| Popis: |
Heavy metals are notable chemicals that threaten river ecosystems and freshwater supplies from surface waters. The levels of some heavy metals-Mn, Fe, Zn, Pb, Cu, Cr and As-in Cross River were monitored over twelve months in 2018 to establish the pollution status and potability of the river. Water and sediment samples were collected from three stations of the river and analysed according to standard procedures. The result reveals that the heavy metals detected in the surface water and bottom sediment of the river showed temporal patterns of variation. The decreasing order of heavy metal concentration in the water was Fe > As > Pb > Zn > Mn > Cr > Cu, while that of the sediment was Fe > Mn > Zn > Pb > As > Cr > Cu. The bottom sediment was observed to contain higher concentrations of heavy metals than the surface water, signifying the accumulation of these chemicals in the bottom sediment. Fe, Pb, As and Cr in the surface water correlated significantly (p < 0.05) and positively with their respective type in the bottom sediment. Most of the heavy metals (Fe, Mn, Pb, As and Cr) were detected at higher levels above the SON, WHO, EU and USEPA permissible limits, hence, the water was polluted with these metals and that made the potability of the river objectionable. |
