Pesticide and heavy metal concentration in irrigation dams: (a case study of the Botanga and Golinga Dams)

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Pesticides and heavy metal concentrations in irrigation dams of Botanga and Golinga were studied to ascertain the level of pollution. The pesticides Atrazine and Glyphosate were extracted from water using diethyl ether and analysed using HPLC with mixture of acetronitrile and ammonium acetate buffer at a pH of 6.0 as the mobile phase and methanol as the stationary phase. The waters of the Botanga dam had an initial Atrazine concentration of 0.0198ig/m1. However, no Atrazine could be detected after the 12 day. On: the other hand, the waters of the Golinga dam had an initial concentration of 0.0265ig/m1, which could also not be detected after 15 days of the first rains. Glyphosate concentration in the waters of both dams were initially 0.0001 µg/m1 and could not be detected after 3 days. The rapid degradation of the pesticide was attributed to the alkaline nature of the reservoirs, water and the high temperatures. A bivirate correlation of degradation with temperature and pH showed a negative correlation and was significant (p>O.O5) which attributes the degradation to these factors. Since the exposure time to these chemicals was short and the concentrations in water lower than the WHO recommended values, they do not constitute a hazard to the consumers of the water. Heavy metals including Cu, Zn, Ni, Cd and Cr were analyzed using the atomic absorption spectrophotometer. It was found that the concentration of all the metals analyzed increased with an increasing depth of the waters with the highest concentration being found in the sediments. Whereas the concentration of Cu, Zn, and Ni were below the WHO guidelines for drinking water, those of Cd and Cr were above the standard. Cd and Cr therefore constitute a health hazard to the people.
A thesis submitted in partial fulfillment of the requirements for the award of the Master of Science degree (Msc) in Environmental Resources Management, 2005