Dates: 17th - 21st October 2016
Location: EPFL, Lausanne, Switzerland
Local organiser: Tom Battin
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TW3 group photos: Participants, lecturers, and organizers: one dry at EPFL and one wet at Pont-de-Nant (field trip)
Summary of the workshop:
The training workshop at EPFL, Lausanne, Switzerland, was all about gas exchange between inland waters and the atmosphere. Besides 7 of the C-Cascades ESRs, several PhD students, technicians and postdocs from EPFL and several other universities joined the interesting lectures, which addressed four main topics: measurement of pCO2 and pCH4 with sensors, calculation of pCO2 using the chemical properties, estimating metabolism and the gas transfer velocity (k) from O2 curves, and the assessment of CH4 ebullition.
At the beginning, Peer Fietzek (KM Contros GmbH) introduced us deeply into the world of CO2 and CH4 sensors, their deployment and necessary considerations concerning calibration and validation of results. This theoretical part was accompanied by an afternoon excursion to one of the field sites of the Stream Biofilm and Ecosystem Research (SBER) Group at EPFL. In the Vallon de Nant, western Switzerland, they are using a set of sensors to monitor the seasonal changes in pCO2, O2 and several other parameters. Thanks to marvellous weather, water was ubiquitous…mainly from above, draining rain jackets, trousers and shoes, which were dried again close to the fire place while having traditional Swiss Cheese-Fondue for dinner.
Tuesday started with small presentations of the participants which showed the links of the workshop content to their own research. In the afternoon, Bernhard Wehrli (ETH Zürich) explained how pCO2 can be calculated via alkalinity and pH relations and the pitfalls associated with that. In the following computer exercise, led by Marie-Sophie Maier (ETH Zürich), the students gained hands-on experience with CO2SYS.
The next block moved stream metabolism into the centre of attention, while emphasising the importance of gas transfer estimates for calculations of metabolic parameters such as gross primary production (GPP) and ecosystem respiration (ER) from O2-time series. Bob Hall (University of Wyoming) presented the underlying theory, as well as a little recap on different measurements used to assess the gas transfer coefficient (k). With the R-package streamMetabolizer, he introduced a valuable tool to evaluate metabolism parameters and estimate the net ecosystem production (NEP).
Natacha Pasche (EPFL) acquainted us on Thursday morning with the carbon evasion dynamics of a seasonally ice-covered bay in Lake Onego, Russia. Her talk was followed by a presentation from Daniel McGinnis (University of Geneva) on CH4 emissions from lakes and reservoirs. Amongst other topics, he introduced us to a bubble dissolution model, which estimates the concentration changes within rising CH4 gas bubbles.
The last day was used for a thorough wrap up and discussion of the things encountered during the previous days, especially with regard to upscaling of locally measured CO2 and CH4 fluxes to a global estimate. Main focus were potential sources of error or uncertainties.
Overall, the workshop was very inspiring for many of us and especially the tools introduced during the afternoon exercises will be useful for our individual data analysis. Thanks to the organizers at EPFL!
written by Åsa Horgby and Marie Maier
List of the participants:
1. Åsa Horgby (ESR2 - C-CASCADES) - EPFL
2. Jo Snöälv (ESR3 - C-CASCADES) - UNEXE
3. Anna Nydahl (ESR4 - C-CASCADES) - UU
4. Audrey Marescaux (ESR5 - C-CASCADES) - CNRS-IPSL
5. Marie-Sophie Maier (ESR6 - C-CASCADES) - ETHZ
6. Matteo Puglini (ESR10 - C-CASCADES) - MPI
7. Fabrice Lacroix (ESR15 - C-CASCADES) - MPG
8. Antonin Verlet-Banide - UU
9. Chiara Volta - ULB
10. Edurne Estévez Caño - University of Cantabria
11. Juliana Valle das Neves - Technische Universität München
12. Maja Pelve - UU
13. Marta Boix-Canadell - EPFL
14. Pier-Luigi Segatto - EPFL
List of lecturers:
- Peer Fietzek (KM Contros GmbH): Technologies and Applications for dissolved CO2 and CH4 Measurements
- Dr. Bernhard Wehrli (ETHZ): Calculating pCO2 (and fluxes) from standard monitoring data
- Dr. Robert Odgen Hall (University of Wyoming): Metabolism and gas exchange
- Dr. Natacha Pasche (EPFL): Impact of river water inflow on under ice spatial distribution of CO2 in Petrozavodsk Bay, Lake Onego in Russia
- Dr. Daniel McGinnis (University of Geneva): Limnology: Methane transport and emissions