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| Titel |
Primary marine aerosol emissions from the Mediterranean Sea during pre-bloom and oligotrophic conditions: correlations to seawater chlorophyll a from a mesocosm study |
| VerfasserIn |
A. N. Schwier, C. Rose, E. Asmi, A. M. Ebling, W. M. Landing, S. Marro, M.-L. Pedrotti, A. Sallon, F. Iuculano, S. Agustí  , A. Tsiola, P. Pitta, J. Louis, C. Guieu, F. Gazeau, K. Sellegri |
| 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 ; 15, no. 14 ; Nr. 15, no. 14 (2015-07-20), S.7961-7976 |
| Datensatznummer |
250119912
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| Publikation (Nr.) |
 copernicus.org/acp-15-7961-2015.pdf |
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| Zusammenfassung |
| The effect of ocean acidification and changing water conditions on primary
(and secondary) marine aerosol emissions is not well understood on a regional
or a global scale. To investigate this effect as well as the indirect effect
on aerosol that changing biogeochemical parameters can have,
~ 52 m3 pelagic mesocosms were deployed for several weeks in
the Mediterranean Sea during both winter pre-bloom and summer oligotrophic
conditions and were subjected to various levels of CO2 to simulate the
conditions foreseen in this region for the coming decades. After seawater
sampling, primary bubble-bursting aerosol experiments were performed using a
plunging water jet system to test both chemical and physical aerosol
parameters (10–400 nm). Comparing results obtained during pre-bloom and
oligotrophic conditions, we find the same four log-normal modal diameters
(18.5 ± 0.6, 37.5 ± 1.4, 91.5 ± 2.0, 260 ± 3.2 nm)
describing the aerosol size distribution during both campaigns, yet pre-bloom
conditions significantly increased the number fraction of the second (Aitken)
mode, with an amplitude correlated to virus-like particles, heterotrophic
prokaryotes, TEPs (transparent exopolymeric particles), chlorophyll a and
other pigments. Organic fractions determined from kappa closure calculations for
the diameter, Dp ~ 50 nm, were much larger during the
pre-bloom period (64 %) than during the oligotrophic period (38 %),
and the organic fraction decreased as the particle size increased. Combining
data from both campaigns together, strong positive correlations were found
between the organic fraction of the aerosol and chlorophyll a
concentrations, heterotrophic and autotrophic bacteria abundance, and
dissolved organic carbon (DOC) concentrations. As a consequence of the
changes in the organic fraction and the size distributions between pre-bloom
and oligotrophic periods, we find that the ratio of cloud condensation nuclei
(CCN) to condensation nuclei (CN) slightly decreased during the pre-bloom
period. The enrichment of the seawater samples with microlayer samples did
not have any effect on the size distribution, organic content or the CCN
activity of the generated primary aerosol. Partial pressure of CO2,
pCO2, perturbations had little effect on the physical or chemical
parameters of the aerosol emissions, with larger effects observed due to the
differences between a pre-bloom and oligotrophic environment. |
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