HR: 1340h
AN: A33D-1548    [Abstracts]
TI: Particulate and Gaseous Species in fog and Clear air in Highly Polluted Urban Region of South Asia
AU: * Farhana, B
EM: bkf01@health.state.ny.us
AF: Wadsworth Center, New York State Department of Health, Albany, NY 12201, United States
AU: Husain, L
EM: lhusain@albany.edu
AF: Wadsworth Center, New York State Department of Health, Albany, NY 12201, United States
AU: Husain, L
EM: lhusain@albany.edu
AF: Department of Environmental Health Sciences, School of Public Health, State University of NY, Albany, NY 12201, United States
AB: An extensive study of PM2.5 composition was conducted in Lahore, Pakistan during winter of 2005-2006 that included both clear air and periods of fog. We deployed a low-volume sampler connected with an annular denuder system, which consisted of two diffusion denuders and a filter pack consisting of Teflon and nylon filters in series, to sample acidic gases, ammonia, and PM2.5. Teflon filter samples were used to determine PM2.5 mass, anions (F^-, BrO₃^-, Cl^-, NO₂^-, Br^-, NO₃^-, SO₄^2- and C₂O₄^2-), cations (Na⁺, NH₄⁺, K⁺, Mg²⁺ and Ca²⁺) and elements (Be, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Sr, Mo, Ag, Cd, Sn, Sb, Ba, Tl and Pb). Denuder samples were used to measure selected gaseous species; HCl, HONO, HNO₃, SO₂ and NH₃. Exceedingly high concentrations of all species, relative to major urban areas of US and Europe, were observed. Mean concentrations of the PM2.5 mass, Pb, HONO and NH₃ were 191, 96, 19.6 and 50 μg m^-3, respectively, which are exceptionally high even at the polluted atmospheric context. Concentrations of most species showed a distinct diurnal variation. Mixing heights, sun index and wind speed played a major role in defining the diurnal pattern. Our data showed a distinct enhancement in the oxidation of SO₂ with duration of fog. We use air parcel back trajectories, intercomponent relationships and meteorological observations to explain the sources and the impacts of fog chemistry and mixing heights on atmospheric processing of the chemical constituents. Aerosols were found to carry the signatures of emissions from coal and oil combustion, industrial processes, construction activities and biomass burning in North and Central Pakistan, North India and West Afghanistan, in addition to the local pollution sources. Source apportionment based on positive matrix factorization is in progress. Findings of our study will improve the understanding of the critical roles and interactions between chemical composition and size of atmospheric particles, atmospheric boundary layer and meteorological phenomena that manipulate the chemistry of an urban atmosphere.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 4801 Aerosols (0305, 4906)
DE: 4906 Aerosols (0305, 4801)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting