资源环境科技发展态势分析平台

Quantifying the unfrozen water content of permafrost is critical for assessing impacts of surface warming on the reactivation of groundwater flow and release of greenhouse gasses from degrading permafrost. Unfrozen water content was determined along an similar to 12-km transect in the Adventdalen valley in Svalbard, an area with continuous permafrost, using surface nuclear magnetic resonance and controlled source audio-magnetotelluric data. This combination of measurements allowed for differentiation of saline from fresh pore water, and frozen from unfrozen pore water. Above the limit of Holocene marine transgression, no unfrozen water was detected, associated with high electrical resistivity. Below the marine limit, within several kilometers of the coast, up to similar to 10% unfrozen water content was detected, associated with low resistivity values indicating saline pore water. These results provide evidence for unfrozen water within continuous, thick permafrost in coastal settings, which has implications for groundwater flow and greenhouse gas release in similar Arctic environments.

Plain Language Summary This manuscript presents the first study to combine two geophysical methods, controlled source audio-magnetotellurics and surface nuclear magnetic resonance, to quantify the unfrozen water content within a coastal permafrost environment. Quantifying the unfrozen water content of permafrost is critical for assessing impacts of surface warming on the reactivation of groundwater flow and release of greenhouse gasses from degrading permafrost. Measurements were collected along an similar to 12-km transect in the Adventdalen valley, in Svalbard at 78 degrees N. The combination of controlled source audio-magnetotellurics and surface nuclear magnetic resonance measurements allowed for the differentiation of saline from fresh pore water, and frozen from unfrozen pore water. Within several kilometers of the coast, up to similar to 10% unfrozen water content was detected; the unfrozen water was associated with low resistivity values indicating saline pore water. Further from the coast, above the limit of Holocene marine transgression, no unfrozen water was detected. The results from this study provide evidence for unfrozen water within continuous, thick permafrost in a coastal setting. Combining the results presented in this study with additional thermal and geochemical data will allow for the development of a full assessment of the ice-content and thermal state of permafrost in Adventdalen, Svalbard.