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| Titel |
Holocene environmental changes in an Arctic lake |
| VerfasserIn |
Trine Holm, Al Werner, Anne Hormes, Gerhard Kuhn, Matthias Forwick, Roland Psenner, Karin A. Koinig |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250053470
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| Zusammenfassung |
| High Arctic lakes are among the most sensitive ecosystems and are highly responsive
to climate change and anthropogenic pollution. Human activities have more than
doubled the atmospheric nitrogen in the biosphere and this problem will greatly
exacerbate Arctic ecosystem responses to climate change. Svalbard, the high Arctic
archipelago, has been identified as a region with high climatic sensitivity because of its
location at the rim of the Arctic Ocean and east of the northern branch of the North
Atlantic thermohaline circulation, the West Spitsbergen Current. Climate warming
in Svalbard was pronounced especially during the recent decades and increased
anthropogenic pollution has influenced Svalbard during the last century. To study climate
and anthropogenic impacts in the Arctic environment, sediment cores and water
samples have been obtained from three lakes in Svalbard: Hajeren, Blokkvatn and
Kongressvatn. These lakes were selected based on their size and maximum depth, and
their catchment characteristics, especially the absence or scarcity of glacier and
seabird nutrient deposition, and distance to the ocean. Three short sediment cores
(12-26 cm) were taken for multi-proxy analyses including biologic (diatoms, organic
parameters) and abiotic parameters (bulk geochemistry, nitrogen (15N, 14N) isotopes).
In addition, two long cores (450 cm) are available from Kongressvatn. Dating is
based on 210Pb, 137Cs, and 241Am for recent sediment sections and on 14C for
older core sections. Preliminary results show that the nitrogen and carbon content
in the sediment were generally low (0.01-0.26% N, 0.15-1.8% C), variable and
showing a similar trend throughout the cores. In the long cores from Kongressvatn, the
nitrogen and carbon contents decreased in the middle, but increased towards the top
sediment section. In the short sediment core from Blokkvatn nitrogen and carbon both
increased from the older to the younger layers, while both remained at constantly low
levels in all sediment layers in the core from Hajeren. The C:N molar ratio showed
the same trend as nitrogen and carbon in Kongressvatn and Blokkvatn, while it
was decreasing in the most recent sediment layers of Hajeren. C:N ratios were low
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