Storage and transformation of organic matter fractions in cryoturbated permafrost soils across the Siberian Arctic

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dc.identifier.uri Gentsch, Norman Mikutta, Robert Alves, Ricardo J. Eloy Barta, Jin Čapek, Petr Gittel, Antje Hugelius, Gustaf Kuhry, Peter Lashchinskiy, Nikolay Palmtag, Juri Richter, Andreas Šantrůčková, Hana Schnecker, Jörg Shibistova, Olga Urich, Tim Wild, B. Guggenberger, Georg 2015-08-06T12:32:33Z 2015-08-06T12:32:33Z 2015
dc.identifier.citation Gentsch, N.; Mikutta, R.; Alves, R.J.E.; Barta, J.; Čapek, P.; Gittel, A. et al.: Storage and transformation of organic matter fractions in cryoturbated permafrost soils across the Siberian Arctic. In: Biogeosciences 12 (2015), S. 4525-4542. DOI:
dc.description.abstract In permafrost soils, the temperature regime and the resulting cryogenic processes are important determinants of the storage of organic carbon (OC) and its small-scale spatial variability. For cryoturbated soils, there is a lack of research assessing pedon-scale heterogeneity in OC stocks and the transformation of functionally different organic matter (OM) fractions, such as particulate and mineral-associated OM. Therefore, pedons of 28 Turbels were sampled in 5 m wide soil trenches across the Siberian Arctic to calculate OC and total nitrogen (TN) stocks based on digital profile mapping. Density fractionation of soil samples was performed to distinguish between particulate OM (light fraction, LF, < 1.6 g cm−3), mineral associated OM (heavy fraction, HF, > 1.6 g cm−3), and a mobilizable dissolved pool (mobilizable fraction, MoF). Across all investigated soil profiles, the total OC storage was 20.2 ± 8.0 kg m−2 (mean ± SD) to 100 cm soil depth. Fifty-four percent of this OC was located in the horizons of the active layer (annual summer thawing layer), showing evidence of cryoturbation, and another 35 % was present in the upper permafrost. The HF-OC dominated the overall OC stocks (55 %), followed by LF-OC (19 % in mineral and 13 % in organic horizons). During fractionation, approximately 13 % of the OC was released as MoF, which likely represents a readily bioavailable OM pool. Cryogenic activity in combination with cold and wet conditions was the principle mechanism through which large OC stocks were sequestered in the subsoil (16.4 ± 8.1 kg m−2; all mineral B, C, and permafrost horizons). Approximately 22 % of the subsoil OC stock can be attributed to LF material subducted by cryoturbation, whereas migration of soluble OM along freezing gradients appeared to be the principle source of the dominant HF (63 %) in the subsoil. Despite the unfavourable abiotic conditions, low C / N ratios and high δ13C values indicated substantial microbial OM transformation in the subsoil, but this was not reflected in altered LF and HF pool sizes. Partial least-squares regression analyses suggest that OC accumulates in the HF fraction due to co-precipitation with multivalent cations (Al, Fe) and association with poorly crystalline iron oxides and clay minerals. Our data show that, across all permafrost pedons, the mineral-associated OM represents the dominant OM fraction, suggesting that the HF-OC is the OM pool in permafrost soils on which changing soil conditions will have the largest impact. eng
dc.description.sponsorship Russian Ministry of Education and Science/14.B25.31.0031
dc.description.sponsorship German Federal Ministry of Education and Research/03F0616A
dc.description.sponsorship Evangelisches Studienwerk Villigst
dc.description.sponsorship DFG
dc.language.iso eng eng
dc.publisher Göttingen : Copernicus
dc.rights CC BY 3.0 Unported
dc.subject permafrost soils eng
dc.subject organic carbon eng
dc.subject carbon eng
dc.subject Geologie ger
dc.subject Biologie ger
dc.subject Permafrostboden ger
dc.subject Kohlenstoff ger
dc.subject organischer Kohlenstoff ger
dc.subject Arktis ger
dc.subject Sibirien ger
dc.subject siberian arctic eng
dc.subject gelogy eng
dc.subject biology eng
dc.subject arctic eng
dc.subject siberia eng
dc.subject.classification Geologie ger
dc.subject.classification Biologie ger
dc.subject.classification Dauerfrostboden ger
dc.subject.classification Kohlenstoff ger
dc.subject.classification Arktis ger
dc.subject.classification Sibirien ger
dc.subject.ddc 550 | Geowissenschaften ger
dc.subject.ddc 570 | Biowissenschaften, Biologie ger
dc.title Storage and transformation of organic matter fractions in cryoturbated permafrost soils across the Siberian Arctic eng
dc.type article
dc.type Text
dc.relation.essn 1726-4189
dc.relation.issn 1726-4170
dc.description.version publishedVersion
tib.accessRights frei zug�nglich

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