The study investigates the impact of frazil ice on biogeochemical processes in the Lena River during winter. It highlights how frazil ice formation creates microzones that extend reaction times for solutes, leading to significant changes in silicon isotope composition and Ge/Si ratios. These microzones facilitate microbially mediated biogeochemical processes, particularly nitrogen cycling, under ice-covered conditions. The research underscores the potential implications of climate change, as shorter river ice durations could alter nutrient processing and greenhouse gas emissions in Arctic river systems.

Laboratory incubations of permafrost, lake, and lagoon sediments from the Bykovsky Peninsula show that salinity shifts initially suppress microbial greenhouse gas production due to limited salt-adapted communities. Over longer timescales, establishment of sulfate-reducing bacteria leads to an eightfold increase in CO₂ production compared to thawed terrestrial permafrost. Methane generation remains limited except under conditions favorable to methanogens, particularly in nearly closed lagoons. Greenhouse gas production peaks under near-natural salinity conditions, with fully marine conditions producing the least, reflecting incomplete microbial adaptation. Expanding thermokarst lagoon formation driven by coastal erosion and sea-level rise is likely to amplify coastal carbon mineralization and CO₂ emissions in Arctic permafrost regions.

Synthesizes recent observational and modeling advances on submarine permafrost across the Arctic, highlighting its distribution, degradation rates, and interaction with coastal processes, groundwater flow, and warming seas. Describes uncertainties in methane sources and pathways, noting varied regional thaw dynamics influenced by temperature, salinity, sediment properties, and glacial history. Reviews geophysical techniques improving detection of permafrost boundaries and emphasizes the need for expanded field measurements to better assess greenhouse gas fluxes and long-term permafrost evolution.