Use of tritium and helium to define groundwater flow conditions in Everglades National Park

Authors

René M. Price, Southeast Environmental Research Center and Department of Earth and Environment, Florida International UniversityFollow
Zafer Top, Marine and Atmospheric Chemistry, Rosenstiel School of Marine and Atmospheric Sciences, University of MiamiFollow
James D. Happell, Marine and Atmospheric Chemistry, Rosenstiel School of Marine and Atmospheric Sciences, University of MiamiFollow
Peter K. Swart, Marine Geology and Geophysics, Rosenstiel School of Marine and Atmospheric Sciences, University of MiamiFollow

Abstract

The concentrations of tritium (³H) and helium isotopes (³He and⁴He) were used as tracers of groundwater flow in the surficial aquifer system (SAS) beneath Everglades National Park (ENP), south Florida. From ages determined by ³H/³He dating techniques, groundwater within the upper 28 m originated within the last 30 years. Below 28 m, waters originated prior to 30 years before present with evidence of mixing at the interface. Interannual variation of the ³H/³He ages within the upper 28 m was significant throughout the 3 year investigation, corresponding with varying hydrologic conditions. In the region of Taylor Slough Bridge, younger groundwater was consistently detected below older groundwater in the Biscayne Aquifer, suggesting preferential flow to the lower part of the aquifer. An increase in ⁴He with depth in the SAS indicated that radiogenic ⁴He produced in the underlying Hawthorn Group migrates into the SAS by diffusion. Higher Δ⁴He values in brackish groundwaters compared to fresh waters from similar depths suggested a possible enhanced vertical transport of⁴He in the seawater mixing zone. Groundwater salinity measurements indicated the presence of a wide (6–28 km) seawater mixing zone. Comparison of groundwater levels with surface water levels in this zone indicated the potential for brackish groundwater discharge to the overlying Everglades surface water.

Comments

Copyright © 2003 American Geophysical Union

The definitive publisher-authenticated version is also available online at http://dx.doi.org/10.1029/2002WR001929

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Price, R.M., J.D. Happell, Z. Top, P.K. Swart. 2003. Use of tritium and helium to define groundwater flow conditions in Everglades National Park. Water Resources Research 39(9): 1267.