Investigation of heavy metal levels of clams (Egeria radiata) sold in open markets in Port Harcourt and Yenagoa, Nigeria

Due to rapid urbanization, increase in coastal population, oil and gas exploration and other array of anthropogenic activities within the Niger Delta region of which Rivers and Bayelsa states are prominent amongst others, the region has been faced with coastal water pollution. There is need therefore, to evaluate the intensity of environmental contamination of the aquatic ecosystem in this region, thus this study was conducted to investigate the heavy metal levels of Clams (Egeria radiata) sold in open markets in Port Harcourt (Rivers State) and Yenagoa (Bayelsa State). Samples were collected from three markets in Port Harcourt (Mile 1, Rumuokoro and Mile 3), and three markets as well in Yenagoa (Opolo, Swali and Tombia) respectively. The samples were collected bi-weekly for 3 months and transported to the laboratory for analysis of heavy metals (Cr, Cd and Pb) levels using standard scientific method of analysis. The analysis was done in triplicates for each sample and data obtained were subjected to statistical analysis using excel spreadsheet and statistical package for social sciences (SPSS) version 21. The results revealed that samples collected from markets in Port Harcourt had higher concentrations of heavy metal than that of Yenagoa, though, the heavy metal levels were below World Health Organisation permissible limits, except for Cadmium (Cd) that ranged from 0.54±0.002 to 0.78±0.00 mg/kg in samples collected from Port Harcourt, against 0.5 mg/kg recommended by WHO. This could be attributed to oil and gas exploration, and discharges of industrial and domestic wastes bearing cadmium, and poses serious health risks. Therefore, routine monitoring and assessment of the aquatic ecosystem will be vital to forestall further contamination.