Consequences of gas flux model choice on the interpretation of metabolic balance across 15 lakes

AbstractEcosystem metabolism and the contribution of carbon dioxide from lakes to the atmosphere can be estimated from free-water gas measurements through the use of mass balance models, which rely on a gas transfer coefficient (k) to model gas exchange with the atmosphere. Theoretical and empirically based models of krange in complexity from wind-driven power functions to complex surface renewal models; however, model choice is rarely considered in most studies of lake metabolism. This study used high-frequency data from 15 lakes provided by the Global Lake Ecological Observatory Network (GLEON) to study how model choice of kinfluenced estimates of lake metabolism and gas exchange with the atmosphere. We tested 6 models of kon lakes chosen to span broad gradients in surface area and trophic states; a metabolism model was then fit to all 6 outputs of kdata. We found that hourly values for kwere substantially different between models and, at an annual scale, resulted in significantly different estimates of lake metabolism and gas exchange with the atmosphere.