Uranium-isotope variations in groundwaters of the Floridan aquifer and Boulder Zone of south Florida

Journal of Hydrology
By: , and 

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Abstract

Water samples from four wells from the main Floridan aquifer (300-400 m below mean sea level) in southeast Florida exhibit 234U 233U activity ratios that are significantly lower than the secular equilibrium value of 1.00. Such anomalous values have been observed previously only in waters from sedimentary aquifers in the near-surface oxidizing environments. These four wells differ from six others, all producing from the same general horizon, in being located in cavernous highly transmissive zones. We hypothesize that the low activity ratios are indicative of a relic circulation pattern whereby water from the surface aquifer was channelled to lower levels when sea level was much lower. At a deeper cavernous level, known as the Boulder Zone (800-1,000 m below mean sea level), the U isotopes, along with other chemical constituents, show progressive changes with increasing distance from an inferred flow source in the Straits of Florida. This tends to support the hypothesized landward flow (though with a more northerly component) of cold seawater in the extensively transmissive Boulder Zone. 

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Publication type Article
Publication Subtype Journal Article
Title Uranium-isotope variations in groundwaters of the Floridan aquifer and Boulder Zone of south Florida
Series title Journal of Hydrology
DOI 10.1016/0022-1694(78)90045-8
Volume 36
Issue 1-2
Year Published 1978
Language English
Publisher Elsevier
Description 12 p.
First page 161
Last page 172
Country United States
State Florida
Other Geospatial south Florida
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