![Sample our Earth Sciences journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5930/TOC-Subject-Sample-2021-Earth-Sciences.jpg"})
Abstract
Methane is a strong greenhouse gas. Inland waters are thought to be important sources of methane, although detailed studies of emissions (diffusion and ebullition) are limited. This is the reason why we investigated the sediments of three anthropogenic lakes with respect to methane formation. Methane of microbial origin could be proved in any case. In one case, methane was released into the atmosphere by ebullition. The measured fluxes ranged between 134 and 935 mg CH4 m−2d−1. The fluxes close above the sediments were higher (274–4107 mg CH4 m−2d−1). The decrease of methane content in the bubbles from greater to lower sampling depths is connected with an increase in its δ13C values. The Rayleigh equation has been used to calculate fractionation factors α between 1.0104 and 1.0163, which means that the changes are due to oxidation processes within the predominant oxic water column. However, large amounts of methane still reach the atmosphere.
Acknowledgements
Our thanks go to A. Jähn and S. Steinbrenner (INC Leipzig) for the laboratory and analytical work. K. Jendryschik (Leipzig) supported us with gas sampling. For the use of the private boat at Windischleuba reservoir, we thank M. Dathe (Windischleuba). For discussion of results, we thank Professor Dr. D. Uhlmann very much. We are grateful for the constructive criticism of Dr. Karin Bräuer whose useful suggestions greatly improved the manuscript.