Enrichment of heavy metals as function of salinity and pH of estuarine sediments, South East Coast of India

Abstract

A predictive model was developed to determine the combined effect of salinity and pH on sediments enrichment of heavy metals; (EF) of Zn, Pb, Cu, and Ni in Uppanar estuary, India. Data covered four seasons of 2008–2009 and 2009–2010, and corresponded to fivestations scattered along Uppanar estuary. Salinity, pH, EFZn, EFPb, EFCu and EFNi were 17.85 ± 9.46, 7.62 ± 0.35, 9.51 ± 2.01, 3.54 ± 1.96, 10.85 ± 1.97, and 0.70 ± 0.20, respectively. For each metal, we fitted a regression model with EF as response, and the interaction between salinity and pH as predictor. We found that the interaction of salinity and pH predicts EFPb (F3,36 = 9.03, P < 0.001) and EFNi (F3,36 = 3.22, P = 0.034). Specifically, salinity and pH were positively associated with EFPb and negatively associated with EFNi. We found no significant effect of salinity and pH interaction on EFZn (F3,36 = 2.56, P = 0.069) and EFCu (F3,36 = 1.68, P = 0.188). We conclude that a joint effect of salinity and pH on EF varies with heavy metals species, and when significant, takes a different pattern depending on the predominant geochemical phase and source of heavy metals

Keywords

• heavy metals
• enrichment factor
• ph
• salinity
• interaction