Looking at the earth’s surface from above would lead one to think that it is not necessary to worry about a water supply.
Although most of the earth is covered with water, only a small portion is in a form that can be used by humans and other land dwellers. The oceans cover about 70% of the earth’s surface and contain about 97% of the water. As we all know this water contains salt which prevents our using it directly for life functions.
Icecaps contain about 2% of the available fresh water leaving the last 1% for our use in a natural state.
As water dissolves more substances than any other single substance and with our living in a closed system, we must therefore conserve our fresh water supply and prevent it from becoming polluted.
At this time, introduce the water cycle to the students. We might also do an electrolysis of water demonstration to show the chemical composition of pure water.
After the water cycle has been discussed, the CEPUP MODULE—CHEMICAL SURVEY & SOLUTIONS AND POLLUTION will be used to gain an understanding of water pollution.
This module begins by having the student answer a survey form on chemicals. They also ask people over the age of 18 to answer the same survey questions. When both are completed they tally the results and write a report comparing their response to adult responses. Upon completion of this exercise they are made to realize that everything that has mass is made up of chemicals.
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Activity one has the student explore the water solubility of various substances learning about solutions and the terms solute, solvent, dilute and concentrated.
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Activity two teaches the student parts per million (ppm) through a visual demonstration using successive dilution of food coloring.
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Activity three has the student explore the reactions of an acid, a base, water and universal indicator when mixed together in various quantities.
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Activity four has them explore the question of whether dilution is the answer to pollution.
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Activity five has the student study neutralization quantitatively.
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Activity six has the student determine the concentration of household vinegar relative to a known acid solution.
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Activity seven has the student use their knowledge to solve a simulated water pollution problem.
We now can use the water cycle chart and our knowledge of an acid to review acid rain.
Using our water cycle chart, we can now discuss groundwater fits into the water cycle. The CEPUP MODULE—INVESTIGATING GROUNDWATER: THE FRUITVALE STORY will be used to gain a better understanding of groundwater.
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Activity one deals with factors that affect the movement of groundwater, how groundwater gets contaminated and how contamination is spread.
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Activity two deals with dilutions of parts per million (ppm) and parts per billion (ppb).
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Activity three has the students read the Fruitvale story and using a map, decide where more test wells should be drilled to discover the source and extent of contamination.
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Activity four has the group deciding on a plan of action, carrying out a simulation of well testing and recording their results on the Fruitvale map.
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Activity five has the students use the information and draw a plume showing the boundary of safe concentration of the pesticide.
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Activities five and six are optional role playing activities.
We are now ready to read and discuss water pollution problems in the real world. Have the students bring in articles from papers and magazines on these problems to be shared and discussed with the class. You might also want to use the the textbook RESOURCES, mentioned earlier as source of articles. There are nine articles with activities on this subject in the book.
The type of discussions and suggestions for handling the water pollution problem can be a way to evaluate the effectiveness of the section.