Molecular composition of humic substances in tundra soils (13C-NMR spectroscopic study)

Лодыгин, Е. Д.; Beznosikov, V. A.; Василевич, Р. С.

doi:10.1134/s1064229314010074

Cited by 57 publications

(57 citation statements)

References 10 publications

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“…In general, the soils from the Shatura plots show a prevalence of alkyl carbon fraction in both the mature and postfire scenarios. This seems to be related to the nature of histic material (Lodygin, Beznosikov, & Vasilevich, ). The postfire soil from the Togliatti plot shows a prevalence of aromatic compounds, whereas the initial mature Togliatti soil exhibits a dominance of alkyl carbon species, which is a typical zonal feature of SOM from the forest steppe of the region investigated (Abakumov et al, ).…”

Section: Resultsmentioning

confidence: 99%

Assessment of postfire soils degradation dynamics: Stability and molecular composition of humic acids with use of spectroscopy methods

2017

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The effect of wildfires on the soils of the south taiga and forest‐steppe environments of Central Russia (Histic Spodosols and Eutric Fluvic Arenosols) was investigated in terms of the content and quality of humic acids (HAs) using instrumental spectroscopic methods (solid‐state carbon‐13 nuclear magnetic resonance and electron spin resonance). The bulk elemental composition of HAs was not essentially altered in postfire soils; however, the organic matter of fire‐affected superficial soil layers was characterized by changes in the structural composition and biochemical activity levels. Solid‐state carbon‐13 nuclear magnetic resonance spectroscopy showed that there is an intensive increase in aromatic compounds in HA molecules in soil from both the south taiga and forest‐steppe environments. There is a pronounced and statistically significant decline of aliphatic chain content in response to exposure to fire. The free radicals content and the degree of molecular stabilization assessed with electron spin resonance showed an essential alteration of the HAs, expressed in the increase in the radical's portion, in postfire soils compared with that found in soils not exposed to fire. It was also shown that the accumulation of aromatic compounds indicates only apparent stabilization of HAs due to the loss of periphery alkylic carbon species, which was confirmed by destabilization of the molecules as illustrated by the increase of free radicals.

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Section: Resultsmentioning

confidence: 99%

Assessment of postfire soils degradation dynamics: Stability and molecular composition of humic acids with use of spectroscopy methods

2017

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“…The area is a gently undulating plain covered with silty loams being less than 10 m thick. Typical soil formation processes in the tundra zone are gleyzation (stagnic processes) and peat accumulation (Lodygin et al 2014). Soil pit (tundra surface-gley soil) was dug on a gentle slope of the Nerusovei-musyur moraine hill (67º31'N, 64º07'E; 220 m a.s.l.).…”

Section: Methodsmentioning

confidence: 99%

“…There are a few indexes established for assessment of humus stability: ratio of humic acids to fulvic acids (Kononova 1984), degree of aromaticity (Ejarque and Abakumov 2015), content of free radicals in molecules (Chukov et al 2017) and elemental composition of both groups of humic substances (Lodygin et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Humic substances elemental composition of selected taiga and tundra soils from Russian European North-East

Лодыгин¹,

Beznosikov²,

Abakumov³

2017

Polish Polar Research

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This paper provides an overview of the results of research on changes in ground temperature down to 50 cm depth, on the Kaffiøyra Plain, Spitsbergen in the summer seasons. To achieve this, measurement data were analysed from three different ecotopes (CALM Site P2A, P2B and P2C) -a beach, a moraine and tundra -collected during 22 polar expeditions between 1975 and 2014. To ensure comparability, data sets for the common period from 21 July to 31 August (referred to as the "summer season" further in the text) were analysed. The greatest influence on temperature across the inves− tigated ground layers comes from air temperature (correlation coefficients ranging from 0.61 to 0.84). For the purpose of the analysis of the changes in ground temperature in the years 1975-2014, missing data for certain summer seasons were reconstructed on the ba− sis of similar data from a meteorological station at Ny−Ålesund. The ground temperature at the Beach site demonstrated a statistically−significant growing trend: at depths from 1 to 10 cm the temperature increased by 0.27-0.28°C per decade, and from 20 to 50 cm by as much as 0.30°C per decade. On the Kaffiøyra Plain, the North Atlantic Oscillation (NAO) has a greater influence on the ground and air temperature than the Arctic Oscilla− tion (AO).

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“…The bioclimatic conditions determine the soil formation in the polar regions, and their specific composition of Has; however, their high diversity, low degree of knowledge of the regions, and the use of classical methods for studying organic matter do not allow us to state the molecular composition of HAs in polar soils with a high degree of confidence. The formation and transformation of HAs is a complex process in which a group of factors is involved, such as climate, composition and activity of the microbiological community, quality of plant residues, pH, and hydrophobicity of environment [26][27][28]36]. At present, there are a number of works devoted to the study of taiga and tundra soils using 13 C (CP/MAS) NMR spectroscopy; however, there are few studies on Antarctic and Arctic soils.…”

Section: Introductionmentioning

confidence: 99%

“…For further study of the fundamental processes of humus formation and the accumulation of specific organic compounds in the polar regions, modern instrumental methods are required. The methods of analysis of molecular composition that we have proposed will help to understand the fundamental processes of soil formation and create new ideas about the complex composition and structure of natural high molecular compounds of HAs in permafrost-affected soils [26][27][28]. 1 H-13 C (HETCOR) and 13 C (CP/MAS) NMR spectroscopy are powerful tools for studying molecular-level structure and dynamics in HAs.…”

Section: Introductionmentioning

confidence: 99%

Humic Acids Isolated from Selected Soils from the Russian Arctic and Antarctic: Characterization by Two-Dimensional 1H-13C HETCOR and 13C CP/Mas NMR Spectroscopy

Polyakov

Abakumov

2019

Geosciences

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Here we describe the molecular composition and resistance to decomposition of humic acids isolated from selected soils of the Russian Arctic and Antarctic. The degree of soil organic matter stabilization was assessed using modern instrumental methods: nuclear magnetic resonance spectroscopy (cross peak magic-angle spinning (CP/MAS) 13C-NMR and 1H-13C heteronuclear-correlation (HETCOR)). Analysis of the humic acids showed that aromatic compounds prevail in the organic matter formed in cryoconites, located on the surfaces of the glaciers. The predominance of aliphatic fragments is revealed in the soils of the Yamal peninsula and Antarctica. This could be caused by sedimentation of fresh organic matter exhibiting low decomposition stage due to the severe climate and processes of hydrogenation in the humic acids, destruction of the C-C bonds, and formation of chains with high hydrogen content. These processes result in formation of aliphatic fragments in the humic acids.

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Molecular composition of humic substances in tundra soils (13C-NMR spectroscopic study)

Cited by 57 publications

References 10 publications

Assessment of postfire soils degradation dynamics: Stability and molecular composition of humic acids with use of spectroscopy methods

Assessment of postfire soils degradation dynamics: Stability and molecular composition of humic acids with use of spectroscopy methods

Humic substances elemental composition of selected taiga and tundra soils from Russian European North-East

Humic Acids Isolated from Selected Soils from the Russian Arctic and Antarctic: Characterization by Two-Dimensional 1H-13C HETCOR and 13C CP/Mas NMR Spectroscopy

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