RADIOCARBON IN DISSOLVED ORGANIC CARBON BY UV OXIDATION: PROCEDURES AND BLANK CHARACTERIZATION AT NOSAMSABSTRACT

TitleRADIOCARBON IN DISSOLVED ORGANIC CARBON BY UV OXIDATION: PROCEDURES AND BLANK CHARACTERIZATION AT NOSAMSABSTRACT
Publication TypeJournal Article
Year of Publication2021
AuthorsXu, L, Roberts, ML, Elder, KL, Kurz, MD, McNichol, AP, Reddy, CM, Ward, CP, Hanke, UM
JournalRadiocarbon
Volume63
Issue1
Pagination357 - 374
Date PublishedJan-02-2021
ISSN0033-8222
Keywordsblank, dissolved organic carbon, radiocarbon, UV oxidation
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 ± 6.0 μg C with Fm of 0.30 ± 0.20 and δ 13 C of-32.0 ± 3.0‰ 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 ± 2.75 μg C, with Fm of 0.14 ± 0.10 and δ 13 C of-31.0 ± 5.5‰. 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.

URLhttps://www.cambridge.org/core/journals/radiocarbon/article/abs/radiocarbon-in-dissolved-organic-carbon-by-uv-oxidation-procedures-and-blank-characterization-at-nosams/AA39A2C74772934B44D9BF81C2DF723C
DOI10.1017/RDC.2020.102