/ N. Gentsch [et al.] // Eur. J. Soil Sci. - 2015. -
Vol. 66,
Is. 4. - P722-734,
DOI 10.1111/ejss.12269
. - ISSN 1351-0754
Аннотация: Permafrost degradation may cause strong feedbacks of arctic ecosystems to global warming, but this will depend on if, and to what extent, organic matter (OM) is protected against biodegradation by mechanisms other than freezing and anoxia. Here, we report on the amount, chemical composition and bioavailability of particulate (POM) and mineral-associated OM (MOM) in permafrost soils of the East Siberian Arctic. The average total organic carbon (OC) stock across all soils was 24.0 ± 6.7 kg m-2 within 100 cm soil depth. Density fractionation (density cut-off 1.6 g cm-3) revealed that 54 ± 16% of the total soil OC and 64 ± 18% of OC in subsoil horizons was bound to minerals. As well as sorption of OM to clay-sized minerals (R2 = 0.80; P 0.01), co-precipitation of OM with hydrolyzable metals may also transfer carbon into the mineral-bound fraction. Carbon:nitrogen ratios, stable carbon and nitrogen isotopes, 13C-
NMR and X-ray photoelectron spectroscopy showed that OM is transformed in permafrost soils, which is a prerequisite for the formation of mineral-organic associations. Mineral-associated OM in deeper soil was enriched in 13C and 15N, and had narrow C:N and large alkyl C:(O-/N-alkyl C) ratios, indicating an advanced stage of decomposition. Despite being up to several thousands of years old, when incubated under favourable conditions (60% water-holding capacity, 15°C, adequate nutrients, 90 days), only 1.5-5% of the mineral-associated OC was released as COinf2/inf. In the topsoils, POM had the largest mineralization but was even less bioavailable than the MOM in subsoil horizons. Our results suggest that the formation of mineral-organic associations acts as an important additional factor in the stabilization of OM in permafrost soils. Although the majority of MOM was not prone to decomposition under favourable conditions, mineral-organic associations host a readily accessible carbon fraction, which may actively participate in ecosystem carbon exchange. © 2015 British Society of Soil Science.
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WOS Держатели документа: Institut für Bodenkunde, Leibniz Universität Hannover, Herrenhäuser Straße 2, Hannovern, Germany
VN Sukachev Institute of Forest, Akademgorodok 50, Krasnoyarsk, Russian Federation
Division of Terrestrial Ecosystem Research, Department of Microbiology and Ecosystem Science, University of Vienna, Althanstr. 14, Vienna, Austria
Austrian Polar Research Institute, Althanstra?e 14, Vienna, Austria
Department of Earth Sciences, University of Gothenburg, Guldhedsgatan 5A, Gothenburg, Sweden
Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH, United States
Department of Ecogenomics and Systems Biology, University of Vienna, Althanstr. 14, Vienna, Austria
Department of Biology, Centre for Geobiology, University of Bergen, Postboks 7803, Bergen, Norway
Department of Bioscience, Norway and Center for Geomicrobiology, Aarhus University, Ny Munkegade 116, Aarhus C, Denmark
Department of Ecosystem Biology, University of South Bohemia, Branisovska 1760, Ceske Budejovice, Czech Republic
Central SiberianBotanical Garden, Siberian Branch of the Russian Academy of Sciences, Zolotodolinskya Street 101, Novosibirsk, Russian Federation
Lehrstuhl fur Bodenkunde, Technische Universitat Munchen, Emil-Ramann Strasse 2, Freising, Germany
Thunen Institute of Climate Smart Agriculture, Bundesallee 50, Braunschweig, Germany
Доп.точки доступа: Gentsch, N.; Mikutta, R.; Shibistova, O.; Wild, B.; Schnecker, J.; Richter, A.; Urich, T.; Gittel, A.; Santruckova, H.; Barta, J.; Lashchinskiy, N.; Mueller, C.W.; Fuß, R.; Guggenberger, G.
