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The role of lake sediments in the carbon cycle: organic carbon preservation and methane emission

Titel Englisch The role of lake sediments in the carbon cycle: organic carbon preservation and methane emission
Gesuchsteller/in Wehrli Bernhard
Nummer 120112
Förderungsinstrument Projektförderung (Abt. I-III)
Forschungseinrichtung Abteilung Oberflächengewässer EAWAG
Hochschule Eidg. Anstalt für Wasserversorgung, Abwasserreinigung und Gewässerschutz - EAWAG
Hauptdisziplin Organische Chemie
Beginn/Ende 01.06.2008 - 31.05.2010
Bewilligter Betrag 272'191.00
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Keywords (10)

remineralization; chemical characterization; redox cinditions; mineral particles; mineralization; redox; oxygen; methane; particles; ebullition

Lay Summary (Englisch)

Lead
Lay summary
The burial of organic carbon in sediments is a major sink in the global carbon cycle. Substantial research efforts in oceanography were therefore directed towards a mechanistic understanding of the factors governing burial efficiencies. Recent estimates show that the total organic carbon burial in lake sediments could amount to about 50% of the marine flux. Published burial rates in different lakes differ by more than two orders of magnitude. Therefore, a more precise assessment of the role of lakes in global carbon budgets requires better mechanistic models of carbon accumulation and remobilization in their sediments. The second important unknown in the carbon balance of many lakes is methane emission, mainly via bubble plumes from sediments. Even though first estimates point towards a dominant role of bubble emission of methane from lakes, the extent and regulation of bubble transport is poorly constrained. With this interdisciplinary project we will analyze these two processes at carefully selected field sites. Based on previous results, we will test the following hypotheses: 1.Oxygen exposure time has a stronger influence on organic carbon burial in lake sediments than protective sorption onto mineral surfaces. 2.Selective accumulation of recalcitrant material from vascular plants and microbial detritus represents an additional factor for high burial efficiency.3.Oxygen exposure time and organic matter concentration strongly influence methane production in sediments.4.Methane release to the atmosphere is most intense at shallow river mouths with high organic carbon inputs. An extensive field campaign conducted at 11 geographically very distinct lake sites with contrasting oxygen exposure, mineral and organic phase characteristics has been initiated, and will be completed in this project. By covering a large range in the governing parameters, the study aims at identifying the important driving factors for carbon burial and methane release. To this end we combine sediment sampling, analysis and dating with micro sensor measurements of oxygen penetration and the analysis of organic matter quality and particle characteristics. Methane fluxes are measured by chamber techniques and acoustic echo sounding.The project will help constraining the role of lakes as organic carbon sinks and methane sources. The mechanistic understanding generated by the research will be used for an assessment of the sensitivity of these carbon fluxes to climatic and environmental change.
Direktlink auf Lay Summary Letzte Aktualisierung: 21.02.2013

Verantw. Gesuchsteller/in und weitere Gesuchstellende

Mitarbeitende

Publikationen

Publikation
Size Does Matter: Importance of Large Bubbles and Small-Scale Hot Spots for Methane Transport
DelSontro T., McGinnis D. F., Wehrli B., Ostrovsky I. (2015), Size Does Matter: Importance of Large Bubbles and Small-Scale Hot Spots for Methane Transport, in Environmental Science & Technology, 49(3), 1268-1276.
Low organic carbon burial efficiency in arctic lake sediments
Sobek S., Anderson N. J., Bernasconi S. M., Del Sontro T. (2014), Low organic carbon burial efficiency in arctic lake sediments, in Journal of Geophysical Research: Biogeosciences, 119(6), 1231-1243.
Extreme organic carbon burial fuels intense methane bubbling in a temperate reservoir
Sobek S., Delsontro T., Wongfun N., Wehrli B. (2012), Extreme organic carbon burial fuels intense methane bubbling in a temperate reservoir, in Geophysical Research Letters, 39(L01401), 1-4.
The burial efficiency of organic carbon in the sediments of Lake Kinneret
Sobek Sebastian, Zurbrügg Roland, Ostrovsky Ilia (2011), The burial efficiency of organic carbon in the sediments of Lake Kinneret, in Aquatic Sciences, 73, 355-364.
Eddy covariance flux measurements confirm extreme CH4 emissions from a Swiss hydropower reservoir and resolve their short-term variability
Eugster W., DelSontro T., Sobek S. (2011), Eddy covariance flux measurements confirm extreme CH4 emissions from a Swiss hydropower reservoir and resolve their short-term variability, in Biogeosciences, 8(9), 2815-2831.
Renewable but not carbon-free
Wehrli B. (2011), Renewable but not carbon-free, in Nature Geoscience, 4(9), 585-586.
Spatial heterogeneity of methane ebullition in a large tropical reservoir
Delsontro T., Kunz M.J., Kempter T., Wüest A., Wehrli B. (2011), Spatial heterogeneity of methane ebullition in a large tropical reservoir, in Environmental Science and Technology, 45(23), 9866-9873.
Extreme methane emissions from a swiss hydropower Reservoir: Contribution from bubbling sediments
Mcginnis D.F., Sobek S., Ostrovsky I., Wehrli B. (2010), Extreme methane emissions from a swiss hydropower Reservoir: Contribution from bubbling sediments, in Environmental Science and Technology, 44(7), 2419-2425.
Organic carbon burial efficiency in lake sediments controlled by oxygen exposure time and sediment source
Sobek S., Durisch-Kaiser E., Zurbrugg R., Wongfun N., Wessels M., Pasche N., Wehrli B. (2009), Organic carbon burial efficiency in lake sediments controlled by oxygen exposure time and sediment source, in Limnology and Oceanography, 54(6), 2243-2254.
Sources and emission of greenhouse gases in Danube Delta lakes.
Pavel A., Durisch-Kaiser E., Balan S., Radan S., Sobek S., Wehrli B. (2009), Sources and emission of greenhouse gases in Danube Delta lakes., in Environmental science and pollution research international, 16 (Suppl 1), S86-S91.

Kommunikation mit der Öffentlichkeit

Kommunikation Titel Medien Ort Jahr
Medienarbeit: Printmedien, Online-Medien Begraben im See – so binden Sedimente CO2 Eawag News Deutschschweiz 2009
Medienarbeit: Printmedien, Online-Medien Séquestration du CO2 dans les sédiments lacustres. Eawag News Westschweiz 2009

Verbundene Projekte

Nummer Titel Start Förderungsinstrument
130097 The role of lake sediments in the carbon cycle: methane emission 01.06.2010 Projektförderung (Abt. I-III)
112274 The role of lake sediments in the carbon cycle: organic carbon preservation and methane emission 01.06.2006 Projektförderung (Abt. I-III)
128707 High resolution in situ nutrient mapping of large rivers and reservoir systems 01.04.2010 R'EQUIP

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