Multivariate Assessment of Metal Contamination in Mtoni Sedimentary Environment, Tanzania

Abstract

Enrichment factor, geo-accumulation factor, contamination factor, degree of contamination, modified degree of contamination and potential contamination index were applied to assess the contamination of metals (Al, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd and Pb ) in the Mtoni estuary sediments in Dar es Salaam, Tanzania. The sediment samples were sampled as appropriate, treated using established methods and analysed using inductively coupled plasma-high resonance mass spectrometry. The calculated enrichment factor values indicated contamination varying from minor (EF > 1) to severe contamination (EF > 50). The determined geo-accumulation index, contamination factor, degree of contamination, modified degree of contamination and potential contamination index values indicated severe contamination of all analysed metals in all the samples (Igeo > 5, CF > 6, DC > 48, mCd > 32 and PCI > 3). There is therefore, an urgent need to institute immediate mitigation measures to reduce the ecological, environmental and human risks taking into consideration that the anthropogenic activities, which are the main sources of these pollutants, are still going on in the area.

Keywords: Marine Sediments; Metal contamination; Pollution indices; Multivariate assessesment; Mtoni estuary