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Evasion of CO₂ from streams

quantifying a carbon component of the aquatic conduit in the boreal landscape

Wallin, Marcus (2011). Evasion of CO₂ from streams. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2011:5
ISBN 978-91-576-7574-3
[Doctoral thesis]

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Lateral export of carbon (C) from soils to running waters is a persistent pathway for C with terrestrial origin. This "aquatic conduit" might be especially important in boreal regions where a significant part of the global C stock is stored in the soil. Even though the awareness of the fate of terrestrially derived C is increasing in regional and global C budgets, the scarcity of data on the contribution of streams is widely acknowledged. In particular, the evasion (degassing) of gaseous C (i.e. CO₂ and CH₄) from the water surface of streams requires better characterization. This thesis aims to quantify the evasion of CO₂ from boreal streams within the 67 km2 Krycklan catchment, and explore the factors controlling this diffuse flux. All streams in the Krycklan catchment were consistently supersaturated in CO₂ and were hence a source for atmospheric CO₂ all year around. The source for this supersaturation of CO₂ was to a great extent explained by the export of respired C from the catchment soils. This was shown by exploring the export of dissolved inorganic carbon (DIC) across the soil/stream/atmosphere interfaces in a headwater catchment. The study also found that CO₂ evasion from the stream surface is a rapid process, and that much of the DIC leaving the soils is returned to the atmosphere as CO2 before leaving the headwaters. Evasion of CO₂ is dependent on the water-atmosphere concentration gradient, but also the gas exchange ability across the water-atmosphere interface (the gas transfer coefficient). The spatiotemporal variability of the gas transfer coefficient for carbon dioxide (KCO2) was found to be large, but the slope of the stream can be used to predict the spatial component of this variability. The positive relationship between KCO2 and stream section steepness was used to determine the spatial distribution of gas exchange ability for the entire stream network of forested Sweden. By combining concentration measurements and field-determined relationships with a high resolution digital elevation model (DEM) we were able to model the CO₂ evasion for each grid-cell of stream in the Krycklan catchment. Evasion of CO₂ from the entire stream network constituted a major component (<69 %) of the entire aquatic C flux. This study highlights the importance of including CO₂ evasion from streams in estimates of the aquatic conduit for carbon in boreal regions.

Authors/Creators:Wallin, Marcus
Title:Evasion of CO₂ from streams
Subtitle:quantifying a carbon component of the aquatic conduit in the boreal landscape
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2011
Number of Pages:44
ALLI. Wallin, M., Buffam. I., Öquist, M., Laudon, H., & Bishop, K. (2010). Temporal and spatial variability of dissolved inorganic carbon in a boreal stream network: Concentrations and downstream fluxes. Journal of Geophysical Research - Biogeosciences 115: G02014, doi:10.1029/2009JG001100. II. Öquist, M., Wallin, M., Seibert, J., Bishop, K., & Laudon, H. (2009). Dissolved inorganic carbon export across the soil/stream interface and its fate in a boreal headwater stream. Environmental Science & Technology 43(19), 7364-7369. doi:10.1021/es900416h III. Wallin, M., Öquist, M., Buffam, I., Billett, M., Nisell, J., & Bishop, K. Spatiotemporal variability of the gas transfer coefficient (KCO2) in boreal streams; implications for large scale estimates of CO₂ evasion (in review). IV. Wallin, M., Grabs, T., Buffam, I., Laudon, H., Ågren, A., Öquist, M., & Bishop, K. Evasion of CO₂ from streams – A major component of the carbon export through the aquatic conduit in a boreal catchment (manuscript).
Place of Publication:Uppsala
ISBN for printed version:978-91-576-7574-3
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:carbon dioxide, carbon, gas exchange, atmosphere, isotopes, peatlands, rivers, boreal forests, landscape, sweden
Keywords:CO₂, DIC, Evasion, Carbon Export, Boreal streams, Krycklan
Permanent URL:
ID Code:2437
Department:(NL, NJ) > Dept. of Aquatic Sciences and Assessment
Deposited By: Marcus Wallin
Deposited On:09 Feb 2011 00:00
Metadata Last Modified:02 Dec 2014 10:18

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