Heavy Metal Analysis of Otamiri River in Imo State, Southeastern Nigeria

This study assesses the heavy metal concentration of Otamiri River in Imo State, Nigeria. Standard sampling and analytical methods were employed during the study. The result shows that in all eleven (11) surface water samples collected, mercury (Hg) and cadmium (Cd) have the least concentrations which are below 0.0001mg/l and below the World Health Organisation limits of 0.001mg/l for mercury and 0.003mg/l for cadmium. Copper (Cu) showed a very low concentration of less than 0.0001mg/l in sample1 collected at the river source in Egbu and also anomalously very low concentration of less than 0.0001mg/l in sample 5 collected at Umuoma Nekede. The highest concentration of copper (Cu) (0.0271mg/l) is noticed in sample 8 collected within FUTO community which is likely to have been introduced by domestic waste water from the University hostels that drain into the Otamiri river. The concentration of copper (Cu) in the other eight samples falls within the range of 0.0032mg/l – 0.0271mg/l and the average concentration of copper (Cu) in all the eleven (11) surface water samples is 0.0039mg/l and all these levels of copper (Cu) concentrations in Otamiri river were below the World Health Organisation (WHO) limit of 2mg/l for copper (Cu) in surface water. Also the concentration of zinc (Zn) ranges from 0.0033mg/l in sample 1 to 0.1377mg/l in sample 7. Samples 7, 10 and 11 collected at Umuchima secondary school, Imo State polytechnic Umuagwo and Ohaji Egbema community showed the highest concentration of 0.1377mg/l, 0.1143mg/l and 0.1039mg/l respectively and the average zinc (Zn) concentration in all eleven (11) samples is 0.0513mg/l. The concentration of iron (Fe) in all eleven (11) surface water samples are above 0.20mg/l which shows that the river has a high concentration of iron (Fe) and the average concentration of iron (Fe) in the sample is 0.2426mg/l, with concentration ranging from 0.21mg/l in sample 1 to 0.28mg/l in sample 2 collected from the river source in Egbu and behind Owerri slaughter respectively. It is recommended that regular monitoring of the Otamiri River be carried out to monitor pollution levels.