soils, especially for Cd and Hg, which are 2.00 and 1.27 times the guide values, respectively. Multivariate and geostatistical analyses suggested that soil Cr, Ni, and Zn had a lithogenic origin. Whereas, soil contamination of Cd and As was mainly related to industrial and agronomic practices, and the main sources of Hg were coal burning exhausts, industrial fumes, domestic waste, and vehicle exhausts. The origin identification of As and heavy metals in agricultural soils is a basis for undertaking appropriate action to reduce their inputs. (C) 2014 Elsevier B.V. All rights reserved.