Trace Metal Contamination in Urban Sediments in Port Louis, Mauritius

The aim of this study was to assess Cu, Pb and Zn contamination in estuarine and urban sediments along Grand River North West (GRNW) during 2009-2013. Pb and Zn were significantly higher in the GRNW estuary though unleaded petrol was introduced since 2002. In fact, the potential sources of Cu, Pb and Zn in the urban estuarine sediments at GRNW were considered to arise from brakedust, road runoff and galvanized road furniture causing significant quantities to be trapped in coastal sediments with increasing vehicles. The mean concentration of Pb and Zn in the urban sediments along GRNW were however still below the limits of 700 and 2500 mg kg -1 quoted for contaminated sediments adopted from the draft standards (24% clay and 10% organic matter by weight) from Netherlands. The concentration of Cu, Pb and Zn were also greatest in the more urbanised lower reaches of the Grand River Bay. Pb remained significantly positively correlated with Zn indicating that the cycling of Pb and Zn were linked indicating a common traffic related source for Pb and Zn in the urban sediments in GRNW. Pb was significantly lower at 5% significance level upstream, downstream, estuary during summer 2013 compared to summer 2010 and could be due to floods which occurred in summer 2013. Cu was also significantly positively correlated with Pb confirming the traffic related common source (brakedust and vehicle emissions) in the urban sediments of GRNW.