The validity of floating chambers in quantifying CO2 flux from headwater streams

The amount of CO2 exiting headwater streams through degassing plays an important role in the global carbon cycle, yet quantification of CO2 degassing remains challenging because of the morphology of headwater streams and because of uncertainty about whether floating or suspended chambers provide val...

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Autores principales:	M. J. Rawitch, G. L. Macpherson, A. E. Brookfield
Formato:	article
Lenguaje:	EN
Publicado:	IWA Publishing 2021
Materias:	co2 degassing floating chamber headwater streams Environmental technology. Sanitary engineering TD1-1066 Environmental sciences GE1-350
Acceso en línea:	https://doaj.org/article/2999d00b7b114f52a83ec90a8e2d429c
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spelling	oai:doaj.org-article:2999d00b7b114f52a83ec90a8e2d429c2021-11-05T18:31:05ZThe validity of floating chambers in quantifying CO2 flux from headwater streams2040-22442408-935410.2166/wcc.2020.199https://doaj.org/article/2999d00b7b114f52a83ec90a8e2d429c2021-03-01T00:00:00Zhttp://jwcc.iwaponline.com/content/12/2/453https://doaj.org/toc/2040-2244https://doaj.org/toc/2408-9354The amount of CO2 exiting headwater streams through degassing plays an important role in the global carbon cycle, yet quantification of CO2 degassing remains challenging because of the morphology of headwater streams and because of uncertainty about whether floating or suspended chambers provide valid measurements in moving water. We show that experiments using large and small floating chambers in flowing water over a moderate range of water velocities (0.13–0.23 m s−1) in a laboratory flume resulted in similar k600s to published field measurements with similar water velocities. We confirmed the flume experiments with paired stirred-still beaker experiments, where resulting k600s fell within the extrapolated trend of the flume experiments. We propose that the floating chambers can provide good estimates of CO2 degassing, particularly in shallow, low-velocity, morphologically complex headwater streams, permitting quantification of this important contributor to the global carbon cycle. HIGHLIGHTS Headwater streams contribute significantly to the C efflux from inland waters, yet the size of their contribution has only recently begun to be quantified.; Floating chambers, to date, are only generally accepted for use in relatively still waters (lakes, oceans), yet are increasingly used in characterizing headwater streams. Thus, we designed laboratory experiments to compare CO2 degassing using a floating chamber in a flume, with other methods of quantifying degassing rates.; In our experiments, k600-CO2 values varied linearly with water velocities from 0.13 to 0.23 m s−1, velocities that are typical of headwater streams. This confirms the importance of water velocity-induced turbulence to k600-CO2. It was not clear whether floating chamber design strongly affected the k600-CO2 results.; We compared CO2 degassing in floating chambers to calculated CO2 degassing based on the pH increase in stirred beakers of flume water, and found that the beaker experiments, although at lower water velocities, fell on the extended trend of the flume experiments.; These results support the use of floating chambers to characterize CO2 degassing in headwater stream type environments.;M. J. RawitchG. L. MacphersonA. E. BrookfieldIWA Publishingarticleco2 degassingfloating chamberheadwater streamsEnvironmental technology. Sanitary engineeringTD1-1066Environmental sciencesGE1-350ENJournal of Water and Climate Change, Vol 12, Iss 2, Pp 453-468 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	co2 degassing floating chamber headwater streams Environmental technology. Sanitary engineering TD1-1066 Environmental sciences GE1-350
spellingShingle	co2 degassing floating chamber headwater streams Environmental technology. Sanitary engineering TD1-1066 Environmental sciences GE1-350 M. J. Rawitch G. L. Macpherson A. E. Brookfield The validity of floating chambers in quantifying CO2 flux from headwater streams
description	The amount of CO2 exiting headwater streams through degassing plays an important role in the global carbon cycle, yet quantification of CO2 degassing remains challenging because of the morphology of headwater streams and because of uncertainty about whether floating or suspended chambers provide valid measurements in moving water. We show that experiments using large and small floating chambers in flowing water over a moderate range of water velocities (0.13–0.23 m s−1) in a laboratory flume resulted in similar k600s to published field measurements with similar water velocities. We confirmed the flume experiments with paired stirred-still beaker experiments, where resulting k600s fell within the extrapolated trend of the flume experiments. We propose that the floating chambers can provide good estimates of CO2 degassing, particularly in shallow, low-velocity, morphologically complex headwater streams, permitting quantification of this important contributor to the global carbon cycle. HIGHLIGHTS Headwater streams contribute significantly to the C efflux from inland waters, yet the size of their contribution has only recently begun to be quantified.; Floating chambers, to date, are only generally accepted for use in relatively still waters (lakes, oceans), yet are increasingly used in characterizing headwater streams. Thus, we designed laboratory experiments to compare CO2 degassing using a floating chamber in a flume, with other methods of quantifying degassing rates.; In our experiments, k600-CO2 values varied linearly with water velocities from 0.13 to 0.23 m s−1, velocities that are typical of headwater streams. This confirms the importance of water velocity-induced turbulence to k600-CO2. It was not clear whether floating chamber design strongly affected the k600-CO2 results.; We compared CO2 degassing in floating chambers to calculated CO2 degassing based on the pH increase in stirred beakers of flume water, and found that the beaker experiments, although at lower water velocities, fell on the extended trend of the flume experiments.; These results support the use of floating chambers to characterize CO2 degassing in headwater stream type environments.;
format	article
author	M. J. Rawitch G. L. Macpherson A. E. Brookfield
author_facet	M. J. Rawitch G. L. Macpherson A. E. Brookfield
author_sort	M. J. Rawitch
title	The validity of floating chambers in quantifying CO2 flux from headwater streams
title_short	The validity of floating chambers in quantifying CO2 flux from headwater streams
title_full	The validity of floating chambers in quantifying CO2 flux from headwater streams
title_fullStr	The validity of floating chambers in quantifying CO2 flux from headwater streams
title_full_unstemmed	The validity of floating chambers in quantifying CO2 flux from headwater streams
title_sort	validity of floating chambers in quantifying co2 flux from headwater streams
publisher	IWA Publishing
publishDate	2021
url	https://doaj.org/article/2999d00b7b114f52a83ec90a8e2d429c
work_keys_str_mv	AT mjrawitch thevalidityoffloatingchambersinquantifyingco2fluxfromheadwaterstreams AT glmacpherson thevalidityoffloatingchambersinquantifyingco2fluxfromheadwaterstreams AT aebrookfield thevalidityoffloatingchambersinquantifyingco2fluxfromheadwaterstreams AT mjrawitch validityoffloatingchambersinquantifyingco2fluxfromheadwaterstreams AT glmacpherson validityoffloatingchambersinquantifyingco2fluxfromheadwaterstreams AT aebrookfield validityoffloatingchambersinquantifyingco2fluxfromheadwaterstreams
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The validity of floating chambers in quantifying CO2 flux from headwater streams

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