Methane ebullition fluxes and temperature sensitivity in a shallow lake

Fan Xun; Muhua Feng; Shuzhan Ma; He Chen; Wangshou Zhang; Zhendu Mao; Yongqiang Zhou; Qitao Xiao; Qinglong L Wu; Peng Xing

doi:10.1016/j.scitotenv.2023.169589

Methane ebullition fluxes and temperature sensitivity in a shallow lake

Sci Total Environ. 2024 Feb 20:912:169589. doi: 10.1016/j.scitotenv.2023.169589. Epub 2023 Dec 25.

Authors

Fan Xun¹, Muhua Feng², Shuzhan Ma³, He Chen¹, Wangshou Zhang², Zhendu Mao¹, Yongqiang Zhou², Qitao Xiao², Qinglong L Wu², Peng Xing⁴

Affiliations

¹ State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
² State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
³ State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; Jiangsu Provincial Key Laboratory of Environmental Engineering, Jiangsu Provincial Academy of Environmental Science, Nanjing 210036, China.
⁴ State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China. Electronic address: pxing@niglas.ac.cn.

PMID: 38151123
DOI: 10.1016/j.scitotenv.2023.169589

Abstract

Inland waters are important sources of atmospheric methane (CH₄), with a major contribution from the CH₄ ebullition pathway. However, there is still a lack of CH₄ ebullition flux (eFCH₄) and their temperature sensitivity (Q₁₀) in shallow lakes, which might lead to large uncertainties in CH₄ emission response from aquatic to climate and environmental change. Herein, the magnitude and regulatory of two CH₄ pathways (ebullition and diffusion) were studied in subtropical Lake Chaohu, China, using the real-time portable greenhouse gas (GHG) analyzer-floating chamber method at 18 sites over four seasons. eFCH₄ (12.06 ± 4.10 nmol m^-2 s^-1) was the dominant contributing pathway (73.0 %) to the two CH₄ emission pathways in Lake Chaohu. The whole-lake mass balance calculation demonstrated that 56.6 % of the CH₄ emitted from the sediment escaped through the ebullition pathway. eFCH₄ was significantly higher in the western (WL: 16.54 ± 22.22 nmol m^-2 s^-1) and eastern lake zones (EL: 11.89 ± 15.43 nmol m^-2 s^-1) than in the middle lake zone (ML: 8.86 ± 13.78 nmol m^-2 s^-1; p < 0.05) and were significantly higher in the nearshore lake zone (NL: 15.94 ± 19.58 nmol m^-2 s^-1) than in the pelagic lake zone (PL: 6.64 ± 12.37 nmol m^-2 s^-1; p < 0.05). eFCH₄ was significantly higher in summer (32.12 ± 13.82 nmol m^-2 s^-1) than in other seasons (p < 0.05). eFCH₄ had a strong temperature dependence. Sediment total organic carbon (STOC) is an important ecosystem level Q₁₀ driver of eFCH₄. The meta-analysis also verified that across ecosystems the ecosystem-level Q₁₀ of eFCH₄ was significantly positively correlated with STOC and latitude (p < 0.05). This study suggests that eFCH₄ will become increasingly crucial in shallow lake ecosystems as climate change and human activities increase. The potential increase in ebullition fluxes in high-latitude lakes is of great importance.

Keywords: CH(4) emissions; Ebullition; Large shallow lakes; Organic matters; Spatial-temporal variability.