加拿大贝德福德海洋研究所Normandeau, Alexandre团队的最新研究，报道了加拿大亚北极地区海底永久冻土层与海底地下水排放有关的证据。2024年8月5日出版的《自然—地球科学》发表了这项成果。

研究人员展示了在拉布拉多沿岸流的影响下，拉布拉多海岸(56°N)存在不连续的海底永久冻土带。高分辨率测深数据显示，加拿大努纳茨亚武特的内恩沿海海底存在海底热岩溶环境，并于2022年7月在水深27m处采集了富含冰的沉积物样本。孔隙水分析表明，由于新鲜的海底地下水渗流在比海水(-1.8°C)更高的温度(0°C)下冻结，地面冰可以持续存在于沉积物中。

海底永久冻土地貌的形成和保存是由于拉布拉多沿岸流的冷水，进入沿海地区并在一年中大部分时间里保持低于0°C。因此，拉布拉多沿海海底永久冻土地貌的证据和北半球底部冷水的分布表明，海底永久冻土可能在亚北极地区的其他地方被保存下来，特别是在新鲜的海底地下水渗流提高了冰点温度的地方。这凸显了对世界沿海海洋海底永久冻土的潜在低估。

据介绍，海底永久冻土的分布和状态在很大程度上是未知的。目前的地图在很大程度上依赖于模型结果，表明海底永久冻土仅限于波弗特海、西伯利亚海和拉普捷夫海。

附：英文原文

Title: Evidence for subsea permafrost in subarctic Canada linked to submarine groundwater discharge

Author: Normandeau, Alexandre, Eamer, Jordan B. R., Way, Robert G., Harrison, Emma J., Cyr, Frdric, Algar, Christopher K., Eamer, Jennifer L., Geizer, Haley D., Haddock, Jessica, Kurylyk, Barret L., Van Nieuwenhove, Nicolas, Pijogge, Liz, Philibert, Genevive, Robert, Katleen, Saunders, Michelle, Tamborski, Joseph, Limoges, Audrey

Issue&Volume: 2024-08-05

Abstract: The distribution and state of subsea permafrost is largely unknown. Present maps, which rely heavily on model results, suggest that subsea permafrost is confined to the Beaufort, Siberian and Laptev seas. Here we show that discontinuous subsea permafrost exists along the Labrador coast (56°N) under the influence of the Labrador Coastal Current. High-resolution bathymetric data reveal the presence of subsea thermokarst environments on the coastal seabed of Nain, Nunatsiavut, where an ice-rich sediment sample was recovered in July 2022 at a water depth of 27m. Porewater analysis indicates that ground ice can persist in the sediments due to freshened submarine groundwater seepage that freezes at higher temperatures (0°C) than seawater (-1.8°C). The formation and preservation of subsea permafrost landforms is due to cold waters of the Labrador Coastal Current entering the coastal areas and remaining less than 0°C for most of the year. Therefore, evidence of subsea permafrost landforms in coastal Labrador and the distribution of cold bottom water in the Northern Hemisphere suggests that subsea permafrost is likely to be preserved elsewhere in subarctic regions, especially where freshened submarine groundwater seepage elevates the freezing temperature. This highlights the potential underestimation of subsea permafrost in the world’s coastal oceans.

DOI: 10.1038/s41561-024-01497-z

Source: https://www.nature.com/articles/s41561-024-01497-z