@article {Jenkins2017,
	title = {The deep distributions of helium isotopes, radiocarbon, and noble gases along the U.S. GEOTRACES East Pacific Zonal Transect (GP16)},
	journal = {Marine Chemistry},
	year = {2017},
	pages = {-},
	abstract = {Abstract We report the deep distributions of noble gases, helium isotopes, and radiocarbon measured during the U.S. \{GEOTRACES\} \{GP16\} East Pacific Zonal Transect between 152 and 77{\textdegree}W at 12{\textendash}15{\textdegree}S in the South Pacific. The dominant feature is an intense tongue of hydrothermal effluent that extends \&gt; 4000 km westward from the East Pacific Rise (EPR) at ~ 2500 m depth. The patterns reveal significant {\textquotedblleft}downstream{\textquotedblright} variations in water mass structure, advection, and mixing that belie the simple perception of a continuous plume extending westward from the EPR. For example, one feature observed at 120{\textdegree}W, 14{\textdegree}S has tracer signatures that are consistent with a water mass originating from an area as much as 2000 km south of this section, suggesting a quasi-permanent northward flow on the western flank of the EPR. Helium isotope variations in the plume show a uniquely high 3He/4He source in the tongue compared with typical mid-ocean ridge basalts (MORB), consistent with the anomalously high ratios observed in \{MORB\} glasses from the \{EPR\} segment just south of this transect. The water column data also reveal that the background 3He/4He east of the \{EPR\} is significantly lower than values characteristic of MORB, suggesting an additional, more geographically distributed radiogenic 4He flux of order 107 mol/y into the deep Pacific. In the western end of the section, incoming bottom waters have relatively less hydrothermal hydrothermal helium, more radiocarbon, and more oxygen, as well as negative saturation anomalies for the heavy noble gases (Ar, Kr, and Xe). During the basin-scale upwelling of this water, diapycnal mixing serves to erase these negative anomalies. The relative magnitudes of the increases for the heavy noble gases (Ar, Kr, and Xe) are quantitatively consistent with this process. This leads us to estimate the relatively smaller effects on He and Ne saturations, which range from near zero to 0.2\% and 0.3\% respectively. With this information, we are able to refine our estimates of the magnitude of 3He and 4He excesses and the absolute 3He/4He ratio of non-atmospheric helium introduced into deep Pacific waters.},
	issn = {0304-4203},
	doi = {http://doi.org/10.1016/j.marchem.2017.03.009},
	url = {http://www.sciencedirect.com/science/article/pii/S0304420316302353},
	author = {W. J. Jenkins and Dempsey E. Lott III and Christopher R. German and Kevin L. Cahill and Joanne Goudreau and Brett Longworth}
}
@article {47,
	title = {Carbonation rates of peridotite in the Samail Ophiolite, Sultanate of Oman, constrained through 14C dating and stable isotopes},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {126},
	year = {2014},
	pages = {371-397},
	abstract = {Detailed 14C dating as well as stable C and O isotope analyses were conducted on carbonates formed during alteration of the peridotite layer of the Samail Ophiolite, Sultanate of Oman. 14C results obtained in this and previous studies indicate that surface travertines range in age from modern to >45,000 yr BP, indicating long-term deposition and preservation. Travertine deposition rates in two localities were \~{}0.1 to 0.3 mm/yr between \~{}30,000 and 45,000 yr BP. Using an estimate of total travertine area, this would result in a maximum of \~{}1000 to 3000 m3/yr of travertine being deposited throughout the ophiolite during this time period. This travertine deposition would have sequestered a maximum of \~{}1 to 3 {\texttimes} 106 kg CO2/yr. Ca-rich carbonate veins that are associated with the surface travertine deposits have ages ranging from \~{}4000 to 36,000 yr BP (average: 15,000 yr BP). Mg-rich carbonate veins exposed in outcrops have ages ranging from \~{}8000 to 45,000 yr BP (average: 35,000 yr BP). Detailed sampling from numerous locations (3 locations in this study and 10 locations in the previous studies) indicates that no carbonate veins from the natural peridotite weathering surface are older than the \~{}50,000 yr BP dating limit of 14C. However, 14C dating of Mg-rich carbonate veins from three roadcut exposures (Qafeefah, Fanja, and Al-Wuqbah) indicates that a significant number of roadcut veins are 14C dead (>50,000 yr BP). A location weighted average indicates that \~{}40\% of veins sampled at the three roadcuts are 14C dead. An average including veins sampled at both roadcuts and outcrops indicates that overall \~{}8\% of Mg-rich carbonate veins are 14C dead. Mg-rich carbonate veins are estimated to sequester on the order of 107 kg CO2/yr throughout the ophiolite.},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2013.11.007},
	url = {http://www.sciencedirect.com/science/article/pii/S0016703713006467},
	author = {Mervine, Evelyn M. and Humphris, Susan E. and Sims, Kenneth W. W. and Kelemen, Peter B. and W. J. Jenkins}
}
@article {93,
	title = {Carbonate as sputter target material for rapid C-14 AMS},
	journal = {Nuclear Instruments \& Methods in Physics Research Section B-Beam Interactions with Materials and Atoms},
	volume = {294},
	year = {2013},
	note = {id: 2244; PT: J; CT: 12th International Conference on Accelerator Mass Spectrometry (AMS); CY: MAR 20-25, 2011; CL: Wellington, NEW ZEALAND; TC: 0; UT: WOS:000313234300064},
	pages = {328-334},
	abstract = {This paper describes a technique for measuring the C-14 content of carbonate samples by producing C- ions directly in the negative ion sputter source of an accelerator mass spectrometer CAMS) system. This direct analysis of carbonate material eliminates the time and expense of graphite preparation. Powdered carbonate is mixed with titanium powder, loaded into a target cartridge, and compressed. Beam currents for optimally-sized carbonate targets (0.09-0.15 mg C) are typically 10-20\% of those produced by optimally-sized graphite targets (0.5-1 mg C). Modern (>0.8 Fm) samples run by this method have standard deviations of 0.009 Fm or less, and near-modern samples run as unknowns agree with values from traditional hydrolysis/graphite to better than 2\%. Targets with as little as 0.06 mg carbonate produce useable ion currents and results, albeit with increased error and larger blank. In its current state, direct sputtering is best applied to problems where a large number of analyses with lower precision are required. These applications could include age surveys of deep-sea corals for determination of historic population dynamics, to identify samples that would benefit from high precision analysis, and for growth rate studies of organisms forming carbonate skeletons. (C) 2012 Elsevier B.V. All rights reserved.},
	issn = {0168-583X},
	doi = {10.1016/j.nimb.2012.05.014},
	author = {Longworth, Brett E. and Robinson, Laura F. and Roberts, Mark L. and Beaupr{\'e}, Steven R. and Burke, Andrea and W. J. Jenkins}
}
@article {129,
	title = {Apparent oxygen utilization rates calculated from tritium and helium-3 profiles at the Bermuda Atlantic Time-series Study site},
	journal = {Biogeosciences},
	volume = {9},
	year = {2012},
	note = {id: 2253; PT: J; TC: 0; UT: WOS:000305830000003},
	pages = {1969-1983},
	abstract = {We present three years of Apparent Oxygen Utilization Rates (AOUR) estimated from oxygen and tracer data collected over the ocean thermocline at monthly resolution between 2003 and 2006 at the Bermuda Atlantic Timeseries Study (BATS) site. We estimate water ages by calculating a transit time distribution from tritium and helium-3 data. The vertically integrated AOUR over the upper 500 m, which is a regional estimate of export, during the three years is 3.1 +/- 0.5 mol O-2 m(-2) yr(-1). This is comparable to previous AOUR-based estimates of export production at the BATS site but is several times larger than export estimates derived from sediment traps or Th-234 fluxes. We compare AOUR determined in this study to AOUR measured in the 1980s and show AOUR is significantly greater today than decades earlier because of changes in AOU, rather than changes in ventilation rates. The changes in AOU are likely a methodological artefact associated with problems with early oxygen measurements.},
	issn = {1726-4170},
	doi = {10.5194/bg-9-1969-2012},
	author = {Stanley, R. H. R. and Doney, S. C. and W. J. Jenkins and Lott, D. E., III}
}
@article {197,
	title = {Rapid radiocarbon ((14)C) analysis of coral and carbonate samples using a continuous-flow accelerator mass spectrometry (CFAMS) system},
	journal = {Paleoceanography},
	volume = {26},
	year = {2011},
	note = {id: 1915; PT: J; UT: WOS:000296649300001},
	pages = {PA4212-PA4212},
	abstract = {Radiocarbon analyses of carbonate materials provide critical information for understanding the last glacial cycle, recent climate history and paleoceanography. Methods that reduce the time and cost of radiocarbon ((14)C) analysis are highly desirable for large sample sets and reconnaissance type studies. We have developed a method for rapid radiocarbon analysis of carbonates using a novel continuous-flow accelerator mass spectrometry (CFAMS) system. We analyzed a suite of deep-sea coral samples and compared the results with those obtained using a conventional AMS system. Measurement uncertainty is},
	issn = {0883-8305},
	doi = {10.1029/2011PA002174},
	author = {McIntyre, Cameron P. and Roberts, Mark L. and Burton, Joshua R. and McNichol, Ann P. and Burke, Andrea and Robinson, Laura F. and von Reden, Karl F. and W. J. Jenkins}
}
@article {246,
	title = {A High-Performance (14)c Accelerator Mass Spectrometry System},
	journal = {Radiocarbon},
	volume = {52},
	year = {2010},
	note = {id: 2095; PT: J; CT: 20th International Radiocarbon Conference; CY: MAY 31-JUN 05, 2009; CL: Big Isl, HI; SI: 1; UT: WOS:000285437800005},
	pages = {228-235},
	abstract = {A new and unique radiocarbon accelerator mass spectrometry (AMS) facility has been constructed at the Woods Hole Oceanographic Institution. The defining characteristic of the new system is its large-gap optical elements that provide a larger-than-standard beam acceptance. Such a system is ideally suited for high-throughput, high-precision measurements of (14)C. Details and performance of the new system are presented.},
	issn = {0033-8222},
	doi = {10.2458/azu_js_rc.52.3657},
	author = {Roberts, M. L. and Burton, J. R. and Elder, K. L. and Longworth, B. E. and McIntyre, C. P. and von Reden, K. F. and Han, B. X. and Rosenheim, B. E. and W. J. Jenkins and Galutschek, E. and McNichol, A. P.}
}
@article {506,
	title = {Reconnaissance dating A new radiocarbon method applied to assessing the temporal distribution of Southern Ocean deep-sea corals},
	journal = {Deep-Sea Research Part I-Oceanographic Research Papers},
	volume = {57},
	year = {2010},
	note = {id: 1924; PT: J; UT: WOS:000284750700012},
	pages = {1510-1520},
	abstract = {We have developed a rapid reconnaissance method of preparing graphite for (14)C/(12)C analysis Carbonate (similar to 15 mg) is combusted using an elemental analyzer and the resulting CO(2) is converted to graphite using a sealed tube zinc reduction method Over 85\% (n=45 replicates on twenty-one individual corals) of reconnaissance ages measured on corals ranging in age from 500 to 33 000 radiocarbon years (Ryr) are within two standard deviations of ages generated using standard hydrolysis methods on the same corals and all reconnaissance ages are within 300 Ryr of the standard hydrolysis ages Replicate measurements on three individual aragonitic corals yielded ages of 1076 +/- 35 Ryr (standard deviation n=5) 10 739 +/- 47 Ryr (n=8) and 40 146 +/- 3500 Ryr (n=9) No systematic biases were found using different cleaning methods or variable sample sizes Analysis of (13)C/(12)C was made concurrently with the (14)C/(12)C measurement to correct for natural fractionation and for fractionation during sample processing and analysis This technique provides a new rapid method for making accurate percent-level (14)C/(12)C analyses that may be used to establish the rates and chronology of earth system processes where survey-type modes of age estimation are desirable For example applications may include creation of sediment core-top maps preliminary age models for sediment cores and growth rate studies of marine organisms such as corals or mollusks We applied the reconnaissance method to more than 100 solitary deep-sea corals collected in the Drake Passage in the Southern Ocean to investigate their temporal and spatial distribution The corals used in this study are part of a larger sample set and the subset that was dated was chosen based on species as opposed to preservation state so as to exclude obvious temporal biases Similar to studies in other regions the distribution of deep-sea corals is not constant through time across the Drake Passage Most of the corals from the Burdwood Bank (continental shelf of Argentina) have ages ranging between 0 and 2500 calendar years whereas most of the corals from the Sars Seamount in the Drake Passage have ages between 10 000 and 12 500 calendar years Such differences may be caused in part by sampling biases but may also be caused by changes in larval transport nutrient supply or other environmental pressures (C) 2010 Elsevier Ltd All rights reserved},
	issn = {0967-0637},
	doi = {10.1016/j.dsr.2010.07.010},
	author = {Burke, Andrea and Robinson, Laura F. and McNichol, Ann P. and W. J. Jenkins and Scanlon, Kathryn M. and Gerlach, Dana S.}
}
@article {460,
	title = {Software development for continuous-gas-flow AMS},
	journal = {Nuclear Instruments \& Methods in Physics Research Section B-Beam Interactions with Materials and Atoms},
	volume = {266},
	year = {2008},
	note = {id: 2091; PT: J; CT: 9th European Conference on Accelerators in Applied Research and Technology; CY: SEP 03-07, 2007; CL: Florence, ITALY; SP: Univ Florence, Dept Phys, Ist Nazl Fis Nucl; UT: WOS:000257185600033},
	pages = {2233-2237},
	abstract = {The National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) Facility at Woods Hole Oceanographic institution is presently completing installation of a novel continuous-flow AMS system. A multi-year development of an AMS microwave gas ion source in collaboration with Atomic Energy Canada Limited (AECL), Chalk River, has preceded this final step of an implementation that is expected to add a new dimension to (14)C AMS. National Instruments, NIM, and CAMAC modules have been programmed with Lab-VIEW on a Windows XP platform to form the basis for data acquisition. In this paper we discuss possible applications and include simulations of expected data acquisition scenarios like real-time AMS analysis of chromatograms. Particular attention will have to be given to issues of synchronization between rapidly changing input amplitudes and signal processing cycles in hardware and software. (C) 2008 Elsevier B.V. All rights reserved.},
	issn = {0168-583X},
	doi = {10.1016/j.nimb.2008.03.001},
	author = {von Reden, K. F. and Roberts, M. L. and W. J. Jenkins and Rosenheim, B. E. and McNichol, A. P. and Schneider, R. J.}
}
@article {462,
	title = {Electromagnetic field modeling and ion optics calculations for a continuous-flow AMS system},
	journal = {Nuclear Instruments \& Methods in Physics Research Section B-Beam Interactions with Materials and Atoms},
	volume = {259},
	year = {2007},
	note = {id: 1698; 182WV Times Cited:6 Cited References Count:14},
	pages = {111-117},
	abstract = {A continuous-flow C-14 AMS (CFAMS) system is under construction at the NOSAMS facility. This system is based on a NEC Model 1.5SDH-10.5 MV Pelletron accelerator and will utilize a combination of a microwave ion source (MIS) and a charge exchange canal (CXC) to produce negative carbon ions from a continuously flowing stream Of CO2 gas. For high-efficiency transmission of the large emittance, large energy-spread beam from the ion source unit, a large-acceptance and energy-achromatic injector consisting of a 45 degrees electrostatic spherical analyzer (ESA) and a 90 degrees double-focusing magnet has been designed. The 45 degrees ESA is rotatable to accommodate a 134-sample MC-SNICS as a second ion source. The high-energy achromat (90 degrees double focusing magnet and 90 degrees ESA) has also been customized for large acceptance. Electromagnetic field modeling and ion optics calculations of the beamline were done with Infolytica MagNet, ElecNet, and Trajectory Evaluator. PBGUNS and SIMION were used for the modeling of ion source unit. (c) 2007 Elsevier B.V. All rights reserved.},
	issn = {0168-583X},
	doi = {10.1016/J.Nimb.2007.01.224},
	author = {Han, B. X. and von Reden, K. F. and Roberts, M. L. and Schneider, R. J. and Hayes, J. M. and W. J. Jenkins}
}
@article {567,
	title = {Progress on a gas-accepting ion source for continuous-flow accelerator mass spectrometry},
	journal = {Nuclear Instruments \& Methods in Physics Research Section B-Beam Interactions with Materials and Atoms},
	volume = {259},
	year = {2007},
	note = {182wvTimes Cited:24Cited References Count:12},
	month = {Jun},
	pages = {83-87},
	abstract = {A gas-accepting microwave-plasma ion source is being developed for continuous-flow accelerator mass spectrometry (AMS). Characteristics of the ion source will be presented. Schemes for connecting a gas or liquid chromatograph to the ion source will also be discussed. (c) 2007 Ellsevier B.V. All rights reserved.},
	issn = {0168-583x},
	doi = {10.1016/j.nimb.2007.01.189},
	author = {Roberts, M. L. and Schneider, R. J. and von Reden, K. F. and Wills, J. S. C. and Han, B. X. and Hayes, J. M. and Rosenheim, B. E. and W. J. Jenkins}
}
