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Radiocarbon Measurements of Black Carbon in Aerosols and Ocean Sediments

Published

Author(s)

C A. Masiello, David L. Urban, Lloyd A. Currie

Abstract

We report the optimization of dichromate-sulfuric acid oxidation for the measurement of radiocarbon in black carbon (BC). We also present comparisons of black carbon 14C measurements on NIST aerosol (14C measurements on NIST aerosol (Urban Dust) standard reference material (SRM) 1649a with previously published bulk aromatic 14C and individual polycyclic aromatic hydrocarbon (PAH) 15C measurements on the same SRM. Dichromate-sulfuric acid oxidation belongs to the chemical class of black carbon methods, a class that relies on the resistance of some forms of black carbon to strong chemical oxidants. Dilute solutions of dichromate-sulfuric acid degrade black carbon and marine-derived carbon at characteristic, reproducible rates, and simple kinetics can be used to calculate concentrations of individual components (Wolbach and Anders, 1989). We show that: (1) dichromate-sulfuric acid oxidation allows clean, reproducible 14C BC measurements; (2) kinetics calculations give more accurate BC yield information when performed on percent organic carbon data (in contrast to percent mass data); (3) calculated kinetics results are similar regardless of whether the oxidation is performed at 25 degrees}C or 50 degrees}C; and (4) this method yields 14C BC results consistent with preciously published aromatic 14C data for the NIST urban dust SRM. For the purposes of intercomparison, we also report percent mass and carbon results for two commercially available BC reference materials.
Citation
Geochimica Et Cosmochimica Acta
Volume
66
Issue
No. 6

Keywords

atmospheric BC, black carbon, dichromate-sulfuric acid oxidation, marine BC, oxidation kinetics, radiocarbon, standard reference material 1649a

Citation

Masiello, C. , Urban, D. and Currie, L. (2002), Radiocarbon Measurements of Black Carbon in Aerosols and Ocean Sediments, Geochimica Et Cosmochimica Acta (Accessed May 24, 2024)

Issues

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Created February 28, 2002, Updated October 12, 2021