Comparison of SF6 and flourescein as tracers for measuring transport processes in a large tidal river

David T. Ho, Peter Schlosser, Robert W. Houghton, Ted Caplow

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


We present the first large-scale comparison of a fluorescent dye [fluorescein (C20H10O5Na2)] and a gas [sulfur hexafluoride (SF6)] as tracers of advection and longitudinal dispersion from a dual tracer release experiment conducted in the tidal Hudson River. At the beginning of the experiment, 36 kg of fluorescein and ∼4.3 mol of SF6 were injected into the Hudson River at an averaged depth of 9.5 m, ∼1 m above the bottom, near Hyde Park, N.Y. After injection, fluorescein distributions were surveyed for 4 days (until it became undetectable) and SF6 distributions were surveyed for 10 days. The dye resolves initial vertical mixing on the day of injection, and then net advection and longitudinal dispersion, whereas SF6 provides information on net advection and longitudinal mixing on larger spatial scales and longer time scales. Quantitative estimates of transport processes (net advection and longitudinal dispersion) calculated from the two methods are consistent for the first three days, and start to deviate on the fourth day when the signal-to-noise ratio of the dye deteriorated.

Original languageEnglish (US)
Pages (from-to)1664-1669
Number of pages6
JournalJournal of Environmental Engineering
Issue number12
StatePublished - Dec 2006
Externally publishedYes


  • Advection
  • Dispersion
  • Dyes
  • Hudson River
  • Mixing
  • Tides
  • Tracers

ASJC Scopus subject areas

  • General Environmental Science
  • Environmental Engineering
  • Environmental Chemistry
  • Civil and Structural Engineering


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