Physio-chemical characteristics and 1-year monitoring of heavy metal pollution and its seasonal variation in seawater of Cape Town harbour, South Africa

Abstract

A 1-year monitoring of priority heavy metals As, Cd, Hg, Pb and Sn in seawater from Cape Town harbour, South Africa with respect to their seasonal variations and their pollution levels were studied. The concentrations of heavy metals were determined using ICP-MS analysis. In addition, the physicochemical parameters, such as pH, temperature, total dissolved solids and conductivity, were measured with a view to obtain a baseline or bankable data of their levels, and to access the seawater quality. High significant variation (P ≤0.05) was observed for all metals between seasons and across locations. Seasonal variations of heavy metals showed that Sn and Cd are more prevalent during summer while Hg, Pb and As are more prevalent during winter season. According to EEC and ANZECC guidelines, the values recorded for Cd across all locations were within the permissible limit for aquatic life. Accord-ing to WHO, EPA, TSE 266 guidelines for Pb in seawater, the concentration values recorded in locations 1, 3, 5, 6, 9 and 10 were more than the permissible value (10 µg/L). High values of heavy metals recorded could be due to anthropogenic and natural sources.