Identification of sources and estimation of emission profiles from highly time-resolved pollutant measurements in Tampa, FL

摘要

Aerosol slurry samples were collected at 30-min intervals for sequential 1-month periods at each of two sites (Sydney and "Dairy") in the Tampa Bay area during the 2002 Bay Regional Atmospheric Chemistry Experiment using the University of Maryland Semicontinuous Elements in Aerosol Sampler-Ⅱ (SEAS-Ⅱ). More than 500 samples, believed to be affected by plumes from local utility and industrial sources, were selected for electrothermal atomic absorption spectrophotometric analyses for elemental markers (Al, Fe, Cr, Cu, Mn, Pb, Se, As, Ni, Zn and Cd) based on excursions in SO_2 and NO_x measurements. Correlation of short-term excursions in metals and SO_2, and surface wind directions observed between May 23 and 26th, 2002, revealed the influence of an animal feed supplements production facility (AFS), 17 km upwind at a station angle of 81°, for which emissions had not previously been detected by standard monitoring methods. Emission "profiles" for this source were developed, separately, from the time series data and by using principle components analysis (PCA) and positive matrix factorization (PMF). In addition, a local dust component was evident in Al and Fe concentration profiles during periods of elevated wind speeds and was resolved by PCA/PMF. Similarly, large but brief 1.5-h excursions in Zn (maximum, 403 ng m~(-3)), Cd, and Pb on May 17th were correlated with winds from the direction of an incinerator (station angle, 250°) 17 km from Sydney. Lastly, large excursions in As concentrations (maximum, 86 ng m~(-3)) observed (May 4th and 5th at Sydney and November 2nd and 3rd at the Dairy) were used to locate previously unrecognized sources, tentatively associated with combustion/production of pressure-treated lumber. Profiles developed directly from the time series data were in the range of those derived from PCA-PMF (AFS); and those for the incinerator, with previously published values.