Materials

Phosphate test kit Bottle with closeable lid Data Collection Student Worksheet (optional)

Background Information
Phosphorus is usually present in natural waters as phosphate. Phosphates are present in fertilizers and laundry detergents and can enter the water from agricultural runoff, industrial waste, and sewage discharge. Phosphates, like nitrates, are plant nutrients. When too much phosphate enters the water, plant growth flourishes.

Phosphates also stimulate the growth of algae which can result in an algae bloom. Algae blooms are easily recognized as layers of green slime, and can eventually cover the water's surface. As the plants and algae grow, they choke out other organisms. These large plant populations produce oxygen in the upper layers of the water but when the plants die and fall to the bottom, they are decomposed by bacteria which use a lot of the dissolved oxygen (DO) in the lower layers. Bodies of water with high levels of phosphates usually have high Biological Oxygen Demand (BOD) levels due to the bacteria consuming the organic plant waste and subsequent low DO levels.

Test Procedure

Prior to the test, all vials or test tubes used must be extremely clean, preferably rinsed with distilled or demineralized water.   Take out the phosphate test kit. Closely follow the instructions provided with the kit.   When recording your results for this project, phosphate measurements should be reported in ppm.

What to Expect

Phosphate Level (in ppm)	Water Quality
0.0 - 1.0	Excellent
1.1 - 4.0	Good
4.1 - 9.9	Fair
10.0 or greater	Poor

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