Periglacial slopewash dominated by solute transfers and subsurface erosion on a High Arctic slope

Abstract

AbstractArctic slope hydrology studies suggest that water follows preferential subsurface flow paths known as water tracks. While subsurface flow is usually expected to transport only dissolved solids, periglacial studies have indicated some evidence of lessivage associated with flow through sorted patterned ground. We investigated the transport of dissolved and suspended sediments in water tracks on a polar desert slope, and linked this transport to slope and flow path geomorphology. Solute transfer was dominated by carbonate weathering products, and concentrations of other ions increased disproportionately when the active layer thawed. Suspended sediment transport occurred in water tracks, but fluxes were supply‐limited, indicating competent subsurface mechanical erosion. Solute mass fluxes were 5–10 times greater than sediment fluxes. In this dry landscape dominated by snowmelt, surface seepage leads to sediment deposition, while subsurface flow promotes lessivage. A conceptual model of nivation slopes is presented, taking into consideration the influence of flow path morphology and adaptation of the hydrological system to localized water sources from wind‐drifted snowbanks. Climate‐driven permafrost degradation and the increased frequency of rainfall events may result in new sediment sources and changes in flow pathways, modifying the physico‐chemical properties and ecology of downstream receiving waters.