This study was aim to determined the levels of some heavy metals in the gills, liver, stomach, kidney, bones and flesh of four fish species (Tilapia zilli, Clarias anguillaris, Synodentis budgetti and Oreochronmis niloticus) collected at River Benue in Vinikilang, Adamawa State, Nigeria for analysis of Cu, Zn, Co, Mn, Fe, Cr, Cd, Ni and Pb. These metals were chosen because at higher concentrations there might be toxic to the fish and by extension humans that depends on such fish as food. The concentrations of the metals were carried out using Flame Atomic Absorption Spectrophotometer (AAS, Unicam 969). Large differences in trace metal concentrations were observed between different tissues within each fish. The highest concentration of Fe (12.65 µg/g) was recorded in gill of Synodentis budgetti, while the lowest value of 0.68 µg/g was recorded in the flesh of Oreochronmis niloticus. The liver of Synodentis budgetti accumulates significant higher levels of Mn and Cd than other species; Fe and Zn was highest in the stomach of Tilapia zilli, while Clarias angullaris shows more of Cr, Pb, Cd and Co. The stomach of Synodentis budgetti accumulate significant higher levels of Fe than other species; Zn was highest in the stomach of Tilapia zilli, while Clarias angullaris shows more of Mn, Cr, Cu, Cd and Pb. Similarly, the bone of Synodentis budgetti accumulates significant higher levels of Mn and Cd than other species; Zn and Fe were highest in the bone of Tilapia zilli, while Clarias angullaris shows more of Cr, Pb, Ni, and Co. The highest levels of Fe (12.65 µg/g) observed in this study was recorded in the gill of Synodentis budgetti and it was below the high residue concentrations of Fe (34 -107 ppm) in fish samples. Based on the above results, it can therefore be concluded that metals bioaccumulation in the entire fish species study did not exceeds the permissible limits set for heavy metals by FAO, FEPA and WHO.

Abstract:The concentrations of some heavy metals and anions were determined in vegetable samples (spinach (Amaranth caudatus), lettuce (lactuca sativa), Cabbage (Brassica olemcea) and Onion (Allium cepa) which were freshly harvested within four agricultural locations(Mirnga, Zira, Wangaga and Malang) in Biu Local Government Area, Borno State, Nigeria. Metal concentrations in the vegetable samples were determined using Atomic Absorption Spectroscopy (AAS), while anions were determined by Smart spectrophotometer (model 2000). The results for vegetable samples showed that leaves contained much higher concentrations of heavy metals and anions than roots and stems.The concentrations of Cr detected in the vegetable samples ranged from 0.23 to 3.22mg/kg; 0.23 to 3.43mg/kg Mn; 0.23 to 3.45mg/kg Fe; 0.21 to 3.54mg/kg Ni; 0.25 to 4.56mg/kg Pb; 0.87 to 8.34mg/kg Zn; 0.34 to 5.44mg/kg Cd and 0.21 to 3.22mg/kg Cu. These valueswere higher than those recommended by Food and Agricultural Organization (FAO) and the WHO/EU joint limits. The high levels of these heavy metals place the consumers of these vegetable crops grown within the study area at health risk with time unless an urgent step is taken by relevant agencies to address this issue.