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Medientyp:
E-Artikel
Titel:
Laboratory investigation of inorganic carbon uptake by cryoconite debris from Werenskioldbreen, Svalbard
Beteiligte:
Stibal, Marek;
Tranter, Martyn
Erschienen:
American Geophysical Union (AGU), 2007
Erschienen in:Journal of Geophysical Research: Biogeosciences
Sprache:
Englisch
DOI:
10.1029/2007jg000429
ISSN:
0148-0227
Entstehung:
Anmerkungen:
Beschreibung:
<jats:p>Laboratory experiments were undertaken to determine the inorganic carbon uptake rate and the interactions between photosynthesis and water chemistry, particularly pH and nutrient concentrations, for cryoconite debris from Werenskioldbreen, a well‐researched Svalbard glacier. Microorganisms in cryoconite debris took up inorganic carbon at rates between 0.6 and 15 <jats:italic>μ</jats:italic>g C L<jats:sup>−1</jats:sup> h<jats:sup>−1</jats:sup> and fixed it as organic carbon. Cyanobacterial photosynthesis (75–93%) was the main process responsible for inorganic carbon fixation, while heterotrophic uptake (6–15%) only accounted for a minor part. The microbes in cryoconite debris were active shortly after melt and fixed carbon as long as there were favorable conditions. They were not truly psychrophilic: their physiological optimum temperature was higher than is prevalent in cryoconite holes. The pH was also a factor affecting photosynthesis in the cryoconite slurry. The highest dissolved inorganic carbon (DIC) uptake rates per liter of slurry occurred at pH ∼7, and there was a significant correlation between the initial pH and DIC fixation on a per cell basis, showing increasing DIC uptake rates when pH increased from ∼5.5 to 9. Inorganic carbon fixation resulted in an increased pH in solution. However, the microbes were able to photosynthesize in a wide range of pH from ∼4 to ∼10. The average C:N:P molar ratios in solution were ∼350:75:1. Unlike nitrogen, phosphorus concentrations decreased with increasing carbon uptake, and when the rate approached ∼15 <jats:italic>μ</jats:italic>g C L<jats:sup>−1</jats:sup> h<jats:sup>−1</jats:sup>, all available dissolved phosphorus was utilized within 6 h. Hence phosphorus is probably biolimiting in this system.</jats:p>