@article {1284,
	title = { Allochthonous sources and dynamic cycling of ocean dissolved organic carbon revealed by carbon isotopes},
	journal = {GEOPHYSICAL RESEARCH LETTERS},
	volume = {44},
	year = {2017},
	month = {03/2017},
	pages = {2407-2415},
	abstract = {We present concentration and isotopic profiles of total, size, and polarity fractionated dissolved organic carbon (DOC) from Station ALOHA (A Long-term Oligotrophic Habitat Assessment), an oligotrophic site in the North Pacific Ocean. The data show that, between the surface and 3500 m, low molecular weight (LMW) hydrophilic DOC, LMW hydrophobic DOC, and high molecular weight (HMW) DOC constitute 22-33\%, 45-52\%, and 23-35\% of DOC, respectively. LMW hydrophilic DOC is more isotopically depleted (delta C-13 of -23.9 parts per thousand to -31.5 parts per thousand and Delta C-14 of -304 parts per thousand to -795 parts per thousand; mean age of 2850 to 15000 years) than the LMW hydrophobic DOC (delta C-13 of -22 parts per thousand to -23 parts per thousand and Delta C-14 of -270 parts per thousand to -568 parts per thousand; 2470 to 6680 years) and HMW DOC (delta C-13 of similar to-21 parts per thousand and Delta C-14 of -24 parts per thousand to -294 parts per thousand; 135-2700 years). Our analyses suggest that a large fraction of DOC may be derived from allochthonous sources such as terrestrial and hydrothermal DOC and cycle on much longer time scales of > 10000 years or enter the ocean as preaged carbon.},
	keywords = {ATLANTIC BIGHT, BLACK CARBON, C-14, HUMIC SUBSTANCES, MATTER, NORTH PACIFIC-OCEAN, RADIOCARBON ANALYSIS, SARGASSO SEA, SEAWATER, SPECTROMETRY},
	doi = {10.1002/2016GL071348},
	author = {Zigah, Prosper K. and McNichol, Ann P. and Xu, Li and Johnson, Carl and Santinelli, Chiara and Karl, David M. and Repeta, Daniel J.}
}
@conference {1692,
	title = {Microscale AMS (super <sup>14</sup>) C measurement at NOSAMS},
	volume = {40},
	year = {1998},
	note = {id: 2237; Source type: conferencepapers\&proceedings; Object type: Article; Object type: Conference Paper; Copyright: GeoRef, Copyright 2007, American Geological Institute.; CSAUnique: 1999-044438; AccNum: 1999-044438; ISSN: 0033-8222; CODEN: RACAAT},
	month = {1998},
	pages = {61-75},
	publisher = {University of Arizona, Department of Geosciences, Tucson, AZ, United States (USA)},
	organization = {University of Arizona, Department of Geosciences, Tucson, AZ, United States (USA)},
	address = {United States (USA)},
	abstract = {Techniques for making precise and accurate radiocarbon accelerator mass spectrometry (AMS) measurements on samples containing less than a few hundred micrograms of carbon are being developed at the NOSAMS facility. A detailed examination of all aspects of the sample preparation and data analysis process shows encouraging results. Small quantities of CO (sub 2) are reduced to graphite over cobalt catalyst at an optimal temperature of 605 degrees C. Measured (super 14) C/ (super 12) C ratios of the resulting targets are affected by machine-induced isotopic fractionation, which appears directly related to the decrease in ion current generated by the smaller sample sizes. It is possible to compensate effectively for this fractionation by measuring samples relative to small standards of identical size. Examination of the various potential sources of background (super 14) C contamination indicates that the sample combustion process is the largest contributor, adding ca. 1 mu g of carbon with a less-than-modern (super 14) C concentration.},
	keywords = {03, absolute age, accelerator mass spectroscopy, accuracy, C-14, C-14/C-12, carbon, Carbon dioxide, combustion, data processing, Geochronology, graphite, isotope fractionation, isotopes, mass spectroscopy, mathematical methods, methods, native elements, radioactive isotopes, sample preparation, size, spectroscopy, Stable isotopes},
	doi = {10.1017/S0033822200017902},
	url = {http://hdl.handle.net/10150/653650},
	author = {Pearson, Ann and McNichol, Ann P. and Schneider, Robert J. and von Reden, Karl F. and Zheng, Yan}
}
@conference {1800,
	title = {(super 14) C AMS measurements of},
	volume = {40},
	year = {1998},
	note = {id: 2239; Source type: conferencepapers\&proceedings; Object type: Article; Object type: Conference Paper; Copyright: GeoRef, Copyright 2007, American Geological Institute.; CSAUnique: 1999-044459; AccNum: 1999-044459; ISSN: 0033-8222; CODEN: RACAAT},
	month = {1998},
	pages = {247-253},
	publisher = {University of Arizona, Department of Geosciences, Tucson, AZ, United States (USA)},
	organization = {University of Arizona, Department of Geosciences, Tucson, AZ, United States (USA)},
	address = {United States (USA)},
	abstract = {The NOSAMS facility at Woods Hole Oceanographic Institution has started to develop and apply techniques for measuring very small samples on a standard Tandetron accelerator mass spectrometry (AMS) system with high-current hemispherical Cs sputter ion sources. Over the past year, results on samples ranging from 7 to 160 mu g C showed both the feasibility of such analyses and the present limitations on reducing the size of solid carbon samples. One of the main factors affecting the AMS results is the dependence of a number of the beam optics parameters on the extracted ion beam current. The extracted currents range from 0.5 to 10 mu A of (super 12) C (super -) for the sample sizes given above. We here discuss the setup of the AMS system and methods for reliable small-sample measurements and give the AMS-related limits to sample size and the measurement uncertainties.},
	keywords = {03, absolute age, accelerator mass spectroscopy, C-14, carbon, dilution, Geochronology, ions, isotopes, mass spectroscopy, precision, radioactive isotopes, sample preparation, spectroscopy, volume},
	author = {von Reden, Karl F. and McNichol, Ann P. and Pearson, Ann and Schneider, Robert J.}
}
