Figure 5.Example titration curves of four theoretical titration curves and measured data from the Link River to Keno Dam reach of the Klamath River, Oregon. DOC, dissolved organic carbon. (A) In this sample at Miller Island July 17, 2007, alkalinity was 52.8 mg/L as CaCO₃, ammonia concentration was 1.1 mg/L as N, phosphate concentration was 0.171 mg/L, and DOC concentration was 11.1 mg/L. Ammonia had a visible effect on the theoretical titration curve, but organic matter was important in capturing the shape of the measured curve. (B) In this sample at Link River August 14, 2007, alkalinity was 44.2 mg/L as CaCO₃, ammonia concentration was 0.068 mg/L as N, phosphate concentration was 0.104 mg/L, and DOC concentration was 11.4 mg/L. Ammonia had little effect on the shape of the curve because the ammonia concentration was low, but organic matter was important to the shape of the titration curve. (C) In this sample at Keno August 14, 2007, alkalinity was 65.2 mg/L as CaCO₃, ammonia concentration was 1.01 mg/L as N, phosphate concentration was 0.165 mg/L, and the DOC concentration was 12.5 mg/L. Because the sample pH was less than 8.0, ammonia and organic matter had little effect on the high end of the titration curve, but organic matter had a slight effect on the lower part of the curve.

First posted March 1, 2013