Methane and nitrous oxide sources and emissions in a subtropical freshwater reservoir, South East Queensland, Australia
Reservoirs have been identified as an important source of non-carbon dioxide (CO<sub>2</sub>) greenhouse gases with wide ranging fluxes for reported methane (CH<sub>4</sub>); however, fluxes for nitrous oxide (N<sub>2</sub>O) are rarely quantified. This study inve...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2014-09-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/11/5245/2014/bg-11-5245-2014.pdf |
| _version_ | 1818217968269524992 |
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| author | K. Sturm Z. Yuan B. Gibbes U. Werner A. Grinham |
| author_facet | K. Sturm Z. Yuan B. Gibbes U. Werner A. Grinham |
| author_sort | K. Sturm |
| collection | DOAJ |
| description | Reservoirs have been identified as an important source of non-carbon dioxide
(CO<sub>2</sub>) greenhouse gases with wide ranging fluxes for reported methane
(CH<sub>4</sub>); however, fluxes for nitrous oxide (N<sub>2</sub>O) are rarely
quantified. This study investigates CH<sub>4</sub> and N<sub>2</sub>O 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 CH<sub>4</sub> and N<sub>2</sub>O.
Atmospheric CH<sub>4</sub> fluxes were dominated by ebullition (60 to 99%)
relative to diffusive fluxes and ranged from 4.14 × 10<sup>2</sup> to
3.06 × 10<sup>5</sup> μmol CH<sub>4</sub> m<sup>−2</sup> day<sup>−1</sup> across
the sampling sites. Dissolved CH<sub>4</sub> concentrations were highest in the
anoxic water column and sediment pore waters (approximately 5 000 000%
supersaturated). CH<sub>4</sub> production rates of up to
3616 ± 395 μmol CH<sub>4</sub> m<sup>−2</sup> day<sup>−1</sup> were found
during sediment incubations in anoxic conditions. These findings are in
contrast to N<sub>2</sub>O where no production was detected during sediment
incubations and the highest dissolved N<sub>2</sub>O concentrations were found in
the oxic water column which was 110 to 220% supersaturated with
N<sub>2</sub>O. N<sub>2</sub>O 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 CH<sub>4</sub>
fluxes with an appropriate spatial resolution to ensure capture of ebullition
zones, whereas assessment of N<sub>2</sub>O fluxes should focus on the diffusive
pathway. |
| first_indexed | 2024-12-12T07:16:17Z |
| format | Article |
| id | doaj.art-6fb1b71bd3b6412ca1e1735c5dee26ec |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-12T07:16:17Z |
| publishDate | 2014-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-6fb1b71bd3b6412ca1e1735c5dee26ec2022-12-22T00:33:31ZengCopernicus PublicationsBiogeosciences1726-41701726-41892014-09-0111185245525810.5194/bg-11-5245-2014Methane and nitrous oxide sources and emissions in a subtropical freshwater reservoir, South East Queensland, AustraliaK. Sturm0Z. Yuan1B. Gibbes2U. Werner3A. Grinham4Advanced Water Management Centre (AWMC), The University of Queensland, Level 4, Gehrmann Building, Brisbane, Queensland 4072, AustraliaAdvanced Water Management Centre (AWMC), The University of Queensland, Level 4, Gehrmann Building, Brisbane, Queensland 4072, AustraliaSchool of Civil Engineering, The University of Queensland, Level 5, Advanced Engineering Building, Brisbane, Queensland 4072, AustraliaAdvanced Water Management Centre (AWMC), The University of Queensland, Level 4, Gehrmann Building, Brisbane, Queensland 4072, AustraliaAdvanced Water Management Centre (AWMC), The University of Queensland, Level 4, Gehrmann Building, Brisbane, Queensland 4072, AustraliaReservoirs have been identified as an important source of non-carbon dioxide (CO<sub>2</sub>) greenhouse gases with wide ranging fluxes for reported methane (CH<sub>4</sub>); however, fluxes for nitrous oxide (N<sub>2</sub>O) are rarely quantified. This study investigates CH<sub>4</sub> and N<sub>2</sub>O 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 CH<sub>4</sub> and N<sub>2</sub>O. Atmospheric CH<sub>4</sub> fluxes were dominated by ebullition (60 to 99%) relative to diffusive fluxes and ranged from 4.14 × 10<sup>2</sup> to 3.06 × 10<sup>5</sup> μmol CH<sub>4</sub> m<sup>−2</sup> day<sup>−1</sup> across the sampling sites. Dissolved CH<sub>4</sub> concentrations were highest in the anoxic water column and sediment pore waters (approximately 5 000 000% supersaturated). CH<sub>4</sub> production rates of up to 3616 ± 395 μmol CH<sub>4</sub> m<sup>−2</sup> day<sup>−1</sup> were found during sediment incubations in anoxic conditions. These findings are in contrast to N<sub>2</sub>O where no production was detected during sediment incubations and the highest dissolved N<sub>2</sub>O concentrations were found in the oxic water column which was 110 to 220% supersaturated with N<sub>2</sub>O. N<sub>2</sub>O 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 CH<sub>4</sub> fluxes with an appropriate spatial resolution to ensure capture of ebullition zones, whereas assessment of N<sub>2</sub>O fluxes should focus on the diffusive pathway.http://www.biogeosciences.net/11/5245/2014/bg-11-5245-2014.pdf |
| spellingShingle | K. Sturm Z. Yuan B. Gibbes U. Werner A. Grinham Methane and nitrous oxide sources and emissions in a subtropical freshwater reservoir, South East Queensland, Australia Biogeosciences |
| title | Methane and nitrous oxide sources and emissions in a subtropical freshwater reservoir, South East Queensland, Australia |
| title_full | Methane and nitrous oxide sources and emissions in a subtropical freshwater reservoir, South East Queensland, Australia |
| title_fullStr | Methane and nitrous oxide sources and emissions in a subtropical freshwater reservoir, South East Queensland, Australia |
| title_full_unstemmed | Methane and nitrous oxide sources and emissions in a subtropical freshwater reservoir, South East Queensland, Australia |
| title_short | Methane and nitrous oxide sources and emissions in a subtropical freshwater reservoir, South East Queensland, Australia |
| title_sort | methane and nitrous oxide sources and emissions in a subtropical freshwater reservoir south east queensland australia |
| url | http://www.biogeosciences.net/11/5245/2014/bg-11-5245-2014.pdf |
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