Preliminary investigation into feasibility of dissolved methane measurement using cavity ringdown spectroscopy technique

Abstract

For the exploration of gas hydrate resources by measuring the dissolved methane concentration in seawater, a continuous-wave cavity ringdown spectroscopy (CW-CRDS) experimental setup was constructed for trace methane detection. A current-modulation method, rather than a cavity-modulation method using an optical switch and a piezoelectric transducer, was employed to realize the cavity excitation and shutoff. Such a current-modulation method enabled the improvement of the experimental setup construction and stability, and the system size and stability are critical for a sensor to be deployed underwater. Ringdown data acquisition and processing were performed, followed by an evaluation of the experimental setup stability and sensitivity. The obtained results demonstrate that great errors are introduced when a large fitting window is selected if the analog-to-digital converter has an insufficient resolution. The ringdown spectrum of methane corresponding to the 2v3 band R(4) branch was captured, and the methane concentration in lab air was determined to be 2.06 ppm. Further experiments for evaluating the quantitative ability of this CW-CRDS experimental setup are underway from which a high-sensitivity methane sensor that can be combined with a degassing system is expected.

Keywords

gas hydrate / methane / continuous-wave cavity ringdown spectroscopy / current-modulation method

References

[1] R. D. Hyndman and G. D. Spence, A seismic study of methane hydrate marine bottom simulating reflectors, J. Geophys. Res. 97(B5), 6683 (1992)

[2] R. D. Hyndman and E. E. Davis, A mechanism for the formation of methane hydrate and seafloor bottomsimulating reflectors by vertical fluid expulsion, J. Geophys. Res. 97(B5), 7025 (1992)

[3] W. S. Holbrook, H. Hoskins, W. T. Wood, R. A. Stephen, and D. Lizarralde, Methane hydrate and free gas on the Blake Ridge from vertical seismic profiling, Science 273(5283), 1840 (1996)

[4] J. Yuan and R. N. Edwards, The assessment of marine gas hydrates through electrical remote sounding: Hydrate without a BSR? Geophys. Res. Lett. 27(16), 2397 (2000)

[5] T. F. Yang, P. C. Chuang, S. Lin, J. C. Chen, Y. Wang, and S. H. Chung, Methane venting in gas hydrate potential area offshore of SW Taiwan: evidence of gas analysis of water column samples, Terr. Atmos. Ocean. Sci. 17, 933 (2006)

[6] C. K. Paull, W. Ussler, W. S. Borowski, and F. N. Spiess, Methane-rich plumes on the Carolina continental rise: Associations with gas hydrates, Geology 23(1), 89 (1995)

[7] C. A. Chen, Abnormally high CH₄ concentrations in seawater at mid-depths on the continental slopes of the northern South China Sea, Terr. Atmos. Ocean. Sci. 17, 951 (2006)

[8] Y. Zhang, Methane escape from gas hydrate systems in marine environment, and methane-driven oceanic eruptions, Geophys. Res. Lett. 30(7), 1398 (2003)

[9] H. Zhou, Z. Wu, X. Peng, L. Jiang, and S. Tang, Detection of methane plumes in the water column of Logatchev hydrothermal vent field, Mid-Atlantic Ridge, Chin. Sci. Bull. 52(15), 2140 (2007)

[10] E. J. Sauter, S. I. Muyakshin, J. L. Charlou, M. Schlüter,, A. Boetius, K. Jerosch, E. Damm, J. P. Foucher, and M. Klages, Methane discharge from a deep-sea submarine mud volcano into the upper water column by gas hydratecoated methane bubbles, Earth Planet. Sci. Lett. 243(3-4), 354 (2006)

[11] S. Watanabe, N. Higashitani, N. Tsurushima, and S. Tsunogai, Methane in the western North Pacific, J. Oceanogr. 51(1), 39 (1995)

[12] H. W. Bange, U. H. Bartell, S. Rapsomanikis, and M. O. Andreae, Methane in the Baltic and North Seas and a reassessment of the marine emissions of methane, Global Biogeochem. Cycles 8(4), 465 (1994)

[13] N. J. P. Owens, C. S. Law, R. F. C. Mantoura, P. H. Burkill, and C. A. Llewellyn, Methane flux to the atmosphere from the Arabian Sea, Nature 354(6351), 293 (1991)

[14] B. D. Tilbrook and D. M. Karl, Methane sources, distributions and sinks from California coastal waters to the oligotrophic North Pacific gyre, Mar. Chem. 49(1), 51 (1995)

[15] A. O’Keefe and D. A. G. Deacon, Cavity ring‐down optical spectrometer for absorption measurements using pulsed laser sources, Rev. Sci. Instrum. 59(12), 2544 (1988)

[16] D. Romanini, A. A. Kachanov, N. Sadeghi, and F. Stoeckel, CW cavity ring down spectroscopy, Chem. Phys. Lett. 264(3–4), 316 (1997)

[17] B. L. Fawcett, A. M. Parkes, D. E. Shallcross, and A. J. Orr-Ewing, Trace detection of methane using continuous wave cavity ring-down spectroscopy at 1.65 μm, Phys. Chem. Chem. Phys. 4(24), 5960 (2002)

[18] M. Hippler and M. Quack, High-resolution Fourier transform infrared and cw-diode laser cavity ringdown spectroscopy of the v2+2v₃ band of methane near 7510 cm⁻¹ in slit jet expansions and at room temperature, J. Chem. Phys. 116(14), 6045 (2002)

[19] J. J. Scherer, D. Voelkel, D. J. Rakestraw, J. B. Paul, C. P. Collier, R. J. Saykally, and A. O’Keefe, Infrared cavity ringdown laser absorption spectroscopy (IR-CRLAS), Chem. Phys. Lett. 245(2–3), 273 (1995)

[20] C. Wang, N. Srivastava, B. A. Jones, and R. B. Reese, A novel multiple species ringdown spectrometer for in situ measurements of methane, carbon dioxide, and carbon isotope, Appl. Phys. B 92(2), 259 (2008)

[21] E. R. Crosson, A cavity ring-down analyzer for measuring atmospheric levels of methane, carbon dioxide, and water vapor, Appl. Phys. B 92(3), 403 (2008)

[22] S. A. Yvon-Lewis, L. Hu, J. D. Kessler, F. Garcia Tigreros, E. W. Chan, and M. Du, Methane flux to the atmosphere from the Deepwater Horizon oil leak, AGU Fall Meet. Abstr. 1, 06 (2010)

[23] W. Gülzow, G. Rehder, B. Schneider, J. S. V. Deimling, and B. Sadkowiak,Limnol. A new method for continuous measurement of methane and carbon dioxide in surface waters using off-axis integrated cavity output spectroscopy (ICOS): An example from the Baltic Sea, Oceanogr, Methods 9, 176 (2011)

[24] M. Heimann, Atmospheric science: Enigma of the recent methane budget, Nature 476(7359), 157 (2011)

RIGHTS & PERMISSIONS

2016 Higher Education Press and Springer-Verlag Berlin Heidelberg