Taliks, cryopegs, and permafrost dynamics related to channel migration, Colville River Delta, Alaska
Taliks, cryopegs, and permafrost dynamics related to channel migration, Colville River Delta, Alaska
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DOI：
10.1002/ppp.2046
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发表时间：
2020-03
影响因子：
5
通讯作者：
E. Stephani;J. Drage;D. Miller;B. Jones;M. Kanevskiy
中科院分区：
文献类型：
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作者：
E. Stephani;J. Drage;D. Miller;B. Jones;M. Kanevskiy
在北极三角洲已经观察到与通道迁移相关的冰冻和冰冻发育，但我们对冰冻的结构、性质和速率的了解仍然有限。沿着科尔维尔河三角洲（阿拉斯加）的主河道，我们将79个钻孔的地下数据与遥感分析相结合，以测量1948年至2013年的河道变化。研究发现，活动河道下存在封闭通道，并延伸至河床/河坝下的冻土层和活动洪泛平原下。Cryopegs作为孤立的小口袋也在较老的地形单元深处被发现。在研究走廊中，我们估计talk和cryopeg发生的可能性主要为低（42.2%的面积），但也确定了高可能性（27.0%的面积）。在河道迁移后暴露的土地上，多年冻土的增长速度很快，这可能是由于在盐度增加但温度降低的粗粒土壤中，冻结锋向下推进时，潜热的释放低且延迟。随着沉积物不断冷却，地面冰将继续形成，因此进一步增加了剩余未冻结土壤孔隙水的盐度，并可能阻止与河道迁移有关的冰冻层的完全冻结。
Talik and cryopeg development related to channel migration has been observed in arctic deltas, but our knowledge on the configuration, properties, and rate of freezeback has remained limited. Along a main channel of the Colville River Delta (Alaska), we integrated subsurface data from 79 boreholes with a remote sensing analysis to measure channel changes in 1948–2013. We found that closed taliks occurred under the active channel and extended into intrapermafrost cryopeg layers under the riverbed/riverbar and active floodplain. Cryopegs as isolated small pockets were also identified at depths in older terrain units. In the study corridor, we estimated that the likelihood of talik and cryopeg occurrence was predominantly (42.2% of area) low, yet a high likelihood was also identified (27.0% of area). Permafrost growth occurred at a rapid rate in the land exposed following channel migration, likely due to the low and delayed release of latent heat as the freezing front progresses downward in the coarse‐grained soils of increasing salinity but decreasing temperatures. As the deposits keep cooling, ground ice will continue forming therefore increasing furthermore the salinity of the remaining unfrozen soil pore‐water and likely prevent the complete freezeback of the cryopegs developed in relation to channel migration.