Organochlorine Pesticides Residues in Soil of Cocoa Farms in Ondo State Central District, Nigeria

Abstract

Ondo State being the highest producer of Cocoa in Nigeria constitutes the most probable area with the highest use of chemical pesticides to enhance cocoa production. As effective as these chemicals may be in achieving this goal, the incidence of their residues on non-targeted substances and the total environment, with the attendant adverse effects have being of serious concerns. Our objective in this paper is to assess contamination of farm soils by organochlorine pesticides applied on cocoa farms within the Central Senatorial District of Ondo State, Nigeria. Soil samples were collected from selected cocoa farms and analysed for organochlorine pesticides residues using GC-MS. Some soil physicochemical properties including pH, particle size and organic matter that may influence the dynamics of the pollutants were also determined. Organochlorine compounds detected at varied concentrations include Endosulfan I and Endosulfan II occurring most frequently with highest concentrations of 350.10 mg/kg and 3.55 mg/kg respectively. Other organochlorine compounds detected were Heptachlor, Heptachlor epoxide, Aldrin, Deldrin,, isomers of Benzene hexachloride: ?-BHC, ?-BHC, ?-BHC, and ?-BHC (lindane). The concentrations of the organochlorine pesticides (mg/kg) measured in the soil samples showed significant (p<0.05) correlation with the total organic matter contents of the soil. Findings from this research thus, provide information on the current and health risk residue levels of organochlorine pesticides in soil from this region with which future environmental performance on the use of pesticides on cocoa farms could be progressively monitored.