ASSESSMENT OF THE IMPACT OF IKPOBA RIVER

ABSTRACT

This report presents result obtained from the investigation and water sampling exercise carried out on the segment of Ikpoba river in Benin city, Edo State, Nigeria. The report reveals that while some people uses water from the river for domestic, food production and recreation purposes, others discharge their wastes without any form of pretreatment into it. The multipurpose usage of water from Ikpoba river by local residents thus hinges public health on the self-purification capacity of the river alone. Information on water uses and waste disposal practices of the local residents were obtained through direct observation, questionnaire distribution and oral interview of members of randomly chosen households built along the river at the site of solid waste discharge at distances 0m, 10m, 20m, 30m, 50m, and 100m from the point of discharge. A seventh sample was also obtained 10m upstream from the point of solid waste discharges to furnish information on ambient conditions of the river prior to pollution while an eighth sample which was prepared by diluting the obtained at 0m with distilled water (i.e. 25% steam water, 75% distilled water) was included to serve as control sample. All water sample were transported (within 1 hours of isolating them from the river body) to the laboratory for analysis and the results were subjected to graphical, statistical and mathematical analysis. Pollution from the waste materials caused a drop in dissolved oxygen level of the river from value of 4.6mg/l to 0.01mg/l at the point of discharge. The pollution also caused an increase of 447.5mh/l to 1071.5mh/l in T.S, 0.04mg/l to 4.4mg/l in ammonia, 170mg/l to 670mg/l in BOD, 0.05mg/l to 3.05mg/l, in phosphorus, 50mg/l to 10667mg/l in alkalinity and 18mg/l to 8200mg/l in acidity. The percentage compliance of each of the eight water samples with guideline values (GLV) of WHO and FEPA was performed. None of the sample met the minimum requirement for BOD, COD and TSS, which are indicators of pollution. It was concluded that Ikpoba river in Benin city is being polluted by waste discharge thereby exposing the health of local residents who use the water from the river for domestic’s recreation and food production purposes to avoidable risks.