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dc.contributor.authorTaylor, C. B.
dc.date.accessioned2021-02-11T20:44:44Z
dc.date.available2021-02-11T20:44:44Z
dc.date.issued1997-01-01
dc.identifier.citationTaylor, C. B. (1997). On the isotopic composition of dissolved inorganic carbon in rivers and shallow groundwater: A diagrammatic approach to process identification and a more realistic model of the open system. Radiocarbon, 39(3), 251-268.
dc.identifier.issn0033-8222
dc.identifier.doi10.1017/S0033822200053248
dc.identifier.urihttp://hdl.handle.net/10150/653658
dc.description.abstractRivers and shallow groundwater are deep groundwater precursors. Their dissolved inorganic carbon content (DIC) and its isotopic composition are end members in the evolution of these properties in confined situations, and are therefore essential information when applying carbon isotopes as tracers of groundwater processes and determining aquifer residence times using 14C. During studies of regional aquifer systems in New Zealand, a simple model has been developed to explain the isotopic compositions of DIC encountered in rivers and shallow groundwater. The model format incorporates a diagrammatic approach, providing a framework for tracing the subsequent evolution of DIC in both precipitation-and river-recharged aquifers under closed conditions. DIC concentration of rivers continuously adjusts toward chemical and isotopic equilibrium between direct addition of CO2 to the water (via plant respiration and decay of dead organic material) and exchange of CO2 across the river-air interface. In the shallow groundwater situation, the gaseous reservoir is soil CO2, generally at significantly higher partial pressure. In both cases, calcite dissolution or other processes may be an additional source of DIC directly added to the bicarbonate and dissolved CO2 components; while these may add or remove DIC, steady-state isotopic concentrations are considered to be determined only by the dynamic balance between directly added CO2 and gas exchange. This model allows the calculation of steady states, using selectable parameters in river or groundwater situations. These appear as straight lines in 13C or 14C vs. 1/DIC, or total 14C vs. DIC plots, into which the experimental data can be inserted for interpretation. In the case of 14C, the steady-state balance is very often complicated by the presence of an old component in the directly added DIC; the understanding achieved via the 13C patterns is helpful in recognizing this. Data from four contrasting aquifer systems in New Zealand. The success of the approach has depended crucially on DIC concentrations measured very accurately on the isotope samples, rather than separate chemical analyses.
dc.language.isoen
dc.publisherDepartment of Geosciences, The University of Arizona
dc.relation.urlhttp://radiocarbon.webhost.uits.arizona.edu/
dc.rightsCopyright © by the Arizona Board of Regents on behalf of the University of Arizona. All rights reserved.
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.subjecthydrology
dc.subjectdissolved materials
dc.subjectradioactive tracers
dc.subjectrecharge
dc.subjectinorganic materials
dc.subjectinorganic carbon
dc.subjecthydrologic cycle
dc.subjectManawatu New Zealand
dc.subjectMatemateaonga Aquifer
dc.subjectmovement
dc.subjectPohangina Aquifer
dc.subjectshallow aquifers
dc.subjectTaranaki Basin
dc.subjectsurface water
dc.subjectresidence time
dc.subjecthydrochemistry
dc.subjectopen systems
dc.subjectground water
dc.subjectaquifers
dc.subjectAustralasia
dc.subjectNew Zealand
dc.subjectNorth Island
dc.subjectisotope ratios
dc.subjectsoils
dc.subjectgeochronology
dc.subjectC 14
dc.subjectcarbon
dc.subjectisotopes
dc.subjectradioactive isotopes
dc.subjectcarbon dioxide
dc.subjectC 13 C 12
dc.subjectstable isotopes
dc.subjectC 13
dc.subjectgeochemistry
dc.titleOn the Isotopic Composition of Dissolved Inorganic Carbon in Rivers and Shallow Groundwater: A Diagrammatic Approach to Process Identification and a More Realistic Model of the Open System
dc.typeArticle
dc.typetext
dc.identifier.journalRadiocarbon
dc.description.noteThis material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.
dc.description.collectioninformationThe Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information.
dc.eprint.versionFinal published version
dc.description.admin-noteMigrated from OJS platform February 2021
dc.source.volume39
dc.source.issue3
dc.source.beginpage251
dc.source.endpage268
refterms.dateFOA2021-02-11T20:44:44Z


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