The soils of the Lena River Delta contain significant reserves of soil organic matter, and as a result of riverine erosion and permafrost degradation, the coastal zone is undergoing rapid transformation, releasing substantial amounts of buried carbon from organic‐rich permafrost soils and Ice Complex deposits. To investigate the influence of fluvial processes and cryogenesis on the physical stabilization of SOM, we analyzed the microstructure of Cryosols (15 soil samples) and Ice Complex (4 deposit samples) using polarization microscopy (Leica DM750P) and ImageJ software (National Institute of Health, USA). The study revealed the specifics of soil formation in the Lena River Delta, as well as the features of organic matter release from the frozen state. Thin sections of soils subjected to periodic flooding and long‐term freeze/thaw cycles were examined, alongside organomineral deposits exposed by degradation of the Ice Complex. Results indicate that soils affected by prolonged cryogenic processes (long‐term freezing and thawing cycles) exhibit the highest degree of soil organic matter physical stabilization, likely due to microaggregate formation. In contrast, freshly thawed Ice Complex deposits show lower aggregation stability, suggesting a potential vulnerability to biodegradation upon release from permafrost. These findings highlight the critical role of cryogenic and fluvial dynamics in regulating Arctic carbon cycling under climate change.
Polyakov et al. (Thu,) studied this question.