Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany
Abstract. Ponds play a critical role in biogeochemical carbon cycling and have been identified as hot spots of methane (CH4) emission. Yet, most existing studies focused on ponds in the boreal zone and current estimates of the relevance of ponds in global CH4 budgets as well as knowledge of the environmental factors regulating their emissions are poorly constrained. Both nutrient concentration and temperature can potentially alter CH4 dynamics in shallow ponds, but there are still few investigations into the response of CH4 emission to nutrient enrichment and rising temperatures. Here we studied the magnitude and regulation of two CH4 pathways (diffusion and ebullition) from a shallow and eutrophic pond located in the subtropical zone in Central China. Ebullitive fluxes were on average 96.4 mg CH4 m−2 d−1 and contributed 88.6 % to the total (diffusive + ebullition) CH4 emissions. Daily CH4 fluxes were related to daily mean water temperature, with ebullition having a stronger temperature dependence than diffusion (Q10 of 5.52 vs. 2.05). Relationships between temperature and CH4 emission were affected by seasonal variation of the concentration of total phosphorus. The temperature dependence of both ebullitive and diffusive fluxes increased with increasing phosphorous concentration. Our study highlights that increasing eutrophication by anthropogenic impacts and climate warming will increase CH4 emissions from ponds, thus representing a positive feedback mechanism to global warming.
How to cite. Zhang, W., Xiao, S., Xie, H., Liu, J., Lei, D., and Lorke, A.: Diel and seasonal variability of methane emissions from a shallow and eutrophic pond, Biogeosciences Discuss. [preprint], https://doi.org/10.5194/bg-2020-178, 2020.
Received: 20 May 2020 – Discussion started: 01 Jul 2020
We analyzed CH4 emissions from a shallow and small eutrophic pond and found that 88.6 % of CH4 emissions was directly released by bubbling. The higher the temperature, the higher the eutrophication level and the greater the amount of methane released. Our study highlights that increasing eutrophication by anthropogenic impacts and climate warming will increase CH4 emissions from ponds, thus representing a positive feedback mechanism to global warming.
We analyzed CH4 emissions from a shallow and small eutrophic pond and found that 88.6 % of CH4...