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| Titel |
A spatial investigation of the environmental controls over cryoconite aggregation on Longyearbreen glacier, Svalbard |
| VerfasserIn |
H. J. Langford, T. D. L. Irvine-Fynn, A. Edwards, S. A. Banwart, A. J. Hodson |
| 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 ; 11, no. 19 ; Nr. 11, no. 19 (2014-10-07), S.5365-5380 |
| Datensatznummer |
250117623
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| Publikation (Nr.) |
 copernicus.org/bg-11-5365-2014.pdf |
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| Zusammenfassung |
| A cryoconite granule is a near-spherical aggregation of biota and abiotic
particles found upon glacier surfaces. Recently, microstructural studies
have revealed that photosynthetic microorganisms and extracellular polymeric
substances (EPS) are omnipresent within cryoconite granules and have
suggested their importance as biological "forming factors". To assess these
forming factors, and their biological control over aggregate size and
stability, across a typical Arctic valley glacier surface, a suite of rapid,
spectrophotometric, microplate methods were utilised. Subsequent spatial
mapping of these data revealed distinct patterns. Labile carbohydrates were
found to increase up-glacier, suggestive of EPS production for
cryoprotection and nutrient assimilation. Conversely, pigment concentrations
were found to increase towards the glacier terminus and valley sides,
suggestive of allochthonous input, a general reduction in physical
disturbance and of the build-up of photosynthetic pigments and less labile
cyanobacterial sheath material. Aggregate size was found to increase towards
the glacier edges, linked to the input of particulate matter from the valley
sides, and to broadly increase down-glacier, in the same way as pigment
concentrations. Statistical analyses of transect data revealed that the
photoautotrophic count and carbohydrate–chlorophyll ratio of the cryoconite
sampled could explain 83% of the measured variation in aggregate size and
stability. Considering solely aggregate size, the number and length of
photoautotrophic filaments could explain 92% of the variation in this
parameter. These findings demonstrate the two-dimensional distribution of
key biological controls upon cryoconite aggregation for the first time, and
highlight the importance of filamentous cyanobacteria and EPS production to
the development of stable cryoconite granules. |
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