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Chemical Characterization of Isoprene- and Monoterpene-Derived Secondary Organic Aerosol Tracers in Remote Marine Aerosols over a Quarter Century
journal contribution
posted on 2019-04-29, 00:00 authored by Tianqu Cui, Hilary S. Green, Paul W. Selleck, Zhenfa Zhang, Rachel E. O’Brien, Avram Gold, Melita Keywood, Jesse H. Kroll, Jason D. SurrattIsoprene and monoterpenes
are ubiquitous precursors of biogenic
secondary organic aerosol (SOA) over continental regions; however,
their contributions to organic aerosol (OA) mass and chemical processes
in remote marine atmospheres remain uncertain. Determining exact sources
of organics in marine aerosol is needed to more accurately assess
aerosol climate effects in remote locations through coupled atmospheric
chemistry–climate simulations. Over 200 archived ocean-originated
particulate samples collected from 1991 to 2015 at Cape Grim, Australia,
were analyzed using a suite of chromatographic and mass spectrometric
techniques. To our knowledge, this is one of the longest running continual
archives of marine aerosol samples collected under remote background
conditions. Up to 6.75 and 1.11 ng m–3 of isoprene-
and monoterpene-derived SOA, respectively, were quantified using authentic
standards. Although there was no clear temporal trend over the decades,
consistent seasonal variations were observed, with higher biogenic
SOA in summer, which was moderately to strongly correlated (r = 0.61–0.85) with marine bioactivity indicators,
such as methanesulfonic acid and chlorophyll a. These
correlations indicate that marine biota likely emit biogenic SOA precursors
that are able to contribute to remote background OA levels. On the
basis of historical observations of OA mass estimated in the marine
baseline samples, these biogenic SOA tracers contributed up to 0.71%
(0.26 ± 0.24% on average) of the total OA mass fraction. Our
data suggest that larger sources of OA exist in remote marine atmospheres,
such as primary OA produced from bubble-bursting processes or SOA
precursors derived from photosensitized reactions of dissolved organic
matter present in the sea surface microlayer.
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Organic Aerosol Tracersmarine aerosol samplesaerosol climate effectsOA mass fractionbiogenic SOA precursorsRemote Marine Aerosolsbackground OA levelsmarine baseline samplesmarine atmospheresbiogenic SOA tracerssea surface microlayerQuarter Century Isoprene200 archived ocean-originatedmarine bioactivity indicators
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