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dc.contributor.authorCastanha, Cristina
dc.contributor.authorTrumbore, Susan
dc.contributor.authorAmundson, Ronald
dc.date.accessioned2021-02-11T20:59:21Z
dc.date.available2021-02-11T20:59:21Z
dc.date.issued2008-01-01
dc.identifier.citationCastanha, C., Trumbore, S., & Amundson, R. (2008). Methods of separating soil carbon pools affect the chemistry and turnover time of isolated fractions. Radiocarbon, 50(1), 83-97.
dc.identifier.issn0033-8222
dc.identifier.doi10.1017/S0033822200043381
dc.identifier.urihttp://hdl.handle.net/10150/653926
dc.description.abstractA variety of physical and chemical techniques are used to fractionate soil organic matter, but detailed comparisons of the different approaches and tests of how separation methods influence the properties of isolated organic matter pools are lacking. In this case study based on A horizon samples of 2 California coniferous forests soils, we 1) evaluate the effects of root removal and ultrasonic dispersion on the properties of the 2 g cm3 light fraction and 2) compare the properties of fractions obtained by sequential density separations of ultrasonically treated soil with those obtained by density followed by acid/base hydrolysis (Trumbore et al. 1996). A root-removal effort based on hand-picking visible roots reduced the radiocarbon content and increased the estimated turnover time of the light fraction by roughly 12%. Root-removal protocols that vary between investigators thus can potentially confound variability in carbon cycling for this fraction caused by environmental factors, such as climate. Ultrasonic dispersion did not have a clear effect on the light fraction C and N content or isotopic signature, but led to a decrease in the % C and C/N of the recovered heavy fractions, and losses of 1219% of the total soil C to the sodium metatungstate density solution. Sequentially isolated density fractions clearly differed in mineralogy and organic matter chemistry, but natural-abundance 14C analyses indicated that distinct mineral phases did not correspond to unique C-turnover pools. Density fractions containing kaolinite group minerals alone and in combination with hydroxy-interlayered vermiculite were found to harbor both fast and slow cycling carbon. In contrast, severe chemical treatment isolated a carbon pool with the lowest overall 14C content and longest inferred mean turnover time. Overall, our results show that care must be taken when relying on physical (density) separation to isolate soil fractions with different dynamics, as the details of treatment will influence the results.
dc.language.isoen
dc.publisherDepartment of Geosciences, The University of Arizona
dc.relation.urlhttp://radiocarbon.webhost.uits.arizona.edu/
dc.rightsCopyright © by the Arizona Board of Regents on behalf of the University of Arizona. All rights reserved.
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.titleMethods of Separating Soil Carbon Pools Affect the Chemistry and Turnover Time of Isolated Fractions
dc.typeArticle
dc.typetext
dc.identifier.journalRadiocarbon
dc.description.collectioninformationThe Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information.
dc.eprint.versionFinal published version
dc.description.admin-noteMigrated from OJS platform February 2021
dc.source.volume50
dc.source.issue1
dc.source.beginpage83
dc.source.endpage97
refterms.dateFOA2021-02-11T20:59:21Z


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