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| Titel |
Methane and nitrous oxide sources and emissions in a subtropical freshwater reservoir, South East Queensland, Australia |
| VerfasserIn |
K. Sturm, Z. Yuan, B. Gibbes, U. Werner, A. Grinham |
| 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. 18 ; Nr. 11, no. 18 (2014-09-30), S.5245-5258 |
| Datensatznummer |
250117615
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| Publikation (Nr.) |
 copernicus.org/bg-11-5245-2014.pdf |
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| Zusammenfassung |
| Reservoirs have been identified as an important source of non-carbon dioxide
(CO2) greenhouse gases with wide ranging fluxes for reported methane
(CH4); however, fluxes for nitrous oxide (N2O) are rarely
quantified. This study investigates CH4 and N2O sources and
emissions in a subtropical freshwater Gold Creek Reservoir, Australia,
using a combination of water–air and sediment–water flux measurements and
water column and pore water analyses. The reservoir was clearly a source of
these gases as surface waters were supersaturated with CH4 and N2O.
Atmospheric CH4 fluxes were dominated by ebullition (60 to 99%)
relative to diffusive fluxes and ranged from 4.14 × 102 to
3.06 × 105 μmol CH4 m−2 day−1 across
the sampling sites. Dissolved CH4 concentrations were highest in the
anoxic water column and sediment pore waters (approximately 5 000 000%
supersaturated). CH4 production rates of up to
3616 ± 395 μmol CH4 m−2 day−1 were found
during sediment incubations in anoxic conditions. These findings are in
contrast to N2O where no production was detected during sediment
incubations and the highest dissolved N2O concentrations were found in
the oxic water column which was 110 to 220% supersaturated with
N2O. N2O fluxes to the atmosphere were primarily through the
diffusive pathway, mainly driven by diffusive fluxes from the water column
and by a minor contribution from sediment diffusion and ebullition. Results
suggest that future studies of subtropical reservoirs should monitor CH4
fluxes with an appropriate spatial resolution to ensure capture of ebullition
zones, whereas assessment of N2O fluxes should focus on the diffusive
pathway. |
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