skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Radiocarbon Pretreatment Comparisons of Bald Cypress ( Taxodium Distichum ) wood samples from a massive buried deposit on the Georgia Coast, USA
Title: Radiocarbon Pretreatment Comparisons of Bald Cypress ( Taxodium Distichum ) wood samples from a massive buried deposit on the Georgia Coast, USA
ABSTRACT We sampled individual growth rings from three ancient remnant bald cypress ( Taxodium distichum ) trees from a massive buried deposit at the mouth of the Altamaha River on the Georgia Coast to determine the best technique for radiocarbon ( 14 C) dating pretreatment. The results of our comparison of traditional ABA pretreatment and holocellulose and α-cellulose fractions show no significant differences among the pretreatments (<1 sigma) thereby suggesting that ABA pretreatment will prove sufficient for the development of a high-resolution 14 C tree-ring chronology based on these ancient bald cypresses which will indicate whether the U.S. Southeast is subject to a regional radiocarbon offset.  more » « less
Award ID(s):
1832178
PAR ID:
10132042
Author(s) / Creator(s):
; ; ; ; ;
Date Published:
Journal Name:
Radiocarbon
Volume:
61
Issue:
6
ISSN:
0033-8222
Page Range / eLocation ID:
1755 to 1763
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; (, Radiocarbon)
    ABSTRACT Politiko- Troullia has generated the largest radiocarbon ( 14 C) dataset from a Prehistoric Bronze Age settlement on Cyprus. We present Bayesian modeling of 25 calibrated AMS ages, which contributes to an emerging multi-site 14 C chronology for Cyprus covering most of the Prehistoric Bronze Age. Our analysis places the six stratified phases of occupation at Troullia between about 2050 and 1850 cal BCE, in contrast to a longer estimated occupation inferred from pottery analysis. We provide a rare 14 C determination for the transition from Prehistoric Bronze Age 1 to 2 just after 2000 cal BCE, associated with a major architectural dislocation at Politiko- Troullia in response to local landscape erosion, possibly due to increased regional precipitation. We present a regional 14 C model for Prehistoric Bronze Age Cyprus combining the chronology for Politiko- Troullia with modeled 14 C ages from Sotira Kaminoudhia and Marki Alonia , which is bolstered by individual ages from five other settlements on Cyprus. Through the Prehistoric Bronze Age, agrarian villages on Cyprus developed the foundations for the emergence of urbanized settlement and society during the ensuing Protohistoric Bronze Age. Politiko- Troullia , in conjunction with other key settlements on Cyprus, provides a significant independent contribution to increasingly robust Bronze Age 14 C chronologies in the Eastern Mediterranean. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; ; et al (, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences)
    Radiocarbon (14C) is a critical tool for understanding the global carbon cycle. During the Anthropocene, two new processes influenced14C in atmospheric, land and ocean carbon reservoirs. First,14C-free carbon derived from fossil fuel burning has diluted14C, at rates that have accelerated with time. Second, ‘bomb’14C produced by atmospheric nuclear weapon tests in the mid-twentieth century provided a global isotope tracer that is used to constrain rates of air–sea gas exchange, carbon turnover, large-scale atmospheric and ocean transport, and other key C cycle processes. As we write, the14C/12C ratio of atmospheric CO2is dropping below pre-industrial levels, and the rate of decline in the future will depend on global fossil fuel use and net exchange of bomb14C between the atmosphere, ocean and land. This milestone coincides with a rapid increase in14C measurement capacity worldwide. Leveraging future14C measurements to understand processes and test models requires coordinated international effort—a ‘decade of radiocarbon’ with multiple goals: (i) filling observational gaps using archives, (ii) building and sustaining observation networks to increase measurement density across carbon reservoirs, (iii) developing databases, synthesis and modelling tools and (iv) establishing metrics for identifying and verifying changes in carbon sources and sinks. This article is part of the Theo Murphy meeting issue 'Radiocarbon in the Anthropocene'. 
    more » « less
  3. ; ; ; ; ; ; ; ; ; (, Radiocarbon)
    ABSTRACT Radiocarbon ( 14 C) is an isotopic tracer used to address a wide range of scientific research questions. However, contamination by elevated levels of 14 C is deleterious to natural-level laboratory workspaces and accelerator mass spectrometer facilities designed to precisely measure small amounts of 14 C. The risk of contaminating materials and facilities intended for natural-level 14 C with elevated-level 14 C-labeled materials has dictated near complete separation of research groups practicing profoundly different measurements. Such separation can hinder transdisciplinary research initiatives, especially in remote and isolated field locations where both natural-level and elevated-level radiocarbon applications may be useful. This paper outlines the successful collaboration between researchers making natural-level 14 C measurements and researchers using 14 C-labeled materials during a subglacial drilling project in West Antarctica (SALSA 2018–2019). Our strict operating protocol allowed us to successfully carry out 14 C labeling experiments within close quarters at our remote field camp without contaminating samples of sediment and water intended for natural level 14 C measurements. Here we present our collaborative protocol for maintaining natural level 14 C cleanliness as a framework for future transdisciplinary radiocarbon collaborations. 
    more » « less
  4. ; ; ; ; ; (, The Holocene)
    Characterizing the degree of disturbance in archaeological deposits is critically important for archaeologists assessing foraging strategies, environmental conditions, or behavior patterns of ancient human groups. Qualitative techniques (e.g. micromorphology analysis) have previously been applied to assess the degree of disturbance (age-mixing) in archaeological sites; however, quantitative dating of material in the sites provides a more robust assessment of potential age-mixing. Unfortunately, because of budget constraints, archaeologists are frequently forced to rely on few quantitative age dates for an assemblage, thus obfuscating the signal of age-mixing of the deposit. The development of an affordable and rapid carbonate-target accelerator mass spectrometry (AMS) radiocarbon (14C) dating method provides a cost-effective way to retrieve more quantitative dates from carbonate material in archaeological assemblages to assess the degree of age-mixing in the deposit. This study tests this new technique and dates numerous harvested marine limpet shells from archaeological sites in the Canary Islands to determine whether there is multidecadal to multicentennial age-mixing. A total of 58 shells retrieved from six sites and three islands yielded uncalibrated radiocarbon ages ranging from 2265 ± 40 to 765 ± 35 BP, coinciding with the time of prehistoric human occupation in these islands. While most shells from the same stratum showed statistically equivalent ages, in some cases we detected age ranges that exceeded the imprecisions from analytical errors. This investigation is one of the first to quantitatively illustrate that shells retrieved from depth intervals without evident stratigraphic disturbance do not always contain contemporaneous remains and, therefore, dating each specimen is valuable for developing further paleoclimatic and paleoanthropological inferences. This study presents the first report of carbonate-target14C ages from archaeological shell middens, and suggests that this novel radiocarbon methodology can be applied to these sites, thus allowing the generation of a more comprehensive chronology. 
    more » « less
  5. ; ; ; ; ; ; (, Radiocarbon)
    ABSTRACT Radiocarbon observations (Δ 14 C) in dissolved inorganic carbon (DIC) of seawater provide useful information about ocean carbon cycling and ocean circulation. To deliver high-quality observations, the Laboratory of Ion Beam Physics (LIP) at ETH-Zurich developed a new simplified method allowing the rapid analysis of radiocarbon in DIC of small seawater samples, which is continually assessed by following internal quality controls. However, a comparison with externally produced 14 C measurements to better establish an equivalency between methods was still missing. Here, we make the first intercomparison with the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility based on 14 duplicate seawater samples collected in 2020. We also compare with prior deep-water observations from the 1970s to 1990s. The results show a very good agreement in both comparisons. The mean Δ 14 C of 12 duplicate samples measured by LIP and NOSAMS were statistically identical within one sigma uncertainty while two other duplicate samples agreed within two sigma. Based on this small number of duplicate samples, LIP values appear to be slightly lower than the NOSAMS values, but more measurements will be needed for confirmation. We also comment on storage and preservation techniques used in this study, including the freezing of samples collected in foil bags. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email