Ecological analysis of heavy metals contamination in water from Kaani River, Ogoni, Rivers State, South-South, Nigeria

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Ecological evaluation was carried out to study the surface water of the Kaani River, Ogoni axis, Rivers State, South-South, Nigeria, for contamination factor (Cf), degree of contamination (Cd), and modified contamination degree (mCd). Over the course of a year, surface water samples were taken from the Kaani River at four separate locations every two months. The atomic absorption spectrophotometry (AAS) method was used to determine the amounts of heavy metals in the samples after they had been prepared according to normal procedures. The metals analyzed were manganese (Mn), cadmium (Cd), copper (Cu), chromium (Cr), lead (Pb), iron (Fe), zinc (Zn), arsenic (As), and nickel (Ni) respectively. The result of the metal concentrations in all stations and months showed the order as As < Cd < Pb < Mn < Cr < Ni < Zn < Fe < Cu. A contamination factor test on the various heavy metals based on their concentrations and the WHO standard revealed that the studied heavy metals were at different levels of contamination and pollution classification in the River at different stations. The values observed for all the trace elements studied, with the exception of Fe, were less than the WHO and NAFDAC requirements for drinking water. The River showed no contamination–moderate pollution with Fe, while that of Mn indicated slight contamination- severe contamination range, Cd fell within no contamination to slight contamination range, slight contamination –slight pollution with Cu, no contamination – slight contamination with Zn, slight contamination – very severe contamination with Cr, moderate contamination- very severe contamination with Pb. As and Ni were at the range of slight contamination – moderate contamination. The analysis results from the River indicated that the water should be treated adequately before consumption. The pollution index analysis showed that the River was not polluted with heavy metals. Contamination degree values showed that the River is at different levels of heavy metal contamination. Modified contamination degree indicated that the River experienced nil to very low degree of contamination by the metals examined.