@article {254,
	title = {Antarctic sediment chronology by programmed-temperature pyrolysis: Methodology and data treatment},
	journal = {Geochemistry Geophysics Geosystems},
	volume = {9},
	year = {2008},
	note = {id: 1847; 284ON Times Cited:5 Cited References Count:27Y},
	abstract = {We report a detailed programmed-temperature pyrolysis/ combustion methodology for radiocarbon (C-14) dating of Antarctic sub-ice shelf sediments. The method targets the autochthonous organic component in sediments that contain a distribution of acid-insoluble organic components from several sources of different ages. The approach has improved sediment chronology in organic-rich sediments proximal to Antarctic ice shelves by yielding maximum age constraints significantly younger than bulk radiocarbon dates from the same sediment horizons. The method proves adequate in determining isotope ratios of the pre-aged carbon end-member; however, the isotopic compositions of the low-temperature measurements indicate that no samples completely avoided mixing with some proportion of pre-aged organic material. Dating the unresolved but desired young end-member must rely on indirect methods, but a simple mixing model cannot be developed without knowledge of the sedimentation rate or comparable constraints. A mathematical approach allowing for multiple mixing components yields a maximum likelihood age, a first-order approximation of the relative proportion of the autochthonous component, and the temperature at which allochthonous carbon begins to volatilize and mix with the autochthonous component. It is likely that our estimation of the cutoff temperature will be improved with knowledge of the pyrolysis kinetics of the major components. Chronology is improved relative to bulk acid-insoluble organic material ages from nine temperature interval dates down to two, but incorporation of inherently more pre-aged carbon in the first division becomes more apparent with fewer and larger temperature intervals.},
	issn = {1525-2027},
	doi = {10.1029/2007gc001816},
	author = {Rosenheim, B. E. and Day, M. B. and Domack, E. and Schrum, H. and Benthien, A. and Hayes, J. M.}
}
@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}
}
@conference {1543,
	title = {3-D Electromagnetic Field Modeling and Ion Optics Calculations for a Continuous-Flow AMS System},
	booktitle = {10th International Conference on Accelerator Mass Spectrometry},
	year = {2005},
	note = {id: 1708},
	month = {2005},
	address = {Berkeley, California},
	author = {Han, B. X. and von Reden, K. F. and Roberts, M. L. and Schneider, R. J. and Hayes, J. M.}
}
@article {587,
	title = {Calculation of hydrogen isotopic fractionations in biogeochemical systems},
	journal = {Geochimica Et Cosmochimica Acta},
	volume = {69},
	year = {2005},
	note = {892wiTimes Cited:55Cited References Count:21},
	month = {Feb 1},
	pages = {593-597},
	abstract = {Hydrogen-isotopic data are often interpreted using mathematical approximations originally intended for other isotopes. One of the most common. apparent in literature over the last several decade{\textquoteright}s. assumes that delta values of reactants and products are separated by a constant fractionation factor delta(p) = delta(r) + epsilon(p/r). Because of the large fractionations that affect hydrogen isotopes, such approximations can lead to substantial errors. Here we review and develop general equations for isotopic mass balances that include the differential fractionation of each component in a mixture and discuss their use in three geochemical applications. For the fractionation of a single component. the reactant and product are related by delta(p) = a(p/r)delta(r) + epsilon(p/r), where alpha and epsilon refer to the same fractionation. Regression of delta(p) on delta(r) should give equivalent fractionations based on the intercept and slope, but this has not generally been recognized in studies of D/H fractionation. In a mixture of two components, each of which is fractionated during mixing, there is no unique solution for the three unknown variables (two fractionation factors and the elemental mixing ratio of the two hydrogen sources). The flow of H from CH4 and H2O to bacterial lipids in the metabolism of Methylococcus capsulatus provides an example of such a case. Data and conclusions from an earlier study of that system (Sessions et al., 2002) are reexamined here. Several constraints on the variables are available based on plausible ranges for fractionation factors. A possible refinement to current experimental procedures is the measurement of three different isotopes, which would allow unique determination of all variables. Copyright (C) 2005 Elsevier Ltd.},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2004.08.005},
	author = {Sessions, A. L. and Hayes, J. M.}
}
@conference {1598,
	title = {Continuous-Flow Accelerator Mass Spectrometry},
	booktitle = {the International Symposium on Utilization of Accelerators},
	series = {IAEA-CN-115-09},
	year = {2005},
	note = {id: 767},
	month = {2005},
	address = {Dubrovnik Croatia},
	author = {Roberts, M. L. and von Reden, K. F. and Han, B. X. and Schneider, R. J. and Benthien, A. and Hayes, J. M.}
}
@article {640,
	title = {Moving-wire device for carbon isotopic analyses of nanogram quantities of nonvolatile organic carbon},
	journal = {Anal Chem},
	volume = {77},
	year = {2005},
	note = {Sessions, Alex LSylva, Sean PHayes, John MengResearch Support, U.S. Gov{\textquoteright}t, Non-P.H.S.2005/10/15 09:00Anal Chem. 2005 Oct 15;77(20):6519-27.},
	month = {Oct 15},
	pages = {6519-27},
	abstract = {We describe a moving-wire analyzer for measuring 13C in dissolved, involatile organic materials. Liquid samples are first deposited and dried on a continuously spooling nickel wire. The residual sample is then combusted as the wire moves through a furnace, and the evolved CO2 is analyzed by continuous-flow isotope ratio mass spectrometry. A typical analysis requires 1 microL of sample solution and produces a CO2 peak approximately 5 s wide. The system can measure "bulk" delta13C values of approximately 10 nmol of organic carbon with precision better than 0.2 per thousand. For samples containing approximately 1 nmol of C, precision is approximately 1 per thousand. Precision and sensitivity are limited mainly by background noise derived from carbon within the wire. Instrument conditions minimizing that background are discussed in detail. Accuracy is better than 0.5 per thousand for nearly all dissolved analytes tested, including lipids, proteins, nucleic acids, sugars, halocarbons, and hydrocarbons. The sensitivity demonstrated here for 13C measurements represents a approximately 1000-fold improvement relative to existing elemental analyzers and should allow the use of many new preparative techniques for collecting and purifying nonvolatile biochemicals for isotopic analysis.},
	issn = {0003-2700 (Linking)},
	doi = {10.1021/ac051251z},
	author = {Sessions, A. L. and Sylva, S. P. and Hayes, J. M.}
}
@conference {1759,
	title = {Progress on a Gas Ion Source for Continuous-Flow Accelerator Mass Spectrometry},
	booktitle = {10th International Conference on Accelerator Mass Spectrometry},
	year = {2005},
	note = {id: 768},
	month = {2005},
	address = {Berkeley, California},
	author = {Roberts, M. L. and Schneider, R. J. and von Reden, K. F. and Han, B. X. and Rosenheim, B. E. and Hayes, J. M.},
	editor = {Knezovich, J. and et al.}
}
@article {717,
	title = {Carbon-isotopic shifts associated with heterotrophy and biosynthetic pathways in direct- and indirect-developing sea urchins},
	journal = {Marine Ecology Progress Series},
	volume = {275},
	year = {2004},
	note = {847vnTimes Cited:4Cited References Count:34},
	pages = {139-151},
	abstract = {Natural abundances of C-13 were measured in bulk biomass and in individual lipids isolated from 2 species of sea urchins, Heliocidaris erythrogramma and H. tuberculata, and from calcareous and green benthic algae on which they were feeding. Planktonic larvae of H. erythrogramma are lecithotrophic whereas those of H. tuberculata are planktotrophic. The organisms were collected from a subtidal environment in Botany Bay, Sydney, Australia. The biomass of both consumers was enriched in C-13 relative to their diets by up to 1.8parts per thousand. The carbon skeletons of sterols from the urchins derive at least in part from de novo biosynthesis by the urchins. Depending on chain length and degree of unsaturation, carboxylic acids from the urchins derive from de novo blosynthesis (14:0, unsaturated acids), from the diet (18:0), or from both these sources (16:0). H. tuberculata synthesizes a greater distribution and proportion of unsaturated carboxylic acids. Odd-C and branched-chain carboxylic acids derive in part from bacterial sources and are enriched in C-13 relative to algal lipids and depleted relative to those in urchins. Only H. erythrogramma, which uses wax esters-as storage lipids in its relatively large and buoyant eggs, produces significant quantities of n-alkanols; n-alkanols in H, tuberculata derive from the diet. In terms of molecular distributions and isotopic compositions, the lipids in fecal matter from both heterotrophs resemble those of the diet rather than those of the urchins.},
	issn = {0171-8630},
	doi = {10.3354/meps275139},
	author = {Villinski, J. C. and Hayes, J. M. and Villinski, J. T. and Brassell, S. C. and Raff, R. A.}
}
@article {2020,
	title = {Compound-specific radiocarbon dating of the varved Holocene sedimentary record of Saanich Inlet, Canada},
	journal = {Paleoceanography},
	volume = {19},
	year = {2004},
	note = {819piTimes Cited:18
Cited References Count:69
},
	month = {May 1},
	abstract = {[1] The radiocarbon contents of various biomarkers extracted from the varve-counted sediments of Saanich Inlet, Canada, were determined to assess their applicability for dating purposes. Calibrated ages obtained from the marine planktonic archaeal biomarker crenarchaeol compared favorably with varve-count ages. The same conclusion could be drawn for a more general archaeal biomarker (GDGT-0), although this biomarker proved to be less reliable due to its less-specific origin. The results also lend support to earlier indications that marine crenarchaeota use dissolved inorganic carbon (DIC) as their carbon source. The average reservoir age offset DeltaR of 430 years, determined using the crenarchaeol radiocarbon ages, varied by +/-110 years. This may be caused by natural variations in ocean-atmosphere mixing or upwelling at the NE Pacific coast but variability may also be due to an inconsistency in the marine calibration curve when used at sites with high reservoir ages.},
	keywords = {british-columbia, compound-specific radiocarbon dating, crenarchaeol, ionization mass-spectrometry, marine-sediments, mediterranean sea, membrane-lipids, ne pacific, odp leg 169s, organic-matter, pacific-ocean, rapid isolation, Reservoir age, reservoir ages, saanich inlet},
	isbn = {0883-8305},
	doi = {10.1029/2003PA000927},
	url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2\&amp;SrcAuth=Alerting\&amp;SrcApp=Alerting\&amp;DestApp=WOS\&amp;DestLinkType=FullRecord;UT=WOS:000221326700001},
	author = {Smittenberg, R. H. and Hopmans, E. C. and Schouten, S. and Hayes, J. M. and Eglinton, T. I. and Damste, J. S. S.}
}
@article {464,
	title = {A gas ion source for continuous-flow AMS},
	journal = {Proceedings of the Ninth International Conference on Accelerator Mass Spectrometry},
	volume = {223-224},
	year = {2004},
	note = {id: 2104},
	pages = {149-154},
	abstract = {The first gas-fed ion source for radiocarbon AMS applications (without sputtering) has been operated at the Woods Hole NOSAMS Facility. A three-year, off-line test program resulted in positive carbon ion currents up to 1 mA and negative ion currents up to 80 μA. Recently, the compact, permanent-magnet microwave plasma ion source and magnesium vapor charge-exchange canal were coupled to the recombinator injector of the 2.5 MV Tandetron. When the ion source was operated on CO2 at a flow rate of about 200 μl per minute, negative carbon ion beams up to 20 μA were obtained, at an energy of 35 keV. Radiocarbon measurements were performed on standard reference gases and the dynamic response to square-wave pulses of gas was determined. Time constants in the ion source are less than 1 s, which should allow analysis of chromatographic peaks of CO2 with very little broadening. A combustion device has been constructed to generate CO2 for direct injection into the source. Argon carrier gas is used to buffer the pressure at one atmosphere in the sample gas injector. A dedicated ion-beam injector, with higher angular acceptance and higher transmitted currents, is being constructed for the AMS system.},
	issn = {0168-583X},
	doi = {10.1016/j.nimb.2004.04.031},
	author = {Schneider, R. J. and Kim, S. W. and von Reden, K. F. and Hayes, J. M. and Wills, J. S. C. and Griffin, V. S. and Sessions, A. L. and Sylva, S.}
}
@article {589,
	title = {Isotopic order, biogeochemical processes, and earth history - Goldschmidt Lecture, Davos, Switzerland, August 2002},
	journal = {Geochimica Et Cosmochimica Acta},
	volume = {68},
	year = {2004},
	note = {813fdTimes Cited:17Cited References Count:70},
	month = {Apr},
	pages = {1691-1700},
	abstract = {The impetus to interpret carbon isotopic signals comes from an understanding of isotopic fractionations imposed by living organisms. That understanding rests in turn on studies of enzymatic isotope effects, on fruitful concepts of isotopic order, and on studies of the distribution of (13)C both between and within biosynthetic products. In sum, these studies have shown that the isotopic compositions of biological products are governed by reaction kinetics and by pathways of carbon flow.Isotopic compositions of individual compounds can indicate specific processes or environments. Examples include biomarkers which record the isotopic compositions of primary products in aquatic communities, which indicate that certain bacteria have used methane as a carbon source, and which show that some portions of marine photic zones have been anaerobic. In such studies, the combination of structural and isotopic lines of evidence reveals relationships between compounds and leads to process-related thinking. These are large steps. Reconstruction of the sources and histories of molecular fossils redeems much of the early promise of organic geochemistry by resolving and clarifying paleoenviron-mental signals. In turn, contemplation of this new information is driving geochemists to study microbial ecology and evolution, oceanography, and sedimentology. Copyright (C) 2004 Elsevier Ltd.},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2003.10.023},
	author = {Hayes, J. M.}
}
@article {827,
	title = {Acceptance of the 2002 V. M. Goldschmidt Award},
	journal = {Geochimica Et Cosmochimica Acta},
	volume = {67},
	year = {2003},
	note = {693mfTimes Cited:0Cited References Count:0},
	month = {Jul},
	pages = {2303-2303},
	issn = {0016-7037},
	doi = {10.1016/S0016-7037(02)01278-4},
	author = {Hayes, J. M.}
}
@conference {1597,
	title = {Continuous-Flow Accelerator Mass Spectrometry},
	booktitle = {International Symposium on Radiation Physics},
	year = {2003},
	note = {id: 1683},
	month = {2003},
	address = {Mexico City, Mexico},
	author = {Roberts, M. L. and Benthien, A. and Schneider, R. J. and von Reden, K. F. and Hayes, J. M.}
}
@article {2073,
	title = {Radiocarbon dating of individual fatty acids as a tool for refining Antarctic margin sediment chronologies},
	journal = {Radiocarbon},
	volume = {45},
	year = {2003},
	note = {735tqTimes Cited:25
Cited References Count:29
},
	month = {2003},
	pages = {17-24},
	abstract = {We have measured the radiocarbon contents of individual, solvent-extractable, short-chain (C-14, C-16, and C-18) fatty acids isolated from Ross Sea surface sediments. The corresponding C-14 ages are equivalent to that of the post-bomb dissolved inorganic carbon (DIC) reservoir. Moreover, molecular C-14 variations in surficial (upper 15 cm) sediments indicate that these compounds may prove useful for reconstructing chronologies of Antarctic margin sediments containing uncertain (and potentially variable) quantities of relict organic carbon. A preliminary molecular C-14 chronology suggests that the accumulation rate of relict organic matter has not changed during the last 500 C-14 yr. The focus of this study is to determine the validity of compound-specific C-14 analysis as a technique for reconstructing chronologies of Antarctic margin sediments.},
	keywords = {carbon, ice-sheet, marine-sediments, north-atlantic, organic-matter, ross-sea, southern-ocean},
	isbn = {0033-8222},
	author = {Ohkouchi, N. and Eglinton, T. I. and Hayes, J. M.}
}
@conference {1744,
	title = {Plans for expanded 14C analyses at the NOSAMS facility - a status and progress report},
	booktitle = {International Conference on Accelerator Mass Spectrometry},
	year = {2002},
	note = {id: 1685},
	month = {2002},
	address = {Nagoya, Japan},
	author = {von Reden, K. F. and Donoghue, J. and Elder, K. and Gagnon, A. and Gerlach, D. and Griffin, V. and Healy, R. and Long, P. and McNichol, A. and Percy, D. and Roberts, M. L. and Schneider, R. J. and Xu, L. and Hayes, J. M.}
}
@article {700,
	title = {Spatial and temporal offsets between proxy records in a sediment drift},
	journal = {Science},
	volume = {298},
	year = {2002},
	note = {612mqTimes Cited:147Cited References Count:38},
	month = {Nov 8},
	pages = {1224-1227},
	abstract = {Chronologies for Late Quaternary marine sediment records are usually based on radiocarbon ages of planktonic foraminifera. Signals carried by other sedimentary components measured in parallel can provide complementary paleoclimate information. A key premise is that microfossils and other indicators within a given sediment horizon are of equal age. We show here that haptophyte-derived alkenones isolated from Bermuda Rise drift sediments are up to 7000 years older than coexisting planktonic foraminifera. This temporal offset, which is apparently due to lateral transport of alkenones on fine-grained particles from the Nova Scotian margin, markedly influences molecular estimates of sea surface temperatures. More broadly, the observation raises questions about both the temporal and the geographic delity of paleoenvironmental records encoded by readily transported components of sediments.},
	issn = {0036-8075},
	doi = {10.1126/science.1075287},
	author = {Ohkouchi, N. and Eglinton, T. I. and Keigwin, L. D. and Hayes, J. M.}
}
@article {713,
	title = {Test of negative ion beams from a microwave ion source with a charge exchange canal for accelerator mass spectrometry applications},
	journal = {Review of Scientific Instruments},
	volume = {73},
	year = {2002},
	note = {2522wyTimes Cited:8Cited References Count:7},
	month = {Feb},
	pages = {846-848},
	abstract = {A test facility has been constructed to evaluate negative ion beams from small gaseous samples for accelerator mass spectrometry applications. The positive ion beams from the microwave ion source are passed into a charge-exchange canal (CXC) where the ions exchange electrons with magnesium vapor and become negatively charged. Positive molecular ions were: either neutralized or broken up into atomic ions and neutral atoms and molecules by collision processes. Most of the resulting particles were suspected to be neutrals. In studies with injections of CO2 pulses, the resulting positive and negative C-12 current peaks gave a 0.09\% yield of C- ions from CO2 molecules, which includes a charge-exchange efficiency of 10\%. Since nitrogen does not form a stable negative ion, N-14 background is virtually eliminated after the beam goes through the CXC, which is necessary for radiocarbon measurements. (C) 2002 American Institute of Physics.},
	issn = {0034-6748},
	doi = {10.1063/1.1430517},
	author = {Kim, S. W. and Schneider, R. J. and von Reden, K. F. and Hayes, J. M. and Wills, J. S. C.}
}
@article {1003,
	title = {Algal and archaeal polyisoprenoids in a recent marine sediment: Molecular isotopic evidence for anaerobic oxidation of methane},
	journal = {Geochemistry Geophysics Geosystems},
	volume = {2},
	year = {2001},
	note = {458jvTimes Cited:51Cited References Count:79},
	month = {Jan 17},
	abstract = {Analyses of C-13 contents of individual organic molecules in a marine sediment show that crocetane, 2,6,11,15-tetramethylhexadecane, an isomer of phytane, is produced by microorganisms that use methane as their main source of carbon. The sediments lie at a water depth of 68 m in the Kattegat, the strait between Denmark and Sweden. Crocetane appears first 185 cm below the sediment-water interface, in the zone marking the transition from sulfate reduction to methanogenesis. Its delta C-13 value is -90 +/- 10 parts per thousand versus Vienna Pee Dee Belemnite (VPDB). Its structure, which includes four isoprene units arranged symmetrically around a tail-to-tail linkage, suggests that it is produced by a member of the archaea. Growing at the intersection of the diffusion gradients for sulfate and methane in sedimentary pore waters, the source organism apparently function as a methane-consuming member of the microbial consortium responsible for the anaerobic oxidation of methane [Hoehler et al., 1994], in which, as first demonstrated quantitatively in these sediments [Iversen and Jorgensen, 1985], electrons are transferred from methane to sulfate. The presence of archaeal biomass throughout the sediment section is indicated by significant concentrations of 2,6,10,15,19-pentamethylicosane (PMI) and of ether-bound phytane and biphytane. The PMI reaches a minimum delta value of -47 parts per thousand well below the transition zone. Its isotopic depletion could reflect either methanogenic or methanotrophic sources. The ether-bound lipids are isotopically uniform throughout the section and are presumed to derive from archaea that utilize a carbon source unaffected by the oxidation of methane.},
	issn = {1525-2027},
	doi = {10.1029/2000GC000112},
	author = {Bian, L. Q. and Hinrichs, K. U. and Xie, T. M. and Brassell, S. C. and Iversen, H. and Fossing, H. and Jorgensen, B. B. and Hayes, J. M.}
}
@article {692,
	title = {Comparative analysis of methane-oxidizing archaea and sulfate-reducing bacteria in anoxic marine sediments},
	journal = {Appl Environ Microbiol},
	volume = {67},
	year = {2001},
	note = {Orphan, V JHinrichs, K UUssler, W 3rdPaull, C KTaylor, L TSylva, S PHayes, J MDelong, E FengComparative StudyResearch Support, Non-U.S. Gov{\textquoteright}tResearch Support, U.S. Gov{\textquoteright}t, Non-P.H.S.2001/04/03 10:00Appl Environ Microbiol. 2001 Apr;67(4):1922-34.},
	month = {Apr},
	pages = {1922-34},
	abstract = {The oxidation of methane in anoxic marine sediments is thought to be mediated by a consortium of methane-consuming archaea and sulfate-reducing bacteria. In this study, we compared results of rRNA gene (rDNA) surveys and lipid analyses of archaea and bacteria associated with methane seep sediments from several different sites on the Californian continental margin. Two distinct archaeal lineages (ANME-1 and ANME-2), peripherally related to the order Methanosarcinales, were consistently associated with methane seep marine sediments. The same sediments contained abundant (13)C-depleted archaeal lipids, indicating that one or both of these archaeal groups are members of anaerobic methane-oxidizing consortia. (13)C-depleted lipids and the signature 16S rDNAs for these archaeal groups were absent in nearby control sediments. Concurrent surveys of bacterial rDNAs revealed a predominance of delta-proteobacteria, in particular, close relatives of Desulfosarcina variabilis. Biomarker analyses of the same sediments showed bacterial fatty acids with strong (13)C depletion that are likely products of these sulfate-reducing bacteria. Consistent with these observations, whole-cell fluorescent in situ hybridization revealed aggregations of ANME-2 archaea and sulfate-reducing Desulfosarcina and Desulfococcus species. Additionally, the presence of abundant (13)C-depleted ether lipids, presumed to be of bacterial origin but unrelated to ether lipids of members of the order Desulfosarcinales, suggests the participation of additional bacterial groups in the methane-oxidizing process. Although the Desulfosarcinales and ANME-2 consortia appear to participate in the anaerobic oxidation of methane in marine sediments, our data suggest that other bacteria and archaea are also involved in methane oxidation in these environments.},
	issn = {0099-2240 (Linking)},
	doi = {10.1128/AEM.67.4.1922-1934.2001},
	author = {Orphan, V. J. and Hinrichs, K. U. and Ussler, W. and Paull, C. K. and Taylor, L. T. and Sylva, S. P. and Hayes, J. M. and DeLong, E. F.}
}
@article {830,
	title = {Compound-specific D/H ratios of lipid biomarkers from sediments as a proxy for environmental and climatic conditions},
	journal = {Geochimica Et Cosmochimica Acta},
	volume = {65},
	year = {2001},
	note = {395npTimes Cited:209Cited References Count:64},
	month = {Jan},
	pages = {213-222},
	abstract = {Hydrogen isotope ratios (D/H) of lipid biomarkers extracted from aquatic sediments were measured to determine whether they can be used as a proxy for D/H of environmental water. Values of deltaD were determined by using a recently developed isotope-ratio-monitoring gas chromatograph-mass spectrometer system (irmGCMS) and were confirmed by conventional hydrogen isotopic measurements (i.e., combustion followed by reduction) on individual compounds isolated by preparative capillary gas chromatography. Diverse lipids (alkanes, n-alkanols, sterols, and pentacyclic triterpenols) were analyzed to examine hydrogen-isotopic controls on lipids of varying origin and biosynthetic pathway. For algal sterols (24-methylcholest-3 beta -ol, 24-ethylcholest-5,22-dien-3 beta -ol, and 4,23,24-trimethylcholesterol, or dinosterol), the fractionation between sedimentary lipids and environmental water was -201 +/- 10 parts per thousand and was similar in both marine and freshwater sites. In a sediment from a small lake in a forested catchment, triterpenols from terrestrial sources were enriched in D by 30 parts per thousand relative to algal sterols. Apparent fractionation factors for n-alkyl lipids were smaller than those of triterpenols and were more variable, probably reflecting multiple sources for these compounds. We conclude that hydrogen-isotopic analyses of algal sterols provide a viable means of reconstructing D/H of environmental waters. Results are less ambiguous than reconstructions based on analyses of kerogen or other operationally defined organic matter fractions. Copyright (C) 2001 Elsevier Science Ltd.},
	issn = {0016-7037},
	doi = {10.1016/S0016-7037(00)00520-2},
	author = {Sauer, P. E. and Eglinton, T. I. and Hayes, J. M. and Schimmelmann, A. and Sessions, A. L.}
}
@article {2129,
	title = {Correction of H3+ contributions in hydrogen isotope ratio monitoring mass spectrometry},
	journal = {Anal Chem},
	volume = {73},
	year = {2001},
	note = {Sessions, A LBurgoyne, T W
Hayes, J M
eng
2001/02/24 12:00
Anal Chem. 2001 Jan 15;73(2):192-9.
},
	month = {Jan 15},
	pages = {192-9},
	abstract = {Two fundamentally different approaches, termed "pointwise" and "peakwise," are currently used to correct hydrogen isotope ratio monitoring data for the presence of H3+ ion contributions. Consideration of the underlying assumptions shows that the peakwise approach is valid only for peaks with the same functional shape and only when background signals do not vary. The pointwise correction is much more versatile and can be used even when peak shapes and sizes, as well as background signals, vary significantly. It is not exact and is limited in accuracy by (1) the signal-broadening effects of electronic time constants, (2) the analog-to-digital conversion frequency, and (3) the highest frequency of the sample signal. To minimize errors for typical gas chromatographic signals, time constants of <500 ms and analog-to-digital sampling intervals of < or =250 ms are needed. Errors are further minimized by matching sample and standard peaks in both amplitude and D/H ratio. Using the pointwise algorithm, we demonstrate that a series of 14 homologous n-alkanes varying in concentration over a 5-fold range can be analyzed with a mean precision of 2.3 per thousand and no systematic errors.},
	isbn = {0003-2700 (Print)0003-2700 (Linking)},
	doi = {10.1021/ac000489e},
	url = {https://www.ncbi.nlm.nih.gov/pubmed/11199965},
	author = {Sessions, A. L. and Burgoyne, T. W. and Hayes, J. M.}
}
@article {2128,
	title = {Determination of the the H3 factor in hydrogen isotope ratio monitoring mass spectrometry},
	journal = {Anal Chem},
	volume = {73},
	year = {2001},
	note = {Sessions, A LBurgoyne, T W
Hayes, J M
eng
2001/02/24 12:00
Anal Chem. 2001 Jan 15;73(2):200-7.
},
	month = {Jan 15},
	pages = {200-7},
	abstract = {The H3 factor, K, is a parameter required in high-precision, mass spectrometric analyses of hydrogen isotopic abundances. When H2 is used as the sample gas, R* = R - Ki2, where R* is the true HD/H2 ratio, R is the observed (mass 3)/(mass 2) ion-current ratio, and i2 is the ion current at mass 2. Four different methods for the determination of K were defined and tested under conditions characteristic of isotope ratio monitoring systems. Three of these were peak-based. The fourth employed steady flows of H2 from a conventional inlet system. Results obtained using the latter method were more precise (standard deviation of K = 0.1 versus approximately 0.6 ppm mV(-1) for the peak-based methods). However, use of the resulting values of K for correction of isotope ratio monitoring GC/MS results led to systematic errors as large as 9 per thousand, whereas use of the peak-based values led to no systematic errors. Values of K were only weakly dependent on the pressure of He, declining approximately 5\% for each 10-fold increase in P(He). Small variations in partial pressures of H2O and CH4, potential contaminants under isotope ratio monitoring conditions, had no significant effect on values of K.},
	isbn = {0003-2700 (Print)0003-2700 (Linking)},
	doi = {10.1021/ac000488m},
	url = {https://www.ncbi.nlm.nih.gov/pubmed/11199966},
	author = {Sessions, A. L. and Burgoyne, T. W. and Hayes, J. M.}
}
@article {2147,
	title = {Effects of biosynthesis and physiology on relative abundances and isotopic compositions of alkenones},
	journal = {Geochemistry Geophysics Geosystems},
	volume = {2},
	year = {2001},
	note = {458kdTimes Cited:6
Cited References Count:39
},
	month = {Jan 29},
	pages = {art. no.-2000GC000052},
	abstract = {The number of double bonds in long-chain, unsaturated ketones (alkenones) produced by some members of the Haptophyceae is correlated with the ambient temperature at the time of synthesis. For these same organisms the depletion of carbon-13 in biosynthetic products relative to dissolved inorganic carbon is related directly to the specific growth rate and inversely to the concentration of dissolved carbon dioxide. This report summarizes issues relating to the physiology, metabolism, and biochemistry of alkenone producers and how they affect the abundances and isotopic compositions of alkenones. These considerations show that an understanding of cellular responses to parameters governing uptake of inorganic carbon (C-i), isotopic fractionation, growth under diverse nutrient conditions, and genetic variability, both in the field and in culture, is necessary for developing a conceptual understanding of the biological significance of the epsilonp and U-37(K{\textquoteright}) indices. Emiliana huxleyi is the best known alkenone producer and can serve as a model organism for these studies. This report identifies knowledge gaps and appropriate objectives for both field- and laboratory-based research.},
	keywords = {algae, alkenones, anhydrase, biogeochemical processes, biosynthesis, calcification, carbon-13, emiliania-huxleyi prymnesiophyceae, fractionation, Haptophytes, inorganic carbon utilization, instruments and techniques, isoprenoid biosynthesis, marine diatom, paleoceanography, photosynthesis, physiology, phytoplankton, sea surface temperature},
	isbn = {1525-2027},
	doi = {10.1029/2000GC000052},
	author = {Gonzalez, E. L. and Riebesell, U. and Hayes, J. M. and Laws, E. A.}
}
@article {2135,
	title = {Origins of lipid biomarkers in Santa Monica Basin surface sediment: A case study using compound-specific D14C analysis},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {65},
	year = {2001},
	note = {id: 1419},
	month = {2001},
	pages = {3123-3137},
	author = {Pearson, A. and McNichol, A. P. and Benitez-Nelson, B. C. and Hayes, J. M. and Eglinton, T. I.}
}
@conference {1822,
	title = {Validation of compound-specific 14C dating using the varved sedimentary record of Saanich Inlet, Canada},
	booktitle = {Proceedings of the 20th international meeting on organic geochemistry},
	year = {2001},
	note = {id: 270},
	month = {2001},
	address = {Nancy, France},
	author = {Smittenberg, R. H. and Hopmans, E. C. and Eglinton, T. I. and Hayes, J. M. and Whiticar, M. J. and Schouten, S. and Sinninghe Damst{\'e}, J. S.}
}
@article {831,
	title = {Acceptance of the 1997 Alfred E. Treibs Award},
	journal = {Geochimica Et Cosmochimica Acta},
	volume = {64},
	year = {2000},
	note = {287naTimes Cited:0Cited References Count:0},
	month = {Feb},
	pages = {749-750},
	issn = {0016-7037},
	doi = {10.1016/S0016-7037(00)00325-2},
	author = {Hayes, J. M.}
}
@article {814,
	title = {Molecular and isotopic analysis of anaerobic methane-oxidizing communities in marine sediments},
	journal = {Organic Geochemistry},
	volume = {31},
	year = {2000},
	note = {384quTimes Cited:204Cited References Count:49},
	pages = {1685-1701},
	abstract = {Convergent lines of molecular, carbon-isotopic, and phylogenetic evidence have previously indicated (Hinrichs, K.U., Hayes, J.M., Sylva, S.P., Brewer. P.G.. DeLong, E.F., 1999. Methane-consuming archaebacteria in marine sediments. Nature 398, 802-805.) that archaea are involved in the anaerobic oxidation of methane in sediments from the Eel River Basin. offshore northern California. Now, further studies of those same sediments and of sediments from a methane seep in the Santa Barbara Basin have confirmed and extended those results. Mass spectrometric and chromatographic analyses of an authentic standard of sn-2-hydroxyarchaeol (hydroxylated at C-3 in the sn-2 phytanyl moiety) have confirmed our previous, tentative identification of this compound but shown that the previously examined product was the mono-TMS, rather than di-TMS, derivative. Further analyses of C-13-depleted lipids, appreciably more abundant in samples from the Santa Barbara Basin, have shown that the archaeal lipids are accompanied by two sets of products that are only slightly less depleted in C-13. These are additional glycerol ethers and fatty acids. The alkyl substituents in the ethers (mostly monoethers, with some diethers) are non-isoprenoidal. The carbon-number distributions and isotopic compositions of the alkyl substituents and of the fatty acids are similar, suggesting strongly that they are produced by the same organisms. Their structures, n-alkyl and methyl-branched n-alkyl, require a bacterial rather than archaeal source. The non-isoprenoidal glycerol ethers are novel constituents in marine sediments but have been previously reported in thermophilic, sulfate- and nitrate-reducing organisms which lie near the base of the rRNA-based phylogenetic tree. Based on previous observations that the anaerobic oxidation of methane involves a net transfer of electrons from methane to sulfate, it appears likely that the non-archaeal, C-13-depleted lipids are products of one or more previously unknown sulfate-reducing bacteria which grow syntrophically with the methane-utilizing archaea. Their products account for 50\% of the fatty acids in the sample from the Santa Barbara Basin. At all methane-seep sites examined, the preservation of aquatic products is apparently enhanced because the methane-oxidizing consortium utilizes much of the sulfate that would otherwise be available for remineralization of materials from the water column. Crown Copyright (C) 2000 Published by Elsevier Science Ltd. All rights reserved.},
	issn = {0146-6380},
	doi = {10.1016/S0146-6380(00)00106-6},
	author = {Hinrichs, K. U. and Summons, R. E. and Orphan, V. and Sylva, S. P. and Hayes, J. M.}
}
@article {809,
	title = {Tests of positive ion beams from a microwave ion source for AMS},
	journal = {Nuclear Instruments \& Methods in Physics Research Section B-Beam Interactions with Materials and Atoms},
	volume = {172},
	year = {2000},
	note = {372jrTimes Cited:16Cited References Count:4},
	month = {Oct},
	pages = {252-256},
	abstract = {A test facility has been constructed to evaluate high-current positive ion beams from small gaseous samples for AMS applications. The major components include a compact permanent magnet microwave ion source built at the AECL Chalk River Laboratory and now on loan from the University of Toronto, and a double-focusing spectrometer magnet on loan from Argonne National Laboratory. Samples are introduced by means of a silica capillary injection system. Loop injection into a carrier gas provides a stable feed for the microwave driven plasma. The magnetic analysis system is utilized to isolate carbon ions derived from CO? samples from other products of the plasma discharge, including argon ions of the carrier gas. With a smaller discharge chamber, we hope to exceed a conversion efficiency of 14\% for carbon ions produced per atom, which we reported at AMS-7. The next step will be to construct an efficient charge-exchange cell, to produce negative ions for injection into the WHOI recombinator injector. (C) 2000 Elsevier Science B.V. All rights reserved.},
	issn = {0168-583x},
	doi = {10.1016/S0168-583x(00)00131-2},
	author = {Schneider, R. J. and von Reden, K. F. and Hayes, J. M. and Wills, J. S. C. and Kern, W. G. E. and Kim, S. W.}
}
@conference {1567,
	title = {Application of a compact microwave ion source to radiocarbon analysis},
	booktitle = {The eighth international conference on heavy-ion accelerator technology},
	year = {1999},
	note = {id: 1977},
	month = {1999},
	pages = {422},
	publisher = {American Institute of Physics},
	organization = {American Institute of Physics},
	abstract = {The compact, high current, 2.45 GHz microwave-driven plasma ion source which was built for the Chalk River TASCC facility is presently being adapted for testing as a gas ion source for accelerator mass spectrometry, at the Woods Hole Oceanographic Institution accelerator mass spectrometer. The special requirements for producing carbon-ion beams from micromole quantities of carbon dioxide produced from environmental samples will be discussed. These samples will be introduced into the ion source by means of argon carrier gas and a silicon capillary injection system. Following the extraction of positive ions from the source, negative ion formation in a charge exchange vapor will effectively remove the argon from the carbon beam. Simultaneous injection of the three carbon isotopes into the accelerator is planned.},
	keywords = {carbon, ion sources, mass spectroscopy, spectrochemical analysis, tandem accelerators},
	author = {Schneider, R. J. and von Reden, K. F. and Hayes, J. M. and Wills, J. S. C.},
	editor = {Shepard, K. W.}
}
@conference {1569,
	title = {Application of Compact Microwave Ion Source to Radiocarbon Analysis},
	booktitle = {8th International Conference on Heavy Ion Accelerator Technology},
	volume = {Conference Proceedings 473},
	year = {1999},
	note = {id: 1824},
	month = {1999},
	pages = {422-425},
	publisher = {American Institute of Physics},
	organization = {American Institute of Physics},
	address = {Argonne National Lab.},
	author = {Schneider, R. J. and von Reden, K. F. and Hayes, J. M. and Wills, J. S. C.},
	editor = {Shepard, K.}
}
@article {811,
	title = {Fractionation of hydrogen isotopes in lipid biosynthesis},
	journal = {Organic Geochemistry},
	volume = {30},
	year = {1999},
	note = {254efTimes Cited:281Cited References Count:26},
	pages = {1193-1200},
	abstract = {Isotopic compositions of carbon-bound hydrogen in individual compounds from eight different organisms were measured using isotope-ratio-monitoring gas chromatography-mass spectrometry. This technique is capable of measuring D/H ratios at natural abundance in individual lipids yielding as little as 20 nmol of H-2, and is applicable to a wide range of compounds including hydrocarbons, sterols, and fatty acids. The hydrogen isotopic compositions of lipids are controlled by three factors: isotopic compositions of biosynthetic precursors, fractionation and exchange accompanying biosynthesis, and hydrogenation during biosynthesis. delta D values of lipids from the eight organisms examined here suggest that all three processes are important for controlling natural variations in isotopic abundance. n-Alkyl lipids are depleted in D relative to growth water by 113-262 parts per thousand, while polyisoprenoid lipids are depleted in D relative to growth water by 142-376 parts per thousand. Isotopic variations within compound classes (e.g., n-alkanes) are usually less than similar to 50 parts per thousand, but variations as large as 150 parts per thousand are observed among isoprenoid lipids from a single organism. Phytol is consistently depleted in D by up to 50 parts per thousand relative to other isoprenoid lipids. Inferred isotopic fractionations between cellular water and lipids are greater than those indicated by previous studies. (C) 1999 Elsevier Science Ltd. All rights reserved.},
	issn = {0146-6380},
	doi = {10.1016/S0146-6380(99)00094-7},
	author = {Sessions, A. L. and Burgoyne, T. W. and Schimmelmann, A. and Hayes, J. M.}
}
@article {635,
	title = {Methane-consuming archaebacteria in marine sediments},
	journal = {Nature},
	volume = {398},
	year = {1999},
	note = {Hinrichs, K UHayes, J MSylva, S PBrewer, P GDeLong, E FengResearch Support, Non-U.S. Gov{\textquoteright}tResearch Support, U.S. Gov{\textquoteright}t, Non-P.H.S.England1999/05/11 02:03Nature. 1999 Apr 29;398(6730):802-5.},
	month = {Apr 29},
	pages = {802-5},
	abstract = {Large amounts of methane are produced in marine sediments but are then consumed before contacting aerobic waters or the atmosphere. Although no organism that can consume methane anaerobically has ever been isolated, biogeochemical evidence indicates that the overall process involves a transfer of electrons from methane to sulphate and is probably mediated by several organisms, including a methanogen (operating in reverse) and a sulphate-reducer (using an unknown intermediate substrate). Here we describe studies of sediments related to a decomposing methane hydrate. These provide strong evidence that methane is being consumed by archaebacteria that are phylogenetically distinct from known methanogens. Specifically, lipid biomarkers that are commonly characteristic of archaea are so strongly depleted in carbon-13 that methane must be the carbon source, rather than the metabolic product, for the organisms that have produced them. Parallel gene surveys of small-subunit ribosomal RNA (16S rRNA) indicate the predominance of a new archael group which is peripherally related to the methanogenic orders Methanomicrobiales and Methanosarcinales.},
	issn = {0028-0836 (Linking)},
	doi = {10.1038/19751},
	author = {Hinrichs, K. U. and Hayes, J. M. and Sylva, S. P. and Brewer, P. G. and DeLong, E. F.}
}
@inbook {1473,
	title = {New Developments at the NOSAMS Facility},
	booktitle = {Proceeding of the International Workshop on Frontiers in Accelerator Mass Spectrometry},
	year = {1999},
	note = {id: 1723(JISTEC)
},
	month = {1999},
	pages = {44-52},
	publisher = {National Institute for Environmental Studies, Tsukuba, National Museum of Japanese History},
	organization = {National Institute for Environmental Studies, Tsukuba, National Museum of Japanese History},
	address = {Tsukuba, Japan},
	author = {von Reden, K. F. and Schneider, R. J. and McNichol, A. P. and Hayes, J. M. and Pearson, A. and Eglinton, T. I.},
	editor = {Science, Japan International and Technology Exchange, Center}
}
@conference {1705,
	title = {New Developments at the NOSAMS Facility},
	booktitle = {International Workshop on Frontiers in Accelerator Mass Spectrometry},
	year = {1999},
	note = {id: 1679},
	month = {1999},
	publisher = {National Institute for Environmental Studies Reprot},
	organization = {National Institute for Environmental Studies Reprot},
	address = {Tsukuba, Japan},
	author = {von Reden, K. F. and Schneider, R. J. and McNichol, A. P. and Hayes, J. M. and Pearson, A. and Eglinton, T. I.},
	editor = {Shibata, Y.}
}
@conference {1646,
	title = {High-precision Measurements of 14C as a Circulation Tracer in the Pacific, Indian, and Southern Oceans with Accelerator Mass Spectrometry (AMS)},
	booktitle = {8th International Conference on Heavy Ion Accelerator Technology},
	year = {1998},
	note = {id: 1636},
	month = {1998},
	address = {Argonne National Lab},
	author = {von Reden, K. F. and Peden, J. C. and Schneider, R. J. and Bellino, M. and Donoghue, J. and Elder, K. L. and Gagnon, A. R. and Long, P. and McNichol, A. P. and Morin, T. and Stuart, D. and Hayes, J. M. and Key, R. M.},
	editor = {Shepard, K. American Institute of Physics}
}
@article {2259,
	title = {Preparation for continuous flow accelerator mass spectrometry Radiocarbon},
	journal = {Radiocarbon},
	volume = {1},
	year = {1998},
	note = {id: 1623},
	month = {1998},
	author = {Schneider, R. J. and Hayes, J. M. and von Reden, K. F. and McNichol, A. P. and Eglinton, T. and Wills, J. S. C.}
}
@conference {1753,
	title = {Proceedings of the 8th International Conference on Heavy Ion Accelerator Technology},
	booktitle = {American Institute of Physics, Conference Proceeding Series},
	year = {1998},
	note = {id: 1624; submitted},
	month = {1998},
	address = {Argonne National Lab},
	author = {Schneider, R. J. and von Reden, K. F. and Hayes, J. M. and Wills, J. S. C.}
}
@article {2276,
	title = {Status Report of the National Ocean Sciences AMS Facility at Woods Hole Oceanographic Institution: Operations and Recent Developments},
	journal = {15th International Conference on the Applications of Accelerators in Research and Industry},
	volume = {A.I.P. Conference Proceedings},
	year = {1998},
	note = {id: 1647},
	month = {1998},
	pages = {644-647},
	author = {Bellino, M. and von Reden, K. F. and Schneider, R. J. and Peden, J. C. and Donoghue, J. and Elder, K. L. and Gagnon, A. R. and Long, P. and McNichol, A. P. and Odegaard, A. P. and Stuart, D. and Handwork, S. and Hayes, J. M.}
}
@article {2258,
	title = {Target preparation for continuous flow accelerator mass spectrometry},
	journal = {Radiocarbon},
	volume = {40},
	year = {1998},
	note = {1 Sp. Iss. SI113kt
Times Cited:11
Cited References Count:10
},
	month = {1998},
	pages = {95-102},
	abstract = {For very small samples, it is difficult to prepare graphitic targets that will yield a useful and steady sputtered ion beam. Working with materials separated by preparative capillary gas chromatography, we have succeeded with amounts as small as 20 mu g C. This seems to be a practical limit, as it involves 1) multiple chromatographic runs with trapping of effluent fractions, 2) recovery and combustion of the fractions, 3) graphitization and 4) compression of the resultant graphite/cobalt matrix into a good sputter target. Through such slow and intricate work, radiocarbon ages of lignin derivatives and hydrocarbons from coastal sediments have been determined. If this could be accomplished as an "online" measurement by flowing the analytes directly into a microwave gas ion source, with a carrier gas, then the number of processing steps could be minimized. Such a system would be useful not just for chromatographic effluents, but for any gaseous material, such as CO2 produced from carbonates. We describe tests using such an ion source.},
	keywords = {gas, ion-source},
	isbn = {0033-8222},
	author = {Schneider, R. J. and Hayes, J. M. and von Reden, K. F. and McNichol, A. P. and Eglinton, T. I. and Wills, J. S. C.}
}
@article {935,
	title = {Water-induced errors in continuous-flow carbon isotope ratio mass spectrometry},
	journal = {Anal Chem},
	volume = {70},
	year = {1998},
	note = {Leckrone, K JHayes, J MengResearch Support, Non-U.S. Gov{\textquoteright}tResearch Support, U.S. Gov{\textquoteright}t, Non-P.H.S.1998/07/17Anal Chem. 1998 Jul 1;70(13):2737-44.},
	month = {Jul 01},
	pages = {2737-44},
	abstract = {Formation of HCO2+ from CO2 and background H2O in isotope ratio mass spectrometers has been examined in detail. The process is troublesome because its product is not resolved from 13C16O2+. The resulting, artifactual enhancement of the mass 45 ion current (and analogous enhancement of the mass 46 ion current by transfer of hydrogen to mass 45 species) can cause systematic errors in analyses of 13C based on measurement of ion current ratios in the mass spectrum of CO2. Such errors are neutralized when isotopic analyses are based on differential comparisons in which ion currents and background water levels are precisely equal during admission and ionization of both sample and standard gases. In continuous-flow systems, however, that requirement is generally not met. The resulting systematic error is proportional to the 18/44 ion current ratio. When the widely used MAT252 mass spectrometer is tuned to yield maximum sensitivity, the constant of proportionality is 26 +/- 2/1000 (i.e., the error will be 0.26/1000 if the mass 18 ion current is 100 times smaller than that at mass 44). Errors can be reduced 5-fold when the ion-source residence time of CO2+ is decreased by use of stronger ion-extraction potential gradients. Under those same conditions, sensitivity is decreased by 60\%. For operation at highest sensitivity, carrier gas dew points on the order of -70 degrees C are required to obtain errors < or = 0.1/1000 for samples yielding mass 44 ion currents of 10 nA. Carrier gas dew points < or = -80 degrees C are conveniently reached by use of a Nafion dryer operated at approximately 0 degree C.},
	issn = {0003-2700 (Linking)},
	doi = {10.1021/ac9803434},
	author = {Leckrone, K. J. and Hayes, J. M.}
}
@article {2291,
	title = {Carbon isotopic fractionation associated with lipid biosynthesis by a cyanobacterium: relevance for interpretation of biomarker records},
	journal = {Geochim Cosmochim Acta},
	volume = {61},
	year = {1997},
	note = {Sakata, SHayes, J M
McTaggart, A R
Evans, R A
Leckrone, K J
Togasaki, R K
eng
Research Support, U.S. Gov{\textquoteright}t, Non-P.H.S.
1997/01/01 00:00
Geochim Cosmochim Acta. 1997;61(24):5379-89.
},
	month = {1997},
	pages = {5379-89},
	abstract = {For the cyanobacterium Synechocystis UTEX 2470, grown photoautotrophically to a logarithmic stage of growth, the total lipid extract is depleted in 13C by 4.8\% relative to average biomass. Depletions observed for acetogenic (straight-chain) lipids range from 7.6 (hexadecanoic acid) to 9.9\% (a C16 n-alkyl chain bound in a polar-lipid fraction), with a mass-weighted average of 9.1\%. Polyisoprenoid lipids fall into two isotopic groups, with phytol, diplopterol, and diploptene depleted by 6.4-6.9\% and bishomohopanol (produced from the extracts by the preparative degradation of bacteriohopanepolyol) depleted by 8.4\%. Analysis of the pattern of depletions indicates that two carbon positions in each C5 biomonomer leading to polyisoprenoid products are probably depleted in 13C relative to average biomass. The depletion of bacteriohopanepolyol relative to other polyisoprenoids can be ascribed to changes that occur over the life of each cell: (1) the 13C content of carbon flowing to lipid biosynthesis decreases as the cell size increases and (2) a greater proportion of the bacteriohopanepolyol which, unlike other polyisoprenoids, is present mainly in the cytoplasm rather than in membranes and is synthesized when cells are larger. Chlorophyll a is depleted relative to average biomass by O.7\%. Given the observed depletion of 13C in phytol, the heteroaromatic, chlorophyllide portion of chlorophyll must be enriched in 13C by 2.7\%. This enrichment is large relative to that in chlorophyllides produced by eukaryotes and may be related to a parallel enrichment of 13C in cyanobacterial glutamic acid. As in many previous investigations of cyanobacterial lipids, long-chain n-alkanes (C22-C29) are found in the extracts. They are, however, enriched in 13C relative to biomass and have isotopic compositions suggesting that they are contaminants of petrochemical origin. Available results indicate that cyanobacterial lipids will be depleted relative to dissolved CO2 that has served as a carbon source by 22-30\% and that a wider range of depletions will be characteristic of eukaryotic products. The absence of long-chain n-alkanes in cyanobacteria reduces the possibility that petroleum ever formed from pre-eukaryotic sedimentary debris.},
	keywords = {*Biomass, Acetic Acid/metabolism, Alkanes/*analysis/chemistry, Biomarkers/chemistry, carbon isotopes, Carbon/*chemistry, Chlorophyll/metabolism, Cyanobacteria/chemistry/*metabolism, Geologic Sediments/*chemistry, Lipids/*biosynthesis, NASA Discipline Exobiology, Non-NASA Center, Palmitic Acid/metabolism, Phytol/metabolism, Pigments, Biological/metabolism},
	isbn = {0016-7037 (Print)0016-7037 (Linking)
},
	url = {https://www.ncbi.nlm.nih.gov/pubmed/11540730},
	author = {Sakata, S. and Hayes, J. M. and McTaggart, A. R. and Evans, R. A. and Leckrone, K. J. and Togasaki, R. K.}
}
@article {936,
	title = {Efficiency and temperature dependence of water removal by membrane dryers},
	journal = {Anal Chem},
	volume = {69},
	year = {1997},
	note = {Leckrone, K JHayes, J MengComparative StudyResearch Support, U.S. Gov{\textquoteright}t, Non-P.H.S.1997/03/01 00:00Anal Chem. 1997 Mar 1;69(5):911-8.},
	month = {Mar 01},
	pages = {911-8},
	abstract = {The vapor pressure of water in equilibrium with sorption sites within a Nafion membrane is given by log P(WN) = -3580/T + 10.01, where P(WN) is expressed in Torr and T is the membrane temperature, in kelvin. The efficiency of dryers based on selective permeation of water through Nafion can thus be enhanced by cooling the membrane. Residual water in effluents exceeds equilibrium levels if insufficient time is allowed for water to diffuse to the membrane surface as gas passes through the dryer. For tubular configurations, this limitation can be avoided if L > or = Fc(10(3.8)/120 pi D), where L is the length of the tubular membrane, in centimeters, Fc is the gas flow rate, in mL/ min, and D is the diffusion coefficient for water in the carrier gas at the operating temperature of the dryer, in cm2/s. An efficient dryer that at room temperature dries gas to a dew point of -61 degrees C is described; the same dryer maintained at 0 degrees C yields a dew point of -80 degrees C and removes water as effectively as Mg(ClO4)2 or a dry ice/acetone slush. The use of Nafion membranes to construct devices capable of delivering gas streams with low but precisely controlled humidities is discussed.},
	issn = {0003-2700 (Linking)},
	doi = {10.1021/ac9610220},
	author = {Leckrone, K. J. and Hayes, J. M.}
}
@article {2299,
	title = {An isotopic biogeochemical study of Neoproterozoic and Early Cambrian sediments from the Centralian Superbasin, Australia},
	journal = {Geochim Cosmochim Acta},
	volume = {61},
	year = {1997},
	note = {Logan, G ASummons, R E
Hayes, J M
eng
Research Support, U.S. Gov{\textquoteright}t, Non-P.H.S.
1997/01/01 00:00
Geochim Cosmochim Acta. 1997;61(24):5391-409.
},
	month = {1997},
	pages = {5391-409},
	abstract = {Organic matter from Neoproterozoic and Early Cambrian sediments of the Amadeus and Officer basins of the Centralian Superbasin, Australia, has been studied for biomarker distributions and the carbon isotopic compositions of kerogen and individual hydrocarbons. These sediments represent both shallow and deep water marine facies in the older sections and marine and saline lacustrine carbonate deposits in the Cambrian. Hydrocarbon biomarker patterns were found to be quite consistent with the known sedimentary environments and provide valuable insights into the biogeochemical changes which accompanied the transition from a microbially-dominated ocean to the early stages of metazoan radiation. In particular, carbon isotopic data for n-alkyl and isoprenoid lipids presented here, and in earlier studies, showed a reversal in carbon isotopic ordering between the Proterozoic and Phanerozoic. By comparison with the delta 13C of kerogen, n-alkyl lipids from deep-water Proterozoic sediments were enriched in 13C and appear to be derived mainly from heterotrophs whilst open marine Phanerozoic counterparts are 13C depleted and evidently derived mainly from autotrophs. Data from the samples studied here are consistent with a model invoking a change in the redox structure of the ocean, possibly aided by the innovation of faecal pellets.},
	keywords = {Alkanes/analysis/chemistry, Animals, australia, biomarkers, carbon isotopes, Carbon/analysis/*chemistry, Cyanobacteria, Eukaryota, Feces, Fossils, Geologic Sediments/*analysis/chemistry, Hydrocarbons/analysis, NASA Discipline Exobiology, Non-NASA Center, Paleontology, phytoplankton, SEAWATER, Terpenes/analysis, Zooplankton},
	isbn = {0016-7037 (Print)0016-7037 (Linking)
},
	url = {https://www.ncbi.nlm.nih.gov/pubmed/11540731},
	author = {Logan, G. A. and Summons, R. E. and Hayes, J. M.}
}
@article {939,
	title = {Productivity-induced sulphur enrichment of hydrocarbon-rich sediments from the Kimmeridge Clay Formation},
	journal = {Chem Geol},
	volume = {134},
	year = {1997},
	note = {Lallier-Verges, EHayes, J MBoussafir, MZaback, D ATribovillard, N PConnan, JBertrand, PengResearch Support, Non-U.S. Gov{\textquoteright}tNetherlands1997/01/01 00:00Chem Geol. 1997;134:277-88.},
	pages = {277-88},
	abstract = {This work aims to highlight the relationship between primary productivity, sulphate reduction and organic carbon preservation in cyclic marine sediments from the Kimmeridge Clay Formation. A concomitant increase of the total sulphur content with the preserved organic content (TOC), shows the progressive supply of both metabolisable organic matter and resistant organic matter is linked to primary productivity. However, variations in sulphate reduction efficiency, based on elemental abundance and isotopic composition of sulphur, reveal that the proportion of metabolisable vs. resistant organic matter has varied along the cycles. This is interpreted in terms of the variation in organic delivery. Organic sulphur content is found to be proportional to the organic matter content, whereas concentrations of pyritic sulphur are constant at very high (> 10\% TOC) values. This result is explained by a limitation of available iron for pyritisation at times of very high organic flux. Under such conditions, HS- in excess could be responsible for the early formation of organo-sulphur compounds and thus for the preservation of highly aliphatic (i.e. lipid-rich) organic matter.},
	issn = {0009-2541 (Linking)},
	doi = {10.1016/S0009-2541(96)00093-9},
	author = {Lallier-Verges, E. and Hayes, J. M. and Boussafir, M. and Zaback, D. A. and Tribovillard, N. P. and Connan, J. and Bertrand, P.}
}
@article {2288,
	title = {Target preparation for continuous flow accelerator mass spectrometry: (Proceedings of the 16th International Radiocarbon Conference, 1997)},
	journal = {Radiocarbon},
	volume = {40},
	year = {1997},
	note = {id: 1752},
	month = {1997},
	pages = {95-102},
	author = {Schneider, R. J. and Hayes, J. M. and von Reden, K. F. and McNichol, A. P. and Eglinton, T.}
}
@article {2287,
	title = {Target preparation for continuous flow accelerator mass spectrometry},
	journal = {Radiocarbon},
	volume = {40},
	year = {1997},
	note = {id: 1661},
	month = {1997},
	pages = {95-102},
	author = {Schneider, R. J. and Hayes, J. M. and von Reden, K. F. and McNichol, A. P. and Eglinton, T. I.}
}
@conference {1803,
	title = {Target preparation for continuous flow accelerator mass spectrometry},
	booktitle = {16th International Radiocarbon Conference},
	volume = {Book of Abstracts},
	year = {1997},
	note = {id: 953},
	month = {1997},
	pages = {165},
	address = {Groningen},
	author = {Schneider, R. J. and Hayes, J. M. and Eglinton, T. I. and McNichol, A. P. and von Reden, K. F.}
}
@inbook {1412,
	title = {Global methanotrophy at the Archean-Proterozoic transition},
	booktitle = {Early Life on Earth. Nobel Symposium},
	volume = {84},
	year = {1994},
	note = {id: 1565},
	month = {1994},
	pages = {220-236},
	publisher = {Columbia University Press, New York},
	organization = {Columbia University Press, New York},
	author = {Hayes, J. M.},
	editor = {Bengston, S.}
}
