Dissolved Oxygen in Tecolote Canyon Streams

Recently an Environmental Chemistry class at the University of San Diego went out to Tecolote Canyon to do some field research on the streams that run through the canyon. One of the points of research was to measure the dissolved oxygen content of the water there. Based off a few field trials, the dissolved oxygen content from the entire stream was around 5.504 ppm. Individual samples of the surface stream water were extracted for further analysis in the lab, and they recorded slightly higher dissolved oxygen content of 6.563 ppm.

What do these numbers mean? If you look at the chart at the bottom of this post, you can see what the ranges of dissolved oxygen mean. Both samples suggest that the stream has enough oxygen present to support fish life.  The surface water samples have a bit higher oxygen content because it is easier to have the oxygen in the air enter into a dissolved state in the water.

            Using equations, you can calculate the optimal dissolved oxygen content for a body of water at a given temperature. For this stream’s temperature, the dissolved oxygen should be around 10.41 ppm. Dissolved oxygen is affected by the following: movement of the water, the temperature, the organisms present, the altitude, and organic wastes. Since the recorded values of dissolved oxygen are lower than the calculated values, some of the factors aside from temperature that the equation accounts for are likely affecting the levels in Tecolote Canyon.