There’s carbon buried in Falls Lake: Where did it come from? (2023)
Undergraduate: Laura Flynn
Faculty Advisor: Brent McKee
Department: EMES
Over the past two years, the McKee Lab in EMES have documented that reservoirs are sites of high rates of organic carbon accumulation. These rates are equivalent to those found in Coastal Blue Carbon environments (saltmarsh, seagrass, and mangrove). Blue Carbon environments are reported to have average carbon accumulation rates of 125g C m-2 yr-1 and are thought to be the dominant natural sink for atmospheric CO2. Based on preliminary data from a dozen cores in local reservoirs (Falls Lake), reservoirs accumulate over 200 g C m-2 yr-1 and since there are over half a million in the world, reservoirs may be an important natural sink for atmospheric carbon. The methods for this project was collecting suspended particulates from rivers and streams that enter Falls Lake (4 primary streams that add up to 80% of input). Samples were collected for stable isotope analyses to find that much of the accumulation in Falls lake came from soil organic matter. To find that soil organic matter was a large component in this research, C:N, ∂ 13C, and ∂ 15N ratios were used to distinguish organic matter sources between river and stream inputs (SOM) and in situ algae production (FWA). This research found that fresh water algae was in the water column samples, but only soil organic matter was buried in sediments.
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