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Environmental Tracer Group

David Ho: Doherty Research Scientist

Lamont-Doherty Earth Observatory
61 Route 9W
Palisades, NY 10964

(845) 365-8706

david@ldeo.columbia.edu
http://duck-rabbit.ldeo.columbia.edu

Research Interest

To assess how human impact will affect the natural environment, we need to understand the relevant environmental processes. I have focused my studies on transport processes in natural systems (atmosphere, oceans, lakes, rivers and groundwater), using natural and anthropogenic tracers.

Tracers, whether they are of natural or anthropogenic origin, have the potential to be valuable tools for studies of the dynamics of the atmosphere and natural water systems. The tracer techniques that I have employed could be divided into two categories: 1) transient tracers, which are like 'dyes' with known delivery rates to the environment (CFCs, SF6); and 2) deliberate tracers, which are purposefully released into water bodies (SF6, N2O, 4He, 3He, florescent dyes).

I am currently working on the following projects:

  • Influence of rain on air-water gas exchange
  • Measurement of air-water gas exchange in estuaries and open ocean with 3He/SF6
  • Development of SF6 as a transient tracer for ocean circulation
  • Development of SF5CF3 as an ocean tracer.
  • Transport and mixing in continental waters (wetlands, rivers and estuaries)
  • Use of SF6 as a transient tracer in groundwater

Selected Publications

Ho, D. T., C. S. Law, M. Smith, P. Schlosser, M. Harvey, and P. Hill, Measurements of air-sea gas exchange at high wind speeds in the Southern Ocean: Implications for global parameterizations, Geophy. Res. Lett., 33, L16611, doi:16610.11029/12006GL026817, 2006.

Bender, M. L., D. T. Ho, M. B. Hendricks, R. Mika, M. O. Battle, P. P. Tans, T. J. Conway, B. Sturtevant, and N. Cassar, Atmospheric O2/N2 changes, 1993-2002: Implications for the partitioning of fossil fuel CO2 sequestration, Glob. Biogeochem. Cycle, 19, doi:10.1029/2004GB002410, 2005.

Ho, D. T., C. J. Zappa, W. R. McGillis, L. F. Bliven, B. Ward, J. W. H. Dacey, P. Schlosser, and M. B. Hendricks, Influence of rain on air-sea gas exchange: Lessons from a model ocean, J. Geophys. Res., 109, doi:10.1029/2003JC001806, 2004.

Caplow, T., P. Schlosser, D. T. Ho, and N. Santella, Transport dynamics in a sheltered estuary and connecting tidal straits: SF6 tracer study in New York Harbor, Environ. Sci. Technol., 37, 5116-5126. 2003.

Battle, M., M. Bender, M.B. Hendricks, D.T. Ho, R. Mika, G. McKinley, S.-M. Fan, T. Blaine, and R.F. Keeling, Measurements and models of the atmospheric Ar/N2 ratio, Geophys. Res. Lett., 30, doi:10.1029/2003GL017411, 2003.

Ho, D.T., P. Schlosser, and T. Caplow, Determination of longitudinal dispersion coefficient and net advection in the tidal Hudson River with a large-scale, high resolution SF6 tracer release experiment, Environ. Sci. Technol., 36, 3234-3241, 2002.

Ho, D.T., W.E. Asher, L.F. Bliven, P. Schlosser, and E.L. Gordan, On mechanisms of rain-induced air-water gas exchange, Journal of Geophysical Research, 105, 24,045-24,057, 2000.

Ho,D.T., P. Schlosser, W.M. Smethie, Jr., H.J. Simpson, Variability in atmospheric chlorofluorocarbons (CCl3F and CCl2F2) near a large urban area: Implications for groundwater dating, Environmental Science & Technology, 32, 2377-2382, 1998.

Wanninkhof, R., G. Hitchcock, W.J. Wiseman, G. Vargo, P.B. Ortner, W. Asher, D.T. Ho, P. Schlosser, M.-L. Dickson, M. Anderson, R. Masserini, K. Fanning, and J.-Z. Zhang, Gas exchange, dispersion, and biological productivity on the west Florida shelf: Results from a Lagrangian tracer study, Geophysical Research Letters, 24, 1767-1770, 1997.

Ho, D.T., L.F. Bliven, R. Wanninkhof, and P. Schlosser, The effect of rain on air-water gas exchange, Tellus, 49, 149-158, 1997.

Clark, J.F., P. Schlosser, R. Wanninkhof, H.J. Simpson, W.S.F. Schuster, and D.T. Ho, Gas transfer velocities for SF6 and 3He in a small pond at low wind speeds, Geophysical Research Letters, 22, 93-96, 1995.

 

  July 14, 2007