Circulation, Metabolism, and Greenhouse Gas Emissions from Arctic Lakes and Ponds

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The goals of the proposed research are to examine biological, chemical, and physical conditions in ice-covered Arctic lakes and the associated changes in dissolved gases by analyzing data obtained from five lakes over three years. The data will be used to 1) determine circulation and the resulting habitat for organisms living under the ice, and 2) how biological and physical processes interact to cause a loss of oxygen and the production of greenhouse gases. Despite the importance of mixing within lakes for maintaining healthy habitats, few scientists are trained in lake physics in the United States. This project will provide such training for a postdoctoral scholar. Arctic lakes are ice-covered for nine or more months of the year. With harsh winter conditions, few limnological studies have been conducted on ice-covered arctic lakes. The goal of the proposed research is to analyze an unprecedented dataset obtained from five lakes of different sizes from fall to spring over three years. The data will be used to describe and quantify the lakes' physical limnology and under ice metabolism and to develop scaling laws such that regional generalizations can be made. Analyses and modeling will focus on questions related to the extent to which fall cooling moderates under ice temperatures and circulation; the contribution of respiration and related increases in solutes to circulation patterns and development of anoxia; lake-size dependent controls on the retention of solutes introduced at snowmelt; and lake-size dependent controls on mixing dynamics, which moderate production of CO2 and CH4 in winter and emissions at ice off. Results will provide a basic understanding of circulation and mixing as needed to improve hydrodynamic models and are critical for quantifying the habitat of organisms under the ice and for accurate inclusion of arctic lakes in regional carbon budgets.