Baseline study of heavy metal contamination in the Sangu River estuary, Chattogram, Bangladesh

Sediment samples were collected from twelve selected sites of the Sangu River estuary and seven metals (As, Cr, Cu, Cd, Pb, Ni, Zn) were analyzed with Inductively Coupled Plasma-mass Spectrometry (ICP-MS) to assess the contamination degree of heavy metals in the Sangu River estuary and to represent it as a reference site. This study revealed the descending order of studied metals (mg/kg) observed in sediment as Zn (88.97 +/- 58.97) > Ni (32.75 +/- 16.09) > Cu (29.2 +/- 10.78) > Cr (25.14 +/- 5.20) > Pb (19.57 +/- 7.01) > As (2.58 +/- 2.55). Cadmium was observed below the detection level. Various indices like geo-accumulation index (I-geo), contamination factor (CF), pollution load index (PLI) suggested that the Sangu River estuary is not contaminated by studied metals excepting Pb. PCA and correlation matrix analysis indicates that Pb and Zn may have anthropogenic sources and As, Ni, Zn, Cu, Cr may come from natural sources.