C Groundwater Age and the Importance of Chemical Fluxes Across Aquifer Boundaries in Confined Cretaceous Aquifers of North Carolina, USA
Bibliographic Data
| ID | 9245987 |
|---|---|
| Authors | Casey D Kennedy, David P Genereux |
| Year | 2007 |
| Volume | 49 |
| Issue | 3 |
| Pages | 1181-1203 |
| Publication date | 2007-01-01 |
| Open Access | Yes |
| Type | ARTICLE |
| Venue | Radiocarbon (JOURNAL) |
| Journal identifiers | ISSN: 0033-8222 • E-ISSN: 1945-5755 |
| Publisher | Cambridge University Press (CUP) (PUBLISHER) |
| DOI | 10.1017/s0033822200043101 |
| OpenAlex | W8132167 |
| Language | EN |
| Citations received | 1 |
| References cited | 59 |
Radiocarbon activity, He concentrations, and other geochemical parameters were measured in groundwater from the confined Black Creek (BC) and Upper Cape Fear (UCF) aquifers in the Coastal Plain of North Carolina. 14 C ages adjusted for geochemical and diffusion effects ranged from 400 to 21,900 BP in the BC, and 13,400 to 26,000 BP in the underlying UCF; ages increased coastward in both aquifers. Long-term average linear groundwater velocity is about 2.5 m/yr for the BC, and somewhat larger for the UCF. Aquifer-aquitard exchange is an important influence on the DIC concentration, 14 C activity, and estimated age of aquifer groundwater. Accounting for this exchange in 14 C age calculations places the groundwater samples with the lowest estimated recharge temperatures nearest in time to the last glacial maximum. Traditional geochemical correction models that do not account for aquifer-aquitard exchange significantly overestimate groundwater age. He concentration in groundwater varies with both age and stratigraphic position. Dissolved He data provide strong evidence of upward vertical He transport through the study aquifers; data from the UCF are broadly consistent with the pattern expected for a confined aquifer receiving a concentrated, localized He flux from below (based on a previously published model for this situation), in this case most likely from crystalline bedrock. He has potential as an indicator of groundwater age in the study aquifers, if interpreted within an appropriate analytical framework that includes the observed strong vertical transport. δ 18 O in the oldest groundwater is enriched (relative to modern groundwater) by 1 to 1.2‰, the opposite of the δ 18 O depletion found in many old groundwaters but consistent with the enrichment found in groundwater in this age range in Georgia and Florida
Aquifer · Artesian aquifer · Geochemistry · Groundwater · Groundwater recharge · Geology and Paleoclimatology Research · Groundwater and Isotope Geochemistry · Groundwater flow and contamination studies · Geology
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| Citations per year | 0.33 |
|---|---|
| Citation span | 2023 - 2023 (1) |
| Highly cited | No |