Abstract
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.
Highlights
Over the years, water pollution has become one of the major environmental challenges facing most of the states in Southern Nigeria, the Niger Delta region
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
The results of heavy metals in samples obtained from Mile 3 market (PM3), showed that all the tested metals were present in the following increasing order, Cr, Pb and Cd ranging from 0.036 ± 0.006 to 0.61 ± 0.00 mg/kg
Summary
Water pollution has become one of the major environmental challenges facing most of the states in Southern Nigeria, the Niger Delta region. Amongst other states in the region, Rivers and Bayelsa State coastal waters are faced with massive environmental pollutions due to increased coastal population, rapid urbanization, oil and gas explorations, heavy rainfall throughout the year and other array of anthropogenic activities which are capable of deteriorating the aquatic ecosystem [2, 3] Most of these activities generate wastes that bear heavy metals that cause environmental degradation and oftentimes, these heavy metals which are non-biodegradable, accumulate in organs and tissues of aquatic organisms like Clams, Oysters and Cockles through their diets and respiration, thereby posing a serious health risk to human and other animals when consumed [4].it is important to evaluate the levels of heavy metals in shellfishes like Clam, sold in major open markets in Port Harcourt and Yenagoa because of anthropogenic activities prominent in these areas. It is against this backdrop that the study on investigation of heavy metal levels of Clams sold in open markets in Port Harcourt and Yenagoa was conducted, as results obtained from the study will serve as baseline information for researchers, health experts and regulatory agencies
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