USING STABLE ISOTOPES OF CARBON TO INVESTIGATE THE SEASONAL VARIATION OF CARBON TRANSFER IN A NORTHWESTERN ARKANSAS CAVE

Citation

Material Information

Title:
USING STABLE ISOTOPES OF CARBON TO INVESTIGATE THE SEASONAL VARIATION OF CARBON TRANSFER IN A NORTHWESTERN ARKANSAS CAVE
Series Title:
Journal of Cave and Karst Studies
Creator:
KNIERIM, KATHERINE J.
POLLOCK, ERIK D.
HAYS, PHILLIP D.
KHOJASTEH, JAM
Language:
English

Subjects

Subjects / Keywords:
Co2 ( local )
Isotopes ( local )
Dissolved Inorganic Carbon ( local )
Soil ( local )
Atmosphere ( local )
Genre:
serial ( sobekcm )

Notes

Abstract:
Stable-isotope analyses are valuable in karst settings, where characterizing biogeochemical cycling of carbon along groundwater flow paths is critical for understanding and protecting sensitive cave and karst water resources. This study quantified the seasonal changes in concentration and isotopic composition (d13C) of aqueous and gaseous carbon species—dissolved inorganic carbon (DIC) and gaseous carbon dioxide (CO2)—to characterize sources and transfer of these species along a karst flow path, with emphasis on a cave environment. Gas and water samples were collected from the soil and a cave in northwestern Arkansas approximately once a month for one year to characterize carbon cycling along a conceptual groundwater flow path. In the soil, as the DIC concentration increased, the isotopic composition of the DIC became relatively lighter, indicating an organic carbon source for a component of the DIC and corroborating soil DIC as a proxy for soil respiration. In the cave, a positive correlation between DIC and surface temperature was due to increased soil respiration as the organic carbon signal from the soil was transferred to the cave environment via the aqueous phase. CO2 concentration was lowest in the cave during colder months and increased exponentially with increasing surface temperature, presumably due to higher rates of soil respiration during warmer periods and changing ventilation patterns between the surface and cave atmosphere. Isotopic disequilibrium between CO2 and DIC in the cave was greatest when CO2 concentration was changing during November/ December and March/April, presumably due to the rapid addition or removal of gaseous CO2. The isotopic disequilibrium between DIC and CO2 provided evidence that cave CO2 was a mixture of carbon from several sources, which was mostly constrained by mixture between atmospheric CO2 and soil CO2. The concentration and isotopic composition of gaseous and aqueous carbon species were controlled by month-to-month variations in temperature and precipitation and provi
Original Version:
Journal of Cave and Karst Studies, Vol. 77, no. 1.

Record Information

Source Institution:
University of South Florida Library
Holding Location:
University of South Florida
Rights Management:
This object is protected by copyright, and is made available here for research and educational purposes. Permission to reuse, publish, or reproduce the object beyond the bounds of Fair Use or other exemptions to copyright law must be obtained from the copyright holder.

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University of South Florida
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