Use of [delta][sup 13]C in dissolved inorganic carbon to delineate recharge areas of the Floridan aquifer system, coastal South Carolina
- Geological Survey, Columbia, SC (United States)
- South Carolina Dept. of Health and Environmental Control, Columbia, SC (United States)
Stable carbon composition ([delta][sup 13]C) of dissolved inorganic carbon (DIC) in ground water from the Floridan aquifer system in downdip, coastal portions of South Carolina correlates strongly with ground-water radiocarbon activities and age dates. Ground water sampled from known recharge areas (> 39.5 PMC [Percent Modern Carbon]) has less of the local heavy isotope ([sup 13]C) as shown by relatively light [delta][sup 13]C ([minus]19.9--[minus]9.86 per mil). Ground water sampled from the prevailing discharge regime (<2.5 PMC) has a higher content of the heavy isotope as shown by relatively heavy [delta][sup 13]C ([minus]8.67 to +0.54 per mil). These differences are related to processes affecting the DIC source to ground water. Recharge receives appreciable light carbon from the oxidation of organic matter ([delta][sup 13]C = [minus]25 per mil) in the soil zone. Older discharge regime ground water has received more heavy carbon from the dissolution-precipitation cycling of metastable magnesium-rich calcite. The correlation between the carbon-isotope data collected from this portion of the Floridan aquifer system provides the equation of a line in the form [sup 14]C (as PMC) = K [delta][sup 13]C + B, where K and B are empirically determined constants. The observed strong correlation (r[sup 2] = 0.78) between the [delta][sup 13]C composition and radiometric activities of ground water from the Floridan aquifer system suggests a relatively inexpensive screening method to delineate local recharge areas to that aquifer system, and to similar areas where recharge is added locally to much older geochemically evolved ground water in carbonate aquifers.
- OSTI ID:
- 5950550
- Report Number(s):
- CONF-9304188--
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 25:4; ISSN GAAPBC; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580000* -- Geosciences
AGE ESTIMATION
AQUIFERS
CARBON 13
CARBON ISOTOPES
CHEMISTRY
DEVELOPED COUNTRIES
EQUATIONS
EVEN-ODD NUCLEI
GEOCHEMISTRY
GROUND WATER
HYDROGEN COMPOUNDS
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
NORTH AMERICA
NUCLEI
OXYGEN COMPOUNDS
RECHARGE
SOUTH CAROLINA
STABLE ISOTOPES
USA
WATER