Articles | Volume 7, issue 7
Atmos. Meas. Tech., 7, 1929–1941, 2014
Atmos. Meas. Tech., 7, 1929–1941, 2014

Research article 02 Jul 2014

Research article | 02 Jul 2014

Intercomparison of an Aerosol Chemical Speciation Monitor (ACSM) with ambient fine aerosol measurements in downtown Atlanta, Georgia

S. H. Budisulistiorini1, M. R. Canagaratna2, P. L. Croteau2, K. Baumann3, E. S. Edgerton3, M. S. Kollman4, N. L. Ng4,5, V. Verma5, S. L. Shaw6, E. M. Knipping7, D. R. Worsnop2, J. T. Jayne2, R.J. Weber5, and J. D. Surratt1 S. H. Budisulistiorini et al.
  • 1Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
  • 2Aerodyne Research, Inc., Billerica, MA 01821, USA
  • 3Atmospheric Research & Analysis, Inc., Cary, NC 27513, USA
  • 4School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
  • 5School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
  • 6Electric Power Research Institute, Palo Alto, CA 94304, USA
  • 7Electric Power Research Institute, Washington, D.C. 20036, USA

Abstract. Currently, there are a limited number of field studies that evaluate the long-term performance of the Aerodyne Aerosol Chemical Speciation Monitor (ACSM) against established monitoring networks. In this study, we present seasonal intercomparisons of the ACSM with collocated fine aerosol (PM2.5) measurements at the Southeastern Aerosol Research and Characterization (SEARCH) Jefferson Street (JST) site near downtown Atlanta, GA, during 2011–2012. Intercomparison of two collocated ACSMs resulted in strong correlations (r2 > 0.8) for all chemical species, except chloride (r2 = 0.21) indicating that ACSM instruments are capable of stable and reproducible operation. In general, speciated ACSM mass concentrations correlate well (r2 > 0.7) with the filter-adjusted continuous measurements from JST, although the correlation for nitrate is weaker (r2 = 0.55) in summer. Correlations of the ACSM NR-PM1 (non-refractory particulate matter with aerodynamic diameter less than or equal to 1 μm) plus elemental carbon (EC) with tapered element oscillating microbalance (TEOM) PM2.5 and Federal Reference Method (FRM) PM1 mass are strong with r2 > 0.7 and r2 > 0.8, respectively. Discrepancies might be attributed to evaporative losses of semi-volatile species from the filter measurements used to adjust the collocated continuous measurements. This suggests that adjusting the ambient aerosol continuous measurements with results from filter analysis introduced additional bias to the measurements. We also recommend to calibrate the ambient aerosol monitoring instruments using aerosol standards rather than gas-phase standards. The fitting approach for ACSM relative ionization for sulfate was shown to improve the comparisons between ACSM and collocated measurements in the absence of calibrated values, suggesting the importance of adding sulfate calibration into the ACSM calibration routine.