Abstract
A project entitled “DETECTION, MAPPING, AND CHARACTERIZATION OF GROUNDWATER DISCHARGES TO BISCAYNE BAY SFWMD CONTRACT C-15870” was initiated in January 2004 under a joint effort between NOAA and the University of Miami, under a grant from the South Florida Water Management District (SFWMD) in order to document, categorize, and describe the nature of existing artesian springs in Biscayne Bay, Florida. The study, which spanned one year in duration, accomplished the goals of finding and documenting existing springs, studying their nature, and analyzing the sediments and water chemistry of the spring waters. We found that a few existing larger springs and many ephemeral smaller springs flow readily during the wet season and after large rain events, and diminish or cease in flow during the dry season, or when canal flood gate structures are open, because of a decrease in the fresh water head of the underlying water tables of the mainland. Water analysis revealed that spring water salinities ranged from 8 to 31 ppt and were slightly acidic in the wet season, with a pH just below 7.0. Analysis also revealed silicon contents consistent with a groundwater source. Sediment analyses revealed a foraminifera assemblage pattern similar to that which would exist from a freshwater gradient to a more saline water environment. Scanning electron microscope analyses revealed extensive dissolution on foraminifera tests, primarily those associated with samples obtained from closer to the springs. This dissolution coincides with the foraminifera salinity tolerability range, as well as with the low pH of the spring waters. Despite all the data obtained during the brief period of this project, recommendations include further study into the nature of these springs, exact documentation of flow and spring water sources, and a more extensive study into the increased dissolution of the carbonate sediments of Biscayne Bay. iii