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

摘要

The role of periglacial processes on soil carbon distribution is examined at a HighArctic site in northwest Greenland. A 16-m trench dug across a series of nonsorted stripesat Thule Air Base revealed sand-rich wedges underlying striped, vegetated troughs, andorganic-rich soil horizons buried at depth. The site has sparse prostrate vegetation and isestimated to contain 9.4 kg/m2 of soil organic carbon (SOC) in the active layer. Thedistribution of carbon is variable with nearly half (49%) stored in the sand wedges, whichonly account for 10% of the trench area. Additionally, 62% of the total SOC wasfound below 25 cm, highlighting the significant role of cryoturbation and physicalredistribution of carbon in permafrost-affected soils. Carbon in the active sand-rich wedgesdates from modern at the surface (65 ± 35 radiocarbon years) to 2695 ± 40 radiocarbonyears at depth, and carbon turnover time appears to be ,--,450 years. Buried organichorizons found at 50-70 cm depth have radiocarbon ages of 27,480-31,900 BP. Aconceptual 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 acold-based glacier. As the ice retreated and soils warmed, soil development and activecryoturbation resumed forming nonsorted stripes in the modern surface.