Radiocarbon and stable carbon isotope compositions of chemically fractionated soil organic matter in a temperate-zone forest
To better understand the role of soil organic matter in terrestrial carbon cycle, carbon isotope compositions in soil samples from a temperate-zone forest were measured for bulk, acid-insoluble and base-insoluble organic matter fractions separated by a chemical fractionation method. The measurements...
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Published in | Journal of environmental radioactivity Vol. 79; no. 2; pp. 137 - 156 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Oxford
Elsevier Ltd
2005
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | To better understand the role of soil organic matter in terrestrial carbon cycle, carbon isotope compositions in soil samples from a temperate-zone forest were measured for bulk, acid-insoluble and base-insoluble organic matter fractions separated by a chemical fractionation method. The measurements also made it possible to estimate indirectly radiocarbon (
14C) abundances of acid- and base-soluble organic matter fractions, through a mass balance of carbon among the fractions. The depth profiles of
14C abundances showed that (1) bomb-derived
14C has penetrated the first 16
cm mineral soil at least; (2) Δ
14C values of acid-soluble organic matter fraction are considerably higher than those of other fractions; and (3) a significant amount of the bomb-derived
14C has been preserved as the base-soluble organic matter around litter–mineral soil boundary. In contrast, no or little bomb-derived
14C was observed for the base-insoluble fraction in all sampling depths, indicating that this recalcitrant fraction, accounting for approximately 15% of total carbon in this temperate-zone forest soil, plays a role as a long-term sink in the carbon cycle. These results suggest that bulk soil organic matter cannot provide a representative indicator as a source or a sink of carbon in soil, particularly on annual to decadal timescales. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 0265-931X 1879-1700 |
DOI: | 10.1016/j.jenvrad.2004.06.002 |