Lake – Atmosphere CO2 Exchange

Carbon is the energy currency of ecosystems.  Understanding the dynamics of CO2 and the mechanisms that regulate these dynamics provides insight into how an ecosystem gains and loses energy.  It also improves our knowledge of how lakes contribute to the global carbon budget.  We have developed an automated CO2 monitoring system that we deploy on buoys in Lake Michigan.  The system is designed to make hourly measurements of pCO2 in surface water and the atmosphere above the lake.  A similar system is deployed on the Lake Express high-speed ferry, which makes several round trips per day between the western and eastern shores of Lake Michigan from May through October.  The data from these systems is being used to study the effect of invasive dreissenid mussels on nearshore ecosystem metabolism and the degree to which whole-lake metabolism responds to inter-annual difference in weather conditions.  A parallel study has been conducted on Lake Malawi, where Maxon Ngochera was able to show that this lake is a net sink for atmospheric CO2.

 

The high-speed Lake Express ferry, on which we have installed a continuous monitoring system that measures CO2, O2, temperature and phytoplankton fluorescence.

An example of a cross-lake CO2 transect, illustrating spatial and diurnal variability.