HR: 16:15h
AN: H32H-02 INVITED     [PDF]
TI: Solute Transport and Surface-Subsurface Exchange in the Everglades Characterized by a Tracer Release in Surface Water
AU: * Harvey, J W
EM: jwharvey@usgs.gov
AF: U.S. Geological Survey, 430 National Center, Reston, VA 20192 United States
AU: Saiers, J E
AF: Yale School of Environmental Studies, 205 Prospect Street, New Haven, CT 06511 United States
AU: Newlin, J T
AF: U.S. Geological Survey, 430 National Center, Reston, VA 20192 United States
AB: Solute tracer injections into flowing surface water are useful to characterize water velocity, dispersive mixing, and biogeochemical reactions that result from processes such as solute exchange between surface water and sediment porewater. Presently, there are few data or guidelines to understand transport processes in the Everglades. Our tracer study was conducted in central Shark Slough, Everglades National Park (25$\deg$38' 31.2'' N, 80$\deg$43' 20.4'' W) at an experimental flume facility. The flume consists of 4 side-by-side channels enclosing wetland vegetation in open-ended flow-ways (3-m by 100-m) that are subject to ambient flow conditions. The injection was conducted in one channel that, at the time of the experiment, had 60-cm of surface water and a typical assemblage of Everglades' slough vegetation, including rooted macrophytes (mainly {\it Eleocharis sp.}), and a well-developed layer (15-cm) of periphyton-coated vegetation (mainly {\it Utricularia sp.}) below the water surface. A constant-rate injection of sodium bromide (NaBr) was conducted for 22 hours by dividing the flow between four horizontally oriented soaker hoses that were evenly spaced in the water column. At a distance of 6.8 m downstream of the injection, small-volume (10 to 20-ml) water samples were collected on regular intervals for 48 hrs by withdrawing them by suction from 1/8-inch tubes deployed throughout the water column and in the peat sediment to a depth of 30-cm. Transport was characterized by adjusting the parameters of the USGS model OTIS (One-dimensional Transport with Inflow and Storage). Mean velocity of surface water during the experiment was 0.63 cm/s, longitudinal dispersion was 5 x 10$^{-5}$ m$^{2}$/s, and fluid residence times in two storage zones, where local mixing but no appreciable downstream transport occurred, were 1 hr (in periphyton-dominated floating vegetation)and 24 hrs in peat porewater), respectively. We conclude that storage-exchange affects solute transport in the Everglades by decreasing the mean water velocity and increasing the time available for biogeochemical processing of non-conservative solutes.
UR: http://water.usgs.gov/nrp/jharvey/site/index.html
DE: 1845 Limnology
DE: 1860 Runoff and streamflow
DE: 1890 Wetlands
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2003 Fall Meeting