TY - JOUR T1 - Implications of Single-Step Graphitization For Reconstructing Late Holocene Relative Sea-Level Using Radiocarbon-Dated Organic Coastal Sediment JF - Radiocarbon Y1 - 2022 A1 - Sefton, Juliet P. A1 - Kemp, Andrew C. A1 - Elder, Kathryn L. A1 - Hansman, Roberta L. A1 - Roberts, Mark L. KW - age-depth model KW - mangrove KW - Massachusetts KW - Micronesia KW - Salt marsh AB - Late Holocene relative sea-level reconstructions are commonly generated using proxies preserved in salt-marsh and mangrove sediment. These depositional environments provide abundant material for radiocarbon dating in the form of identifiable macrofossils (salt marshes) and bulk organic sediment (mangroves). We explore if single-step graphitization of these samples in preparation for radiocarbon dating can increase the number and temporal resolution of relative sea-level reconstructions without a corresponding increase in cost. Dating of salt-marsh macrofossils from the northeastern United States and bulk mangrove sediment from the Federated States of Micronesia indicates that single-step graphitization generates radiocarbon ages that are indistinguishable from replicates prepared using traditional graphitization, but with a modest increase in error (mean/maximum of 6.25/15 additional 14C yr for salt-marsh macrofossils). Low 12C currents measured on bulk mangrove sediment following single-step graphitization likely render them unreliable despite their apparent accuracy. Simulated chronologies for six salt-marsh cores indicate that having twice as many radiocarbon dates (since single-step graphitization costs ∼50% of traditional graphitization) results in narrower confidence intervals for sample age estimated by age-depth models when the additional error from the single-step method is less than ∼50 14C yr (∼30 14C yr if the chronology also utilizes historical age markers). Since these thresholds are greater than our empirical estimates of the additional error, we conclude that adopting single-step graphitization for radiocarbon measurements on plant macrofossils is likely to increase precision of age-depth models by more than 20/10% (without/with historical age markers). This improvement can be implemented without additional cost. SN - 0033-8222, 1945-5755 UR - https://www.cambridge.org/core/journals/radiocarbon/article/implications-of-singlestep-graphitization-for-reconstructing-late-holocene-relative-sealevel-using-radiocarbondated-organic-coastal-sediment/41F75E6A0679F0E659C96F438452D64C ER - TY - JOUR T1 - ERRONEOUSLY OLD RADIOCARBON AGES FROM TERRESTRIAL POLLEN CONCENTRATES IN YELLOWSTONE LAKE, WYOMING, USA JF - Radiocarbon Y1 - 2021 A1 - Schiller, Christopher M. A1 - Whitlock, Cathy A1 - Elder, Kathryn L. A1 - Iverson, Nels A. A1 - Abbott, Mark B. KW - AMS dating KW - chronology KW - contamination KW - paleoecology KW - pine AB - Accelerator mass spectrometry (AMS) dating of pollen concentrates is often used in lake sediment records where large, terrestrial plant remains are unavailable. Ages produced from chemically concentrated pollen as well as manually picked Pinaceae grains in Yellowstone Lake (Wyoming) sediments were consistently 1700–4300 cal years older than ages established by terrestrial plant remains, tephrochronology, and the age of the sediment-water interface. Previous studies have successfully utilized the same laboratory space and methods, suggesting the source of old-carbon contamination is specific to these samples. Manually picking pollen grains precludes admixture of non-pollen materials. Furthermore, no clear source of old pollen grains occurs on the deglaciated landscape, making reworking of old pollen grains unlikely. High volumes of CO2 are degassed in the Yellowstone Caldera, potentially introducing old carbon to pollen. While uptake of old CO2 through photosynthesis is minor (F14C approximately 0.99), old-carbon contamination may still take place in the water column or in surficial lake sediments. It remains unclear, however, what mechanism allows for the erroneous ages of highly refractory pollen grains while terrestrial plant remains were unaffected. In the absence of a satisfactory explanation for erroneously old radiocarbon ages from pollen concentrates, we propose steps for further study. VL - 63 SN - 0033-8222, 1945-5755 UR - https://www.cambridge.org/core/journals/radiocarbon/article/erroneously-old-radiocarbon-ages-from-terrestrial-pollen-concentrates-in-yellowstone-lake-wyoming-usa/1DAC6B6CCD52443755E7F725B84CFB3F IS - 1 ER - TY - CONF T1 - The Antarctic Radiocarbon Storage Ring T2 - 8th International Conference on Accelerator Mass Spectrometry Y1 - 1999 A1 - Schneider, Robert J. A1 - McNichol, Ann P. A1 - von Reden, Karl F. A1 - Elder, Kathryn L. A1 - Gagnon, Alan R. A1 - Key, Robert M. A1 - Quay, Paul D. JF - 8th International Conference on Accelerator Mass Spectrometry CY - Vienna, Austria N1 - id: 1791 ER - TY - JOUR T1 - A Correction for Aberrations in the Woods Hole Recombinator. Symposium of North-Eastern Accelerator Personnel JF - World Scientific Y1 - 1998 A1 - Schneider, Robert J. A1 - McNichol, Ann P. A1 - von Reden, Karl F. A1 - Elder, Kathryn L. A1 - Gagnon, Allan R. A1 - Key, Robert M. A1 - Quay, Paul D. VL - SNEAP 1996 N1 - id: 1664 ER -