Spatial and temporal distribution of soil organic carbon in nonsorted striped patterned ground of the High Arctic

摘要

The role of periglacial processes on soil carbon distribution is examined at a High Arctic site in northwest Greenland. A 16-m trench dug across a series of nonsorted stripes at Thule Air Base revealed sand-rich wedges underlying striped, vegetated troughs, and organic-rich soil horizons buried at depth. The site has sparse prostrate vegetation and is estimated to contain 9.4 kg/m2 of soil organic carbon (SOC) in the active layer. The distribution of carbon is variable with nearly half (49%) stored in the sand wedges, which only account for 10% of the trench area. Additionally, 62% of the total SOC was found below 25 cm, highlighting the significant role of cryoturbation and physical redistribution of carbon in permafrost-affected soils. Carbon in the active sand-rich wedges dates from modern at the surface (65 ± 35 radiocarbon years) to 2695 ± 40 radiocarbon years at depth, and carbon turnover time appears to be ～450 years. Buried organic horizons found at 50–70 cm depth have radiocarbon ages of 27,480–31,900 BP. A conceptual model is proposed in which the active sand wedges have developed in an approximately 30 ka surface containing buried soils preserved in permafrost or under a cold-based glacier. As the ice retreated and soils warmed, soil development and active cryoturbation resumed forming nonsorted stripes in the modern surface.