Keith Bein - Speciation of size-resolved individual ultrafine particles in Pittsburgh, Pennsylvania

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      Publication Details (including relevant citation   information):

      Bein, K.J., Zhao, Y., Wexler, A.S., and M.V. Johnston (2005),   Speciation of size-

      resolved individual ultrafine particles in Pittsburgh,   Pennsylvania, J.   Geophys.

      Res., 110, D07S05,   doi:10.1029/2004JD004708.

      Abstract:

      Approximately 236,000 single particle mass spectra were collected   throughout the duration of the Pittsburgh Supersite experiment   using RSMS-3, a third generation single particle mass   spectrometer.  The instrument was operated semi-continuously   for 306 days, sampling particles with aerodynamic diameters in   the range of 30 – 1100 nm and collecting both positive and   negative ion spectra, particle size and time of detection for   each particle measured.  The entire data set has been fully   processed and analyzed.  Spectra have been clustered into 20   distinct particle classes based on the distribution of their   positive ion mass peaks.  Negative ion spectra were   classified independently within each positive ion class.    Frequency of occurrence versus particle size, month of the year   and wind direction has also been calculated for the full data   set, as well as within each class.  Results indicate a rich   array of multi-component ultrafine particles composed primarily   of carbon and ammonium nitrate.  Approximately 54% of all   the particles measured fell into the carbonaceous ammonium   nitrate (CAN) class.  These particles were observed in all   size bins and from most wind directions for the entirety of this   study.  Ubiquitous sources throughout the area, including   vehicular emissions and secondary organic aerosol formation, are   considered to be responsible for a larger fraction of these   particles.  In terms of particle number, metal containing   aerosol dominated the remainder of the particle classes   identified.  These particles were rich in K+,   Na+, Fe+, Pb+, and to a lesser   extent, Ga+ and Zn+.  They tended to   be smaller in size and were highly correlated with specific wind   directions, facilitating the isolation of specific sources.

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