Tuesday, June 5, 2007
434

Reaeration coefficient measurements using a modified propane injection method in western Kentucky streams

Hwa-Seong Jin1, James B. Ramsey2, George W. Kipphut2, and David S. White2. (1) University of Louisville, Department of Biology, Louisville, KY 40292, (2) Murray State University, Hancock Biological Station, 561 Emma Dr, Murray, KY 42071

Reaeration coefficient (k) is an important parameter in accurate estimation of whole-stream community metabolism. We used a modified propane injection method to estimate the k in 4 western Kentucky streams. We bubbled 99% propane gas into a 24 L carboy containing salt solution for 5 min, mixed by shaking, and released at a constant rate for 10-30 min into streams. Propane samples were taken at 3-4 downstream sites and analyzed using the Shimadzu GC 14 with a Flame Ionization Detector. The ratio between propane and background-corrected conductivity was plotted against the longitudinal travel time and stream distance to estimate k. This modified co-injection method resulted k values ranging from 7.7 to 24.4 per day with r2 ranging 0.62-0.96 in these streams. The k values obtained from the current method were consistently higher then the k estimated using the indirect energy dissipation model. We are confident that this modified co-injection method would result in very reliable k estimates for whole-stream metabolism studies while reducing overall time and efforts for measurements.

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