Dresden 2026 – wissenschaftliches Programm

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UP: Fachverband Umweltphysik

UP 7: Aquatic Systems: Limnology, Natural Waters, Wetlands and Soilmoisture

UP 7.3: Vortrag

Mittwoch, 11. März 2026, 11:45–12:00, MER/0002

First Observations of Extreme Gas Accumulation in Meromictic Lake Kilevann — •Bertram Reventlow^1,2, Bertram Boehrer², Florian Meienburg¹, Joshua Marks², Marius Feuerle¹, Martina Schmidt¹, and Werner Aeschbach¹ — ¹Institute of Environmental Physics, Heidelberg, Germany — ²Helmholtz Centre for Environmental Research - UFZ, Magdeburg, Germany

Lake Kilevann in southern Norway is a former fjord that became isolated from the sea about 8000 years ago due to isostatic rebound. In its deepest basin, a strongly stratified layer of ancient seawater remains trapped between 60 and 100 m depth. Such isolated layers in meromictic lakes tend to accumulate gases, which can lead to limnic eruptions. In Lake Kilevann, we measured methane concentrations among the highest ever recorded in lakes. Isotopic analyses of CO₂ and CH₄ indicate long carbon residence times, a biogenic origin, and active methanogenesis in the water column. Preliminary noble gas measurements suggest strong depletion, supporting the hypothesis of bubble-mediated gas transfer, which could potentially trigger an eruption. On the other hand, the water column is strongly stratified, except for a single double-diffusive convection cell near the lake bottom. Major ions exhibit fractionated depletion relative to oceanic values, indicating that molecular diffusion over the lake’s lifetime is a key mechanism driving the dilution of the seawater.

Keywords: Limnology; Meromictic Lake; Methane and Carbon Dioxide; Isotope Hydrology; Flow dynamics