Dominique S Piens1, Stephen T Kelly1, Tristan H Harder1,2, Markus D Petters3, Rachel E O'Brien1, Bingbing Wang4, Ken Teske5, Pat Dowell5, Alexander Laskin4, Mary K Gilles1. 1. Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States. 2. Department of Chemistry, University of California , Berkeley, California 94720, United States. 3. Department of Marine Earth and Atmospheric Sciences, North Carolina State University , Raleigh, North Carolina 27695, United States. 4. William R. Wiley Environmental and Molecular Sciences Laboratory, Pacific Northwest National Laboratory , Richland, Washington 99352, United States. 5. Atmospheric Radiation Monitoring (Southern Great Plains Climate Research Facility), 109596 Coal Road, Billings, Oklahoma 74630 United States.
Abstract
Quantifying how atmospheric particles interact with water vapor is critical for understanding the effects of aerosols on climate. We present a novel method to measure the mass-based hygroscopicity of particles while characterizing their elemental and carbon functional group compositions. Since mass-based hygroscopicity is insensitive to particle geometry, it is advantageous for probing the hygroscopic behavior of atmospheric particles, which can have irregular morphologies. Combining scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDX), scanning transmission X-ray microscopy (STXM) analysis, and in situ STXM humidification experiments, this method was validated using laboratory-generated, atmospherically relevant particles. Then, the hygroscopicity and elemental composition of 15 complex atmospheric particles were analyzed by leveraging quantification of C, N, and O from STXM, and complementary elemental quantification from SEM/EDX. We found three types of hygroscopic responses, and correlated high hygroscopicity with Na and Cl content. The mixing state of 158 other particles from the sample broadly agreed with those of the humidified particles, indicating the potential to infer atmospheric hygroscopic behavior from a selected subset of particles. These methods offer unique quantitative capabilities to characterize and correlate the hygroscopicity and chemistry of individual submicrometer atmospheric particles.
Quantifying how atmospheric particles interact with water vapor is critical for understanding the effects of aerosols on climate. We present a novel method to measure the mass-based hygroscopicity of particles while characterizing their elemental and n class="Chemical">carbon functional group compositions. Since mass-based hygroscopicity is insensitive to particle geometry, it is advantageous for probing the hygroscopic behavior of atmospheric particles, which can have irregular morphologies. Combining scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDX), scanning transmission X-ray microscopy (STXM) analysis, and in situ STXM humidification experiments, this method was validated using laboratory-generated, atmospherically relevant particles. Then, the hygroscopicity and elemental composition of 15 complex atmospheric particles were analyzed by leveraging quantification of C, N, and O from STXM, and complementary elemental quantification from SEM/EDX. We found three types of hygroscopic responses, and correlated high hygroscopicity with Na and Cl content. The mixing state of 158 other particles from the sample broadly agreed with those of the humidified particles, indicating the potential to infer atmospheric hygroscopic behavior from a selected subset of particles. These methods offer unique quantitative capabilities to characterize and correlate the hygroscopicity and chemistry of individual submicrometer atmospheric particles.
Authors: Swarup China; Susannah M Burrows; Bingbing Wang; Tristan H Harder; Johannes Weis; Meryem Tanarhte; Luciana V Rizzo; Joel Brito; Glauber G Cirino; Po-Lun Ma; John Cliff; Paulo Artaxo; Mary K Gilles; Alexander Laskin Journal: Nat Commun Date: 2018-11-19 Impact factor: 14.919