Evaluation of some metals in sediment, water and snail, from an urban flood reservoir in Benin-city, Edo state, Nigeria

Abstract

This study was conducted to ascertain the presence of Iron (Fe), Copper (Cu), Manganese (Mn) and Nickel (Ni) in sediment, snail and water at the urban flood reservoir, Useh. Samples were collected in triplicate over a period of six months (November – April, 2023). Sediment samples were collected using a venier caliper at a depth of 10cm using Van-Veen Grab method. Snail samples were collected by randomly hand picking from the sampling site, and the water was collected using labeled water canisters of 50cl properly rinsed with deionized and site water. At the laboratory, samples were identified, prepared and digested according to standard methods. Analyses of the metals in the digest were then analyzed using the Atomic Adsorption Spectroscopy. The presence of Fe, Cu, Mn were confirmed in all the media during the period of study except for Ni that though was present in sediment and snail was only detected in April in water. The mean concentration of the metals in sediment was higher than the values in water and snail. Fe levels varied between 0.11-2.14mg/l in the snail and water, which were not significantly different (p>0.05) but were significantly different (p<0.05) in the sediment (2.24-97.73mg/l). Cu mean value of 0.43mg/l and 0.04mg/l were recorded in the sediment and snail respectively. ANOVA showed that Cu levels was only significantly different in water. The highest Ni levels observed water (0.08mg/l) and sediment (0.05), were not significantly different (p>0.05) in the sediment. The highest and lowest mean monthly values of 1.12mg/l Mn and 0.01mg/Mn were observed in sediment and snail respectively. Ni and Mn levels in these media showed no significant differences (p<0.05). Hence the free inflow of anthropogenic and other waste observed at the site if not properly managed will greatly increase the pollution level at the flood reservoir. A public awareness campaign of the implication of heavy metal accumulation in aquatic flora and fauna is therefore sacrosanct.