SOURCE:

Faculty: Physical Sciences
Department: Pure And Industrial Chemistry

CONTRIBUTORS:

SALE, J. F
AJIWE, V.I.E
OKOYE, P.A.C

ABSTRACT:

River Niger is a transboundary water on which many people in Kogi state depend for their livelihood. Very many anthropogenic activities that generate pollutants, especially heavy metals are indiscriminately going on along the bank of the River Niger particularly the areas of research. Unfortunately, the water is used for irrigation, farming, domestic purposes without pre-treatment. Again, fishes are obtained from the water for commercial or subsistence purposes. Consequently, this study evaluated the suitability of the River Niger water for agriculture and domestic purposes. Data was generated using laboratory analysis with APHA methods. The physico- chemical parameters and microbial asssay were determined using APHA and Membrane filteration methods respectively. Heavy metals in water, sediment and two species of fishes, as bio-indicators, were determined using atomic absorption spectrophotometeric AAS method. The pollution index of the river was evaluated by calculation, the health risk from individual and combined heavy metals due to dietary intake through consumption of catfish and tilapia were evaluated by calculating the target hazard quotients (THQs), estimated dietary intake (EDI) and hazard index (HI). For the physico-chemical and microbial parameters analyzed, the following ranges were obtained for wet and dry seasons respectively. pH: 7.40-7.80 and 7.54-7.83, temperature (oC) 31.2-31.6 and 31.4-31.7, colour (Pt-Co): 262-939 and 206-820, conductivity (µS/cm): 623-762 and 5933-78.1, TDS(mg/L):36.7-47.3 and 40.2-48.6, TSS(mg/L): 84.1- 276 and 78.5-28.7,turbidity (NTU):36.5-253 and 29.5-248,sodium(mg/L):3.09-41.1 and 3.19-52.2, potassium(mg/L):2.27-2.65 and 1.99-3.48, calcium(mg/L):5.12-5.70 and 4.31-4.80, other are total hardness (mg/L):23.2-72.6 and 22.5-111, total alkalinity (mg/L):25.1-26.7 and 25.7-28.0, chlorides (mg/L): 8.79-18.2 and 6.95-20.4,fluoride(mg/L) 0.39-1.16 and 0.4 to 1.24, nitrate(mg/L): 2.14-3.81 and 2.85- 4.37, SO42- (mg/L): 7.53-19.3 and 8.29-24.7, TOC (mg/L): 4.47-5.64 and 2.5-5.4, DO(mg/L): 5.78-7.48 and 5.44-12.6, COD(mg/L): 11.63-18.0 and 3.03-13.9, BOD (mg/L): 1.62-3.41 and 1.41-5.02, total coliform (cfu):111-246 and 156-324, E.coli(cfu):109-228 and 30.8-168. The results further showed that, pH, conductivity, TDS, Ca, Mg, total hardness, Cl-, NO3- ,NO2-, NH3, and SO42- , were within the WHO prescribed limits; while temperature, total suspended solids, and K were above the WHO stipulated limits . The River was heavily polluted by fecal origin. Pollution index (PI) results indicate critical values of 1.0. The cumulative wet season concentration of metals in sediments of River Niger indicated that, Mn, Pb, Co, Ni and Fe concentration were far above WHO prescribed limits. The fish samples were contaminated with the heavy metals assessed, the hazard indices obtained were below 1.0. Hence, the two species of fish obtained from Idah, Itobe and Lokoja area of the River, if eaten may pose no health risk to the consumers.