Thin boundary layer model underestimates greenhouse gas diffusion from inland waterways

• Published in: Environmental research Vol. 233; p. 116472
• Main Authors: Liu, Boyi, Li, Ziqian, Wang, Jiayi, Zhang, Xinzhi, Kong, Lingwei, Zhu, Lin, Shi, Wenqing
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 15.09.2023
• Subjects: carbon dioxide; China; Gas transfer velocity; Greenhouse gas; greenhouse gases; liquid-air interface; methane; nitrous oxide; Thin boundary layer; Turbulence; turbulent flow; uncertainty; Waterway; wind speed; China; Waterway; Thin boundary layer; Turbulence; Gas transfer velocity; FFT; Greenhouse gas; GHG; CO2; N2O; BHGC; CH4; TBL
• ISSN: 0013-9351; 1096-0953; 1096-0953
• DOI: 10.1016/j.envres.2023.116472

Inland waters are significant sources of atmospheric greenhouse gas (GHG) emissions. The thin boundary layer (TBL) model is often employed as a means of estimating GHG diffusion in inland waters based on gas transfer velocity (k) at the air-water interface, with k being subject to regulation by near-surface turbulence that is primarily driven by wind speed in many cases. This wind speed-based estimation of k (wind-k), however, can introduce substantial uncertainty for turbulent waterways where wind speed does not accurately represent overall turbulence. In this study, GHG diffusion in the Beijing-Hangzhou Grand Canal (China), the first and longest man-made canal in the world, was estimated using the TBL model, revealing that this model substantially underestimated GHG diffusion when relying on wind-k. Strikingly, the carbon dioxide, methane, and nitrous oxide diffusions were respectively underestimated by 159%, 162%, and 124% when using this model. These findings are significant for developing more reliable approaches to evaluate GHG emissions from inland waterways. [Display omitted]