Effects of pesticides on surface and ground water quality in agriculture and forest land use systems in Akumadan in the Offinso District

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More than 75% of the world’s poorest people depend on Agriculture for their livelihoods and survival. Crop production is limited by pests and diseases that must be controlled and pesticides use is the major method available, if farmers are to reduce crop losses. Excessive and misuse of pesticides causes serious contamination of aquifers and surface water bodies, decreasing the quality of water for human consumption. This study was carried out to determine the levels of contamination of ground and surface water bodies with pesticides in Akumadan where farmers apply pesticides in vegetable and other farming operations. Various laboratory equipments were used to test for the physicochemical properties in the samples. The liquid – liquid extraction method was also used for the extraction of the pesticides from water and soil samples and the analysis was done by Gas Chromatograph coupled with electron capture detector. Amongst the physicochemical parameters tested, colour, turbidity and temperature were above the WHO acceptable limits. Five organophosphates were detected namely; Chlorpyrifos, Methamidophos, Ethoprophos, Phorate and Dimethoate. The levels of organophosphate insecticides were below the W.H.O maximum residue limits. This means that the samples were not unduly polluted with organophosphate insecticides. Many organochlorine pesticides were tested for, but those detected were Aldrin, Gamma-chlordane and p,p Dichlorodiphenyldichloroethylene (DDE). Their concentrations in water samples ranged from 0.01µg/L – 0.17µg/L, 0.01µg/L – 1.7µg/L and 0.1µg/L – 0.8µg/L, respectively. In soil sediment the concentrations ranged from 0.02µg/L – 0.22µg/L, 0.1µg/L – 2.0µg/L and 0.1µg/L – 0.9µg/L for aldrin, gamma – chlordane and p,p DDE, respectively. Two pollutant organochlorine insecticides were aldrin and gamma chlordane whose levels were above the W.H.O acceptable limits. Strict restrictions on use of organochlorine insecticides by farmers in the Akumadan area should be undertaken.
A thesis submitted to the School of Graduate Studies, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the award of the Degree of Master of Science in Agroforestry.