Atmospheric Concentrations of Polycyclic Aromatic Hydrocarbons in the Watershed of Lake Victoria, East Africa

摘要

In the first study of its kind in Africa, PAHs were measured in high volume (24 h) air samples collected from two sampling stations, at Kakira and Entebbe (KAK and EBB, respectively) within the Lake Victoria watershed in Uganda, to assess source contributions and generate a baseline reference data set for future studies in the East African region. Sampling was conducted over two periods [2000-2004 (KAK and EBB1) and 2008-2010 (EBB2)]. The samples were extracted by accelerated solvent extraction and analyzed for 30 PAHs by GC-MS. The mean total PAH concentrations (ng/m~3) were found to be 74.3 (range; 19.3-311, N = 39) for KAK, S6.8 (range; 13.3-126, N = 22) for EBB1 and 33.1 (range; 4.91-108, N = 56) for EBB2. The 3-ringed PAHs were the most predominant group with mean concentrations of 35.9 ng/ m~3(EBBl), 30.5 ng/m~3(KAK) and 23.2 ng/m~3(EBB2). Naphthalene had an exceptionally high mean concentration (21.9 ng/m~3) for KAK compared to 0.44 and 0.39 ng/m~3 in EBB1 and EBB2 respectively, likely due to intensive agricultural operations nearby KAK. Principal component and diagnostic ratio analyses showed that the measured levels of PAHs were associated with mixed sources, combustion of petroleum, and biomass being the major sources.