Seasonal Assessment of Heavy Metals in Water at Effluents Discharge Points into the New Calabar River, Port Harcourt, Southern Nigeria
Water samples were collected at three different effluents discharge points into the New Calabar River. The samples were digested using standard methods. The digests were subsequently examined for heavy metals concentrations using atomic absorption spectrophotometer (AAS). Heavy metals results in the samples showed Ni as the most concentrated metal with a mean value of 2.52±0.055, 1.42±0.01 and 1.275±0.045 mg/L at Iwofe, Jetty, Minipity and Police Post stations respectively, this was followed by the concentration values of Cr, which were 1.72±0.06, 2.17±0.02 and 1.355±0.015 mg/L at the Iwofe Jetty, Minipiti and Police Post sample stations respectively. The least concentrated metal observed in this study was Cd with a mean range of 0.03 – 0.28 mg/L in the stations. This was followed by the values of Cu from the station which ranged between 0.035 – 1.22 mg/L. The general order of the concentration of metals was Ni > Cr > Fe > Zn > Pb> Cu > Cd. All the metals examined in the water samples except Zn were higher than the WHO maximum standard for drinking water. Contamination factor analysis showed that the samples were either severely or excessively polluted by most of the metals. However, Zn and Cu were within the range of contamination in the sampled stations. Pollution load index indicated that the stations ranged from severe pollution to excessive pollution. Contamination degree assessment indicated very high degree of contamination and the modified degree of contamination showed that all the stations were within ultra high degree of contamination. Generally, the result indicated a high degree of water pollution by heavy metals at the discharge point. Therefore caution should be taken to control the sources of these pollutants, which have put this aquatic environment under serious threat.
