Title: Water Testing - Phosphorus

Overview- Presentation to students

Phosphorus is very important to aquatic ecosystems; however systems with too much phosphorus can spur the growth of large numbers of algae and other plants. When these plants die they are in such large numbers that they use up all of the available oxygen in the water as they decompose. This in turn can kill large numbers of fish and other aquatic life, and is a very big problem in Kansas lakes and ponds.

Phosphorus can enter surface water from many non-point sources, including runoff from agricultural land and livestock wastes as we discussed in the pre-lesson. It can also come from point sources, such as industrial waste, discharge from wastewater treatment plants, septic system leakage, and storm water runoff. Many of these sources must have a permit to discharge certain levels of phosphorus. However non-point sources are not very well-regulated, and the phosphorus from non- point sources combined with the phosphorus from point sources can result in a troublesome level of phosphorus in rivers and lakes.

A good way to minimize non-point source pollution (runoff from fields and pastures) is by maintaining an area of certain native trees and grasses between the field and the river or lake. These areas of plants, called riparian buffers, help filter the nutrients and other pollutants out of the soil before they can get into the water. This strategy is especially effective for phosphorus, because it binds very tightly to soil particles and is easily retained in the buffer.

Grades: High School  

Learning Objective 

Test the level of available phosphorus in a water sample 

Kansas Grade Level Expectations – Standards/Benchmarks 

Standard 1: Learners demonstrate an understanding that the earth is a physical system. 
9-12 Benchmark 2: Learners analyze and communicate the basic properties of matter and energy. 
9-12 Indicators: By the end of the twelfth grade, the students: 
5. illustrate how different elements and compounds cycle through ecosystems at different rates. 
Example: Use illustrations of carbon, oxygen, nitrogen, phosphorous, and water cycles.
Standard 3: Learners demonstrate an understanding of the varied roles and interactions between humans and the environment. 
9-12 Benchmark 4: Learners identify and evaluate environmental issues from multiple points of view. 
9-12 Indicators: By the end of the twelfth grade, the students: 
1. identify the various uses of soil and water in Kansas. 
Example: Watering lawns and irrigating fields. 
2. identify the risks and benefits that agriculture, petroleum production, manufacturing, energy production, human communities, and other economic development activities can have on soil and water in Kansas. 
Example: Fertilizers used by agriculture and golf courses causing eutrophication of streams. 
3. describe the problems that Kansans face in regard to solid and hazardous waste disposal. 
Example: Finding suitable areas for solid waste disposal. 
4. describe the problems that Kansans face in regard to urban growth. 
Example: Good farmland is taken over by urban sprawl.


1. Water sample.
2. CHEMets phosphate testing kit: sample cup with lid, A-8500 activator solution, ampoule, comparison tubes, and comparator tube for low concentrations.
3. Goggles.


1. Make sure you test the water sample as soon as possible, ideally less than 24 hours since sampling. If you cannot run the test immediately, store your sample in the refrigerator in a sealed container. When you are ready to run the test, fill the sample cup (in the black CHEMets case) to the 25 ml mark with the sample water.

2. Add two drops of the A-8500 activator solution. Place the cap firmly on the sample cup and shake it briefly to mix the contents. It is not necessary to shake it hard, in fact this may affect your results. Try to mix the contents as gently as possible – you may try rolling or inverting the container a few times.


3. BE SURE YOU ARE WEARING YOUR GOGGLES! Place the CHEMets glass tube (ampoule) in the sample cup with the pointed end down. Hold the ampoule diagonally in the cup, and push to snap the tip of the ampoule against the side of the cup.



4. The ampoule will fill with the ample water. Invert the ampoule several times to mix the chemical with the sample water. Wipe any liquid from the outside of the ampoule, and wait at least two minutes for the color to develop.

5. Hold the ampoule next the the 1 to 10 ppm comparison tubes that came in the lid of the CHEMets box. Determine which color is closest to the color in your ampoule. If it seems to be in between two colors, you may estimate the value.

a. If the blue color in your ampoule is lighter than 1 ppm, you will need to find the comparator tube located in the right-hand section of the box. Place the ampoule into the center section of the comparator tube, making sure the flat end is down, sharp end is up. Hold the comparator tube up to the sunlight or an overhead light, and determine the color as compared to the 0 to 1 ppm scale.

6. Record your results on your field sheet using a pencil.

7. Dispose of the chemicals and broken glass properly. Because many soaps and detergents contain phosphorus, you should avoid washing the sampling equipment with soap. You can clean it by rinsing twice with distilled water, and letting it air-dry.



Record a Phosphorus rating on your field sheet according to the chart below:



1 – Poor

2 – Fair

3 – Good

4 – Best


Phosphorus levels
higher than 1.0 ppm.

Phosphorus levels
between 0.1 and 1.0

levels detectable at the
0.1 ppm level or

Zero. No detectable







Interpreting your results

The Kansas Department of Health and Environment (KDHE) has determined that levels of phosphorus greater than 0.1 ppm can have a negative effect on aquatic life. Most large detections of phosphorus occur right after an addition of phosphorus from some source (for example, just after heavy rain or just after a wastewater treatment plant has discharged treated water). If you find a concentration of phosphorus larger than 0.1 ppm, you should note on your field sheet that there was most likely a recent addition of phosphorus. Perhaps from your observation notes, you can even figure out where it is coming from! If you are testing a river at flood stage, there could be phosphorus from many different sources combining to make the concentration larger. If you see agricultural fields all around, you may guess that the phosphorus is coming from fertilizers and manures. Use your observations to guess the most likely source(s) of phosphorus for your testing site. Once the source is isolated, people can begin figuring out how to reduce the amount of phosphorus going into the water.

Laura Calwell,
Apr 22, 2010, 1:31 PM