Comparison of heavy metal contamination during the last decade along the coastal sediment of Pakistan: Multiple pollution indices approach

•Comparative metal contamination was investigated in sediment with special reference to time and space.•The concentrations of Ni, Cr and Cd showed a significant increase during the last decade.•Adverse biological effects to benthic fauna, mainly caused by Ni, Cd, Pb, Cu and Cr•Extremely high enrichments of Cd (176) and Pb (108) were detected in sediments.•The potential ecological risk of metals moved towards higher levels during the last decade.

Heavy metals concentrations (Fe, Cu, Zn, Ni, Cr, Co, Pb, and Cd) were scrutinized during two monitoring years (2001 and 2011) in the coastal sediment of Pakistan. The status of metal contamination in coastal sediment was interpreted using sediment quality guidelines, and single and combined metal pollution indices. Ni, Cr, and Cd were recognized for their significant (p < 0.05) intensification in the sediment during the last decade. Sediment quality guidelines recognized the frequent adverse biological effect of Ni and the occasional adverse biological effect of Cu, Cr, Pb and Cd. Single metal pollution indices (Igeo, EF, CF, and ER) revealed that sediment pollution is predominantly caused by Pb and Cd. Low to moderate contamination was appraised along the coast by multi-metal pollution indices (CD and PERI). Correlation study specifies that heavy metals were presented diverse affiliations and carriers for distribution in the sediment during the last decade.