TOTAL PHOSPHATE

A measure of the total amount of Phosphate in the river. Phosphate is the most important factor in the cultural eutrophication of rivers and streams throughout the world. Phosphate exists in several forms, of which only orthophosphate is available to living organisms. However the other forms can be transformed into orthophosphate in lakes and streams, so that total phosphate gives an estimate of the total amount of phosphate potentially available.

INSTRUCTIONS FOR USING TEST KIT:

*Before testing for total phosphate, carry out the orthophosphate test. Not only will your results in the orthophosphate test advise you if you need to dilute your sample prior to running the much more difficult total phosphate test, it also provides a minimum estimate of the value. Total phosphate concentration cannot be lower than orthophosphate. Therefore, if you obtain a lower total phosphate number than orthophosphate, you should discard the total phosphate value and use the orthophosphate.

1. Fill one square mixing bottle to the 20 ml mark. Pour the sample into a clean 50 ml Erlenmeyer flask.

2. Add one Hach Potassium Sulphate powder pillow to the sample. Swirl to mix.

3. Add 2 ml 5.25N sulfuric acid to the mix, using the dropper provided. It is calibrated to 1.0 ml, so that filling it twice to this mark will provide 2.0 ml.

4. Heat the mixture to boiling, and boil it for 30 minutes. Maintain the total amount of water at a constant level of approximately 20 ml by adding demineralized water when necessary. Note that heat tabs are provided in the Hach kit, but these are quite unsatisfactory. A backpacking stove, preferably one that uses propane or butane, works much better. At the end of the 30 minute boiling period, the total amount of water in the flask should be just under 20 ml. Allow the mixture to cool.

5. Add 2 ml of 5N sodium hydroxide solution to the mixture. Again, use a dropper calibrated to 1.0 ml as in step 3.

6. Return the sample to the square mixing bottle. Add just enough demineralized water to bring the sample to a volume of 20 ml.

7. Perform the orthophosphate test on the sample. See the orthophosphate sheets for complete instructions.

QUESTIONS TO THINK ABOUT:

Is your level higher than 1 mg/l, or much lower than this?

Is your total Phosphate test much higher than your orthophosphate test? If so, why might this be?

EFFECTS OF TOO MUCH PHOSPHORUS

• Promotes algal growth(blooms)
• You get lots of pond scum
• Anaerobic conditions can be created in the water (check your dissolved oxygen test)
• The river begins to smell
• Water and aquatic life quality decreases.
• River recreation use decreases.

WHY YOU HAVE TOO MUCH:

• Is the area rural?
• How do rural people dispose of sewage?
• Are there septic tanks in the area that can leak?
• How efficient is the sewage plant?
• Are there any chemical plants upstream?
• Has there been recent development and stripping of topsoil?
• Are people draining wetlands in the watershed?
• Is the area highly industrialized?
• Is the river slow-moving at this site?
• Has the area lost population recently?
• How much vegetation is present?

Is there a relationship between high phosphorous levels in the river and the problems present in Lake Erie?

*TRY TO PINPOINT WHY YOU HAVE A PROBLEM, AND IDENTIFY THE PEOPLE YOU NEED TO SPEAK TO.

*Click here to return to the Water Quality Index Menu

*Click here to return to the NORP Main Menu