SEDIMENT QUALITY OF AMAGBA-OKOROMA RIVER, BENIN CITY, EDO STATE, NIGERIA

ABSTRACT

The relationship between sediment and water is of paramount importance. The quality of sediment almost always reflects the quality of water and this is usually altered by pollution from natural and anthropogenic activities. This study aims to assess the sediment quality of the Amagba-Okoroma River, Edo State, Nigeria. Three (3) stations were studied and sediment samples were collected for each of these stations both for wet and dry seasons using standard methods. The collection was done along the river course for a period of four (4) months, March to July, 2023 using flat hand shovel. The sediment samples were analyzed for a total of ten (10) physicochemical parameters and trace metals. From the results analyzed, there was no significant variation in the physicochemical parameters across the sampled stations (p>0.05) except for nitrate that showed a significant variation across sampling stations (p<0.05). Sediment physicochemical parameters namely, pH, Cd, Cr, Electrical conductivity, PO4 and Pb positively correlated with one another. All the heavy metals analyzed were within the USEPA Sediment Quality Guidelines and the sampled stations were found to be non-polluted with these metals according to USEPA. The Contamination factor and Contamination degree values recorded indicates a low degree of contamination across the three stations. The PLI values recorded for all stations were below 1 and this indicates no pollution across the stations. The Geoaccumulation Index values recorded also showed no pollution across the three sites. To mitigate the negative effects of increase in anthropogenic activities that will likely take place on Amagba-Okoroma River, it is recommended that water quality monitoring be done regularly and more sediment quality assessment carried out to ascertain the causes and sources of pollution.