Masters Dissertations

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Browsing Masters Dissertations by Author "Ahmed, Kamaria Nasser"

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    An investigation on polycyclic aromatic hydrocarbons contamination in mangrove ecosystems of Zanzibar coastal areas
    (University of Dar es Salaam, 2015) Ahmed, Kamaria Nasser
    The objective of this study was to determine the extent of polycyclic aromatic hydrocarbons (PAHs) contamination in the mangrove ecosystems of Zanzibar coastal areas by identifying and quantifying the PAHs from crabs and adjacent sediments. Sediments and crabs from eight sampling sites were analysed by using eleven selected PAHs standards. Samples were extracted with dichloromethane by ultrasonication, cleaned-up using column chromatography and concentrated using rotary evaporator. GC/MS was used in the analysis of the samples. In general all eleven PAHs were detected in different levels of concentrations in both crabs and sediment samples. However, the concentrations of PAHs in crab samples were lower compared to those in sediments from their respective habitats. The total concentrations of PAHs in sediment samples were found to be higher compared to the total concentrations of the PAHs in crab samples. Total PAHs concentrations in crabs ranged from 1.70 to 28.66 ng/g fw, while the PAHs concentrations ranged from 20.14 to 81.94 ng/g dw in the sediments. Crabs from Wesha were observed to contain the highest concentrations of PAHs while the lowest concentrations were found in crabs from Jozani. The sediments from Kinazini were found to have the highest concentrations of PAHs, whereas the lowest concentrations were found in sediments from Ngezi. Results from this study demonstrated the existence of PAHs contamination in mangrove ecosystems of Zanzibar coastal areas, and it is recommended that PAHs contamination monitoring programme be established.