EGU22-3779
https://doi.org/10.5194/egusphere-egu22-3779
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

A multi-isotopic approach to the reconstruction of palsa hummock formation: the case study from the Central Siberia

Anatoly Prokushkin1,2, Elena Novenko3,4, Sergey Serikov5, and Daria Polosukhina1,2
Anatoly Prokushkin et al.
  • 1Sukachev Institute of Forest SB RAS, Federal Research Center “Krasnoyarsk Science Center SB RAS”, Krasnoyarsk, 660036, Russia
  • 2Siberian Federal University, Krasnoyarsk, 660041, Russia
  • 3Lomonosov Moscow State University, GSP-1, Leninskie Gory, Moscow, 119991, Russia
  • 4Institute of Geography Russian Academy of Science, Staromonetny lane, 29, Moscow, 119017, Russia
  • 5Igarka geocryology laboratory, Melnikov Institute of permafrost SB RAS, Igarka, 663200, Russia

In northern palsa mires stable isotopes of C and N of peat organic matter (OM) and O and H of segregated ice may serve as an important conduit of information about variability of environment conditions and OM turnover in the past millennia and modern time. In our study we applied the multi-isotopic record to distinguish variation in the development of palsa peatlands located in forest-tundra ecotone of Central Siberia.

The study sites are located in vicinity of Igarka settlement (67o31’ N, 86o38’E) within the area underlain discontinuous permafrost. The peat cores were obtained in the central intact parts of perennial frost hummocks located in basins of the Gravijka and Little Gravijka rivers (depth 8.6 and 2.7 m, respectively). Thawed and frozen peat samples were collected at 1.0-5.0 cm step depending on the amount of peat and ice material. Peat (solid) samples were analyzed for C and N content and stable isotopic composition (δ13C and δ15N) by TOC Macro cube (Elementar, Germany) paralleled with Isoprime 100 IRMS (UK). Water stable isotope composition (δ18O and δ2H) of segregated ice samples (melted) were obtained by Picarro L-2120-i (Picarro Inc. USA).

The age of studied peatlands ranged between about 6200 cal yr BP (Gravijka site) and 4300 cal yr BP (Little Gravijka site). Meanwhile, there was the large loss of organic matter in the upper active layer of peat deposits as at 15 cm depth the age of OM was ca. 1800 cal yr BP. These findings suggest OM removal during wildfires and likely erosion processes following fires, and specific isotopic composition mirrors an enhanced OM decomposition in active layer. The large variations in composition of analyzed stable isotopes in frozen peat core captured the changes occurred during the past epochs in an input of OM (changes in vegetation and productivity), peat decomposition rates, nitrogen cycle perturbations as well as hydrothermal regimes and permafrost processes like aggradation (e.g. hummock uplift and cryoturbation) and degradation (e.g. hummock collapse, shifts from minerotrophic to ombrotrophic conditions and vice versa).

This work was supported by the Russian Science Foundation, project № 20-17-00043.

How to cite: Prokushkin, A., Novenko, E., Serikov, S., and Polosukhina, D.: A multi-isotopic approach to the reconstruction of palsa hummock formation: the case study from the Central Siberia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3779, https://doi.org/10.5194/egusphere-egu22-3779, 2022.