Updates from WHRC Research Trek to the Yukon River Ice Break
Over half of the world's soil organic carbon is stored in arctic watersheds. The majority of this carbon is held in permafrost, which is perennially frozen ground. As northern climates warm, permafrost is beginning to thaw, deepening the soil active layer and making the stored carbon available for decomposition to greenhouse gases or for transport downstream. Rivers draining Arctic watersheds carry large amounts of this carbon to the ocean, especially during the spring flood that follows ice melt. This is also a time of year when the quality of river carbon changes due to increased overland flow and flushing of the organic rich-layers in soils. This freshly transported terrestrial carbon tends to be very reactive and can be a high quality food source for aquatic micro-organisms in streams and rivers, as well as in the estuaries that receive the flood water.
Assistant Scientist Robert Spencer, in conjunction with colleagues from the US Geological Survey, is currently at the mouth of the Yukon River Basin (Alaska) quantifying how important the spring ice break-up period is with respect to carbon export from land to ocean and also assessing the reactivity of this material. This is fundamental if we are to understand the fate of this carbon, its role as a food source for aquatic communities, and how rapidly it is respired to carbon dioxide and methane and returned to the atmosphere. This respiration of carbon back to the atmosphere may have positive feedback effects that result in further warming, thawing, and mobilization of the soil carbon stocks in permafrost.
Dr. Spencer's colleague from USGS, Mark Dornblaser, works in their makeshift laboratory.