Organochlorine pesticides (OCPs) in agricultural soils of Southern Nigeria: spatial distribution, source identification, ecotoxicological and human health risks assessment

Abstract

The spatial distribution, source identification, ecotoxicological, and human health risks of 20 organochlorine pesticides (OCPs) in agricultural soils in southern Nigeria were investigated in this study. Soil samples were collected from 18 agricultural soils from 6 different locations. Soil samples were soxhlet extracted using dichloromethane/n-Hexane and purified with florisil and silica gel column. The OCPs were quantified using a gas chromatography-mass spectrometry. The concentrations of the ∑20 OCPs in the soils varied between 5.8 and 395 ng g−1 for all locations and depths. The occurrence profile of OCPs was in the order of ∑Chlordane > ∑HCHs > ∑DDTs > ∑Endosulfan > ∑Endrin > Aldrin > Dieldrin. The TEC-HQ and PEC-HQ values indicated the presence of adverse and frequent ecological effects on biota from OCPs’ exposure in the soils. The HI and TCR values indicated that there were potential non-cancer and cancer risks from the OCPs’ exposure in the soils. The result of PCA and isomeric ratios showed that the OCPs in the soils were from past and fresh usage of OCPs as pesticides in the soils. The government should, therefore, set guidelines to control the use of OCPs in agricultural soils to prevent further contaminations.