Dissolved Organic Carbon (DOC) in Ground Ice: Is It Significant?

摘要

Permafrost soils are believed to hold approximately 50% of the global soil carbon pool [Tarnocai et al. 2009], mostly as particulate organic carbon (POC). In the Arctic coastal lowlands of Eurasia and North America ground ice can occupy a large proportion of the soil volume. Calculations of permafrost organic C stocks usually substract the ground ice content [Zimov et al. 2006; Tarnocai et al. 2009] and therefore disregard the organic carbon, especially the amount of dissolved organic carbon (DOC) contained in massive ground ice bodies such as ice wedges and buried glacier ice. Although these numbers might be small compared to the POC stocks in peat and mineral soils, DOC is chemically labile and may directly enter local food webs. Due to its liability DOC is quickly mineralized and returned to the atmosphere when released due to permafrost degradation. Here, we present the first results of a permafrost study on DOC in ground ice. We report DOC contents from different massive ground ice types, put them into context of the Arctic organic carbon pools and fluxes, and evaluate their contribution to the Arctic carbon budget against the background of increasing permafrost degradation and enhancing coastal erosion in the future.