Carbon isotope analysis of dissolved organic carbon in fresh and saline (NaCl) water via continuous flow cavity ring-down spectroscopy following wet chemical oxidation

AbstractThe radiocarbon content of dissolved organic carbon (DOC) in rivers, lakes, and other non-saline waters can provide valuable information on carbon cycling dynamics in the environment. DOC is typically prepared for 14C analysis by accelerator mass spectrometry (AMS) either by ultraviolet (UV) oxidation or by freeze-drying and sealed tube combustion. We present here a new method for the rapid analysis of 14C of DOC using wet chemical oxidation (WCO) and automated headspace sampling of CO2. The approach is an adaption of recently developed methods using aqueous persulfate oxidant to determine the δ13C of DOC in non-saline water samples and the 14C content of volatile organic acids. One advantage of the current method over UV oxidation is higher throughput: 22 samples and 10 processing standards can be prepared in one day and analyzed in a second day, allowing a full suite of 14C processing standards and blanks to be run in conjunction with samples. A second advantage is that there is less potential for cross-contamination between samples.

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Measurement of dissolved organic carbon by wet chemical oxidation with persulfate: influence of chloride concentration and reagent volume

Marine Chemistry ◽

10.1016/0304-4203(94)00049-j ◽

1995 ◽

Vol 48 (2) ◽

pp. 109-114 ◽

Cited By ~ 35

Author(s):

James H. McKenna ◽

Peter H. Doering

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Chloride Concentration ◽

Chemical Oxidation ◽

Wet Chemical

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Carbon Isotope Analysis for Inorganic Samples by a Continuous Flow Mass Spectrometer

Journal of the Mass Spectrometry Society of Japan ◽

10.5702/massspec.52.196 ◽

2004 ◽

Vol 52 (4) ◽

pp. 196-204 ◽

Cited By ~ 1

Author(s):

Takayuki FUJIMOTO ◽

Chikako NISHIMURA ◽

Hidehiro OMORI ◽

Jun-ichi MATSUDA

Keyword(s):

Carbon Isotope ◽

Mass Spectrometer ◽

Continuous Flow ◽

Isotope Analysis ◽

Carbon Isotope Analysis

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Towards Organic Carbon Isotope Records from Stalagmites: Coupled δ13C and 14C Analysis Using Wet Chemical Oxidation

Radiocarbon ◽

10.1017/rdc.2019.35 ◽

2019 ◽

Vol 61 (03) ◽

pp. 749-764

Author(s):

Franziska A Lechleitner ◽

Susan Q Lang ◽

Negar Haghipour ◽

Cameron McIntyre ◽

James U L Baldini ◽

...

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Carbon Isotope ◽

Method Development ◽

Chemical Oxidation ◽

Low Concentrations ◽

Crucial Information ◽

Isotopic Characterization ◽

Wet Chemical

AbstractSpeleothem organic matter can be a powerful tracer for past environmental conditions and karst processes. Carbon isotope measurements (δ13C and 14C) in particular can provide crucial information on the provenance and age of speleothem organic matter, but are challenging due to low concentrations of organic matter in stalagmites. Here, we present a method development study on extraction and isotopic characterization of speleothem organic matter using a rapid procedure with low laboratory contamination risk. An extensive blank assessment allowed us to quantify possible sources of contamination through the entire method. Although blank contamination is consistently low (1.7 ± 0.34 – 4.3 ± 0.86 μg C for the entire procedure), incomplete sample decarbonation poses a still unresolved problem of the method, but can be detected when considering both δ13C and 14C values. We test the method on five stalagmites, showing reproducible results on samples as small as 7 μg C for δ13C and 20 μg C for 14C. Furthermore, we find consistently lower non-purgeable organic carbon (NPOC) 14C values compared to the carbonate 14C over the bomb spike interval in two stalagmites from Yok Balum Cave, Belize, suggesting overprint of a pre-aged or even fossil source of carbon on the organic fraction incorporated by these stalagmites.

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