Chronology and Isotope Geochemistry of Ground Waters in the Florida Keys and Offshore Areas

This project involves sampling surface waters and ground waters from Florida Bay, the Keys, and offshore to the barrier reef. Analyses will be done on a variety of isotopic and chemical species that have been used elsewhere to determine ground-water ages, contaminant sources, and geo- chemical reactions. Water Research Discipline researchers will coordinate ground water sampling and analytical work; Geologic Discipline researchers will provide access to wells and back- ground data, handle field logistics, etc.

A significant issue of concern in South Florida is the potential effect of anthropogenic pollutants from the Florida Keys or elsewhere on the water quality and health of offshore marine ecosystems. It has been suggested that certain contaminants (e.g., bacteria, excess nutrients) found in some offshore ground waters may be transported 'in the subsurface to discharge sites beneath Florida Bay or the reef tract, where they may be contributing to declining ecosystem health. But not much is known about the origins of the ground waters underlying the region, how the subsurface flow systems operate, and what is the fate of contaminants emplaced in ground water in the Keys. Ground waters are potential sources, sinks, and carriers of nutrients and other contaminants beneath the Florida Keys and offshore regions to the north and south. This project is designed to provide new data on the sources, flow directions, exchange rates, and chemical characteristics of ground waters underlying the region of Florida Bay, the Keys, and offshore reefs. The results, to be derived in part from analyses of environmental tracers and isotopes, will provide general empirical information about subsurface transport processes and their potential impact on surface water chemistry.