Temporal Variations of Heavy Metal Concentrations in Selected Fishes, Sediments and Surface Water along an Artisanal Refinery Site, Rivers State, Nigeria

This study determined the temporal variations of heavy metal (Lead (Pb), Iron (Fe), Zinc (Zn), Arsenic (As), Copper (Cu) and Cadmium (Cd) concentrations in selected fishes, sediments and surface water along an artisanal refinery site in Rivers State, Nigeria. Water and sediment samples were collected aseptically in screw-capped bottles at both low and high tides from approximately 20 cm below the surface. Live Flathead grey mullet (Mugil cephalus), swimming crabs (Callinectes amnicola), periwinkles (Tympanotonus fuscatus) and Guinean tilapia (Tilapia guineensis) were collected at the Ibaka waterfront for six months at an interval of one month from local fishermen. The sampling was carried out between November 2022 and April 2023 for statistical variation. Heavy metal content was analyzed using standard methods. The study found temporal variations in Cu, Zn, and Fe concentrations in four fish species from Ibaka Creek in Okrika, indicating potential contamination. However, Pb, Cd, and As concentrations remained constant throughout the sampling period. Cd and Fe concentrations exceeded recommended threshold values, raising concerns about health and environmental risks. Pb, Zn, As, and Cu concentrations remained within acceptable limits, indicating lower risks to human health and the environment. Sediment samples showed variation in Pb concentrations, exceeding EPA thresholds but within WHO guidelines. The findings emphasize the urgent need for attention to address heavy metal contamination in the area, including strict regulations and monitoring of artisanal refinery activities.