Increased mineralization of the organic matter (OM) stored in permafrost is expected to constitute the largest additional global warming potential from terrestrial ecosystems exposed to a warmer ...climate. Chemical composition of permafrost OM is thought to be a key factor controlling the sensitivity of decomposition to warming. Our objective was to characterise OM from permafrost soils of the European Arctic: two mineral soils—Adventdalen, Svalbard, Norway and Vorkuta, northwest Russia—and a “palsa” (ice-cored peat mound patterning in heterogeneous permafrost landscapes) soil in Neiden, northern Norway, in terms of molecular composition and state of decomposition. At all sites, the OM stored in the permafrost was at an advanced stage of decomposition, although somewhat less so in the palsa peat. By comparing permafrost and active layers, we found no consistent effect of depth or permafrost on soil organic matter (SOM) chemistry across sites. The permafrost-affected palsa peat displayed better preservation of plant material in the deeper layer, as indicated by increasing contribution of lignin carbon to total carbon with depth, associated to decreasing acid (Ac) to aldehyde (Al) ratio of the syringyl (S) and vanillyl (V) units, and increasing S/V and contribution of plant-derived sugars. By contrast, in Adventdalen, the Ac/Al ratio of lignin and the Alkyl C to O-alkyl C ratio in the NMR spectra increased with depth, which suggests less oxidized SOM in the active layer compared to the permafrost layer. In Vorkuta, SOM characteristics in the permafrost profile did not change substantially with depth, probably due to mixing of soil layers by cryoturbation. The composition and state of decomposition of SOM appeared to be site-specific, in particular bound to the prevailing organic or mineral nature of soil when attempting to predict the SOM proneness to degradation. The occurrence of processes such as palsa formation in organic soils and cryoturbation should be considered when up-scaling and predicting the responses of OM to climate change in arctic soils.
The results of the Internet discussion on the classification of urban soils aimed at evaluating their possible inclusion into the modern Russian soil classification system adopted by a wide range of ...specialists are presented. The first step was to address the
urban
diagnostic horizons as the basis for identifying soil types according to the rules of the Russian soil classification. New diagnostic horizons were proposed for urban soils: urbic (UR), filled compost-mineral (RAT), and filled peat (RT). The combination of these horizons with other diagnostic horizons and layers of technogenic materials correspond to different soil types. At the subtype level, the diagnostic properties (qualifiers) that may reflect both natural phenomena (gley, alkalinity) and technogenic impacts on the soils (urbistratified; phosphatic; or poorly expressed
urban
—ur, rat, rt) are used. Some corrections were proposed for the system of parent materials in urban environments. Urban soils formerly described in another nomenclature—urbanozems, urbiquasizems, and culturozems—are correlated with the taxa in all the trunks of the system. The proposals accepted can be used for the next updated version of the new Russian soil classification system.
► A suite of lipid biomarkers from a European Russian Arctic peat core was analyzed. ► The peat sequence records a vegetation transition from a wetter fen to a drier bog. ► The n-alkan-2-ones derive ...from oxidation of n-alkanes and decarboxylation of n-acids. ► Both n-alkanoic acids and n-alkanols are useful paleoenvironmental proxies.
Lipid biomarkers from a peat plateau profile from the Northeast European Russian Arctic were analyzed. The peat originated as a wet fen ca. 9ka BP and developed into a peat bog after the onset of permafrost ca. 2.5ka BP. The distributions and abundances of n-alkanols, n-alkanoic acids, n-alkanes, n-alkan-2-ones and sterols were determined to study the effect of degradation on their paleoclimate proxy information. Plant macrofossil analysis was also used in combination with the lipid distributions. The n-alkanol and n-alkanoic acid distributions in the upper part of the sequence generally correspond to compositions expected from plant macrofossil assemblages. Their carbon preference index (CPI) values increase with depth and age, whereas those of the n-alkanes decrease. The different CPI patterns suggest that n-alkanoic acids and n-alkanols deeper in the sequence may be produced during humification through alteration of other lipids. Excursions in the n-alkanoic acid content also suggest an important contribution of invasive roots to the lipid biomarker composition. The CPIs associated with these compounds show that under permafrost conditions organic material from Sphagnum is better preserved than material from vascular plants. Increasing stanol/stenol ratio values and decreasing n-alkane CPI values indicate progressive degradation of organic matter (OM) with depth. The n-alkan-2-one/n-alkane and n-alkan-2-one/n-alkanoic acid ratios were shown to be useful proxies that can reflect the degree of OM preservation and suggest that both microbial oxidation of n-alkanes and decarboxylation of n-alkanoic acids produce n-alkan-2-ones in this peat sequence.
Carbon balance in East European tundra Heikkinen, J.E.P; Virtanen, T; Huttunen, J.T ...
Global biogeochemical cycles,
March 2004, Letnik:
18, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We studied the carbon dioxide and methane fluxes from early June to mid‐September 2001 in the Russian tundra of northeast Europe. Gas fluxes were measured with chamber techniques to determine the ...seasonal (100 days) carbon gas balance for terrestrial ecosystems representing various vegetation types. Also, the gas balance for aquatic ecosystems in the region was measured. The 2001 fluxes were compared to colder and wetter season fluxes from 1999. The Sphagnum sp. dominated peat plateau fen and Carex sp. and Sphagnum sp. dominated intermediate flarks were carbon sinks of 106 and 110 g C m−2, respectively. In addition, methane emissions were highest from these sites. Other terrestrial surfaces lost carbon to the atmosphere (28–118 g C m−2). The thermokarst lake and the river had seasonal carbon losses of 15 and 34 g C m−2, respectively. For areal integration, the distributions of the various functional surfaces were classified based on Landsat TM satellite image and on‐site validation. This data was used to integrate the carbon fluxes for the entire Lek Vorkuta catchment. The upscaling indicated that the catchment (114 km2) lost 4 (±3.5) Gg C to the atmosphere in summer 2001. The results suggest that predicted warming in the tundra region would induce a substantial loss of carbon. In the warm summer of 2001, the carbon gas released from the whole northeast European tundra (area 205,000 km2) was 8 Tg C when calculated from the Lek Vorkuta data.
Two new species of the family Spilapteridae,
Homaloneura brauckmanni
sp. nov. and
Baeoneura desperata
sp. nov. are described from the Lower Permian insect bearing deposits of the Vorkuta Coal Basin. ...For
Vorkutoneura variabilis
Sinitshenkova, 1977 (Spilapteridae), the imaginal forewing and nymphal hindwings are described for the first time. The dictyoneuridan assemblage does not agree with the existing dating of these deposits as Late Permian, as the insect assemblage suggests an Early Permian age.
Long‐term (1982–1995) observations of the ground thermal regime of a drained thaw‐lake basin in the Pechora Lowlands of the Russian European north revealed a high spatial and temporal variability in ...the ground temperature response to artificial drainage. The thermal response was controlled by the atmospheric climate and by evolution of the landsurface following drainage. Observed changes in permafrost conditions were related to three climatic subperiods identified from air and ground temperature trends. The first (1982–1984) was characterized by gradual ground cooling associated with partial formation of permafrost patches under the initial stage of formation of marshy meadows. The second (1985–1987) involved strong ground cooling, resulting in the formation of a subsurface permafrost layer beneath most of the basin. The third (1988–1995) was marked by a gradual increase in annual mean ground temperature, promoting partial permafrost degradation under marshy meadows and willow stands. Initially, newly aggraded permafrost remained under peat mounds and tundra meadows. The spatial pattern of permafrost change can be attributed to heterogeneous landsurface evolution and variable snow thickness. Four distinct ground temperature regimes are distinguished: (i) thawed ground, (ii) deep permafrost, (iii) unstable permafrost and (iv) stable permafrost.
The content of polycyclic aromatic hydrocarbons (PAHs) and carbon isotope composition in the peat of a palsa near Eletsky settlement, Vorkuta urban district, Komi Republic are analyzed. The carbon ...isotope composition of peat varies from –28.05 to –30.05‰ (average –29.15‰). The total PAH content varies from 11 to 360 ppb, with an average of 63 ppb and a median value of 34 ppb. Heavy compounds, such as benzo(
a
)anthracene and benzofluoranthenes, are prevalent among PAHs. The presence of PAHs in the peat is determined by three main factors: technogenic impact, wildfires, and biogeochemical soil processes. The prevalence of benzo(
a
)anthracene in the upper part of the palsa down to the bottom of the active layer suggests an anthropogenic impact (the influence of transport and domestic fuel combustion). The share of benzo(
a
)anthracene decreases with depth, while the share of benzofluoranthenes increases. Two sharp peaks of PAH content (260 and 360 ppb) are observed; they coincide with a local increase of carbon isotope values, most likely resulting from wildfires. The minimums in PAH content are presumably determined by the biogeochemical factor and the input of polyarenes generated by decomposition of plant residues. Carbon isotope composition of peat mainly reflects the isotope composition of vegetation, the degree of peat moistening, and the influence of pyrogenic factor.
Humic substances are polydisperse mixtures of structurally complex matters with different molecular weights. The complexity of molecular composition of humic substances is reflected through their ...physical and chemical properties and results in diverse interactions both with inorganic components and living organisms. The correlation of the molecular composition of humic and fulvic acids and their molecular weight distribution were analyzed by means of CP/MAS 13C NMR spectroscopy and size exclusion chromatography. Humic acids are a dynamic system containing macromolecular, oligomeric and low-molecular components. Fulvic acids are a monodisperse mixture of relatively low-molecular (up to 2 kDa) organic compounds. A significant correlation between the content of high and medium weight molecular fractions with labile fragments and low molecular weight fractions with hydrophobous fragments of humic acids has been revealed.
—
A new genus and two new species
Taigahymen borealis
gen. et sp. nov. from the family Bardohymenidae and
Cyclocelis devexa
sp. nov. from the family Sphecopteridae are described from the Permian ...insect-bearing deposits of the Vorkuta basin. No representatives of the order Mischopterida have been previously recorded from the Vorkuta basin. The both new species are the latest and northernmost species of their families. These species, similar to those from the Carboniferous and Lower Permian deposits, do not contradict the Ufimian age of the Vorkuta Group.
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