Spatio-temporal Variability of Heavy Metal Concentrations in Soil-rice System and Its Socio-environmental Analysis

Ninety nine surface soils and the corresponding rice grain samples from Wenling County in 2011 were used for the spatio temporal variability investigation and evaluation of Cd, Cu, Ni, Pb and Zn concentrations to compare with values found in 2006. All heavy metals pose potential pollution risks in soil, especially Cd and Cu. The trend of increasing Cd contamination in rice was obvious. There were large percentage increases in Cd and Cu concentrations in soil and Cd and Ni in some rice regions. The regions with increased soil Cd concentrations were located in the north of Wenling with presence of intensive private small E-waste recycling companies. Concentrations of Cu in soil increased mainly in the east. Increases in the concentrations of Cd and Ni were observed for rice in the southwest and significantly different. Redundancy analysis (RDA) was used to provide a survey of variations in soil metal concentrations and then interpreted by consideration of soil properties and socio-economical observations. It was concluded that Zn concentration was related to the rapid development of local industry. The socio-environmental factors explained 43.3% of the variations in metal concentrations in soil. This study demonstrates the situation and accumulating trend of heavy metal concentrations in a soil-rice system caused by intensive human activities in Wenling County. (C) 2016 Friends Science Publishers