Seasonality of surface water contamination by heavy metals in the lower Enyong creek, s.e. Nigeria)

Surface water samples from three locations in the Lower Enyong Creek, S.E. Nigeria were sampled over six months i.e June to October (wet season) and November in dry season for heavy metals such as Cd, Mn, Fe, Cu, Ni, Pb, Zn, Cr) using Atomic absorption spectroscopic method. Some specific physicochemical characteristics, such as temperature, hardness, alkalinity, salinity, TDS, TSS, pH and conductivity which are known to influence the interactions and dynamics of trace metal loads in water bodies were also determined. The result of the analysis indicated significant monthly variation of these parameters for the six months. Monthly summary statistics revealed a few seasonal patterns that echoed the hydrologic regime. During the short dry season in August–September period, all the sampled stream channels had lower levels of Cd, Ni, Zn, Cu Cr, Pb and Fe. Salinity, for instance, correlated strongly (p<0.05) with Cu (0.70); Cr (0.56); Ni (0.72); nitrate (0.61) and Na (0.49). However, the concentrations of most heavy metals were low, while Zn content was higher than the WHO standard for surface water which indicated significant contamination by Zn in the water body.