The control of sediment gas accumulation on spatial distribution of ebullition in Lake Kinneret
| Autor: | Regina Katsman, Liu Liu, Ilia Ostrovsky, Klajdi Sotiri, J. Wilkinson, Ernst Uzhansky, Stephan Hilgert, Yannick Dück, Revital Bookman, Andreas Lorke, Boris Katsnelson |
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| Rok vydání: | 2019 |
| Předmět: |
Hydrology
010504 meteorology & atmospheric sciences Sediment Environmental Science (miscellaneous) 010502 geochemistry & geophysics Geotechnical Engineering and Engineering Geology Oceanography Spatial distribution 01 natural sciences Methane Waves and shallow water chemistry.chemical_compound chemistry Earth and Planetary Sciences (miscellaneous) Littoral zone Spatial variability Sulfate Transect Geology 0105 earth and related environmental sciences |
| Zdroj: | Geo-Marine Letters. 40:453-466 |
| ISSN: | 1432-1157 0276-0460 |
| Popis: | In freshwater lakes, ebullition is an important pathway for biogenic methane (CH4) to escape from sediment and reach the atmosphere. However, the high spatial and temporal variability of ebullition limits our ability to accurately measure or predict CH4 fluxes from lakes. To explore factors controlling the spatial distribution of ebullition, we investigated free gas accumulation in bottom sediment of Lake Kinneret, Israel. Sediment cores were collected from four sites at different water depth and distance from the shore. Sediment porewater was analyzed for dissolved CH4 concentration, pH, DOC, acetate, and sulfate. Anaerobic CH4 production rates in sediment were determined by incubating sediment samples. For characterizing in situ sediment volumetric gas content, hydroacoustic measurements at various frequencies were conducted at the coring sites and along multiple transects across the lake. A minimum in CH4 production was observed in the upper 30 cm of sediment, which coincided with enriched porewater sulfate. The depth-integrated sediment CH4 production provides a robust estimate for long-term ebullition of CH4 from sediment, while short-term variability was associated with seasonal lake level change. Acoustic measurements revealed the absence of free gas in sediments of the littoral zone and low ebullition rates in the shallow water zones. For the first time, this study reports the role of CH4 production in determining the spatial variability of free gas content in freshwater sediments. The results further demonstrate the importance of sediment gas content in explaining spatial variability of gas ebullition in lakes. |
| Databáze: | OpenAIRE |
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