43. The Role of Lakes, Ponds, and Reservoirs in the Freshwater Carbon Budget

Lakes, ponds, and reservoirs (collectively “lakes”) are freshwater ecosystems that emit carbon dioxide and methane (C-gas) to the atmosphere while simultaneously storing organic carbon (OC) within buried sediments.  They exhibit this dual role primarily because of hydrologic inputs of terrestrial OC from their watersheds (Cole and others, 2007). Carbon cycling and flux in lakes is intense, commonly resulting in very high rates of C-gas emission and OC sediment deposition. Even though their global surface area is relatively small, lake OC storage likely exceeds oceanic sediment carbon storage (Dean and Gorham, 1998; Downing and others, 2008).  Although hypothesized to be closely linked, there is limited understanding of how C-gas emission and OC storage are coupled in lakes, especially those smaller than ~ 100 km2. This limits our ability to regionally quantify current carbon flux and storage in lakes, ponds and reservoirs and to project how lake carbon cycling might change in the future.  Although combined estimates of C-gas emission and OC sedimentation have been made for large natural lakes (Alin and Johnson, 2007), small water bodies comprise most of the global freshwater surface area and exhibit the most intense rates of carbon cycling. In these smaller lakes, C-gas emission and OC sedimentation rates are believed to be inversely proportional to lake size, but accurate syntheses of relationships between lake carbon cycling processes and lake size or geographic setting do not exist. Small water bodies are very numerous and diverse and relevant carbon data for them are diffusely disseminated because they were typically collected by different scientific disciplines for different purposes. Consequently, the role of small lakes in the carbon cycle and their related responses to climate or land use changes are not well quantified. 

This Mendenhall Research Opportunity is focused on the study of carbon dynamics of small lakes, ponds, and reservoirs towards explicitly quantifying their importance in regional to global carbon budgets.  An improved understanding of lake carbon flux and storage will be gained by critically evaluating existing data from USGS and other data sources to relate lake carbon dynamics to easily quantifiable properties such as lake size, watershed characteristics, climate, and hydrogeologic setting. This insight will then be used to quantify the role of small lakes in regional carbon budgets and their responses to climate and land use change.  This research problem will be addressed by applying principles of limnology, biogeochemistry, hydrology, and sediment geochemistry. 

Current estimates of lake carbon burial and carbon gas emissions from freshwater ecosystems are based on first-order assumptions that minimize the importance of hydrogeologic setting, climate, and watershed characteristics on carbon cycling (Cole and others, 2007; Dean and Gorham, 1998).  We invite research proposals that relate carbon flux and storage of small lakes to other easily quantifiable lake properties.  The increased understanding of carbon dynamics is then to be used to develop more detailed estimates of carbon burial and gas emissions from small lakes in the United States and their projected responses to change.  Proposals could explore utilizing existing data in new and innovative ways, field based studies, remotely sensed analyses, or combined strategies.

The successful candidate will have access to ongoing USGS studies at the Loch Vale and Trout Lake Water, Energy and Biogeochemical Budgets (WEBB) project sites in Colorado and Wisconsin; USGS research sites in the Upper Colorado River basin, the Yukon River basin, and northern Minnesota; and to USGS lake databases from throughout the USA. 

References

Alin, S. R., and Johnson, T.C., 2007, Carbon cycling in large lakes of the world: A synthesis of production, burial, and lake-atmosphere exchange estimates: Global Biogeochemical Cycles, v. 21, GB3002, doi:10.1029/2006GB002881.

Cole, J.J., Prairie, Y.T., Caraco, N.F., McDowell, W.H., Tranvik, L.J., Striegl, R.G., Duarte, C.M., Kortelainen, P., Downing, J.A., Middleburg, J.J., and Melack, J., 2007, Plumbing the global carbon cycle: Integrating inland waters into the terrestrial carbon budget: Ecosystems, v. 10, no. 1, p. 172–185. DOI: 10.1007/s10021-006-9013-8.

Dean, W. E., and Gorham, E., 1998, Magnitude and significance of carbon burial in lakes, reservoirs, and peatlands: Geology, v. 26, p. 535–538.

Downing, J.A., Cole, J. J., Middelburg, J.J., Striegl, R.G., Duarte, C.M., Kortelainen, P., Prairie, Y.T., and Laube, K.A., 2008, Sediment organic carbon burial in agriculturally eutrophic impoundments over the last century: Global Biogeochemical Cycles, v. 22, GB1018, doi:10.1029/2006GB002854.

Proposed Duty Station: Boulder, CO; Denver, CO

Areas of Ph.D.: Hydrology, geochemistry, biogeochemistry, geology, limnology

Qualifications: Applicants must meet one of the following qualifications: Research Hydrologist, Soil Scientist, Research Chemist, Research Geologist, Research Ecologist, Research Physical Scientist

(This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the Human Resources specialist.)

Research Advisor(s): Robert Striegl, (303) 236-4993, rstriegl@usgs.gov; David Clow, (303) 236-4882, x-294, dwclow@usgs.gov; Randy Hunt, (608) 821-3847, rjhunt@usgs.gov; Lesleigh Anderson, (303) 236-1296, land@usgs.gov

Human Resources Office contact: Vanessa Chambless, (303) 236-9584, vchambless@usgs.gov

Summary of Opportunities