Characterization and source apportionment of organic aerosol using offline aerosol mass spectrometry

[摘要] Field deployments of the Aerodyne Aerosol Mass Spectrometer (AMS)have significantly advanced real-time measurements and sourceapportionment of non-refractory particulate matter. However, thecost and complex maintenance requirements of the AMS make its deployment at sufficient sites to determine regionalcharacteristics impractical. Furthermore, the negligible transmission efficiencyof the AMS inlet for supermicron particles significantly limits thecharacterization of their chemical nature and contributingsources. In this study, we utilize the AMS to characterize thewater-soluble organic fingerprint of ambient particles collectedonto conventional quartz filters, which are routinely sampled atmany air quality sites. The method was applied to 256 particulatematter (PM) filter samples (PM₁, PM_2.5, and PM₁₀, i.e., PM with aerodynamic diameters smaller than 1, 2.5, and 10 µm, respectively), collected at 16 urban and rural sites during summerand winter. We show that the results obtained by the presenttechnique compare well with those from co-located onlinemeasurements, e.g., AMS or Aerosol Chemical Speciation Monitor(ACSM). The bulk recoveries of organic aerosol (60–91 %)achieved using this technique, together with low detection limits(0.8 µg of organic aerosol on the analyzed filterfraction) allow its application to environmental samples. We willdiscuss the recovery variability of individual hydrocarbon ions, ions containingoxygen, and other ions. The performance of such data in sourceapportionment is assessed in comparison to ACSM data. Recoveries oforganic components related to different sources as traffic, woodburning, and secondary organic aerosol are presented. This technique,while subjected to the limitations inherent to filter-basedmeasurements (e.g., filter artifacts and limited time resolution) maybe used to enhance the AMS capabilities in measuringsize-fractionated, spatially resolved long-term data sets.

[学科分类] 几何与拓扑