@article {castrillejo_comparability_2023,
	title = {Comparability of Radiocarbon Measurements in Dissolved Inorganic Carbon of Seawater Produced at ETH-Zurich},
	journal = {Radiocarbon},
	year = {2023},
	note = {Publisher: Cambridge University Press},
	month = {03/2023},
	pages = {1{\textendash}10},
	abstract = {Radiocarbon observations (Δ14C) 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 14C 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 Δ14C 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.},
	keywords = {14C, comparison, DIC, dissolved inorganic carbon, radiocarbon, SEAWATER},
	issn = {0033-8222, 1945-5755},
	doi = {10.1017/RDC.2023.16},
	url = {https://www.cambridge.org/core/journals/radiocarbon/article/comparability-of-radiocarbon-measurements-in-dissolved-inorganic-carbon-of-seawater-produced-at-ethzurich/B9F6C6AA45835FA3ED0BF8E0CD9788E3},
	author = {Castrillejo, Maxi and Hansman, Roberta L. and Graven, Heather D. and Lester, Joanna G. and Bollhalder, Silvia and K{\"u}ndig, Kayley and Wacker, Lukas}
}
@article {hanke_sequential_2023,
	title = {Sequential thermal analysis of complex organic mixtures: Procedural standards and improved CO2 purification capacity},
	journal = {Radiocarbon},
	volume = {65},
	number = {2},
	year = {2023},
	note = {Publisher: Cambridge University Press},
	month = {03/2023},
	pages = {389{\textendash}409},
	abstract = {Sequential thermal analysis allows for deconvoluting the refractory nature and complexity of carbon mixtures embedded in mineral matrices for subsequent offline stable carbon and radiocarbon (14C) isotope analyses. Originally developed to separate Holocene from more ancient sedimentary organic matter to improve dating of marine sediments, the Ramped Pyrolysis and Oxidation (RPO) apparatus, or informally, the {\textquotedblleft}dirt burner{\textquotedblright} is now used to address pressing questions in the broad field of biogeochemistry. The growing interest in the community now necessitates improved handling and procedures for routine analyses of difficult sample types. Here we report on advances in CO2 purification during sample processing, modifications to the instrumentation at the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility, and introduce sodium bicarbonate procedural standards with differing natural abundance 14C signatures for blank assessment. Measurements from different environmental samples are used to compare the procedure to the different generations of sequential thermal analyses. With this study, we aim to improve the standardization of the procedures and prepare this instrumentation for innovations in online stable carbon isotopes and direct AMS-interface measurements in the future.},
	keywords = {chemical analysis, dirt burner, full oxidation (FOX) mode, Radiocarbon dating, ramped pyrolysis oxidation},
	issn = {0033-8222, 1945-5755},
	doi = {10.1017/RDC.2023.13},
	url = {https://www.cambridge.org/core/journals/radiocarbon/article/sequential-thermal-analysis-of-complex-organic-mixtures-procedural-standards-and-improved-co2-purification-capacity/E225F01B421614EE176553014E7B38BE},
	author = {Hanke, Ulrich M. and Gagnon, Alan R. and Reddy, Christopher M. and Gaylord, Mary C. Lardie and Cruz, Anne J. and Galy, Valier and Hansman, Roberta L. and Kurz, Mark D.}
}
@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.}
}
