Nutrient limitations in Texas watersheds
Work has been done to develop techniques to undertake a limiting nutrient determination study. Techniques are as follows: 1. The high turbidity levels found in Texas river waters has an adverse effect on the reproducibility of the primary productivity results using standard carbon 14 nutrient uptake techniques. This was shown to be true on unfiltered samples using naturally occurring phytoplankton as well as for autoclaved samples inoculated with a monoculture. 2. Good reproducibility using the carbon 14 technique could be obtained by first filtering the river water samples through a roughing filter made of glass wool followed by a 0.45 micron membrane filter to remove the turbidity. However, because the membrane filter would also remove the natural algal culture the sample must be reinnoculated before testing. 3. The differential organic carbon technique (DOC) that was developed during this study and outlined in Chapter IV has a number of advantages over the carbon 14 method. These advantages include: a) the ability to utilize unfiltered samples, b) the use of naturally occurring algal cultures, c) the method is less time consuming. The study also contains conclusions that can be developed based on the work specifically directed toward the Trinity River Basin.