Application of Atomic Absorption Spectrophotometry in Monitoring Heavy Metal Pollution in the Chad Basin, Borno State

The Lake Chad Basin in North East Nigeria has experienced dramatic ecological transformation due to climate change and land use pressures, which have concentrated pollutants in residual water bodies and sediments and raised concerns about contamination of water resources relied upon by millions of people in Borno State. This study applied atomic absorption spectrophotometry to comprehensively monitor heavy metal distribution in water, sediment, and fish tissues from six sampling stations in the Nigerian sector of the Chad Basin. Samples were collected across wet and dry seasons. Sediment samples were digested with aqua regia, and biological samples underwent microwave-assisted acid digestion. Metals determined included chromium, cobalt, copper, iron, lead, manganese, nickel, and zinc. Lead concentrations in sediments ranged from 24 to 156 mg/kg dry weight, exceeding sediment quality guidelines at three stations. Fish tissue lead levels were 0.4 to 2.8 mg/kg wet weight, with the highest values in bottom-feeding species. Chromium and nickel were present in sediments at levels consistent with geogenic background contributions. Seasonal variability was significant, with higher metal concentrations in water during the dry season as a result of concentration effects. Bioaccumulation factors for lead and cadmium were above unity in all fish species. The findings provide a comprehensive heavy metal baseline for the Chad Basin and highlight priority pollutants requiring ongoing management attention as part of the Lake Chad Basin Commission's environmental restoration agenda.

Keywords: atomic absorption spectrophotometry, heavy metals, Lake Chad Basin, Borno State, sediment contamination