Technique

When taking samples we used a bucket and string to get water, which was then placed into storage bottles until testing was done. Temperature was taken at the sampling location with a Vernier CBL and temperature probe, and also with a standard thermometer. The pH was taken in the lab with a Vernier Ph probe using a Macintosh computer and Data Logger. The conductivity was taken in the lab with a Vernier conductivity probe, also using the computer set up. When doing nitrate analysis we first filtered the sample using a .45 micron filter attached to a 30 ml syringe. An InQuest Nitrate FS test kit was used to add color to the sample. After this was done, 3 ml of distilled water was added, and the sample was put into a Spec 20 colorimeter. The colorimetric analysis was used to find a y value (absorbency), which was then put into the equation y=.022655x+.018. This equation was used to find the concentration of the nitrates in the sample. This equation was derived by making nitrate stock solutions of known concentration (1-10 ppm) and then graphing the absorbency values obtained (using Graphical Analysis on a Macintosh computer). During earlier tests done on the creek, a Vernier colorimeter was used to obtain the y value for the equation, which was also different due to different stock solutions. The data obtained from these tests is included although the nitrate levels are significantly higher. The drastic between the two sets of data is contributed largely to the equipment used, poor stock solutions, and learning the process of sample collection, equipment use, and lab technique. This first set of data was collected by Andy Aley during an independent study course, and is presented only to illustrate the differences in equipment, stock solutions, and technique.