Ecological and human health risk assessment of heavy metal in sediment and demersal marine fish in Gulf of Guinea western offshore Nigeria

Abstract

This study was focused to assess contamination status of heavy metals in sediments, and human health risk associated with fish consumption from western Nigerian offshore in the Gulf of Guinea. Fish stock assessments were carried out across five fishing grounds. Triplicate samples of demersal marine fish species and sediments were collected and analysed for heavy metals (mercury- Hg, cadmium- Cd, lead- Pb and Arsenic- As) by ICP-OES (inductively coupled plasma optical emission spectrometry) using US EPA 200.7 standard method. The geospatial variation of As and Hg revealed that the concentrations were relatively highest at station 1, while Cd and lead Pb concentrations were highest at station 3. Levels of heavy metal in sediment fell below sediment quality guidelines (SQG). While, metal concentrations (As, Cd, Hg and Pb) in demersal marine fish also fell within the permissible levels of FAO/WHO. The ecological indices [Probable contamination index (PCI), mean effect level quotients, newly modified hazard quotient and Hazard quotient (HQ)] indicated low contamination level of heavy metals in sediment. Hazard index (HI) of metals in fish species associated with human health were within recommended threshold of 1 and thus revealed that there would be no significant health risk to the consumers. Percentage of total variance for PC1 is 52.26% whereas PC2 is 27.56% showed weak loading of metals. The study established scientific basis for assessment of metal contamination and risk management of food safety within the western Nigerian offshore waters.