ECOLOGICAL EFFECTS OF EFFLUENT OF FOOD INDUSTRY ON WATER, SEDIMENT AND FISH OF RIVER ONA, IBADAN, NIGERIA

Abstract

Effects of effluent discharged from food industry at Oluyole Industrial Estate Ibadan on fish, water and sediment
of River Ona was investigated. The water, effluent, sediment and fish were sampled monthly (March - December,
2019). Four sampling points (viz-a- viz the effluent discharge outlet; point source - where effluent meets with the
receiving river; upstream and downstream of the river to the effluents) were chosen. Water physico-chemical
parameters and metal concentrations were determined in-situ and ex-situ using electrometric built-in portable
electronic Lamotte tracer pocket tester (Model 1766), portable digital Dissolved Oxygen probes (Model HI9146)
and Atomic Absorption Spectrophotometer respectively. Sediment and fish samples were collected at each
sampling points by Scoop and cast net respectively. Temperature ranged from 31.930C - 40.030C and 31.470C -
34.830C in dry and wet season respectively. Electric Conductivity, pH and Biological Oxygen Demand ranged
between 311.51μScm-1 and 2267.19μScm-1, 7.24 and 9.31 and 14.15mgl-1 and 37.43mgl-1 in dry season and
313.51μScm-1 and 1984.70μScm-1, 7.19 and 9.01 and 50mgl-1 and 35.14mgl-1 in wet season respectively.
Meanwhile, Dissolved Oxygen level was low in both seasons. Many physico-chemical parameters of River Ona
deviated from Standard permissible limit. Generally, Zinc (Zn) > manganese (Mn) > lead (Pb) > iron (Fe) > copper
(Cu) in both wet and dry seasons and were higher than standard permissible limit except Zn and Cu. All the metals
were concentrated in the effluents > point source > upstream > downstream, while the physico-chemical properties
of the sediments were higher than the River water. Oreochromis niloticus accumulate least metals at the point
source, followed by upstream and then, downstream. Fe > Mn > Zn > Cu > Pb in gills, Fe > Zn > Mn > Pb > Cu
in flesh and Fe > Mn > Zn > Pb > Cu in liver in both seasons. The study revealed that the industry discharge
effluents with high BOD and COD values amongst others are not in compliance with the standards.