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List of Abstracts 199December 2008-January 2009 over BoB to understand the mass concentration and chemical composition ofaerosols. Aerosol mass loading as well as that of various chemical constituents showed distinct spatialvariation over BoB and AS. Aerosol mass concentration is found to be high during winter period. While theeffect of advection from nearby landmass is more pronounced over BoB, the wind-induced sea saltproduction is found to be more significant over Arabian Sea during premonsoon. The total aerosol massconcentration as well as the concentration of individual chemical components showed enhancement over thenorthern BoB due to advection of continental aerosols from Indo Gangetic Plains as revealed by thechemical composition of aerosols and the airmass back trajectories. Based on these measurements meanchemical models are evolved for both the oceanic regions. While the sea-salt aerosols contributed ~31% ofthe aerosols mass over AS, it was ~11% over BoB. Abundance of nss-SO4 has been observed over both theoceanic environments, with higher concentration over BoB, revealing significant anthropogenic influence.Mineral dust contribution is fairly uniform in both these oceanic environments. These models have beencompared with those obtained from previous campaigns over Indian land mass and oceanic regions.P-Observations 2.66 ID:4418 10:30Atmospheric pollution in Dakar: focus on aerosols in the frame of the POLCA programEl Hadji Thierno Doumbia 1 , Catherine Liousse 1 , Ababacar Ndiaye 2 , Corinne Galy-Lacaux 1 , BabacarDiop 3 , Véronique Yoboué 4 , Luc Sigha 5 , Eric Gardrat 1 , Pierre Castera 1 , Cyril Zouiten 61 laboratoire d'aérologie2 university of dakar, Senegal3 university of bamako, Mali4 university of abidjan, ivory coast5 university of yaoundé6 Laboratoire des Mécanismes et Transferts en Géologie, Toulouse, FranceContact: doueh@aero.obs-mip.frBlack carbon (BC) were measured from April 2008 to July 2009 at 2-mn intervals using a seven-wavelengthAethalometer at an urban site in Dakar (Senegal), within the framework of the POLCA program (Frenchacronym for ''POLlution des Capitales Africaines''). Daily mean [BC] values varied from about 1000 to20000 ng m-3. However, short-term spikes exceeding 50000 ng m-3 were commonly observed, mainlyoccurring during the morning and evening rush-hour periods, suggesting the paramount role of traffic. BCvalues were highest from November to April (13000 ng m-3) and lowest from May to August (6000 ng m-3). Diurnal, seasonal, and mondays to Thursdays/Fridays/saturdays and sundays trends are discussed.Differences in BC diurnal variations in Dakar and Bamako (two POLCA sites) reveal that BC sourcesstrongly vary at regional scale. It appears that BC levels in Dakar were lower than at other West Africancapitals (e.g. Bamako), but comparable to reported values for European and Asian mega-cities. BCconcentrations, as measured by Aethalometer, is comparable with measured BC on filters using a DRIanalyzer (thermo-optical method), though consistently about 1.8 times higher. Using Al content of aerosols,Bowen ratio (Bowen, 1966) and other aerosol chemical contents (Galy et al., 2007), we have reconstructedPM2.5 mass concentrations in Dakar. Average PM2.5 mass concentrations for the study period from 16November 2007 to 11 February 2008 were 29 µg m-3, well above the WHO threshold of 10 µg m-3. Thispaper clearly highlights high pollution levels in African large cities with ensuing important impacts onpopulation health. More detailed results will be issued from the intensive POLCA campaigns.P-Observations 2.67 ID:4498 10:30Distributions and diurnal variations of dicarboxylic acids and related compounds in suburbanaerosols collected at Mangshan, northern ChinaNannan He 1 , Kimitaka Kawamura 2iCACGP-IGAC 2010 14 July, 2010