Polycyclic aromatic hydrocarbons (pahs) contamination of surface water, sediment and fish of Dar es salaam nearshore area, Tanzania

Polycyclic aromatic hydrocarbons contamination along the coast of major and/or fast growing cities like Dar es Salaam is coming to an alarming level in different parts of the world. High levels of PAHs had already been reported in sediments along the nearshore area of Dar es Salaam coast but information on the PAHs levels in fish tissues and water columns was still limited. This study therefore, analyzed for 10 polycyclic aromatic hydrocarbons (PAHs) namely Naphthalene, Benz[a]anthracene, Acenaphthylene, Benzo[K]fluoranthene, Fluorine, Phenanthrene, Benz[b]fluoranthene, Benzo[j]fluoranthene, Indeno[1,2,3-cd]pyrene and Dibenz[a,h]anthracene in surface sediments, water and fish samples from Dar es Salaam nearshore area using GC-MS. Higher concentrations were observed in sediments as compared to water and fish while the harbour and Mtoni estuary showed relatively higher concentrations than the other sub sites in all samples for sediments, water and fish. Concentration of PAHs in sediment samples ranged from 139.14 ± 58.59 ng/g of dry weight at Kunduchi to 1849.8 ± 67.25 ng/g of dry weight at the Harbour area. In water samples concentrations ranged from1.06 ± 0.09 ng/ml to 21.93 ± 3.15 ng/ml and 36.89 ± 12.21 ng/g of dry weight to 295.94 ± 33.1 ng/g of dry weight in fish samples at Kunduchi and the Harbour respectively. As observed, PAHs levels in water were generally low but fish seem to have accumulated a significant amount of the pollutants. The study’s results therefore call for an immediate control of pollutants entering the sea through various routes such as boating activities, shipping operations and input through rivers and creeks.