Levels of Pesticide Residues in Soil and Water Samples from Waanpu Dam in the Bimbilla District, Ghana

Abstract

Nine pesticide residues were detected in soil and water samples from the Waanpu Dam in the Bimbilla District of Ghana at varying mean concentrations using Gas Chromatography. The pesticide residues detected in the soil and water samples were chlorpyrifos, beta-endosulfan, cypermethrin, aldrin, heptachlor, beta-BHC, heptachlor-epoxide, dieldrin, and methoxychlor. The concentration of beta-endosulfan was the highest among all the pesticides detected. It ranged from 0.001 – 0.070 μg/g for soil samples and 0.001 – 0.036 μg/g for water samples. The mean concentrations of pesticide residues in the soil samples analysed from the study sites were generally below WHO 2017 maximum residue levels, MRLs, for agricultural soils except for beta-endosulfan in all soil samples and chlorpyrifos at AS1, AS2, AS3, BS1, BS2, and BS3. The mean concentrations of beta-endosulfan and chlorpyrifos at the above mentioned sites were found to be above the respective WHO 2017 MRLs for agricultural soils. All pesticide residues recorded in the water samples from the various zones were below the respective WHO 2017 MRLs for potable water except for beta-endosulfan at W1, W2, W3, E1, E2, and E3 which exceeded the WHO 2017 MRLs of 0.03 μg/g. Pesticide residues of beta-BHC, Dieldrin, Heptachlor, Heptachlor-epoxide, Methoxychlor, cypermethrin, chlorpyrifos, and beta-endosulfan showed significant differences at p<0.05. The presence of pesticide residues in the samples analysed was an indication of the use of the pesticides by farmers in the study area to control pests and diseases.