Order-picking Method

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CHAPTER FIVE Conclusion and Recommendation

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Similarly, potassium values for both seasons were above the maximum allowable WHO limit.

Calcium values obtained were all below the WHO standard for surface water. The value of magnesium in general is within theWHO allowable limit of 50mg/L

The total hardness was found to be higher in dry season than in wet season, but were within theallowable limit set by WHO. The maximum value of Total alkalinity was obtained in dry season. But the values for both seasons were within the WHO presecribed limit. The highest average value of Chloride was obtained in dry season. But the values obtained in both season were below the WHO values of 250mg/L. The results obtained showed no nitrate and nitrite pollution in the water samples analysed. The concentration of ammonia and sulphate in the water samples were found to be within WHO prescribed limit. The phosphate concentration was higher in dry season than in wet season.

The highest average value of total organic compound obtained in wet season may be duetothe influx of organic matter into the river by rain. The concentration of DO and COD were higher in dry season than in wet season while BOD had lower value in both seasons. The River was heavily polluted of fecal origin judging from the high value of the total coliform and E. Coli obtained in the water smaples for both seasons. The pollution index oftheriver gives a result that indicates critical value of approximately 1.0.

The water of River Niger was found tobe contaminated with all theheavy metals analysed for (Fe, Ni, Zn, Cu, Cr, Mn, Co, Cd and Pb). The wet season values were significantly higher than the dry season except for Cadmium.

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The metals had accumulated above critical value of 1.0 as indicated by the MPI. The MPI of the wet season was found to be much lower than that of the dry season. Iron alone accumulated above the critical value 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 theWHO recommended limit Cd was notdetected in wet season but overshoot the WHO limits in dry season. There was strong positive linear correlation in metals concentration in water and sediments. Increased concentration of metals in sediment also lead to increased concentration of metals in water.

All the fish samples obtained from all the 3 areas of River Niger assessed were all contaminated with the heavy metals analysed for except cadmium and lead that were not detected in catfish while tilapia was found to accumulate these metals from Lokoja area. Here, Ni, Mn, Co and Pb exceeded the limit set by WHO. The concentrations of the metals in the two species of fish were accumulated close to the critical value of 1.0 in Idah area of River Niger while Itobe and Lokoja are relatively lower.

Iron was found to be the most accumulated through the consumption of tilapia and catfish from these areas sampled. The hazard indices obtained were below 1.0 which is the critical value hence the fish specie obtained from this area may pose no significant health risks to the consumers.

112 5.2 Recommendation

The following recommendations are made as a result of the present study:

1. Due to the importance of the River Niger to the inhabitant along its course, periodic physico-chemical analysis should be carried out to ascertain its uses for agro-domestic purposes.

2. The level of the metals concentrations in the river should also be determined using fish and other bio-indicator for the determination.

3. Public awareness fora should be organized from time to time by the state environmental protection agency to educate the populace especially those living on the River Bank and the town through which the River transverses on the ill effect of indiscriminate dumping of wastes at non-designated areas.

4. Industries located close to the River course should treat their wastes effectively before dumping in the river body.

5. Farmers should be assisted in fertilizers and agro-chemical applications by agricultural extension officers of the ministry of agriculture to avoid high incidence of chemical contaminant on surface water.

6. Indiscriminate disposal of wastes of fecal origin should be legislated and discouraged to avoid disease ransmission through water.

7. Human health risk assessment of heavy metals should be extended to the numerous dietary products that are consumed daily over a life time in order to translate the level of concern arising from the environment into potential risks to human health, modifying

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factors that may enhance or prohibit the body’s ability to cope with metal exposure should also be taken into consideation.