UIS Commission on Karst Hydrogeology and Speleogenesis
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Karstbase Bibliography Database

Pace-Graczyk, Kali J
Isotopic investigations of cave drip waters and precipitation in central and northern florida, usa, msc.Thesis

A temperature, drip rate, and stable isotopic study (δ18O and δD) was undertaken in three caves in central and northern Florida. Both surface and cave temperatures were collected, as were precipitation, cave drip water and drip rates. All data were collected on a weekly basis to investigate the isotopic relationships between precipitation and cave drip waters. The objective of this study was to provide a calibration of the oxygen and hydrogen isotopic values in precipitation and cave drip water for future paleoclimate work in the Florida peninsula.Based on the steady annual cave temperature and high relative humidity (95% or above), all three caves are suitable locations for paleoclimate work. A spike in the cave drip rate is seen following precipitation events at both Legend and Jennings Caves. A lag time of 52 days between the date of the storm event and the increase in drip rate was found at Legend Cave.

Legend and Jennings Caves in central Florida show a relationship between the amount of precipitation and the δ18O values. The isotopic values in precipitation were more depleted after a large precipitation event, suggesting the amount effect is influential in this location. At Florida Caverns State Park tourist cave in northern Florida, the association between 18O and precipitation was weak while a relationship between 18O and temperature may be present; here the seasonal effect or latitude effect may be significant.
The monthly mean isotopic values of the drip waters were found to approximate those of the precipitation. The steady isotopic values of the drip water are due to a homogenization of water infiltrating into the epikarst and mixing with water already present in the karst storage. This finding is important for future paleoclimate research in the Florida peninsula. An important assumption in paleoclimate work is that the value of δ18O in calcite at the time of precipitation represents the mean annual δ18O of precipitation at the time of deposition. The ultimate objectives of this research were to assess the isotopic relationship between precipitation and cave drip waters in order to interpret paleoclimate data sets. Although the data were limited to a single year, it appears that a sufficient isotopic signal exists in central-north Florida precipitation and drip water to apply for paleoclimate studies.

Central Florida, Northern Florida, paleoclimate, stable isotopic, epikarst