Abstract
The New Calabar River is an important commercial river in Rivers State. Surface sediment samples were collected from four stations and analyzed for some heavy metals concentrations. The results obtained revealed that the concentrations of the metals were iron (Fe) > zinc (Zn) > nickel (Ni) > chromium (Cr) > copper (Cu) > lead (Pb) > cadmium (Cd) > arsenic (As). Their respective mean values were; Fe, 147.84±90.13; Zn, 5.49±2.01; Ni, 3.50±1.48; Cr, 3.42±1.00; Cu, 2.48±1.11; Pb, 2.42±1.09; Cd, 0.089±0.12 and As, 0.006±0.005 mg/Kg. The results were further evaluated with some model indices (contamination factor, ecological risk and enrichment factor assessments. Sediment contamination factor analysis showed that the sediments were slightly contaminated. Ecological risk assessment revealed that the metals at the present concentrations are not harmful or cannot cause risk to the environment. However, enrichment factor analysis indicated that all the metals had significant anthropogenic enrichment at the various stations except As at Aluu, Choba and Iwofe and Cd at Aluu. Therefore, adequate and continuous monitoring should be put in place to prevent upsurge of anthropogenic heavy metals input into the river. Keywords: Heavy metals, ecological risk, enrichment factor, sediment quality
Highlights
In recent years, the accumulation of heavy metals in the environment has received increased attention from both scholars and officials saddled with legislation
The buildup of trace metals in any water environment and sediments is contingent on diverse influences, which are the type of sediment constituents and the physicochemical conditions under which the environment is operating (Nemr et al, 2007)
The discharge of heavy metals and other environmental pollutants to the shoreline zones is on the increase majorly due to the fact that economic activities is on the rise worldwide (Nasehi et al, 2012)
Summary
The accumulation of heavy metals in the environment has received increased attention from both scholars and officials saddled with legislation. Heavy metal concentrations higher than required levels have toxicological character in aquatic environment. Despite the limitations of sediment quality procedures and background standards, they are extensively used determining or assessing different risk associated with heavy metal contamination in any water environments (Burton, 2002).
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