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| Titel |
Source to sink characterization of dissolved organic matter in a tropical
karst system |
| VerfasserIn |
Franziska Lechleitner, Susan Q. Lang, Cameron McIntyre, James U. L. Baldini, Thorsten Dittmar, Timothy I. Eglinton |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250131868
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| Publikation (Nr.) |
 EGU/EGU2016-12316.pdf |
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| Zusammenfassung |
| Karst systems are widespread surface features present on all continents. They are
characterized by complex hydrology with a multitude of possible flow regimes, from diffuse
seepage through the host rock to fracture flow in larger conduits. As stalagmite proxy records
are important indicators of past terrestrial climate conditions, detailed understanding of the
biogeochemistry of cave systems and their relationships to the overlying karst network is
crucial. Microbial communities that drive the carbon cycle in caves are nourished by
dissolved organic matter (DOM) carried with water into the cave system. Water samples
from the Yok Balum cave in Belize were collected for DOM analysis, including
soil waters, drip waters and pool waters from inside the cave. Additionally, DOM
extracts from a stalagmite from the same cave were analysed to examine DOM
signatures and test their applicability for reconstruction of environmental conditions.
Ultrahigh-resolution mass spectrometry (via the ESI-FT-ICR-MS technique) yielded detailed
molecular fingerprints on DOM from these samples. Several thousand molecular
formulae of DOM compounds were identified. In addition, radiocarbon analyses were
performed on the DOM samples to gain information on karst turnover times. A principal
component analysis of the molecular data revealed a clear gradient between soil waters
and cave waters, as soil waters were enriched in highly unsaturated oxygen-rich
compounds (typical for vascular plants), which were much less abundant in drip
waters. Conversely, peptides, which can originate from bacterial processes, were
present only in the drip waters. Our data clearly show connectivity between the cave
and overlaying soils, and reworking of DOM by the cave bacterial community.
Furthermore, we found molecular evidence for the selective removal of vascular
plant-derived DOM in the caves, possibly due to abiotic interactions with minerals. |
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