Black carbon aerosols in urban air in South Asia |
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Authors: | Vincent A. Dutkiewicz Sofia Alvi Badar M. Ghauri M. Iqbal Choudhary Liaquat Husain |
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Affiliation: | 1. Wadsworth Center, New York State Department of Health, Albany, NY 12201-0509, USA;2. Department of Environmental Health Sciences, School of Public Health, State University of New York, Albany, NY 12201-0509, USA;3. HEJ Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi-75270, Pakistan;4. PCSIR Laboratories Complex Karachi, Off University Road, Karachi 75280, Pakistan;5. SUPARCO, Division of Space and Environment, PO Box 8402, University Road, Karachi, Pakistan;1. Department of Physics, University of Peshawar, Khyber Pakhtunkhwa, Pakistan;2. Department of Space Science, Institute of Space Technology, Islamabad, Pakistan;3. Department of Geoinformatics – Z_GIS, University of Salzburg, Hellbrunnerstrasse 34, Salzburg 5020, Austria;1. Atmospheric Composition Research, Finnish Meteorological Institute, P.O. Box 503, FI-00101, Helsinki, Finland;2. Helsinki Region Environmental Services Authority, P.O. Box 100, FI-00066 HSY, Helsinki, Finland;3. Department of Technology, Metropolia University of Applied Sciences, P.O. Box 4021, FI-00180, Helsinki, Finland;4. Aerosol Physics, Faculty of Natural Sciences, Tampere University of Technology, P.O. Box 692, FI-33720, Tampere, Finland |
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Abstract: | We report data from a yearlong (2006–2007) study of black carbon concentrations ([BC]) measured at 5-min intervals with an Aethalometer in Karachi, Pakistan. Daily mean [BC] varied from about 1 to 15 μg m?3. However, short-term spikes exceeding 40 μg m?3 were common, occurring primarily during the morning and evening rush-hour periods. The [BC] values were highest during November through February, ~10 μg m?3, and lowest during June through September, ~2 μg m?3. Diurnal, seasonal, and day-of-the-week trends are discussed. It is demonstrated that these trends are strongly affected by meteorological patterns. A simple expression is applied to the concentration profiles to separate the effects of meteorological conditions and elucidate the underlying emissions patterns. Daily emissions varied from 14,000 to 22,000 kg of BC per day. When integrated over the year emissions for Karachi Proper were estimated at 6.7 kilometric tons per year and emissions for greater Karachi were 17.5 kilometric tons per year. Folding in the populations of each area yields BC emissions of 0.74 and 1.1 kg per person per year, respectively. Applying the model to previously collected data at Lahore, Pakistan yields emissions during November–January that are around a factor of two higher than those in Karachi, but because the BC measurements in Lahore covered only three months, no estimates of annual emissions were attempted. Given the large populations of these cities the local health impact from PM alone is expected to be severe but because of the high [BC] emissions the impact on the global climate may be equally significant. |
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