Effect of tides on solute flushing from a strait: Imaging flow and transport in the East River with SF6

Publication Type  Journal Article
Year of Publication  2004
Authors  Caplow, T.; Schlosser, P.; Ho, D. T.; Enriquez, R. C.
Journal Title  Environmental Science & Technology
Volume  38
Issue  17
Pages  4562-4571
Journal Date  Sep 1
ISBN Number  0013-936X
Accession Number  ISI:000223678900023
LDEO Publication Number  6602
Key Words  tracer-release experiment; long-island sound; hudson-raritan estuary; water gas-exchange; large urban area; new-york harbor; sulfur-hexafluoride; atmospheric sf6; coefficient; rates

In June 2003, two injections of similar to3.9 mol of sulfur hexafluoride (SF6) were made 8 days apart in the East River, a 25 km tidal strait, to observe solute mixing and dissipation. The first injection occurred at slack before flood, and the second at slack before ebb (flood = northward flow). Tidally synchronized surveys of the SF6 tracer patch, supplemented by vertical profiles, were conducted by boat for 6 and 4 days following the flood and ebb injections, respectively. Residence times for the tracer-tagged water mass in the East River were estimated to be 3.3 +/- 0.7 days and 1.7 +/- 0.5 days for the flood and ebb injections, respectively, after correcting SF6 inventories for losses of SF6 from the water column by air-water gas exchange. The data indicate that the majority of East River solutes are transported to New York Harbor and that tidal mixing dominates subtidal circulation with respect to solute transport. Surveys of the adjacent lower Hudson River revealed a northward-moving, intermediate layer of East River water. Our results suggest that tidal phasing of contaminant discharges in the East River could reduce environmental impacts, by increasing flushing rates and directing a greater fraction of material away from Long Island Sound.


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URL  <Go to ISI>://000223678900023