Page 25 - Read online

Page 2 of 21 Artyukhov et al. Carbon Footprints 2026, 5, 8

contamination. Priority pollutants were lead (Pb), vanadium (V), and cobalt (Co), with spatial patterns indicating
vehicle emissions as a major contamination source near transport arteries. The radial differentiation coefficient
revealed distinct redistribution patterns of elements across soil profiles. Overall, the soil cover of northern Western
Siberia exhibits generally low anthropogenic contamination, though moderate to high contamination levels were
found in areas associated with oil and gas production facilities and roadside territories. The integrative analysis
suggests that areas of high anthropogenic pressure coincide with significant carbon stocks, warranting further
investigation into the interplay between pollution and carbon cycle feedbacks.

INTRODUCTION
The soil organic matter (SOM) pool is the largest carbon reservoir in terrestrial ecosystems and plays a
crucial role in the global carbon cycle. SOM is approximately 3.3 times larger than the atmospheric carbon
pool and 4.5 times larger than the biomass carbon pool of terrestrial ecosystems . Even minor changes in its
[1]
dynamics can significantly influence the concentration of climate-active gases in the atmosphere. In Russia
alone, the total annual CO emission into the atmosphere is estimated at approximately 2,500 million tons of
2
CO -equivalents , which corresponds to about 681 million tons of carbon (681 Mt C) .
[2]
[3]
2
The increasing concentration of climate-active gases in the atmosphere will further exacerbate climate
warming. In turn, climate warming may promote the release of soil carbon, creating a positive feedback loop
with global warming . Thus, SOM distribution and transformation have a major impact on the global
[4]
carbon balance and climate change. In this context, soils of the Polar Regions gain particular importance, as
they contain immense stocks of organic carbon in a sequestered form. Occupying about 15% of the total land
area, cryogenic soils contain, according to various estimates, 30-50% of global SOM stocks . Arctic climates
[5,6]
facilitated the long-term sequestration of organic matter. Soil carbon exists predominantly in an organic
form as part of SOM, and partially in an inorganic form as carbonates, constituting a complex
multifunctional system within the conglomerate of soil mineral particles . SOM is a system ranging from
[7]
coarse, solid organic particles 2-0.053 mm in size (Particulate Organic Matter, POM) to fine organic
substances associated with minerals smaller than 0.053 mm (Mineral-Associated Organic Matter, MAOM) .
[8]
SOM stocks and resistance to biodegradation depend on the combination of external and internal factors,
which determine not only its decomposition but also its stabilization . The key factors influencing SOM
[9]
stability are vegetation type and climate .
[10]
Currently, climate change in Polar Regions is exhibiting a faster warming trend than elsewhere in the
world . The rate of warming in the Arctic is 2-2.5 times higher than the global average . Arctic
[11]
[12]
temperature increases cause permafrost degradation, making large volumes of previously sequestered
organic matter vulnerable to microbial decomposition . This context places special emphasis on
[13]
quantifying carbon stocks in permafrost soils and carbon emissions from them. Studies conducted on Arctic
soils during freeze-thaw cycles show that CO emissions intensify after each thaw. For example, the ratio of
2
the average CO production rate before freezing to the average CO production rate after thawing ranged
2
2
from 0.85 to 0.89 for tundra soil, and the specific CO -C production rate (CO -C/SOM) was 0.16 in the study
2
2
by Ludwig (2006) [14,15] . Thus, permafrost degradation accompanied by the mobilization of previously
sequestered SOM can lead to its rapid mineralization and the release of climate-active gases . Directly or
[15]
indirectly related to the stocks and quality of SOM are soil resistance to external influences, the rate of
biogenic element cycling and nutrient balance, the sorption capacity of the soil absorbing complex, and the
efficiency of its remediation, the structure and biodiversity of the microbial communities . The most
[16]
sensitive characteristics of SOM are the kinetic parameters of its decomposition and mineralization .
[16]
Therefore, assessing SOM mineralization across different soil types in the polar regions and collecting data