Federal University of Viçosa, PH Rolfs Avenue, s/n, Department of Soil, Center, 36570-000 Viçosa, MG, Brazil.
Federal University of Pampa, Antônio Trilha Avenue, 1847, Vila Camita, 97300-162 São Gabriel, RS, Brazil.
An Acad Bras Cienc. 2023 Aug 14;95(suppl 3):e20210692. doi: 10.1590/0001-3765202320210692. eCollection 2023.
Active layer and permafrost are important indicators of climate changes in periglacial areas of Antarctica, and the soil thermal regime of Maritime Antarctica is sensitive to the current warming trend. This research aimed to characterize the active layer thermal regime of a patterned ground located at an upper marine terrace in Half Moon Island, during 2015-2018. Temperature and moisture sensors were installed at different soil depths, combined with air temperature, collecting hourly data. Statistical analysis was applied to describe the soil thermal regime and estimate active layer thickness. The thermal regime of the studied soil was typical of periglacial environment, with high variability in temperature and water content in the summer, resulting in frequent freeze-thaw cycles. We detected dominant freezing conditions, whereas soil temperatures increased, and the period of high soil moisture content lasted longer over the years. Active layer thickness varied between the years, reaching a maximum depth in 2018. Permafrost degradation affects soil drainage and triggers erosion in the upper marine terrace, where permafrost occurrence is unlikely. Longer monitoring periods are necessary for a detailed understanding on how current climatic and geomorphic conditions affect the unstable permafrost of low-lying areas of Antarctica (marine terraces).
活动层和多年冻土是南极冰缘地区气候变化的重要指标，而南极洲海洋区的土壤热状况对当前的变暖趋势非常敏感。本研究旨在描述 2015-2018 年期间位于半月岛海洋上层阶地上的地貌区的活动层热状况。在不同的土壤深度安装了温度和湿度传感器，并与空气温度相结合，每小时收集一次数据。统计分析用于描述土壤热状况并估计活动层厚度。研究土壤的热状况是典型的冰缘环境，夏季温度和水分变化很大，导致频繁的冻融循环。我们检测到主要的冻结条件，而土壤温度升高，多年冻土的高土壤湿度期持续时间更长。活动层厚度在不同年份有所变化，2018 年达到最大深度。多年冻土的退化影响土壤排水，并引发上层阶地的侵蚀，而在这些地方多年冻土不太可能存在。需要更长的监测期来详细了解当前的气候和地貌条件如何影响南极洲（海洋阶地）低洼地区不稳定的多年冻土。
