Determination of Arsenic and Mercury Levels in Selected Fish Species from the Niger Delta, Bayelsa State

Arsenic and mercury are highly toxic elements that accumulate in aquatic organisms, posing serious health risks to communities that depend on fish as their primary protein source. In the Niger Delta, chronic hydrocarbon pollution and industrial discharges have raised concerns about the accumulation of toxic elements in commercially harvested fish species. This study determined arsenic and mercury concentrations in three fish species, namely Chrysichthys nigrodigitatus, Clarias gariepinus, and Tilapia zillii, collected from Brass Creek in Bayelsa State. Samples were collected from artisanal fishers at three landing sites. Mercury was determined by cold-vapour atomic absorption spectrophotometry after acid digestion, while arsenic was measured by hydride generation atomic absorption spectrophotometry. Mercury concentrations ranged from 0.08 to 0.62 mg/kg wet weight, with Chrysichthys nigrodigitatus recording the highest values. The WHO and EU maximum permissible level of 0.5 mg/kg was exceeded in fourteen percent of Chrysichthys nigrodigitatus samples. Arsenic concentrations ranged from 0.14 to 1.84 mg/kg, with 28 percent of samples exceeding the EU regulatory limit of 1.0 mg/kg for fish. No significant difference in elemental concentrations between wet and dry season samples was observed. These findings raise serious food safety concerns for communities relying on fish from Bayelsa creeks and call for expanded monitoring, source tracking, and community health education regarding consumption frequency guidelines for fish from potentially contaminated water bodies.

Keywords: arsenic, mercury, fish contamination, Niger Delta, Bayelsa State