Residues of Organochlorine Pesticides in Watermelon (Citrulus lanatus) and Soil Samples from Gashua, Bade Local Government Area Yobe State, Nigeria

摘要

Watermelon (Citrulus lanatus) samples were freshly harvested from the Mashangwari, Katakamand Krigasawaagricultural locations in Gashua, Bade Local Government Area, Yobe State Nigeria. The watermelon samples were divided into peel, pulp, seed, leaf, root and stem for the determination of some organochlorine pesticide residues (o, p-DDE, p,p’-DDD, o,p’-DDD, p,p’-DDT, dieldrin and aldrin). Soil samples were also collected at different depths for the determination of the above pesticides. Sample collection and preparation was conducted using standard procedures. The concentrations of all the pesticides in the soil and watermelon samples were determined using GC/MS SHIMADZU (GC-17A) equipped with electron capture detector (ECD). The determined pesticides were detected in all the watermelon and soil samples from the three agricultural locations. For DDT and its metabolites, p,p’-DDD showed the highest concentration with a value of 0.08±0.03 μg/g in the peel from the Mashangwari agricultural location, while the lowest concentration of 0.01±0.01 μg/g of p,p’-DDT was observed in the root. For the Katakam and Krigasawaagricultural locations, o,p’-DDE showed the highest concentrations of 0.09±0.04 and 0.09±0.03 μg/g. The concentrations of dieldrin and aldrin from the three agricultural locations were observed in the range of 0.01±0.01 and 0.28±0.06 μg/g. The highest concentration of 0.28±0.06 μg/g dieldrin was observed in the peel, while the root showed the lowest value. The total o,p:-DDE, p,p’-DDD, o,p’-DDD, p,p’-DDT in the peel, pulp than leaf, seed, roots and stem of the watermelon samples from the three agricultural locations were lower than the EU set maximum residue limit (MRL) for total DDT, DDD and DDE in watermelon which is 0.05μg/g, while the concentrations of aldrin and dieldrin found in all the watermelon samples from the three agricultural locations were much higher than the EU set maximum residue limits (MRLs) 0.01 μg/kg. These high concentrations of aldrin and dieldrin could probably explain their persistence in the environment or continued use in the study area. Despite bans and restrictions on the use of some of these pesticides in Nigeria, the observed concentrations of the studied pesticides from the agricultural locations could explain either their persistence in the environment or continued use in the study area. Hence, routine monitoring of pesticide residues in these study locations is necessary for the prevention, control and reduction of environmental pollution, so as to minimize health risks.