Organochlorine Pesticides in Soils of Municipal Solid Waste Dumpsites in Delta State: Spatial and Seasonal Variations, Potential Risks and Sources

This study assessed the spatial and seasonal variations, potential risks and sources of organochlorine pesticides in municipal solid waste dumpsites (MSWDs) in Delta State. Soil samples were obtained from twenty-seven MSWDs in Delta State. Soil samples were extracted with hexane/dichloromethane and cleaned up in a column of silica gel and florisil. The OCPs in the extracts were quantified with a gas chromatograph-mass spectrometry (GC-MS). The ∑20 OCPs levels in the soils varied between 0.74 and 7.29 ng g-1for the dry season and from 0.09 to 9.47 ng g-1 for the wet season. The result showed significant spatial and seasonal variation in the concentrations of OCPs in the soils. The distribution pattern of OCPs homologues in the soils of the MSWD was in the order of ∑Chlordanes > ∑BHCs > ∑Drins > ∑DDTs > ∑Endosulfans for the dry season and ∑Chlordanes > ∑BHCs > ∑Drins > ∑Endosulfans > ∑DDTs for the wet season. The computed soil quality guideline quotients (SQGQs) indicated that there is no adverse ecological risk of OCPs in the MSWD soils. The hazard index and total cancer risk values indicated that non-carcinogenic and carcinogenic risks were not associated with the OCPs exposure in these soils. The isomeric ratios indicated that the sources of OCPs in the MSWD soils include recent and historical pesticide usage.