Established empirical equations of K DO using stream characteristics did a poor job predicting K DO for both creeks. In Martis Creek, K Xe was slightly higher (21%) than K SF6, but the calculated K DO from SF 6 agreed with the calculated K DO from Xe within about 15% this difference may be due to bubble-enhanced gas transfer. Mean K SF6 for upper and lower Sagehen and Martis Creeks were, respectively, 34 day −1, 37 day −1 and 33 day −1, with corresponding K DOs of 61 day −1, 66 day −1 and 47 day −1. Measuring gas loss along the creek, which was approximated with the one-dimensional advection-dispersion equation, allows for the estimation of the SF 6 or Xe reaeration coefficient ( K SF6, K Xe), which is converted to DO reaeration ( K DO or K 2) using Schmidt numbers. Two continuous release experiments were conducted in different creeks in the Sierra Nevada of California: Sagehen Creek in September, 2009, using SF 6 and Martis Creek in August, 2012, using both SF 6 and Xe. Oxygen reaeration rates can be accurately measured using deliberate gas tracers, like sulfur hexafluoride (SF 6) or xenon (Xe).
Gas exchange across the air-water interface is a critical process that maintains adequate dissolved oxygen (DO) in the water column to support life.
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