@article {2994, title = {14C Blank Corrections for 25{\textendash}100 μg Samples at the National Ocean Sciences AMS Laboratory}, journal = {Radiocarbon}, volume = {61}, year = {2019}, month = {10/2019}, pages = {1403 - 1411}, abstract = {Replicate radiocarbon (14C) measurements of organic and inorganic control samples, with known Fraction Modern values in the range Fm = 0{\textendash}1.5 and mass range 6 μg{\textendash}2 mg carbon, are used to determine both the mass and radiocarbon content of the blank carbon introduced during sample processing and measurement in our laboratory. These data are used to model, separately for organic and inorganic samples, the blank contribution and subsequently {\textquotedblleft}blank correct{\textquotedblright} measured unknowns in the mass range 25{\textendash}100 μg. Data, formulas, and an assessment of the precision and accuracy of the blank correction are presented.}, keywords = {AMS, AMS dating, blank corrections}, isbn = {0033-8222, 1945-5755}, doi = {10.1017/RDC.2019.74}, url = {https://www.cambridge.org/core/journals/radiocarbon/article/14c-blank-corrections-for-25100-g-samples-at-the-national-ocean-sciences-ams-laboratory/494B9CF72445198570213B4A2CC303D0}, author = {Roberts, M. L. and Elder, K. L. and Jenkins, W. J. and Gagnon, A. R. and Xu, L. and Hlavenka, J. D. and Longworth, B. E.} } @article {1831, title = {A Continuous-Flow Gas Chromatography C-14 Accelerator Mass Spectrometry System}, journal = {Radiocarbon}, volume = {52}, year = {2010}, note = {Sp. Iss. 1696jn Times Cited:4 Cited References Count:24 }, month = {2010}, pages = {295-300}, abstract = {Gas-accepting ion sources for radiocarbon accelerator mass spectrometry (AMS) have permitted the direct analysis of CO2 gas, eliminating the need to graphitize samples. As a result, a variety of analytical instruments can be interfaced to an AMS system, processing time is decreased, and smaller samples can be analyzed (albeit with lower precision). We have coupled a gas chromatograph to a compact C-14 AMS system fitted with a microwave ion source for real-time compound-specific C-14 analysis. As an initial test of the system, we have analyzed a sample of fatty acid methyl esters and biodiesel. Peak shape and memory was better then existing systems fitted with a hybrid ion source while precision was comparable. C-14/C-12 ratios of individual components at natural abundance levels were consistent with those determined by conventional methods. Continuing refinements to the ion source are expected to improve the performance and scope of the instrument.}, keywords = {ams system, gc-ams, negative-ion source, RADIOCARBON ANALYSIS}, isbn = {0033-8222}, author = {McIntyre, C. P. and Galutschek, E. and Roberts, M. L. and von Reden, K. F. and McNichol, A. P. and Jenkins, W. J.} } @article {1835, title = {The Passage of the Bomb Radiocarbon Pulse into the Pacific Ocean}, journal = {Radiocarbon}, volume = {52}, year = {2010}, note = {Sp. Iss. 2696jo Times Cited:7 Cited References Count:38 }, month = {2010}, pages = {1182-1190}, abstract = {We report and compare radiocarbon observations made on 2 meridional oceanographic sections along 150 degrees W in the South Pacific in 1991 and 2005. The distributions reflect the progressive penetration of nuclear weapons-produced (14)C into the oceanic thermocline. The changes over the 14 yr between occupations are demonstrably large relative to any possible drift in our analytical standardization. The computed difference field based on the gridded data in the upper 1600 m of the section exhibits a significant decrease over time (approaching 40 to 50 parts per thousand in Delta(14)C) in the upper 200-300 m, consistent with the decadal post-bomb decline in atmospheric (14)C levels. A strong positive anomaly (increase with time), centered on the low salinity core of the Antarctic Intermediate Water (AAIW), approaches 50-60 parts per thousand in Delta(14)C, a clear signature of the downstream evolution of the (14)C transient in this water mass. We use this observation to estimate the transit time of AAIW from its "source region" in the southeast South Pacific and to compute the effective reservoir age of this water mass. The 2 sections show small but significant changes in the abyssal (14)C distributions. Between 1991 and 2005, Delta(14)C has increased by 9 parts per thousand below 2000 m north of 55 degrees S. This change is accompanied overall by a modest increase in salinity and dissolved oxygen, as well as a slight decrease in dissolved silica. Such changes are indicative of greater ventilation. Calculation of "phosphate star" also indicates that this may be due to a shift from the Southern Ocean toward North Atlantic Deep Water as the ventilation source of the abyssal South Pacific.}, keywords = {AMS, antarctic intermediate water, anthropogenic co2, atlantic, c-14 data, carbon, distributions, graphite, south-pacific, tritium}, isbn = {0033-8222}, author = {Jenkins, W. J. and Elder, K. L. and McNichol, A. P. and von Reden, K.} } @conference {1659, title = {Isotopes as tracers of the oceanic circulation: results from the world ocean circulation experiment}, booktitle = {International Conference on the Study of Environmental Change Using Isotope Techniques, I.A.E.A.}, year = {2001}, note = {id: 318}, month = {2001}, author = {Schlosser, P. and Jenkins, W. J. and Key, R. and Lupton, J.} } @inbook {1460, title = {Ocean Circulation and Climate}, booktitle = {Observing and Modelling the Global Ocean}, year = {2001}, note = {id: 309}, month = {2001}, pages = {431-452}, publisher = {Academic Press}, organization = {Academic Press}, author = {Schlosser, P. and Bullister, J. L. and Fine, R. and Jenkins, W. J. and Key, R. and Lupton, J. and Roether, W. and Smethie, W. M., Jr.}, editor = {Siedler, G.} }