Ecological risk assessments of heavy metals in polluted drainage sediments from the Malacca Industrial Area and the Malacca River, Malaysia

The surface sediment of drainages of Malacca Industrial Area (MIA) and Malacca River were analysed for Cd, Cu, Fe, Ni, Pb, and Zn. The order of non-resistant (NR) of the metals was Zn (82.3%) > Cd (72.1%) > Ni (66.1%) > Cu (60.4%) > Pb (54.6%)> Fe (19.3%). This indicated that Cd, Ni, Pb, Cu and Zn were the most prevalent metals in the NR fractions. The ranges of total metal concentrations (mg/kg dry weight) were 1.88-7.01 for Cd, 18.9-1689 for Cu, 26.0-850 for Ni, 56.5-307 for Pb, and 75.4-312 for Zn while for Fe, it ranged from 1.76 to 6.15%. Based on ecological risk assessment and geochemical fractions, it was concluded that sites at 1 (drainage at Power Weld), 4 (Malacca River-2) and 7 (drainage at Omega) were polluted by heavy metals. Based on potential ecological risk index (PERI), sites 1 and 7 were also categorized as 'considerable ecological risk'. Therefore, it was evidently shown that elevated levels of heavy metals in the drainages at MIA and Malacca River sediment were most probably attributed to untreated (or incomplete treatment of) industrial effluents. Therefore, future mitigation of the heavy metal pollution at the study areas should be given priority in future sustainable developmental programs.