Quantifying the contribution of methane diffusion and ebullition from agricultural ditches

Xueqi Niu; Wenxin Wu; Weiwei Shi; Zihuan Fu; Xingxing Han; Si-Liang Li; Zhifeng Yan

doi:10.1016/j.scitotenv.2024.170912

Quantifying the contribution of methane diffusion and ebullition from agricultural ditches

Sci Total Environ. 2024 Apr 1:919:170912. doi: 10.1016/j.scitotenv.2024.170912. Epub 2024 Feb 12.

Authors

Xueqi Niu¹, Wenxin Wu², Weiwei Shi¹, Zihuan Fu¹, Xingxing Han¹, Si-Liang Li³, Zhifeng Yan⁴

Affiliations

¹ Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China.
² Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China. Electronic address: wwxin@tju.edu.cn.
³ Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China; Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China; Tianjin Bohai Rim Coastal Earth Critical Zone National Observation and Research Station, Tianjin University, Tianjin 300072, China.
⁴ Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China; Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China; Tianjin Bohai Rim Coastal Earth Critical Zone National Observation and Research Station, Tianjin University, Tianjin 300072, China. Electronic address: yanzf17@tju.edu.cn.

PMID: 38354794
DOI: 10.1016/j.scitotenv.2024.170912

Abstract

Agricultural ditches are significant methane (CH₄) sources since substantial nutrient inputs stimulate CH₄ production and emission. However, few studies have quantified the role of diffusion and ebullition pathways in total CH₄ emission from agricultural ditches. This study measured the spatiotemporal variations of diffusive and ebullitive CH₄ fluxes from a multi-level ditch system in a typical temperate agriculture area, and assessed their contributions to the total CH₄ emission. Results illustrated that the mean annual CH₄ flux in the ditch system reached 1475.1 mg m^-2 d^-1, among which 1376.7 mg m^-2 d^-1 was emitted via diffusion and 98.5 mg m^-2 d^-1 via ebullition. Both diffusive and ebullitive fluxes varied significantly across different types of ditches and seasons, with diffusion dominating CH₄ emission in middle-size ditches and ebullition dominating in large-size ditches. Diffusion was primarily driven by large nutrient inputs from adjacent farmlands, while hydrological factors like water temperature and depth controlled ebullition. Overall, CH₄ emission accounted for 86 % of the global warming potential across the ditch system, with 81 % attributed to diffusion and 5 % to ebullition. This study highlights the importance of agricultural ditches as hotspots for CH₄ emissions, particularly the dominant role of the diffusion pathway.

Keywords: Agricultural ditches; Diffusion; Ebullition; Global warming potential; Methane (CH(4)) emissions.