Organochlorine Pesticides in Selected Sewage Sludge in South Africa : Assessment and Method Validation

摘要

The purpose of this study was to determine the concentrations of organochlorine pesticides (OCPs) in sewage sludge from three wastewater treatment plants (WWTPs), with a view to study their contribution to the environmental pollution of the Amathole District in Eastern Cape, South Africa. Analyses were performed by gas chromatography joined with micro electron capture detector (mu ECD). The limits of detection (LODs) of the tested congeners varied from 0.04 ng/g alpha-Lindane (alpha-BHC) to 0.49 ng/g (endosulfan sulfate), and the limits of quantification ranged from 0.22 ng/g (aldrin) to 2.17 ng/g delta-lindane (delta-BHC). Total concentrations of the 17 congeners for different seasons in the sludge ranged from 191 to 947 ng/g dw. For the six predominant congeners, the total highest concentration levels were found in this order dichlorodiphenyl trichloroethane (DDT), dichlorodiphenyl dichloroethane (DDD), alpha-BHC, gamma-BHC, aldrin and endosulphate 1, and with values of 1512, 1330, 1095, 998, 994 and 547 ng/g respectively. For this result the contamination levels of some congeners for South African sludge can be categorized as high compared with European countries, but moderate to lower compared to other countries worldwide. Some congener (alpha-BHC, gamma-BHC, aldrin, endosulphate 1, DDD and DDT) contents in the samples exceeded limits set by the European Commission for 1000 ng/g set for Sigma DDT and 500 ng/g for other pesticide use of sludge in agriculture.