Bioavailability of Leachable Dissolved Organic Carbon from Subnival Soils

Over the past few decades, freshwater streams in the North Eastern U.S. have seen significant changes in concentrations of Dissolved Organic Carbon (DOC). During this same time, forested catchments in the North Eastern U.S. have experienced increases in pH as these systems have begun to recover from acid rain deposition and a connection between recovery and DOC dynamics seems likely. Because in snow-dominated systems snowmelt constitutes a very significant hydrologic event that can flush DOC from soils into streams, winter processes must be studied carefully. We hypothesize that during the wintertime, the cold temperatures limit subnival (under snowpack) microbial activity, allowing soils to accumulate large amounts of organic material that is available for flushing. We also hypothesize that these materials will be very biodegradable as soon as it enters the stream. To test these hypotheses we sampled subnival soil cores from Sleepers River Research Watershed in Northeastern Vermont and leached the soils with several types of solution of varying ionic strength and pH. We also incubated each set of samples to quantify biodegradability. Results from these experiments will provide useful information on the mechanism of DOC liberation during recovery form acidification and biodegradability of soil-derived DOC during winter times