Measurements of Cayuga Lake Production
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This study aims to compare estimates of primary productivity in Cayuga Lake based on in situ measurements of dissolved carbon dioxide (CO2) and dissolved oxygen (DO). Historically, productivity was estimated using the light/dark bottle method. More recent procedures have used in situ DO measurements. However, DO is a by-product of production. Directly using CO2 to determine productivity could offer a faster and more accurate result. Four locations at the southern end of Cayuga Lake were sampled between July 3, 2012 and October 9, 2012. Free aqueous CO2 was measured using an OxyGuard Dissolved CO2 meter. Citric acid was added to the water sample to lower the pH to the range of 3-4, so that most of the inorganic carbon would be in the CO2 form. Additionally, DO readings were taken using a Hydrolab DS 5. Average diel differences in CO2 and DO were found at each of the four sampling sites. To evaluate production, diel DO concentrations were corrected for atmospheric diffusion. In addition, diel CO2 differences were assumed to be adequate measures of production. Direct ambient CO2 concentration differences were found to have a strong, linear relationship with net ecosystem production.
Cayuga Lake; production