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| Titel |
On the impacts of phytoplankton-derived organic matter on the properties of the primary marine aerosol – Part 1: Source fluxes |
| VerfasserIn |
E. Fuentes, H. Coe, D. Green, G. Leeuw, G. McFiggans |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 19 ; Nr. 10, no. 19 (2010-10-01), S.9295-9317 |
| Datensatznummer |
250008802
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| Publikation (Nr.) |
 copernicus.org/acp-10-9295-2010.pdf |
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| Zusammenfassung |
The effect of biogenic dissolved and colloidal organic matter on the
production of submicron primary sea-spray aerosol was investigated via the
simulation of bubble bursting in seawater enriched with
phytoplankton-released organics.
Seawater samples collected along a transect off the West African coast during
the RHaMBLe cruise (RRS Discovery cruise D319), conducted as part of the
SOLAS UK program, were analysed in order to identify the dominant oceanic
algal species in a region of high biological activity. Cultures of microalgal
strains representative of the species found in the collected seawater were
grown in order to produce natural bioexudate. Colloidal plus dissolved
organic fraction in this material remaining after <0.2 μm
filtration was employed to prepare organic-enriched seawater proxies for the
laboratory production of marine aerosol using a plunging-waterjet system as
an aerosol generator. Submicron size distributions of aerosols generated from
different organic monolayers and seawater proxies enriched with biogenic
exudate were measured and compared with blanks performed with artificial
seawater devoid of marine organics. A shift of the aerosol submicron size
distribution toward smaller sizes and an increase in the production of
particles with dry diameter (Dp0)<100 nm was repeatedly observed with
increasing amounts of diatomaceous bioexudate in the seawater proxies used
for aerosol generation. The effect was found to be sensitive to the organic
carbon concentration in seawater and the algal exudate type. Diatomaceous
exudate with organic carbon concentration (OC<0.2 μm)
>175 μM was required to observe a significant impact on the size
distribution, which implies that effects are expected to be substantial only
in high biological activity areas abundant with diatom algal populations. The
laboratory findings were in agreement with analogous bubble-bursting
experiments conducted with unfiltered oceanic seawater collected during the
RHaMBLe cruise, which revealed a higher production of particles with
Dp0<100 nm at regions with high biological activity. These findings
suggest that the increase in the atmospheric aerosol modal sizes from winter
to summer, reported by long-term observations in North Atlantic waters, is
not directly due to an impact of the higher primary organic matter production
occurring during warm periods.
A novel sub-micrometric size-resolved source flux function, explicitly
defined as a function of the diatomaceous exudate concentration, was derived
from the size distribution measurements and the estimation of the fractional
whitecap coverage. According to the defined parameterisation, a
300 μM OC<0.2 μm concentration of diatomaceous
exudate in seawater produces an overall increment in the total source
particle flux of ~20% with respect to the organics-free seawater case.
The effect increases with decreasing particle size for Dp0<100 nm,
resulting in multiplicative factors between 1.02–2 with respect to the
particle flux generated from seawater devoid of marine organics. The total
source flux derived from the presented parameterisation was compared to
recent definitions of sea-spray source fluxes based on laboratory and field
observations in the literature. |
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