Relationship between the carbon isotope composition of soil CO 2 and dissolved carbonate species in groundwater

Autor: Craig T. Rightmire, Bruce B. Hanshaw
Rok vydání: 1973
Předmět:
Zdroj: Water Resources Research. 9:958-967
ISSN: 1944-7973
0043-1397
DOI: 10.1029/wr009i004p00958
Popis: To understand the carbonate geochemistry of an aquifer system, it is helpful to determine the sources of carbon in the dissolved carbonate species. Samples of ground litter, soil organic matter, soil CO2, and groundwater were collected in the area of recharge to the principal artesian aquifer of central Florida and were analyzed for 3C content. Analytical results yield consistent 3C/2C values for soil organic matter, $aCrDB = 23 4- l0o. TheaC/2C ratio of the litter samples ranges from $SCrDB of --18.2 to --29.500 and indicates the presence of both Calvin and Hatch-Slack cycle plants. The xaC/x2C of the soil CO2 ranges from -14.7 to -21.3o, which is consistent with the trend observed in the litter. The relationship between x3C/x2C of the dissolved carbonate and the percent calcite saturation indicates that the $aCDB of the source CO_ is within the range of -25 4- 5o, as is expected for a humid, subtropical environment. To understand the carbonate chemistry of an aquifer system, it is necessary to determine the various sources of carbonate in that system. One approach is the use of stable carbon isotopes. The use of stable carbon isotope analyses in conjunction with standard chemical analyses aids in determining the sources of carbon in ground- water, because the carbon isotope compositions of various components of the global carbon reservoir generally fall within distinct ranges (Table 1). Carbon isotope data are reported in the standard notation relative to the PDB standard
Databáze: OpenAIRE
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