@article {2922,
	title = {RADIOCARBON IN DISSOLVED ORGANIC CARBON BY UV OXIDATION: PROCEDURES AND BLANK CHARACTERIZATION AT NOSAMSABSTRACT},
	journal = {Radiocarbon},
	volume = {63},
	year = {2021},
	month = {Jan-02-2021},
	pages = {357 - 374},
	abstract = {This study describes a procedural blank assessment of the ultraviolet photochemical oxidation (UV oxidation) method that is used to measure carbon isotopes of dissolved organic carbon (DOC) at the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS). A retrospective compilation of Fm and δ 13 C results for secondary standards (OX-II, glycine) between 2009 and 2018 indicated that a revised blank correction was required to bring results in line with accepted values. The application of a best-fit mass-balance correction yielded a procedural blank of 22.0 {\textpm} 6.0 μg C with Fm of 0.30 {\textpm} 0.20 and δ 13 C of-32.0 {\textpm} 3.0{\textperthousand} for this period, which was notably higher and more variable than previously reported. Changes to the procedure, specifically elimination of higher organic carbon reagents and improved sample and reactor handling, reduced the blank to 11.0 {\textpm} 2.75 μg C, with Fm of 0.14 {\textpm} 0.10 and δ 13 C of-31.0 {\textpm} 5.5{\textperthousand}. A thorough determination of the entire sample processing blank is required to ensure accurate isotopic compositions of seawater DOC using the UV oxidation method. Additional efforts are needed to further reduce the procedural blank so that smaller DOC samples can be analyzed, and to increase sample throughput.},
	keywords = {blank, dissolved organic carbon, radiocarbon, UV oxidation},
	issn = {0033-8222},
	doi = {10.1017/RDC.2020.102},
	url = {https://www.cambridge.org/core/journals/radiocarbon/article/abs/radiocarbon-in-dissolved-organic-carbon-by-uv-oxidation-procedures-and-blank-characterization-at-nosams/AA39A2C74772934B44D9BF81C2DF723C},
	author = {Xu, Li and Roberts, Mark L and Elder, Kathryn L and Kurz, Mark D and McNichol, Ann P and Reddy, Christopher M and Ward, Collin P and Hanke, Ulrich M}
}
@article {2871,
	title = {Dissolved organic carbon in basalt-hosted deep subseafloor fluids of the Juan de Fuca Ridge flank},
	journal = {Earth and Planetary Science Letters},
	volume = {513},
	year = {2019},
	month = {Jan-05-2019},
	pages = {156 - 165},
	abstract = {Marine dissolved organic carbon (DOC) is highly depleted in radiocarbon and thus inferred to be largely refractory to removal processes that operate on less than millennial timescales. However, a growing number of reports have shown that a large fraction of marine DOC can be effectively removed during circulation through submarine hydrothermal systems. What is not clear, however, is whether the DOC that remains in hydrothermal fluids is remnant non-reactive DOC from recharged seawater, or DOC that has been largely produced in the subsurface. We collected and characterized warm (\~{}65 {\textdegree}C) hydrothermal fluids from deep (18, 40, 73, 200 m) within the basalt-hosted basement of the Juan de Fuca Ridge flank in the Northeast Pacific Ocean. DOC concentrations in hydrothermal fluids were 9 to 18 μM, much lower than measured in local deep seawater (37.5 μM). DOC C values of -683{\textperthousand} to -856{\textperthousand} were much lower than the C-dissolved inorganic carbon (DIC) values of -880{\textperthousand} to -918{\textperthousand}, while DOC C values of -23.6{\textperthousand} to -27.0{\textperthousand} were much heavier than that of the particulate organic carbon (POC) pool ({\textperthousand}), suggesting that biological production in the subsurface is not a primary source of DOC. Rather, our data suggest that isotopically enriched DOC are selectively removed from recharged seawater, leaving DOC that is very isotopically depleted in the basaltic basement fluids. Despite the removal of 50{\textendash}75\% of DOC in the subsurface, nuclear magnetic resonance (NMR) functional group analyses indicate that aromatic compounds were added to basaltic basement fluids during passage through the deep subseafloor and may partly contribute to the depleted 14C DOC in the ridge-flank basement fluids.},
	keywords = {aromatic organic compound, basaltic basement fluid, carbon isotopes, dissolved organic carbon, Juan de Fuca, selective removal, subseafloor},
	issn = {0012821X},
	doi = {10.1016/j.epsl.2019.02.008},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0012821X19300998},
	author = {Lin, Huei-Ting and Repeta, Daniel J. and Xu, Li and Rapp{\'e}, Michael S.}
}
@article {2638,
	title = {Hidden cycle of dissolved organic carbon in the deep ocean},
	journal = {Proceedings of the National Academy of Sciences},
	volume = {111},
	year = {2014},
	month = {Jan-11-2016},
	pages = {16706 - 16711},
	abstract = {Marine dissolved organic carbon (DOC) is a large (660 Pg C) reactive carbon reservoir that mediates the oceanic microbial food web and interacts with climate on both short and long timescales. Carbon isotopic content provides information on the DOC source via [Formula: see text]C and age via [Formula: see text]C. Bulk isotope measurements suggest a microbially sourced DOC reservoir with two distinct components of differing radiocarbon age. However, such measurements cannot determine internal dynamics and fluxes. Here we analyze serial oxidation experiments to quantify the isotopic diversity of DOC at an oligotrophic site in the central Pacific Ocean. Our results show diversity in both stable and radio isotopes at all depths, confirming DOC cycling hidden within bulk analyses. We confirm the presence of isotopically enriched, modern DOC cocycling with an isotopically depleted older fraction in the upper ocean. However, our results show that up to 30\% of the deep DOC reservoir is modern and supported by a 1 Pg/y carbon flux, which is 10 times higher than inferred from bulk isotope measurements. Isotopically depleted material turns over at an apparent time scale of 30,000 y, which is far slower than indicated by bulk isotope measurements. These results are consistent with global DOC measurements and explain both the fluctuations in deep DOC concentration and the anomalous radiocarbon values of DOC in the Southern Ocean. Collectively these results provide an unprecedented view of the ways in which DOC moves through the marine carbon cycle.},
	keywords = {Carbon cycle, carbon isotopes, dissolved organic carbon, Oceanography, radiocarbon},
	issn = {0027-8424},
	doi = {10.1073/pnas.1407445111},
	url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1407445111https://syndication.highwire.org/content/doi/10.1073/pnas.1407445111},
	author = {Follett, Christopher L. and Repeta, Daniel J. and Rothman, Daniel H. and Xu, Li and Santinelli, Chiara}
}
