CARBON CYCLE - CLIMATE CHANGE FEEDBACKS IN LAKES IN ARCTIC ALASKA: THE ROLE OF DISSOLVED ORGANIC CARBON

There are large amounts of organic carbon stored in old peat lands in Arctic Alaska and held in the ground by continuous permafrost. Underneath Arctic lakes the frozen soils have high quantities of carbon reserves, almost twice the amount as in the atmosphere (Tarnocai et al., 2009). When the permafrost beneath the lakes thaws, the frozen carbon is exposed to microbial processes in the lake sediments that can release dissolved organic carbon (DOC) to overlying water and methane (CH₄) and carbon dioxide (CO₂) to the atmosphere. Permafrost thaw may also contribute to increased primary production in lakes via release of nitrogen and phosphorus to lakes. We are interested in studying the dissolved organic carbon (DOC) in lakes in Arctic Alaska over time, in order to see any changes in the input to and release of carbon from these lakes. The data we present here are from a field trip in August 2014 and represent the DOC concentration and carbon isotope ratios (δ¹³C) of 51 lakes in Arctic Alaska. DOC concentrations in lakes ranged from 1.8mg/L to 22.3 mg/L, with total dissolved nitrogen (TDN) concentrations ranging from 0.1 mg/L to 1.07mg/L. Stable isotopic composition of DOC is used to infer the proportion of autochthonous to allochthonous carbon in each lake, with possible correlation to lake temperature, latitude, and/or chlorophyll-a concentration.