Geochemistry pollution status and ecotoxicological risk assessment of heavy metals in the Pahang River sediment after the high magnitude of flood event

The present work is aimed at assessing the aftermath effects of the 2014 flood tragedy on the distribution, pollution status and ecological risks of the heavy metals deposited in the surface river sediment. A series of environmental pollution indexes, specifically the enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), modified degree of contamination (mCd), pollution load index (PLI), potential ecological risk index (PERI) and sediment quality guidelines (SQGs) have been adopted. Results revealed that the freshly deposited sediments collected soon after the flood event were dominated by Cu, Fe, Pb, Ni, Zn, Cr and Cd, with the average concentrations of 38.74, 16,892, 17.71, 4.65, 29.22, 42.36 and 0.29 mg/kg, respectively. According to the heavy metal pollution indexes, Pahang River sediments were moderately to severely contaminated with Pb, Ni, Cu, Zn and Cr, while Cd with the highest risk of 91.09 was the predominant element that illustrated an aesthetic ecological risk to the water body after the tragic flood event. The findings highlighted a critical deterioration of the heavy metals content, driven by the catastrophic flood event, which has drastically altered their geochemical cycles, sedimentary pollution status and biochemical balance of the river's environment. HIGHLIGHTS The 2014 flood has been recognized as the most severe tragedy in the history of Malaysia for the past 30 years.; Heavy metal pollution and sediment geochemical profile of Pahang River were analyzed.; A series of geochemical pollution indexes, including enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), modified degree of contamination (mCd), and pollution load index (PLI) were thoroughly evaluated.; The synergistic ecotoxicological risks in relation to sediment quality were studied using comprehensive potential ecological risk index (PERI) and consensus-based sediments quality guidelines (SQGs).; Establishment of a reliable reference on the sedimentology, geochemistry, pollution status and ecological risk assessments under different environmental settings for future protection, restoration or rehabilitation of the river system after the flood tragedy.