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An isotopic calibration study of precipitation, cave dripwater, and climate in west‐central Florida
Author(s) -
Polk Jason S.,
van Beynen Philip,
Wynn Jonathan
Publication year - 2011
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.8169
Subject(s) - cave , speleothem , precipitation , δ18o , paleoclimatology , isotopes of oxygen , stalagmite , climatology , environmental science , geology , meteoric water , stable isotope ratio , atmospheric sciences , climate change , groundwater , meteorology , geochemistry , geography , oceanography , archaeology , geotechnical engineering , physics , quantum mechanics
A calibration study of oxygen and hydrogen isotopic composition from precipitation and cave dripwater was conducted in west‐central Florida at Legend Cave during 2007–2008. This study was performed to better understand how modern precipitation patterns can be discerned through examination of cave dripwater and speleothem calcite for paleoclimate reconstruction. The ‘amount effect’ was shown to be a dominant control on the oxygen isotopic composition of precipitation for the study area. A meteoric water line with a slope of 6·7 suggests evaporative effects occur either during precipitation or subsequent hydrological processes. However, δ 18 O values of cave dripwater averaged near the mean annual amount‐weighted average of precipitation, suggesting that the isotopic composition of dripwater tracks the long‐term average of rainfall. An observed weak seasonal influence occurred in the d ‐excess values, with summer precipitation being more enriched due to increased evaporative effects. Comparison of precipitation δ 18 O values to synoptic weather data shows the dominant amount effect influence occurs due to strong convective storms producing highly 18 O‐depleted rainfall at greater amounts during the year. Constant δ 18 O values of the dripwater indicate that paleoclimate reconstructions using speleothems from this area would record changes in annual to interannual shifts in precipitation amount above the cave. Copyright © 2011 John Wiley & Sons, Ltd.