Jonas Stage Sø, Kenneth Thorø Martinsen, Theis Kragh, Kaj Sand-Jensen
{"title":"Hourly methane and carbon dioxide fluxes from temperate ponds","authors":"Jonas Stage Sø, Kenneth Thorø Martinsen, Theis Kragh, Kaj Sand-Jensen","doi":"10.1007/s10533-024-01124-4","DOIUrl":null,"url":null,"abstract":"<div><p>Ponds are regarded as greenhouse gas (GHG) emission hot spots, but how hot are they? We examined this question by measuring methane (CH<sub>4</sub>) and carbon dioxide (CO<sub>2</sub>) fluxes in six forest and open land ponds on grasslands in Denmark during summer and winter. We used floating chambers with do-it-yourself sensors and automated headspace venting, allowing for 7404 hourly measurements. We found highly variable gas fluxes within ponds and between seasons and pond types. Ebullitive CH<sub>4</sub> fluxes were more variable than diffusive CH<sub>4</sub> fluxes. Ebullition was absent when total CH<sub>4</sub> fluxes were lowest (15 µmol m<sup>−2</sup> h<sup>−1</sup>), dominant (> 90%) at the highest fluxes (> 400 µmol m<sup>−2</sup> h<sup>−1</sup>), and increased with water temperature. In summer, a minor daily increase in diffusive fluxes was found on days with high wind speed, while CH<sub>4</sub> ebullition remained constant. CO<sub>2</sub> fluxes paralleled the day-night balance of photosynthesis and respiration. Mean CH<sub>4</sub> ebullition in open and forest ponds exceeded CH<sub>4</sub> diffusive fluxes 4.1 and 7.1-fold in summer (avg. 22.5 °C) and 2.3 and 2.5-fold in winter (9.6 °C), respectively. CO<sub>2</sub> emissions were higher on a molar basis than CH<sub>4</sub> emissions, both in summer and winter, while their annual global warming potentials were similar. Mean annual gas emissions from open and forest ponds (1092 and 2527 g CO<sub>2</sub>e m<sup>−2</sup> y<sup>−1</sup>) are naturally high due to extensive external input of dissolved CO<sub>2</sub> and organic carbon relative to pond area and volume.</p></div>","PeriodicalId":8901,"journal":{"name":"Biogeochemistry","volume":"167 2","pages":"177 - 195"},"PeriodicalIF":3.9000,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10533-024-01124-4.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Biogeochemistry","FirstCategoryId":"93","ListUrlMain":"https://link.springer.com/article/10.1007/s10533-024-01124-4","RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENVIRONMENTAL SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Ponds are regarded as greenhouse gas (GHG) emission hot spots, but how hot are they? We examined this question by measuring methane (CH4) and carbon dioxide (CO2) fluxes in six forest and open land ponds on grasslands in Denmark during summer and winter. We used floating chambers with do-it-yourself sensors and automated headspace venting, allowing for 7404 hourly measurements. We found highly variable gas fluxes within ponds and between seasons and pond types. Ebullitive CH4 fluxes were more variable than diffusive CH4 fluxes. Ebullition was absent when total CH4 fluxes were lowest (15 µmol m−2 h−1), dominant (> 90%) at the highest fluxes (> 400 µmol m−2 h−1), and increased with water temperature. In summer, a minor daily increase in diffusive fluxes was found on days with high wind speed, while CH4 ebullition remained constant. CO2 fluxes paralleled the day-night balance of photosynthesis and respiration. Mean CH4 ebullition in open and forest ponds exceeded CH4 diffusive fluxes 4.1 and 7.1-fold in summer (avg. 22.5 °C) and 2.3 and 2.5-fold in winter (9.6 °C), respectively. CO2 emissions were higher on a molar basis than CH4 emissions, both in summer and winter, while their annual global warming potentials were similar. Mean annual gas emissions from open and forest ponds (1092 and 2527 g CO2e m−2 y−1) are naturally high due to extensive external input of dissolved CO2 and organic carbon relative to pond area and volume.
期刊介绍:
Biogeochemistry publishes original and synthetic papers dealing with biotic controls on the chemistry of the environment, or with the geochemical control of the structure and function of ecosystems. Cycles are considered, either of individual elements or of specific classes of natural or anthropogenic compounds in ecosystems. Particular emphasis is given to coupled interactions of element cycles. The journal spans from the molecular to global scales to elucidate the mechanisms driving patterns in biogeochemical cycles through space and time. Studies on both natural and artificial ecosystems are published when they contribute to a general understanding of biogeochemistry.