Where and What Is Pristine Marine Aerosol?

Thursday, 18 December 2014
Lynn M Russell1, Amanda A Frossard1, Michael S Long2, Susannah M Burrows3, Scott Elliott4, Timothy S Bates5 and Patricia Quinn6, (1)University of California San Diego, La Jolla, CA, United States, (2)Harvard University, Cambridge, MA, United States, (3)Pacific Northwest National Laboratory, Richland, WA, United States, (4)Los Alamos National Laboratory, Los Alamos, NM, United States, (5)University of Washington Seattle Campus, Seattle, WA, United States, (6)NOAA/PMEL, Seattle, WA, United States
The sources and composition of atmospheric marine aerosol particles have been measured by functional group composition (from Fourier transform infrared spectroscopy) to identify the organic composition of the pristine primary marine (ocean-derived) particles as 65% hydroxyl, 21% alkane, 6% amine, and 7% carboxylic acid functional groups [Frossard et al., 2014a,b]. Pristine but non-primary components from photochemical reactions (likely from biogenic marine vapor emissions) add carboxylic acid groups. Non-pristine contributions include shipping effluent in seawater and ship emissions, which add additional alkane groups (up to 70%), and coastal or continental emissions mix in alkane and carboxylic acid groups. The pristine primary marine (ocean-derived) organic aerosol composition is nearly identical to model generated primary marine aerosol particles from bubbled seawater, indicating that its overall functional group composition is the direct consequence of the organic constituents of the seawater source.

While the seawater organic functional group composition was nearly invariant across all three ocean regions studied and the ratio of organic carbon to sodium (OC/Na+) in the generated primary marine aerosol particles remained nearly constant over a broad range of chlorophyll-a concentrations, the generated primary marine aerosol particle alkane group fraction increased with chlorophyll-a concentrations. In addition, the generated primary marine aerosol particles have a hydroxyl group absorption peak location characteristic of monosaccharides and disaccharides, where the seawater hydroxyl group peak location is closer to that of polysaccharides.

References Cited

Frossard, Amanda A., Lynn M. Russell, Paola Massoli, Timothy S. Bates, and Patricia K. Quinn, “Side-by-Side Comparison of Four Techniques Explains the Apparent Differences in the Organic Composition of Generated and Ambient Marine Aerosol Particles,” Aerosol Science and Technology – Aerosol Research Letter, 48:v-x, doi10.1080/02786826.2013.879979, 2014a.

Frossard, A.A., L.M. Russell, M.S. Long, S.M. Burrows, S.M. Elliot, T.S. Bates, and P.K. Quinn, “Sources and Composition of Submicron Organic Mass in Marine Aerosol Particles,” Journal of Geophysical Research – Atmospheres, submitted 2014b.