Distribution, source identification and potential ecological risk of heavy metals in surface sediments of the Mongla port area, Bangladesh

Abstract

This study comprehensively investigated the distribution, source identification, and potential ecological risk of heavy metals (As, Ni, Pb, Cd, Cr, Cu, and Zn) in surface sediments of the Mongla port area of Bangladesh. The sediment samples were collected from ten sampling points during the wet and dry season and heavy metals were analyzed by atomic absorption spectrophotometer. The average concentration of heavy metal in sediments was higher during the dry season (11.36 to 118.55 mg/kg) as compared with the wet season (8.70 to 88.58 mg/kg). Certain indices, including the enrichment factor, geoaccumulation index, and contamination factor demonstrated that Cd was highly responsible for sediment pollution. The range of pollution load index values was 1.12 to 1.55 during wet and 1.59 to 2.27 during the dry season, indicating progressive deterioration of sediments by studied heavy metals. Multivariate principal component analysis showed that the source of As, Cd, Cr, Ni, Cu and, Zn in the port area surface sediment mainly due to anthropogenic activities. Considering the potential ecological risk, surface sediments of the Mongla port area showed moderate to considerable ecological risk. Potential acute toxicity results in most of the sampling points during the dry season was greater than 4, shows moderate to the severe toxicity of heavy metals in sediment. Further studies to assess the widespread risk of heavy metals are recommended to protect the aquatic ecosystem from heavy metal contamination.