Temperature and sediment properties drive spatiotemporal variability of methane ebullition in a small and shallow temperate lake

Abstract

Ebullition is a major pathway of methane (CH 4 ) fluxes from lakes to the atmosphere. Small and shallow lakes can have high emissions but have only recently gained more attention. We studied the quantity and spatiotemporal variability of CH 4 ebullition from a small (1.4 ha) and shallow (max 1.5 m) temperate lake in Germany during 2017 and 2018. We found a high range of fluxes (0-872 mg m −2 d −1 ) and > 90% of the fluxes were emitted between May and August. Fluxes in early spring and late autumn were below 4 mg m −2 d −1 . Also, on a spatial scale, fluxes varied distinctly and generally increased from the shore to the center of the lake. To identify drivers of observed emissions patterns, we measured temperature and air pressure, the quantity and quality of the sedimented organic matter (OM) as well as chemical and physical properties of the sediment. Generalized linear models identified temperature, sediment porosity and organic matter content as the best predictors for the observed spatiotemporal differences, whereas temperature was accountable for the observed temporal, and porosity and organic matter content for the spatial variability. We suggest that in small lakes, temperature could serve as master variable to predict site-specific CH 4 ebullition while spatial within-lake differences are determined by varying physical sediment properties more than quantity or quality of the OM.

Geospatial analysis of Alaskan lakes indicates wetland fraction and surface water area are useful predictors of methane ebullition

“…Both lake area and temperature, for example, are commonly cited as correlates of methane ebullition flux in detailed field studies (e.g. Praetzel, Schmiedeskamp, and Knorr 2021), which is also consistent with the results of our broad-domain study. While the reported correlations are stronger than the ones presented here, they also consider far fewer lakes and smaller spatial domains.…”

“…Nonetheless, many regression-based ebullition studies report lake area to be a leading predictor variable Deemer and Holgerson 2021;, along with temperature (air, water, and sediment temperature are inherently correlated and thus variously used, e.g. Aben et al 2017;Praetzel, Schmiedeskamp, and Knorr 2021;Yvon-Durocher et al 2014).…”

Lake Sediments From Littoral and Profundal Zones are Heterogeneous but Equivalent Sources of Methane Produced by Distinct Methanogenic Communities—A Case Study From Lake Remoray

“…However, sediment methane concentration and diffusion were measured during the summer oxygen depletion period and would probably be even higher in late fall when stronger hypoxia/anoxia prevails in the hypolimnion. Our work only focused on the diffusive component of the methane transfer from the sediment to the water column, and ebullition fluxes, which could also lead to the transfer of the important amount of methane to the water column and the atmosphere, were not addressed (Praetzel et al., 2021).…”

Simulated methane emissions from Arctic ponds are highly sensitive to warming

“…When estimating the landscape-scale impact of methane emissions from ponds and lakes, many studies concentrate on diffusive emissions (Juutinen et al, 2009;Holgerson and Raymond, 2016;Polishchuk et al, 2018;Hughes-Allen et al, 2021;Zabelina et al, 2020), though some also include ebullition (Sepulveda-Jauregui et al, 2015;Wik et al, 2016;Kuhn et al, 2021). We find that including ebullition is important because, in ponds, ebullition contributes more than diffusion to the total emissions (Kuhn et al, 2021;Praetzel et al, 2021) and becomes much more important with warming (Fig. 10).…”