Coastal Marine Pollution in Dar es Salaam (Tanzania) relative to Recommended Environmental Quality Targets for the Western Indian Ocean

Abstract

Pollution surveys were undertaken during 2007 and 2008 in the coastal marine environment of Dar es Salaam and the remote Ras Dege Creek. The objective was to determine the levels of microbial contamination, heavy metals and persistent organic pollutants and compare these with the recommended environmental quality targets (EQTs) for the West Indian Ocean (WIO). Levels of microbial pollution in urban coastal waters off Dar es Salaam were excessive, indicating that water within the port channel was not safe for contact recreation. Seafood from areas adjacent to Msimbazi Creek and the Ocean Road sewer outfall was unfit for human consumption. Conversely, the water quality of Ras Dege Creek was excellent for contact recreation as well as for the collection of seafood. Concentrations of heavy metals, even in the coastal marine environment off Dar es Salaam, were not significantly high compared with the recommended EQTs. Although some persistent organic pollutants exceeded the recommended EQTs in sediment and oysters along the coast of Dar es Salaam, this was not the case at Ras Dege. The lack of sufficient wastewater treatment facilities is the main cause of current levels of some pollution in the coastal marine environment off Dar es Salaam. The implementation of industrial and municipal wastewater management would greatly improve this situation. The results show that the proposed EQTs would constitute appropriate standards for coastal marine water quality in Tanzania.

Keywords: Dar es Salaam, environmental quality targets, heavy metals, marine pollution, microbial pollution, persistent organic pollutants.