Source or sink? Integrating biogeochemical, trophic, and landscape processes to model lake carbon budgets

FACUNDO SCORDO; KAITLIN J. FARRELL; IAN MCCULLOUGH; ANA MORALES-WILLIAMS; DEREK ROBERTS; ZUTAO OUYANG; HILARY DUGAN; PAUL HANSON; SARAH BARTLETT; SAMANTHA BURKE; JONATHAN DOUBEK; FLORA E. KRIVAK-TETLEY; NICHOLAS SKAFF; JAMIE SUMMERS; GRACE HONG; KATHLEEN WEATHERS

Lunz

Workshop; GLEON 18 Lunz & Gaming, Austria; 2016

Global Lake Ecological Observatory Network - WasserCluster Lunz Biologische Station GmbH, Austria - University of Vienna - University of Innsbruck - U.S. National Science Foundation

For years, the role of inland waters in global carbon budgets has been largely ignored, and only relatively recently has it been recognized that lakes actively process rather than simply transport terrestrially-derived organic carbon (OC). This recognition has brought forward the larger question: are lakes sources or sinks of OC? To date, most studies that have modeled OC budgets (i.e., mass balances) have focused on a single lake over a relatively short time period. Further, few effectively incorporated the full suite of ecologically relevant drivers of OC, which include surface and groundwater inflows, sedimentation, and net primary production. We are developing a dynamic, process-based OC mass balance model that incorporates these processes and applying it to six well-studied lakes in the United States, Canada, and Sweden. Our focal lakes vary widely in climate, productivity, morphometry, hydrology, and watershed composition, which permit us to ask the broad question: how do lake carbon budgets change along environmental gradients? Although model results are preliminary, we have found that lakes fluctuate as net OC sources and sinks and that the overall carbon budgets of some lakes appear more stable than others. Ongoing work will continue to investigate 1) principal drivers of OC budgets across these six lakes, 2) the sensitivity of key drivers to climate and land use changes, and 3) how these six case studies can be used to advance our knowledge of the broader role of lakes in global OC cycling.