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| Titel |
Contrasting responses of DMS and DMSP to ocean acidification in Arctic waters |
| VerfasserIn |
S. D. Archer, S. A. Kimmance, J. A. Stephens, F. E. Hopkins, R. G. J. Bellerby, K. G. Schulz, J. Piontek, A. Engel |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 3 ; Nr. 10, no. 3 (2013-03-20), S.1893-1908 |
| Datensatznummer |
250018162
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| Publikation (Nr.) |
 copernicus.org/bg-10-1893-2013.pdf |
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| Zusammenfassung |
| Increasing atmospheric CO2 is decreasing ocean pH most rapidly in colder
regions such as the Arctic. As a component of the EPOCA (European Project on Ocean Acidification) pelagic mesocosm
experiment off Spitzbergen in 2010, we examined the consequences of decreased
pH and increased pCO2 on the concentrations of dimethylsulphide (DMS).
DMS is an important reactant and contributor to aerosol formation and growth
in the Arctic troposphere. In the nine mesocosms with initial pHT 8.3 to
7.5, equivalent to pCO2 of 180 to 1420 μatm, highly
significant but inverse responses to acidity (hydrogen ion concentration
[H+]) occurred following nutrient addition. Compared to ambient
[H+], average concentrations of DMS during the mid-phase of the 30 d
experiment, when the influence of altered acidity was unambiguous, were
reduced by approximately 60% at the highest [H+] and by 35% at
[H+] equivalent to 750 μatm pCO2, as projected for
2100. In contrast, concentrations of dimethylsulphoniopropionate (DMSP), the
precursor of DMS, were elevated by approximately 50% at the highest
[H+] and by 30% at [H+] corresponding to 750 μatm
pCO2. Measurements of the specific rate of synthesis of DMSP by
phytoplankton indicate increased production at high [H+], in parallel to
rates of inorganic carbon fixation. The elevated DMSP production at high
[H+] was largely a consequence of increased dinoflagellate biomass and
in particular, the increased abundance of the species Heterocapsa
rotundata. We discuss both phytoplankton and bacterial processes that may
explain the reduced ratios of DMS:DMSPt (total dimethylsulphoniopropionate) at higher [H+]. The experimental
design of eight treatment levels provides comparatively robust empirical
relationships of DMS and DMSP concentration, DMSP production and
dinoflagellate biomass versus [H+] in Arctic waters. |
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