Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 9 5 2009 10.5194/acpd-9-22143-2009 http://www.atmos-chem-phys-discuss.net/9/22143/2009/ http://www.atmos-chem-phys-discuss.net/9/22143/2009/acpd-9-22143-2009.html http://www.atmos-chem-phys-discuss.net/9/22143/2009/acpd-9-22143-2009.pdf 22143 22175 2009-10-21 Toward a real-time measurement of atmospheric mercury concentrations using cavity ring-down spectroscopy X. Faïn xavier.fain@dri.edu H. Moosmüller D. Obrist Division of Atmospheric Sciences, Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512, USA A new sensor based on cavity ring-down spectroscopy (CRDS) has been developed for the measurement of gaseous elemental mercury (Hg0) mass concentration with sub-ng m−3 detection limit and high temporal resolution. Cavity ring-down spectroscopy is a direct absorption technique that utilizes path lengths of up to multiple kilometers in a compact absorption cell and has a significantly higher sensitivity than conventional absorption spectroscopy. Our prototype uses a frequency-doubled, tuneable dye laser emitting pulses at ~253.65 nm with a pulse repetition frequency of 50 Hz. The dye laser incorporates a unique piezo element attached to its tuning grating allowing it to tune the laser on and off the Hg0 absorption line on a pulse to pulse basis to facilitate differential absorption measurements. Hg0 absorption measurements with this CRDS laboratory prototype are highly linearly related to Hg0 concentrations determined by a Tekran 2537B analyzer over a Hg0 concentration range of four orders of magnitude, from 0.2 ng m−3 to 573 ng m−3 implying excellent linearity of both instruments. The current CRDS instrument has a~sensitivity of 0.10 ng m−3 at 10 s time resolution. This tool opens new prospects for the study of Hg0 because of its high temporal resolution and reduced limited sample volume requirements (<0.5 l of sample air). Future applications may include ambient Hg0 flux measurements with eddy covariance techniques, which require measurements of Hg0 concentrations with sub-ng m−3 sensitivity and sub-second time resolution. Anderson,~T N., Magnuson,~J K., and Lucht,~R P.: Diode-laser-based sensor for ultraviolet absorption measurements of atomic mercury, Appl. Phys. B-Lasers O., 87(2), 341–353, doi:10.1007/s00340-007-2604-z, 2007. ASTM: Standard practice for preparation and use of an ice-point bath as a~reference temperature, E563-082008. Bauer,~D., D'Ottone,~L., Campuzano-Jost,~P., and Hynes,~A J.: Gas phase elemental mercury: a~comparison of LIF detection techniques and study of the kinetics of reaction with the hydroxyl radical, J Photoch. Photobio A, 157, 247–256, doi:10.1016/S1010-6030(03)00065-0, 2003. Berden,~G., Peeters,~R., and Meijer,~G.: Cavity ring-down spectroscopy: experimental schemes and applications, Int. Rev. Phys. Chem., 19(4), 565–607, 2000. Carruthers,~A E., Lake,~T K., Shah,~A., Allen,~J W., Sibbett,~W., and Dholakia,~K.: Single-scan spectroscopy of mercury at 253.7 \unitnm by sum frequency mixing of violet and red microlensed diode lasers, Opt. Commun., 255(4–6), 261–266, doi:10.1016/j.optcom.2005.06.009, 2005. Carter,~C C.: A~Cavity Ring-Down Spectroscopy Mercury Continuous Emission Monitor, Sensor Research and Development Corporation, Orono, Maine 04473, 118~pp., 2004. Daly,~E J., Williamson,~G I., Rusbridge,~M G., and Jacobson,~A R.: The boxcar method for the analysis of non-gaussian random signals, Plasma Phys. Contr F., 27(7), 761–775, 1985. Duan,~Y X., Wang,~C J., Scherrer,~S T., and Winstead,~C B.: Development of alternative plasma sources for cavity ring-down measurements of mercury, Anal. Chem., 77(15), 4883–4889, doi:10.1021/ac050704x, 2005. Ebinghaus,~R., Jennings,~S G., Schroeder,~W H., Berg,~T., Donaghy,~T., Guentzel,~J., Kenny,~C., Kock,~H H., Kvietkus,~K., Landing,~W., Muhleck,~T., Munthe,~J., Prestbo,~E M., Schneeberger,~D., Slemr,~F., Sommar,~J., Urba,~A., Wallschlager,~D., and Xiao,~Z.: International field intercomparison measurements of atmospheric mercury species at Mace Head, Ireland, Atmos. Environ., 33(18), 3063–3073, 1999. Finkelstein,~N.: An ultraviolet laser source and spectral imaging filters for non-intrusive laser-based diagnositc, PhD thesis, Princeton University (Mechanical and aerospace engineering), 232~pp., 1998. Frohlich,~C. and Shaw,~G E.: New determination of Rayleigh-scattering in the terrestrial atmosphere, Appl. Opt., 19(11), 1773–1775, 1980. Jongma,~R T., Boogaarts,~M G H., Holleman,~I., and Meijer,~G.: Trace gas-detection with cavity ring down spectroscopy, Rev. Sci. Instrum., 66(4), 2821–2828, 1995. Moosmüller,~H., Varma,~R., and Arnott,~W P.: Cavity ring-down and cavity-enhanced detection techniques for the measurement of aerosol extinction, Aerosol Sci. Technol., 39, 30–39, doi:10.1080/027868290903880, 2005. O'Keefe,~A. and Deacon,~D A G.: Cavity ring-down optical spectrometer for absorption-measurements using pulsed laser sources, Rev. Sci. Instrum., 59(12), 2544–2551, 1988. Obrist,~D., Hallar,~A G., McCubbin,~I., Stephens,~B B., and Rahn,~T.: Atmospheric mercury concentrations at Storm Peak Laboratory in the Rocky Mountains: evidence for long-range transport from Asia, boundary layer contributions, and plant mercury uptake, Atmos. Environ., 42(33), 7579–7589, doi:10.1016/j.atmosenv.2008.06.051, 2008. Ramponi,~A J., Milanovich,~F P., Kan,~T., and Deacon,~D.: High-sensitivity atmospheric transmission measurements using a~Cavity Ringdown technique, Appl. Optics, 27(22), 4606–4608, 1988. Scheid,~M., Markert,~F., Walz,~J., Wang,~J Y., Kirchner,~M., and Hansch,~T W.: 750 \unitmW continuous-wave solid-state deep ultraviolet laser source at the 253.7 \unitnm transition in mercury, Opt. Lett., 32(8), 955–957, 2007. Schroeder,~W H., Keeler,~G., Kock,~H., Roussel,~P., Schneeberger,~D., and Schaedlich,~F.: International field intercomparison of atmospheric mercury measurement methods, Water Air Soil Pollut., 80, 611–620, 1995. Schroeder,~W H. and Munthe,~J.: Atmospheric mercury – an overview, Atmos. Environ., 32(5), 809–822, 1998. Spuler,~S., Linne,~M., Sappey,~A., and Snyder,~S.: Development of a~cavity ringdown laser absorption spectrometer for detection of trace levels of mercury, Appl. Optics, 39, 2480–2486, 2000. Stanford Research Systems: Application Note #4: photon counting, lock-in detection, or Boxcar averaging, Sunnyvale, CA, 2001. Tao,~S Q., Mazzotti,~F J., Winstead,~C B., and Miller,~G P.: Determination of elemental mercury by cavity ringdown spectrometry, Analyst, 125(6), 1021–1023, 2000. Tian,~G., Moosmüller,~H., and Arnott,~W P.: Simultaneous photoacoustic spectroscopy of aerosol and oxygen A-band absorption for the calibration of aerosol light absorption measurements, Aerosol Sci. Technol., 43, 1084–1090, doi:10.1080/02786820903170972, 2009. Valente,~R J., Shea,~C., Humes,~K L., and Tanner,~R L.: Atmospheric mercury in the Great Smoky Mountains compared to regional and global levels, Atmos. Environ., 41(9), 1861–1873, doi:10.1016/j.atmosenv.2006.10.054, 2007. Wang,~C J., Scherrer,~S T., Duan,~Y X., and Winstead,~C B.: Cavity ringdown measurements of mercury and its hyperfine structures at 254 \unitnm in an atmospheric microwave plasma: spectral interference and analytical performance, J Anal. Atom. Spectrom., 20(7), 638–644, doi:10.1039/b504318b, 2005.