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

Abstract

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).

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

“…Sample numbers correspond to Table 2 According to the 13 C (CP/MAS) NMR spectroscopy, a significant amount of aliphatic fragments accumulate in HAs of soils from the Yamal peninsula (Figure 2A). Our data are in line with previous studies in the Arctic region [28,[47][48][49]. The accumulation of C,H-substituted aliphatic fragments leads to the conservation and accumulation of organic substances in the soils of Yamal peninsula.…”

“…The use of modern instrumental methods such as one-and two-dimensional NMR spectroscopy is a reliable way to study the molecular composition of HAs in soils. Our results about 13 C (CP/MAS) NMR spectroscopy are in agreement with previous studies [6,11,18,19,24,[26][27][28]46,47,49]; the accumulation of aliphatic compounds in HAs composition can be related to the activity and composition of microbiota, hydrophobicity, and the composition of humification precursors [27,28,36,46,47]. Excessive moisture in the areas of King George isl.…”

“…The accumulation of C,H-substituted aliphatic fragments leads to the conservation and accumulation of organic substances in the soils of Yamal peninsula. The accumulation of oxygen-containing (-O-CH) fragments of HAs is also characteristic of Arctic soils, which is associated with better solubility in water, migration of organic acids along the profile, and their accumulation at the permafrost table [28,49,50].…”

“…The accumulation of C,H-substituted aliphatic fragments leads to the conservation and accumulation of organic substances in the soils of Yamal peninsula. The accumulation of oxygen-containing (-O-CH) fragments of HAs is also characteristic of Arctic soils, which is associated with better solubility in water, migration of organic acids along the profile, and their accumulation at the permafrost table [28,49,50]. The low content of aromatic fragments in the HAs indicates a low level of humification of organic matter, which is associated with the condensation of low-molecular precursors of humification and a low level of stabilization of organic matter [49].…”

“…The accumulation of oxygen-containing (-O-CH) fragments of HAs is also characteristic of Arctic soils, which is associated with better solubility in water, migration of organic acids along the profile, and their accumulation at the permafrost table [28,49,50]. The low content of aromatic fragments in the HAs indicates a low level of humification of organic matter, which is associated with the condensation of low-molecular precursors of humification and a low level of stabilization of organic matter [49]. The accumulation of aliphatic fragments is due to the composition of organic residues entering the soil, moss-lichen tundra vegetation predominates in the Yamal, which is more enriched in aliphatic compounds [27].…”