In the present investigation concentrations of Cr, As, Cd and
Pb were higher than the safe recommended values, which suggested
that the river Korotoa is polluted by heavy metals and might
create an adverse effect on this riverine ecosystem. The overall
pollution load was significantly higher in winter than in summer.
The contamination factor (CF), geoaccumulation index (Igeo) and
enrichment factor (EF) revealed that sediments in this study were
considerably polluted by Cd and Pb and moderately polluted by
other metals. This study suggested that chemical fractionation of
sediments should be considered to provide more accurate appraisal
of the risk of heavy metals in aquatic ecosystems.