Advancing the understanding of the aquatic methane cycle through cutting-edge isotopic approaches and methane oxidation analysis (AMIOX)

Goals

• Improve classification and identification of CH₄ sources and sinks in temperate and Arctic aquatic environments
• Validate the novel stable isotope parameter Δ(2,13) for correcting isotopic fractionation caused by methane oxidation (MOx)
• Update established classification schemes (¹³C vs. ²H plots, Bernard plots)

Specifically

• Laboratory incubation experiments with three methanotrophic bacterial species to assess the influence of MOx on Δ(2,13) values
• Quantification of simultaneous oxidation of CH₄, C₂H₆ and C₃H₈ and its impact on Bernard ratios
• Field campaigns at temperate lakes (Lake Willersinnweiher, Lake Stechlin) and Arctic lakes (Nuussuaq Peninsula, Greenland)
• Stable isotope analyses (δ¹³C-CH₄, δ²H-CH₄) and concentration measurements of CH₄, C₂H₆ and C₃H₈

Project Lead

• Heidelberg University — Biogeochemistry Group
• Dr. Moritz Schroll

Cooperation Partners

• Heidelberg University — Biogeochemistry Group (Prof. Frank Keppler, Dr. Markus Greule)
• IGB Stechlinsee/University of Potsdam— Plankton and Microbial Ecology Group (Prof. Hans-Peter Grossart)
• COS Heidelberg University (Dr. Steffen Greiner)
• University of Copenhagen (Assoc. Prof. Jesper R. Christiansen)

Funding

German Research Foundation (DFG)

Activities & Progress

• Incubation experiments with Methylocystis hirsuta, Methylocystis rosea and Methylosinus sp. B4S
• Laboratory studies on simultaneous oxidation of CH₄, C₂H₆ and C₃H₈ and effects on Bernard plots
• Field campaign on the Nuussuaq Peninsula, Greenland (Summer 2025)