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Analysis of Water-Soluble Organic Content in Ambient & Sea Aerosols with LC/MS

This study focuses on identifying specific organic compounds in aerosols through LC/MS analysis, targeting carbohydrates and organic acids. The research compares the composition of sea spray aerosols with land and marine sources. Techniques involve aerosol collection, organic carbon analysis, and carbohydrate identification, shedding light on aerosol sources encountered during the CalNEX research cruise.

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Analysis of Water-Soluble Organic Content in Ambient & Sea Aerosols with LC/MS

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  1. Analysis of the Water-Soluble Organic Content of Ambient and Sea Sweep Aerosols and Parallel POC Seawater Samples with LC/MS Langley DeWitt NOAA PMEL

  2. R/V Atlantis Voyage

  3. Some Aerosols Sources Encountered on the CalNEX Research Cruise

  4. LC/MS aerosol analysis • Allows identification of specific compounds through 1) retention time and 2) mass. • Classes of water soluble species targetted in this work: • Carbohydrates • C2-C9 organic acids. • Samples analyzed: submircron impactor samples of ambient and SeaSweep aerosol particles, particulate organic carbon seawater samples.

  5. Carbohydrate Content of Aerosols • Marine Aerosols: from ocean biota, transferred to aerosols in seaspray processes (7-20% of OM in remote marine aerosols, Russell et al., 2010).

  6. Carbohydrate sources in Ambient Aerosols • Land Sources: • Plant Sources: Fructose, Glucose, Galactose, Sucrose (0.1-100s of ng/m3, Medeiros et al, 2005). • Fungal Spores: Mannitol (3-30 ng/m3, Heald and Spracklen 2009) • Biomass burning products: Levoglucosan (a few ng/m3-10,000+ ng/m3 in a burning event), Xylose.

  7. Analysis Methods: SeaSpray Aerosol Collection Particulate Organic Carbon (POC) From Seawater Collection Seawater Particulate organic carbon From tubing to submicron impactor. Dissolved organic carbon Combusted Quartz Fiber Filter. Combusted Quartz Fiber Filter. To Pump

  8. Analysis Methods Sonicate filters in DI water for 30 minutes.

  9. LC/MS Analysis: Carbohydrate analysis DI H2O 20 mM Ammonium Acetate signal Sample Injection Luna NH2 column Acetonitrile Retention Time Retention time used for identification. Area ~ Mass

  10. LC/MS Analysis: Carbohydrate analysis DI H2O 20 mM Ammonium Acetate Sample Injection Luna NH2 column ESI ionization source: soft ionization, low fragmentation, parent ion high Need sample to have a charge in solution, so form sugar adducts: Sugar[NH4]+ Quad detector Single Ion Monitoring increases sensitivity Acetonitrile

  11. POC EC mass: Chlorophyll Concentration

  12. Carbohydrate Content in SeaSweep Aerosols * Divided by 10 because unrealistically high carbohydrate content.

  13. Total Measured Carbohydrate Content in Sweep Aerosols does not scale to Chlorophyll

  14. A Closer Look at the SeaSweep Aerosol Carbohydrate Composition Port Hueneme, evening Farallon Islands, Foggy Rainy morning m/z 168: Xylose m/z 180: levoglucosan m/z 198: fructose, galactose, glucose m/z 200: Mannitol m/z 360: disaccharide In lee of R/V Atlantis Lee of Catalina Islands, evening Farallon Islands, Fog, afternoon No Real Trend in Photochemistry/Location (or at least not enough data to determine one) W. Of shipping lanes of Point Vincente, afternoon

  15. Total Measured Carbohydrate Content in SeaSweep versus POC data

  16. SeaSweep and POC carbohydrate content comparison. 0.125 mg/L Chlorophyll 1: Xylose 2: Levoglucosan 3: Glucose, Fructose, Galactose Mannitol Sucrose, Maltose, Cellobiose Normalized to total measured carbohydrate signal

  17. SeaSweep Aerosol Comparison to Ambient Aerosols

  18. LC/MS Analysis: Acid Analysis analysis DI H2O 20 mM Ammonium Acetate Sample Injection Kinetex C18 column Methanol • Easier for acids than sugars to have charge, operate in the negative ion mode. DI H2O (w/ 0.1 v:v formic acid)

  19. Water Soluble Carboxylic Acids Targeted • Glycolic Acid: C2H4O3, smallest AHA, aqueous oxidation product of isoprene • Pyruvic Acid: C3H4O3, aqueous oxidation product of isoprene • Oxalic Acid: H2C2O4, end product of many aerosol oxidation processes (isoprene, fatty acid, etc.), generally most prevalent atmospheric dicarboxylic acid (91-350 ng/m3, Hungarya, 25-45 ng/m3, remote north pacific marine aerosols+) • Succinic Acid: C4H6O4, Oxidation product, intermediate between C5b dicarboxylic acids and oxalic acid, less prevalent in lower latitudes because more photochemically reactiveb. • Malic Acid: C4H6O5, Hydroxalated C4 organic acid, 0.2c-78a, associated with biogenic emissions in marine environments (c). • Cis-Pinonic Acid: C9H12O4, biogenic emisison associated with forested areas, 0.6-45 ng/ m3 in mixed urban/forest areasd A:Kourtchev et al., 2009; b:Kawamura and Sakagutchi, 1999; c: Miyazaki et al., 2010; d: Cheng et al., 2004

  20. Organic Acid Content of Sea Spray Aerosols Miyazaki et al., 2010

  21. Reaction Mechanisms of Photochemical Production of Soluble Organic Acids in a Marine Environment.

  22. Organic Acid in SeaSweep Aerosols No obvious trend with increasing chlorophyll

  23. Organic Acid in SeaSweep Aerosols Morning, overcast with drizzle, sun at end. Evening, in lee of Catalina

  24. Organic Acid in SeaSweep Aerosols Separation Zone around Santa Monica, boat surges, low acid and unreasonably high carbohydrate content.

  25. Organic Acid in SeaSweep Aerosols Foggy afternoon off Farallon Islands Evening SeaSweep off Port Hueneme

  26. Organic Acid in SeaSweep Aerosols Possible increase in Malic:Succinic ratio with increasing biological activity.

  27. Are these trends reflected in the POC of the seawater?

  28. POC Acid Analysis No obvious trend in Acid:Chlorophyll Any trends?

  29. POC Acid Analysis South of Shipping Lanes of Point Hueneme: Afternoon West of shipping lanes of Point Vincent: Afternoon

  30. POC Acid Analysis Morning, overcast with drizzle, sun at end. Farallon Islands, foggy, afternoon

  31. POC Acid Analysis Evening, Santa Barbara Shipping Channel

  32. POC Acid Analysis Malic:Succinic Acid ratio increasing as biological activity increases Agrees with previous work by Kawamura and Sakaguchi (1999), Miyazaki et al., (2010)

  33. POC and SeaSweep Comparison: Not an obvious correlation between their organic acids concentrations

  34. Ambient and SeaSweep Aerosol Acid Concentrations

  35. Conclusions • SeaSweep • Conditions other than chlorophyll concentration affecting water soluble seaspray aerosol chemistry • POC:SeaSpray aerosols do not have a direct correlation for carbohydrates or organic acids in this work. • Malic:Succinic acid ratio in POC and SeaSweep aerosols could be indicator of high marine biological activity. • ~2-20% of seasweep aerosols carbohydrates, 1-10% organic acids. • Ambient Aerosols • See a mix of biogenic emissions (carbohydrates, cis-pinonic acid) and aged organics (oxalic acid, succinic acid). • Distinct differences in targeted compound signatures for different air masses.

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