@article {3004, title = {Implications of Single-Step Graphitization For Reconstructing Late Holocene Relative Sea-Level Using Radiocarbon-Dated Organic Coastal Sediment}, journal = {Radiocarbon}, year = {2022}, month = {08/2022}, pages = {1 - 20}, abstract = {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.}, keywords = {age-depth model, mangrove, Massachusetts, Micronesia, Salt marsh}, isbn = {0033-8222, 1945-5755}, doi = {10.1017/RDC.2022.55}, url = {https://www.cambridge.org/core/journals/radiocarbon/article/implications-of-singlestep-graphitization-for-reconstructing-late-holocene-relative-sealevel-using-radiocarbondated-organic-coastal-sediment/41F75E6A0679F0E659C96F438452D64C}, author = {Sefton, Juliet P. and Kemp, Andrew C. and Elder, Kathryn L. and Hansman, Roberta L. and Roberts, Mark L.} } @article {2995, title = {ERRONEOUSLY OLD RADIOCARBON AGES FROM TERRESTRIAL POLLEN CONCENTRATES IN YELLOWSTONE LAKE, WYOMING, USA}, journal = {Radiocarbon}, volume = {63}, year = {2021}, month = {02/2021}, pages = {321 - 342}, abstract = {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{\textendash}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.}, keywords = {AMS dating, chronology, contamination, paleoecology, pine}, isbn = {0033-8222, 1945-5755}, doi = {10.1017/RDC.2020.118}, url = {https://www.cambridge.org/core/journals/radiocarbon/article/erroneously-old-radiocarbon-ages-from-terrestrial-pollen-concentrates-in-yellowstone-lake-wyoming-usa/1DAC6B6CCD52443755E7F725B84CFB3F}, author = {Schiller, Christopher M. and Whitlock, Cathy and Elder, Kathryn L. and Iverson, Nels A. and Abbott, Mark B.} } @conference {1564, title = {The Antarctic Radiocarbon Storage Ring}, booktitle = {8th International Conference on Accelerator Mass Spectrometry}, year = {1999}, note = {id: 1791}, month = {1999}, address = {Vienna, Austria}, author = {Schneider, Robert J. and McNichol, Ann P. and von Reden, Karl F. and Elder, Kathryn L. and Gagnon, Alan R. and Key, Robert M. and Quay, Paul D.} } @article {2257, title = {A Correction for Aberrations in the Woods Hole Recombinator. Symposium of North-Eastern Accelerator Personnel}, journal = {World Scientific}, volume = {SNEAP 1996}, year = {1998}, note = {id: 1664}, month = {1998}, pages = {123-128}, author = {Schneider, Robert J. and McNichol, Ann P. and von Reden, Karl F. and Elder, Kathryn L. and Gagnon, Allan R. and Key, Robert M. and Quay, Paul D.} }