@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.}
}
@article {2348,
	title = {Improvements in procedural blanks at NOSAMS: Reflections of improvements in sample preparation and accelerator operation},
	journal = {Radiocarbon},
	volume = {37},
	year = {1995},
	note = {Ud868Times Cited:16
Cited References Count:6
},
	month = {1995},
	pages = {683-691},
	abstract = {During the four years the Sample Preparation Laboratory (SPL) at the National Ocean Sciences Accelerator Mass Spectrometer (NOSAMS) Facilty has been in operation we have accumulated much data from which we can assess our progress. We evaluate our procedural blanks here and describe modifications in our procedures that have improved our analyses of older samples. In the SPL, we convert three distinct types of samples-seawater, CaCO3 and organic carbon-to CO2 prior to preparing graphite for the accelerator and have distinct procedural blanks for each procedure. Dissolved inorganic carbon (Sigma CO2) is extracted from acidified seawater samples by sparging with a nitrogen carrier gas. We routinely analyze {\textquoteright}{\textquoteright}line blanks{\textquoteright}{\textquoteright} by processing CO2 from a C-14-dead source through the entire stripping procedure. Our hydrolysis blank, IAEA C-1, is prepared by acidifying in vacuo with 100\% H3PO4 at 60 degrees C overnight, identical to our sample preparation. We use a dead graphite, NBS-21, or a commercially available carbon powder for our organic combustion blank; organic samples are combusted at 850 degrees C for 5 h using CuO to provide the oxidant. Analysis of our water stripping data suggests that one step in the procedure contributes the major portion of the line blank. At present, the contribution from the line blank has no effect on our seawater analyses (fraction modern (fm) between 0.7 and 1.2). Our hydrolysis blanks can have an fm value as low as 0.0006, but are more routinely between 0.0020 and 0.0025. The fm of our best organic combustion blanks is higher than those routinely achieved in other laboratories and we are currently altering our methods to reduce it.},
	keywords = {SPECTROMETRY},
	isbn = {0033-8222},
	author = {McNichol, A. P. and Gagnon, A. R. and Osborne, E. A. and Hutton, D. L. and vonReden, K. F. and Schneider, R. J.}
}
