Thawing of subsea permafrost can impact offshore infrastructure, affect coastal erosion, and release permafrost organic matter. Thawing is usually modeled as the result of heat transfer, although salt diffusion may play an important role in marine settings. To better quantify nearshore subsea permafrost thawing, we applied the CryoGRID2 heat diffusion model and coupled it to a salt diffusion model. We simulated coastline retreat and subsea permafrost evolution as it develops through successive stages of a thawing sequence at the Bykovsky Peninsula, Siberia. Sensitivity analyses for seawater salinity were performed to compare the results for the Bykovsky Peninsula with those of typical Arctic seawater. For the Bykovsky Peninsula, the modeled ice‐bearing permafrost table (IBPT) for ice‐rich sand and an erosion rate of 0.25 m/year was 16.7 m below the seabed 350 m offshore. The model outputs were compared to the IBPT depth estimated from coastline retreat and electrical resistivity surveys perpendicular to and crossing the shoreline of the Bykovsky Peninsula. The interpreted geoelectric data suggest that the IBPT dipped to 15–20 m below the seabed at 350 m offshore. Both results suggest that cold saline water forms beneath grounded ice and floating sea ice in shallow water, causing cryotic benthic temperatures. The freezing point depression produced by salt diffusion can delay or prevent ice formation in the sediment and enhance the IBPT degradation rate. Therefore, salt diffusion may facilitate the release of greenhouse gasses to the atmosphere and considerably affect the design of offshore and coastal infrastructure in subsea permafrost areas.

中文翻译：

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使用 CryoGRID2 模拟海底永久冻土中的热流和盐流

海底永久冻土的融化会影响近海基础设施，影响海岸侵蚀，并释放永久冻土有机物。尽管盐扩散在海洋环境中可能发挥重要作用，但解冻通常被建模为热传递的结果。为了更好地量化近岸海底永久冻土融化，我们应用了 CryoGRID2 热扩散模型并将其与盐扩散模型耦合。我们模拟了西伯利亚拜科夫斯基半岛的海岸线退缩和海底永久冻土的演变，因为它通过融化序列的连续阶段而发展。对海水盐度进行敏感性分析，以将拜科夫斯基半岛的结果与典型北极海水的结果进行比较。对于拜科夫斯基半岛，模拟的含冰永久冻土台 (IBPT) 为富含冰的沙子，侵蚀率为 0.25 m/年，位于离岸 350 m 海床以下 16.7 m。将模型输出与根据海岸线后退和垂直于及穿过拜科夫斯基半岛海岸线的电阻率测量估计的 IBPT 深度进行比较。解释的地电数据表明，IBPT 在离岸 350 m 处下降至海底以下 15-20 m。这两项结果都表明，冷盐水在浅水中的接地冰和漂浮海冰下方形成，导致低温海底温度。盐扩散产生的冰点降低可以延缓或阻止沉积物中冰的形成，提高IBPT的降解速率。因此，盐扩散可能会促进温室气体向大气的释放，并极大地影响海底永久冻土地区近海和沿海基础设施的设计。