Distribution of Heavy Metals in Groundwater of Sewage Irrigation Area in Guangdong Province, China

Abstract

The research reveals the distribution and correlation of heavy metals in groundwater of sewage irrigation area in Guangdong province. 14 groundwater samples were collected in August 2008, and the groundwater samples were filtrated through 0.45 µm membranes and acidified in the field. Determinations of Cd, Cu, Zn, Pb, Ni, and Cr in all the samples were performed using ICP-OES, and determinations of As and Se in all the samples were performed employing HG-AFS. The result shows that the groundwater of sewage irrigation area has been contaminated with As and Ni, whereas the concentrations of other heavy metals (Pb, Zn, Cu, Cr, Cd, Se) in groundwater did not reach the upper limit for drinking water in China. High As concentrations in groundwater may due to the weak alkaline character of groundwater in sewage irrigation area, because groundwater with weak alkaline is beneficial to enrichment of As. According to correlation and cluster analysis, it is shown that Ni, Se, Zn and Cd may have the common source (sewage irrigation) or by chemical similarity in groundwater, Pb and Cu may have the similar environmental geochemical behavior in groundwater since they are chalcophile elements, whereas As is out of other heavy metals due to the pH of groundwater, because groundwater with weak alkaline is beneficial to enrichment of As, in contrast, for Pb, Cu, Zn etc. In addition, weak correlation relationships between pH and heavy metals concentrations in groundwater of study area suggest that heavy metals concentrations in groundwater of sewage irrigation area are not governed by simple relationships with pH.