DETERMINATION OF SOME HEAVY METALS CONCENTRATIONS IN WATER

ABSTRACT

This study was carried out to ascertain the presence, levels and variability of Chromium (Cr), Cadmium (Cd), Lead (Pb) and Nickel (Ni), in water, Macrobrachium vollenhovenii and sediment collected from Benin River, Delta State. Water, prawn and sediment samples were collected in triplicate from three sampling stations along the stretch of the river (Koko beach, N.P.A, Koko market) for a period of three months (June, July, August). The sampling stations were chosen based on anthropogenic activities (industrial and petrochemical installations and loading). Water, prawn and sediment samples were prepared and digested in the laboratory before they were analyzed for heavy metals, using Buck scientific 210 VGP Atomic Absorption Spectrophotometer (AAS). The results showed heavy metal concentrations were higher in sediments compare to the prawn and water during the study period. Result for mean concentration of heavy metal variation for prawn varied significantly (P<0.05) in Cd but did not vary significantly (P>0.05) in Cr, Pb and Ni across the sampling stations. Cr had a higher mean value of 16.09±3.84mg/kg in sediment, 4.42±1.50mg/kg in prawn and 0.07± 0.01mg/l in water. Cd had a higher mean value of 1.92±0.49mg/kg in sediment, 0.06±0.01mg/kg in prawn and 0.01± 0.00mg/l in water. The levels of Pb recorded it highest mean values of 6.83± 1.15mg/kg in sediment, 0.27±0.25mg/kg in prawn and 0.02±0.00mg/l in water. While Ni had a higher mean value of 8.68±4.46mg/kg in sediment, than prawn and water which recorded values of 0.48±0.23mg/kg and 0.06±0.01mg/l respectively. These results suggest that prawns and water from Benin River are not safe for human consumption as their values were above WHO and FAO recommended limits, and it is recommended that proper managerial policy be put in place to check the influx of these metals into the river. xii