I've been looking at some journals lately that look at carbon emission from lakes where some lakes act as sources and other act as sinks. The paper that I have been looking at is
http://www3.nd.edu/~underc/east/publications/documents/Cole_94Science.pdf
where they show that lakes are sources of CO2 to the atmosphere. What are the equations that are used to determine the saturation of CO2 in surface waters?
The recent IPCC report also mentions that lakes act as sources of CO2 but does not give any indication of the equations used to come up with these values. Presumably, to determine the concentration of carbon in the surface water you need to use other measured variables such as temperature. Can anyone suggest a method for estimating this concentration ?