Chemical and Biological Analysis Of Samples Collected From Test Site
- Time Span:
4 to 5 days (class periods)
- Brief Description:
Students run the chemical analysis on the water samples collected and identify the benthic
macroorganisms collected. Using this data, students will assess the overall quality of
the stream, pond etc...
- Students will learn to use a variety of chemical tests for water quality determination.
- Students will learn to identify keystone biological species for water quality determination.
- Students will collaborate with each other to share data and analysis of results.
- Chemical analysis test kits. (Note: there are several companies and types of kits available.
We use kits from HACH and LaMotte. The analysis we run includes turbidity, hardness, dissolved oxygen,
alkalinity, iron, nitrate/nitrite, hydrogen sulfide, and coliform. Choose kits appropriate
for your area.)
- Microscopes, magnifying glasses, forceps, wash bottles, alcohol jars, pans/trays (preferably white),
benthic macroinvertebrate keys
As noted in the Materials section, there are a number of chemical tests that can be chosen to use.
Follow the procedures outlined for those individual tests.
- To identify Macroinvertebrates use the Macroinvertebrate Data Recording Sheet.
- Pour some of the stream water from the collection bucket into a tray along with some debris (rocks, silt, sand etc..).
- Carefully study the pan for movement as you pick through the debris.
- Rinse any organisms you find and key them using a macroorganism identification key.
- All mollusks should be returned to the collection site, so note their presence and return
to another container for future delivery back to the stream. All other organisms can be placed into an alcohol
jar after they have been noted on the Macroinvertebrate Data Recording Sheet.
- After recording the information on the organisms present, calculate a Biotic Index. A biotic
index is a way of measuring the quality of the stream. This is done by the fact that certain keystone species are more or less tolerant
to pollution. For example, the presence of large numbers of stoneflies would indicate good water while the presence of mosquito larvae and
leeches might indicate polluted water.
- Use the information presented on the Macroinvertebrate Data Recording Sheet to learn how to calculate the biotic index.
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