Water Resources of the United States

Dispersion of Nonpoint Pollutants

Introduction

One of the difficult problems associated with the control of nonpoint sources of pollution is the identification of the source. Different soil types and the properties of underground rock formations affect how water pollutants travel. Pollutants can behave differently once they come in contact with soil. Biological processes can alter pollutants and their behavior. Many factors affect the physical, chemical, and biological makeup of water pollution.

Objective

Students will become aware of the difficulty in determining the source of pollution.

Materials -- Each group will need:

1. One coffee filter (15-20 cm in diameter);
2. One piece of aluminum foil 30 cm x 30 cm;
3. Water to wet filters;
4. Eye dropper; and
5. One paper plate approximately 25 cm in diameter for each group. Teacher needs: one container each of red, yellow, and blue food dyes.

Teacher Preparation

1. Prepare a mixture of one part each of the three food dyes and one part water in large enough quantity that each group of students can receive five drops of the resulting mixture. Do not tell the students what the mixture is.
2. Provide each group with one filter, one paper plate, and a piece of aluminum foil.

Procedure

1. Divide students into groups of two. Have group members write their names on the coffee filter with a pencil. Then each group should place an 'X' and a 'Y' somewhere on the filter paper to represent imaginary wells.
2. Loosely crumple a piece of aluminum foil and place it in the middle of the paper plate.
3. Wet the coffee filter with water and drape it over the crumpled aluminum foil' The coffee filter represents soil on land surface. The aluminum foil represents bedrock on which the soil sits.