Pollution and risk assessment of heavy metals in water, sediment and fish (Clarias gariepinus) in a fish farm cluster in Niger Delta region, Nigeria

Abstract

The study determined the following heavy metals: cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), lead (Pb) and zinc (Zn) concentrations in surface water and in fish pond (water, sediments and farmed fish (Clarias gariepinus)) from a fish farm cluster with the view of assessing its pollution level and associated human health exposure risk to these heavy metals through fish consumption. Samples were digested with aqua regia and metal concentrations were determined with an atomic absorption spectrophotometer equipped with an air acetylene flame. Mean concentrations of the heavy metals (ppm) in surface and pond water ranged as follows: cadmium (below detection limit (bdl): 0.298); chromium (bdl: 0.257); copper (bdl: 0.067); manganese (bdl: 0.163); lead (bdl: 0.736) and zinc (bdl: 0.078) while in sediment, the ranges (mg/kg dry weight) were as follows: cadmium (1.156–3.329); chromium (9.439–14.373); copper (26.710–121.819); manganese (3.143–37.202); lead (0.340–1.537) and zinc (87.681–371.060). The mean concentrations of the metals in surface water were significantly different (p<0.05) from those in sediment in all the sampling sites. The mean metal concentrations (mg/kg dry weight) in C. gariepnus were in the following ranges: cadmium (0.733–1.405); chromium (0.593–1.692); copper (175.882–245.321); manganese (bdl: 3.326); lead (0.221–0.263) and zinc (248.191–292.333). Some of the heavy metal concentrations obtained in water, sediment and catfish analyzed were above the permissible limit set by some National (DPR) and International organisations (WHO, FEPA and FAO). The pollution studies showed that lead, cadmium and chromium contaminated the surface water samples. Sediment from all sites showed low to considerable contamination by the heavy metals. The human exposure risk assessment of the metals showed that the total hazard index was less than one which indicates no probable adverse health effect from the consumption of fish from the ponds, although, this case is different for Pb since there is no estimation of oral reference dose (RfDo) for lead according to EPA (2020).

Hazard Identification and Potential Risk Analysis of Toxic Metals in Redbelly Tilapia (Coptodon zillii) Consumed and Surface Water from the Niger Delta Estuary

“…Children are more susceptible to the toxic effects of heavy metals due to their developmental stage and lower body weight (Davies and Anyanwu, 2023). In other research findings in the Niger Delta region of Nigeria, similar levels of heavy metals have been reported in different fish species and other aquatic organisms (Okoye et al 2021;Abarshi et al, 2017;Ehiemere et al, 2022) (Emoyan et al, 2021;Iwegbue et al, 2021). These findings highlight the potential widespread pollution of water bodies in the region, which may pose a significant risk to human health.…”

A multi-criteria approach to drinking and irrigation water assessment of spring water in Igbo-Etiti, Nigeria

“…The quality of spring water can be altered by geochemical reactions, agricultural activities (Ehiemere et al 2022), saline water intrusion, improper waste disposal (Alum et al 2021), urbanization, and others that are classed as natural or anthropogenic (Akhtar et al 2014). Spring water quality monitoring on regular basis, most importantly in areas with a high risk of pollution, is paramount for the protection of the rural dweller's health especially in developing countries like Nigeria.…”

The EU Interreg Project “ADRINET”: Assessment of Well-Known and Emerging Pollutants in Seafood and Their Potential Effects for Food Safety

“…were thawed and oven-dried at 105 • C for 24 h to a constant weight. Subsequently, acid digestion of the mantle and gland of fish samples followed standard methods [21][22][23]. They were dried at 105 • C for 4 h and grounded into a fine powder using a mortar and pestle.…”