A comparative study of atomic absorption spectrophotometry and anodic stripping voltammetry for the determination of trace metals Zn, Cd, Pb and Cu in coastal waters of Visakhapatnam, east coast of India

Abstract

Concentration levels of some of the dissolved trace metals like Zn, .Cd, Pb and Cu have been determined in the coastal waters along three transects (Gangavaram, Harbour and Rushi hill) near Visakhapatnam. Estimations, made by anodic stripping voltammetry in the present study are in good agreement with the reported values by atomic absorption spectrophotometry. Vertical distribution of dissolved Zn, Cd and Cu showed an increasing trend from the surface waters to bottom. Surface depletion and bottom enrichment of these elements resembling those of the distribution pattern of nutrients are attributed to their involvement in bio-geochemical cycles. Dissolved Pb showed enrichment in surface compared to bottom waters indicating anthropogenic input. Dissolved Zn, Cd and Cu showed significant positive correlations among

<span style="font-size:14.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:"times="" roman";color:black;mso-ansi-language:en-in;="" mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">themselves and with nutrients indicating their common association and source of occurrence. The atomic ratios of Zn to Si and Cd to N were found to be higher while, that of Cd to P was lower when compared with those of the offshore waters of the Bay of Bengal. This was attributed to the differences in the biological uptake of these metals.</span>