Risk Evaluation and Source Tracing on Heavy Metal Contaminations in Soil at Tea Plantations in Wuyishan

Risk evaluation and source tracing on the environmental pollution from heavy metal contamination in soil at tea plantations in Wuyishan were conducted. Contents of 8 major heavy metals in the soil samples were analyzed using multivariate statistics, evaluated according to the Hakanson potential ecological risk assessment index, and traced to their origins by a principal component analysis. The results indicated that (1) the average concentrations of Pb, Cd, and Hg were 2.2, 3.6, and 2.6 times, respectively, higher than the respective reference values for Fujian standards on these elements, while, although less severe, those of Cu, Zn, Ni, Cr, and Pb also apparently showed their presences in the surface soils; (2) using the potential ecological risk assessment index, the risk levels of Cd and Hg were categorized as medium and moderately heavy, those of Cu, Zn, Pb, Cr, Ni and As graded as low, and overall, the soils at the plantations were under medium and heavy levels (78.9%); and, (3) the principal component analysis suggested that the main source of Pb contamination stemmed from traffic pollution, those of Cu, Cr, and Ni from the natural components in soil at the sites, that of Hg from agricultural sources, that of Zn from natural, geological background and/or traffic at the surrounding areas, and, that of Cd from transportation and/or agricultural origins. Consequently, special attention must be paid on Cd and Hg as they also inherently post greater risks than others on human health.