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In situ 13 CO 2 pulse‐labeling in a temperate heathland – development of a mobile multi‐plot field setup
Author(s) -
Reinsch Sabine,
Ambus Per
Publication year - 2013
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.6584
Subject(s) - chemistry , analytical chemistry (journal) , soil respiration , isotope ratio mass spectrometry , isotope , mass spectrometry , carbon dioxide , isotopes of carbon , carbon cycle , accelerator mass spectrometry , carbon fibers , tracer , environmental chemistry , soil water , soil science , environmental science , ecosystem , total organic carbon , chromatography , ecology , physics , materials science , organic chemistry , quantum mechanics , biology , composite number , nuclear physics , composite material
RATIONALE Pulse‐labeling with 13 CO 2 and the subsequent analysis of 13 C‐carbon via isotope ratio mass spectrometry (IRMS) have been shown to be an excellent method to investigate the terrestrial carbon cycle. Improving 13 CO 2 manipulation experiments will facilitate our understanding of carbon cycling processes. METHODS A mobile field setup for in situ 13 CO 2 pulse‐labeling was developed for low vegetation field experiments. Two pulse‐labeling experiments were conducted in a Danish heathland in September 2010 (Exp1) and May 2011 (Exp2). A flow‐through system was developed where labeling chambers were supplied with 13 CO 2 ‐enriched air from a gas reservoir. Reservoir and chamber air was sampled over the course of the experiments and analyzed for CO 2 concentration and isotopic composition on a GasBench II interfaced with an isotope ratio mass spectrometer. The soil CO 2 efflux and the atom% excess in soil respiration were assessed after the 13 CO 2 ‐pulse to verify the setup performance. RESULTS The carbon dioxide concentrations and 13 CO 2 enrichments were stable during the experiments. The CO 2 concentrations conformed to the aimed values, whereas the 13 CO 2 enrichments were lower than expected. The sources of error for the deviation in observed atom% 13 CO 2 values are discussed, and a measurement procedure is suggested for samples highly enriched in 13 C by using adjusted resistor settings of the mass spectrometer. However, more work has to be done. Enrichment patterns in soil respiration agree with published observations indicating satisfactory performance of the developed system. CONCLUSIONS A mobile flow‐through system suitable for continuous in situ 13 CO 2 pulse‐labeling was successfully developed that is easily applicable in remote natural ecosystems. Copyright © 2013 John Wiley & Sons, Ltd.