Труды сотрудников ИЛ им. В.Н. Сукачева СО РАН

/ M. L. Bagard [et al.] // Geochim. Cosmochim. Acta. - 2013. - Vol. 114. - P169-187, DOI 10.1016/j.gca.2013.03.038. - Cited References: 104. - We thank T. Bullen and two anonymous reviewers for their thorough and constructive reviews and A. Jacobson for editorial handling. S. Gangloff is thanked for her assistance with Ca isotope chemistry and T. Perrone for his help in measuring Sr isotopes. This work was supported by the French INSU-CNRS program "EC2CO-Cytrix", and CNRS program "GDRI CAR-WET-SIB, ANR "Arctic Metals", programs of presidium UroRAS and RAS. It was also supported by the funding from the Region Alsace, France, and the CPER 2003-2013 "REALISE". MLB benefited the funding of a Ph.D. scholarship from the French Ministry of National Education and Research. This is an EOST-LHyGeS contribution. . - 19. - ISSN 0016-7037РУБ Geochemistry & Geophysics

Аннотация: Stable Ca and radiogenic Sr isotope compositions were measured in different compartments (stream water, soil solutions, rocks, soils and soil leachates and vegetation) of a small permafrost-dominated watershed in the Central Siberian Plateau. The Sr and Ca in the area are supplied by basalt weathering and atmospheric depositions, which significantly impact the Sr isotopic compositions. Only vegetation significantly fractionates the calcium isotopes within the watershed. These fractionations occur during Ca uptake by roots and along the transpiration stream within the larch trees and are hypothesised to be the result of chromatographic processes and Ca oxalate crystallisations during Ca circulation or storage within plant organs. Biomass degradation significantly influences the Ca isotopic compositions of soil solutions and soil leachates via the release of light Ca, and organic and organo-mineral colloids are thought to affect the Ca isotopic compositions of soil solutions by preferential scavenging of Ca-40. The imprint of organic matter degradation on the delta Ca-44/40 of soil solutions is much more significant for the warmer south-facing slope of the watershed than for the shallow and cold soil active layer of the north-facing slope. As a result, the available stock of biomass and the decomposition rates appear to be critical parameters that regulate the impact of vegetation on the soil-water system in permafrost areas. Finally, the obtained delta Ca-44/40 patterns contrast with those described for permafrost-free environments with a much lower delta Ca-44/40 fractionation factor between soils and plants, suggesting specific features of organic matter decomposition in permafrost environments. The biologically induced Ca isotopic fractionation observed at the soil profile scale is not pronounced at the scale of the streams and large rivers in which the delta Ca-44/40 signature may be controlled by the heterogeneity of lithological sources. (C) 2013 Elsevier Ltd. All rights reserved.

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Держатели документа:
[Bagard, Marie-Laure
Schmitt, Anne-Desiree
Chabaux, Francois
Stille, Peter] Univ Strasbourg, F-67084 Strasbourg, France
[Bagard, Marie-Laure
Schmitt, Anne-Desiree
Chabaux, Francois
Stille, Peter] CNRS, EOST, LHyGeS, F-67084 Strasbourg, France
[Schmitt, Anne-Desiree] Univ Franche Comte, CNRS, UMR 6249, F-25030 Besancon, France
[Pokrovsky, Oleg S.
Viers, Jerome] Univ Toulouse 3, CNRS, UMR 5563, Geosci & Environm Toulouse, F-31400 Toulouse, France
[Pokrovsky, Oleg S.] Russian Acad Sci, Inst Ecol Problems North, Arkhangelsk, Russia
[Labolle, Francois] Univ Strasbourg, Inst Zool & Biol Gen, F-67000 Strasbourg, France
[Prokushkin, Anatoly S.] VN Sukachev Inst Forest SB RAS, Krasnoyarsk, Russia
Институт леса им. В.Н. Сукачева Сибирского отделения Российской академии наук : 660036, Красноярск, Академгородок 50/28

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Bagard, M.L.; Schmitt, A.D.; Chabaux, F...; Pokrovsky, O.S.; Viers, J...; Stille, P...; Labolle, F...; Prokushkin, A.S.

[Text] / O. V. Menyailo, B. A. Hungate // Glob. Biogeochem. Cycle. - 2006. - Vol. 20, Is. 3. - Ст. GB3025, DOI 10.1029/2005GB002527. - Cited References: 47 . - 10. - ISSN 0886-6236РУБ Environmental Sciences + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: Measuring the stable isotope composition of nitrous oxide ( N(2)O) evolved from soil could improve our understanding of the relative contributions of the main microbial processes ( nitrification and denitrification) responsible for N(2)O formation in soil. However, interpretation of the isotopic data in N(2)O is complicated by the lack of knowledge of fractionation parameters by different microbial processes responsible for N(2)O production and consumption. Here we report isotopic enrichment for both nitrogen and oxygen isotopes in two stages of denitrification, N(2)O production and N(2)O reduction. We found that during both N(2)O production and reduction, enrichments were higher for oxygen than nitrogen. For both elements, enrichments were larger for N(2)O production stage than for N(2)O reduction. During gross N(2)O production, the ratio of delta(18)O- to-delta(15)N differed between soils, ranging from 1.6 to 2.7. By contrast, during N(2)O reduction, we observed a constant ratio of delta(18)O- to-delta(15)N with a value near 2.5. If general, this ratio could be used to estimate the proportion of N(2)O being reduced in the soil before escaping into the atmosphere. Because N(2)O- reductase enriches N(2)O in both isotopes, the global reduction of N(2)O consumption by soil may contribute to the globally observed isotopic depletion of atmospheric N(2)O.

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Russian Acad Sci, Siberian Branch, Inst Forest, Krasnoyarsk 660036, Russia
No Arizona Univ, Dept Biol Sci, Flagstaff, AZ 86011 USA
No Arizona Univ, Merriam Powell Ctr Environm Res, Flagstaff, AZ 86011 USA

Доп.точки доступа:
Menyailo, O.V.; Hungate, B.A.

[Text] / O. S. Pokrovsky [et al.] // Chem. Geol. - 2013. - Vol. 355. - P103-116, DOI 10.1016/j.chemgeo.2013.07.016. - Cited References: 65. - We are grateful to Associate Editor Carla Koretsky for her significant efforts in improving this manuscript and two anonymous reviewers for their helpful and constructive comments. This work was supported by the BIO-GEO-CLIM Mega-grant of the Ministry of Education and Science of the Russian Federation and Tomsk State University (No 14.B25.31.0001), ANR "Arctic Metals", GDRI CAR WET SIB and LIA LEAGE International Laboratories, Grants RFFI 10-05-92513, and 11-04-10056, the CRDF RUG1-2980-KR-10 and Programs of Presidium RAS (No 12-P-5-1021) and UrORAS (No 12-U-5-1034). . - 14. - ISSN 0009-2541РУБ Geochemistry & Geophysics

Аннотация: This work is devoted to the characterization of natural mechanisms of silicon isotope fractionation within Siberian watersheds and predicting the climate warming effect on Si fluxes from the land to the Arctic Ocean. To unravel the different sources of silica generated by basalt weathering in Central Siberia under permafrost and larch deciduous forest conditions, we measured the Si isotopic composition of large and small rivers, surface flow, interstitial soil solutions, plant litter and soils. The average annual discharge-weighted delta Si-30 values of the second largest tributary of the Yenissei River, Nyzhnaya Tunguska and its main northern tributary (Kochechum) are equal to 1.08 +/- 0.10% and 1.67 +/- 0.15%, respectively, while their average annual Si concentrations are very similar (3.46 and 3.50 mg/L, respectively). During summer baseflow, the dissolved Si isotope composition of both large rivers and a small stream ranges between 1.5 and 2.5%. This is much heavier compared to the source basaltic rocks but similar to the fresh litter of Larix gmelinii, the dominating tree species in this region. It could be consistent with litter degradation in the uppermost soil horizons being the dominant source of solutes annually exported by Central Siberian rivers. During spring flood, accounting for 60-80% of annual Si flux, the delta Si-30 of the large rivers' dissolved load decreases by 1-1.5%, thus approaching the value of the bedrock and the silicate suspended matter of the rivers (RSM). This may reflect the dissolution of the silicate suspended load at high water/mineral ratio. The winter delta Si-30 values of the large river dissolved load range between 1.0 and 2.5%. During this period, contributing to <= 10% of the annual Si chemical flux, the interaction between bedrock (porous tuffs) and deep ground waters occurs at a very high solid/solution ratio, leading to the precipitation of isotopically light secondary minerals and enrichment of Si-30 in the fluids that feed the river through the unfrozen flowpaths. Results of this study imply that more than a half of the silica transported by Siberian rivers may transit through the biogenic pool and that, like in other stable basaltic regions, bedrock-water interactions account for a lesser fraction of the silica flux. As a result of projected future climate warming and weathering increases in boreal regions, the delta Si-30 isotopic composition of large Siberian rivers is likely to shift towards less positive values. (c) 2013 Elsevier B.V. All rights reserved.

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Держатели документа:
[Pokrovsky, O. S.
Schott, J.
Viers, J.] Univ Toulouse, GET CNRS UMR 5563, F-31400 Toulouse, France
[Pokrovsky, O. S.] UroRAS, Inst Ecol Problems North, Arkhangelsk, Russia
[Reynolds, B. C.] Swiss Fed Inst Technol, Inst Geochem & Petr, Zurich, Switzerland
[Prokushkin, A. S.] RAS, Inst Forest, Siberian Branch, Krasnoyarsk, Russia

Доп.точки доступа:
Pokrovsky, O.S.; Reynolds, B.C.; Prokushkin, A. S.; Прокушкин, Анатолий Станиславович; Schott, J.; Viers, J.; BIO-GEO-CLIM Mega-grant of the Ministry of Education and Science of the Russian Federation; Tomsk State University [14.B25.31.0001]; ANR "Arctic Metals"; GDRI CAR WET SIB and LIA LEAGE International Laboratories [RFFI 10-05-92513, 11-04-10056]; CRDF [RUG1-2980-KR-10]; Program of Presidium RAS [12-P-5-1021]; Program of Presidium UrORAS [12-U-5-1034]