Temporary stratification promotes large greenhouse gas emissions in a shallow eutrophic lake
<p>Shallow lakes and ponds undergo frequent temporary thermal stratification. How this affects greenhouse gas (GHG) emissions is moot, with both increased and reduced GHG emissions hypothesised. Here, weekly estimations of GHG emissions, over the growing season from May to September, were comb...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2024-01-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/21/93/2024/bg-21-93-2024.pdf |
| _version_ | 1797367490366406656 |
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| author | T. A. Davidson T. A. Davidson M. Søndergaard M. Søndergaard M. Søndergaard J. Audet J. Audet E. Levi C. Esposito C. Esposito T. Bucak A. Nielsen A. Nielsen |
| author_facet | T. A. Davidson T. A. Davidson M. Søndergaard M. Søndergaard M. Søndergaard J. Audet J. Audet E. Levi C. Esposito C. Esposito T. Bucak A. Nielsen A. Nielsen |
| author_sort | T. A. Davidson |
| collection | DOAJ |
| description | <p>Shallow lakes and ponds undergo frequent temporary thermal stratification. How this affects greenhouse gas (GHG) emissions is moot, with both increased and reduced GHG emissions hypothesised. Here, weekly estimations of GHG emissions, over the growing season from May to September, were combined with temperature and oxygen profiles of an 11 ha temperate shallow lake to investigate how thermal stratification shapes GHG emissions. There were three main stratification periods with profound anoxia occurring in the bottom waters upon isolation from the atmosphere. Average diffusive emissions of methane (CH<span class="inline-formula"><sub>4</sub></span>) and nitrous oxide (N<span class="inline-formula"><sub>2</sub></span>O) were larger and more variable in the stratified phase, whereas carbon dioxide (CO<span class="inline-formula"><sub>2</sub></span>) was on average lower, though these differences were not statistically significant. In contrast, there was a significant order of magnitude increase in CH<span class="inline-formula"><sub>4</sub></span> ebullition in the stratified phase. Furthermore, at the end of the period of stratification, there was a large efflux of CH<span class="inline-formula"><sub>4</sub></span> and CO<span class="inline-formula"><sub>2</sub></span> as the lake mixed. Two relatively isolated turnover events were estimated to have released the majority of the CH<span class="inline-formula"><sub>4</sub></span> emitted between May and September. These results demonstrate how stratification patterns can shape GHG emissions and highlight the role of turnover emissions and the need for high-frequency measurements of GHG emissions, which are required to accurately characterise emissions, particularly from temporarily stratifying lakes.</p> |
| first_indexed | 2024-03-08T17:18:04Z |
| format | Article |
| id | doaj.art-a254f47bc0aa4f2789ba646cdbe81521 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-03-08T17:18:04Z |
| publishDate | 2024-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-a254f47bc0aa4f2789ba646cdbe815212024-01-03T10:25:07ZengCopernicus PublicationsBiogeosciences1726-41701726-41892024-01-01219310710.5194/bg-21-93-2024Temporary stratification promotes large greenhouse gas emissions in a shallow eutrophic lakeT. A. Davidson0T. A. Davidson1M. Søndergaard2M. Søndergaard3M. Søndergaard4J. Audet5J. Audet6E. Levi7C. Esposito8C. Esposito9T. Bucak10A. Nielsen11A. Nielsen12Lake Ecology, Department of Ecoscience, Aarhus University, Aarhus, DenmarkWATEC – Aarhus University Centre for Water Technology, Aarhus University, Aarhus, DenmarkLake Ecology, Department of Ecoscience, Aarhus University, Aarhus, DenmarkWATEC – Aarhus University Centre for Water Technology, Aarhus University, Aarhus, DenmarkSino-Danish Center for Education and Research (SDC), Beijing, ChinaLake Ecology, Department of Ecoscience, Aarhus University, Aarhus, DenmarkWATEC – Aarhus University Centre for Water Technology, Aarhus University, Aarhus, DenmarkLake Ecology, Department of Ecoscience, Aarhus University, Aarhus, DenmarkLake Ecology, Department of Ecoscience, Aarhus University, Aarhus, DenmarkWATEC – Aarhus University Centre for Water Technology, Aarhus University, Aarhus, DenmarkLake Ecology, Department of Ecoscience, Aarhus University, Aarhus, DenmarkLake Ecology, Department of Ecoscience, Aarhus University, Aarhus, DenmarkWaterITech Aps, Døjsøvej 1, 8660 Skanderborg, Denmark<p>Shallow lakes and ponds undergo frequent temporary thermal stratification. How this affects greenhouse gas (GHG) emissions is moot, with both increased and reduced GHG emissions hypothesised. Here, weekly estimations of GHG emissions, over the growing season from May to September, were combined with temperature and oxygen profiles of an 11 ha temperate shallow lake to investigate how thermal stratification shapes GHG emissions. There were three main stratification periods with profound anoxia occurring in the bottom waters upon isolation from the atmosphere. Average diffusive emissions of methane (CH<span class="inline-formula"><sub>4</sub></span>) and nitrous oxide (N<span class="inline-formula"><sub>2</sub></span>O) were larger and more variable in the stratified phase, whereas carbon dioxide (CO<span class="inline-formula"><sub>2</sub></span>) was on average lower, though these differences were not statistically significant. In contrast, there was a significant order of magnitude increase in CH<span class="inline-formula"><sub>4</sub></span> ebullition in the stratified phase. Furthermore, at the end of the period of stratification, there was a large efflux of CH<span class="inline-formula"><sub>4</sub></span> and CO<span class="inline-formula"><sub>2</sub></span> as the lake mixed. Two relatively isolated turnover events were estimated to have released the majority of the CH<span class="inline-formula"><sub>4</sub></span> emitted between May and September. These results demonstrate how stratification patterns can shape GHG emissions and highlight the role of turnover emissions and the need for high-frequency measurements of GHG emissions, which are required to accurately characterise emissions, particularly from temporarily stratifying lakes.</p>https://bg.copernicus.org/articles/21/93/2024/bg-21-93-2024.pdf |
| spellingShingle | T. A. Davidson T. A. Davidson M. Søndergaard M. Søndergaard M. Søndergaard J. Audet J. Audet E. Levi C. Esposito C. Esposito T. Bucak A. Nielsen A. Nielsen Temporary stratification promotes large greenhouse gas emissions in a shallow eutrophic lake Biogeosciences |
| title | Temporary stratification promotes large greenhouse gas emissions in a shallow eutrophic lake |
| title_full | Temporary stratification promotes large greenhouse gas emissions in a shallow eutrophic lake |
| title_fullStr | Temporary stratification promotes large greenhouse gas emissions in a shallow eutrophic lake |
| title_full_unstemmed | Temporary stratification promotes large greenhouse gas emissions in a shallow eutrophic lake |
| title_short | Temporary stratification promotes large greenhouse gas emissions in a shallow eutrophic lake |
| title_sort | temporary stratification promotes large greenhouse gas emissions in a shallow eutrophic lake |
| url | https://bg.copernicus.org/articles/21/93/2024/bg-21-93-2024.pdf |
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