Environmental Heavy Metal Contamination in Some Selected Cocoa Plantations in Oyo State, Nigeria

The frequent use of copper-based pesticides for the control of cocoa pests and diseases by farmers in Oyo State, Nigeria has necessitated the determination of heavy metal contamination in soil samples obtained from randomly selected cocoa plantations in Longe, Abaagbo, Sikiti, Idi-Ope, Alaagba, and Idi-Ogun in the State. Presence and quantities of copper, chromium, cadmium, manganese, lead and zinc were assayed in the collected samples. Levels of contamination of each of the soil samples were also assessed using contamination factor, degree of contamination, index of geo-accumulation and pollution load index (PLI). Results obtained from the study revealed a gradual deterioration of the analyzed cocoa soils. The PLI values also gave an indication of pollution. Cocoa farmers in the State therefore need to be properly enlightened on the use of synthetic pesticides, and be encouraged to adopt integrated pest management practices that place less emphasis on the use of chemicals.