Organochlorine, Organophosphorus and Pyrethroid Pesticides Residues in Water and Sediment Samples from River Benue in Vinikilang, Yola, Adamawa State, Nigeria Using Gas Chromatography-Mass Spectrometry Equipped with Electron Capture Detector

Water and sediment samples from ten (10) different sampling points along river Benue, in Vinikilang, Yola, Adamawa State, Nigeria, were collected for the determination of organochlorine (o, p-DDE, p,p’-DDD, o,p’-DDD, p,p’-DDT , p,p’-DDT dieldrin and aldrin), organophosphorus (dichlorvos, diazinon, chlorpyrifos, fenitrothion and Malathion) and pyrethriod (cypermethrin, bifenthrin, permethrin and deltamethrin) pesticide residues. Sample collection and preparation were carried out using standard procedures. The concentrations of all the pesticides in water and sediment samples were determined using GC/MS SHIMADZU (GC-17A) equipped with electron capture detector. The concentrations of organochlorine, organophosphorus and Pyrethriod pesticide residues were significantly higher in the sediment samples than water samples. According to the concentrations and detection frequency, dieldrin and aldrin were the most dominant compounds among the organochlorine pesticide residues. The total concentration of aldrin in the water sample was 2.96 mg/l compared to 11.25 µg/g in the sediment sample and the total concentration of dieldrin in the water sample was 4.36 mg/l compared to 13.37 µg/g in the sediment sample. Chlorpyrifos and dichlovos were the most dominant compounds among the organophosphoruses with the total concentration of Dichlorvos in the water sample being 0.57 mg/l and 22.16 µg/g in the sediment sample. Permethrin and deltamethrin were the dominant compounds among the pyrethroid pesticides. The total concentration of cypermethrin in the water sample was 0.69 mg/l, whereas in the sediment samples, 10.64 µg/g was detected. Results from this study indicates that the water and sediment samples within the study area were contaminated by the studied pesticides. The results also show that there still exists a variety of the studied pesticides in the water and sediment from river Benue, Vinikilang, Yola, Adamawa State. Despite bans and restrictions on the usage of some of these pesticides in Nigeria, the observed concentrations of the Organochlorine, Organophosphorus and Pyrethroid pesticides from the ten sampling points could explain either their persistence in the environment or continued use within the banks and tributary of river Benue.