Composition and optical properties of secondary organic aerosol particles

Transcription

1 Concordia University - Portland From the SelectedWorks of Matthew E. Wise November, 2014 Composition and optical properties of secondary organic aerosol particles Felisha Imholt, Concordia University - Portland Ryan Caylor, Concordia University - Portland Matthew E. Wise, Concordia University - Portland John Shilling, Pacific Northwest National Laboratory Available at:

2 Felisha Imholt 1, Ryan Caylor 1, Matthew Wise 1 and John Shilling 2 1 Math and Science Department, Concordia University, Portland, OR 2 Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA

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4 IPCC 2013: Climate Change 2013: The Physical Science Basis

5 Black Carbon (BC) Optical properties fairly well known Absorb wavelengths above ~500 nm Brown Carbon (BrC) Optical properties not as well known as BC Different in nature than BC Absorbs at ~300 to 500 nm Secondary Organic Aerosols (SOA) could be a form of BrC Absorbs between ~300 to 500 nm

6 What is the chemical composition of SOA? Does SOA absorb UV/Vis radiation? If SOA does absorb UV/Vis radiation, how strong of an absorber is it?

7 10.6 m 3 Teflon chamber 25 o C, 0% RH UV blacklights (340 nm) 1,2,4 trimethylbenzene (TMB (g)) NaNO 2 (aq) H 2 SO 4 (aq) Creates gas phase OH and NO radicals after lights are turned on pump 9 L/min ~3-4 hrs SOA Teflon filter Possible product Liu et al. (2012)

8 Chemistry is complicated and not well known Xu, L. et al. (2014)

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10 Responsible for light absorption? Absorbance (arbitrary units) Wavenumbers (cm -1 )

11 New research question?

12 Absorbance (arbitrary units) Day 1 Day Wavenumbers (cm -1 )

13 Absorbance (arbitrary units) 1 hr. 26 hrs. 82 hrs. 111 hrs Wavenumbers (cm -1 )

14 1 hour compared to 111 hours Absorbance (arbitrary units) <30 % decrease 6% 4% increase 300 % 152 % Wavenumbers (cm -1 )

15 Integration (Arbitrary units) Days in Storage

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17 UV/Vis light source Liquid Waveguide Capillary Cell (LWCC) UV/Vis Spectrometer Light in Light out Instruments Light source - Ocean Optics Inc. model DT- MINI-2-GS LWCC - World Precision Instruments model LWCC-3100 Spectrometer - Ocean Optics, Inc. Jaz model UX Sample in Sample out

18 Solvent Amount FA Amount solvent Final Concentration Water g 50.5 g 120 mg/l

19 Mass Specific Absorption Cross-Section (MAC) MAC allows comparison between samples at different concentrations AA MMMMMM UUUU/VVVVVV = [SSSSSS] ee xx LL Imaginary Refractive Index (k) kk = MMMMMM xx λλλλ MAC and k values of SOA will be used in climate models 4ππ System MAC (m 2 /g) k FA/H 2 O 0.15 ± ± Literature FA/H 2 O MAC = 0.17 m 2 /g Ghabbour, E. A. & Davies, G. (2009)

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21 UV/Vis Spectrometry UV/Vis technique was optimized for water MAC and k values of FA are consistent with the literature values Specific types of SOA absorb radiation (between 350 and 600 nm) more strongly than FA IR Spectrometry Chemical composition of SOA very complicated and not fully elucidated by IR spectra SOA exhibited significant compositional changes during sample storage New research question: How does sample storage effect light absorbance?

22 Determination of the SOA chemical composition necessary to absorb more UV/Vis radiation than fulvic acid Determination of the effect storage time has on SOA composition and its resulting UV/Vis absorbance Studying the effects different precursors have on the composition and absorbance of SOA

23 Dr. Matthew Wise Dr. John Shilling PNNL Visiting Faculty Program Concordia University

24 IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp. Ghabbour, E. A. & Davies, G. (2009). Spectrophotometric analysis of fulvic acid solutions - A second look. Annals of Environmental Science: 3(10). Liu, S., Shilling, J., Song, C., Hiranuma, N., Zaveri, R., & Russell, L. (2012). Hydrolysis of Organonitrate Functional Groups in Aerosol Particles. Aerosol Science and Technology, 46(12), Xu, L., Kollman, M. S., Song, C., Shilling, J. E., & Ng, N. L. (2014). Effects of NOx on the volatility of secondary organic aerosol from isoprene photooxidation. Environmental Science & Technology, 48(4), doi: /es