Teresa Watson

Ecosystem Services – Water Purification

“Purpose: To use the example of natural water purification to show students that healthy ecosystems provide services to people that are essential to life as we know it.

Context: This lesson was developed by Dr. Penny Firth, a scientist, as part of a set of interdisciplinary Science NetLinks lessons aimed at improved understanding of environmental phenomena and events.
Ecosystem services are valuable for many reasons, including economic benefits, protection of human health and safety, and support of recreational or aesthetic enjoyment. Students should know that when ecosystems are not healthy, some or all of the services they provide to people may be lost. Replacing these services is often completely beyond current technology, and even when we can replace them, it is usually prohibitively expensive to do so. Historically, the vital role of natural ecosystem services has not been given much attention. Because they are “free” these services are sometimes thought of as “without value.” Nothing could be farther from the truth. Ecosystem services are essential to life as we know it. In this interdisciplinary lesson, students explore the concept of ecosystem services by investigating natural water purification in their home watershed.
A few key points before getting started:

• Most water pollution is invisible. Trash in our waterways may look unsightly, but the really serious problems come from poisons, very fine sediments, and excess nutrients.
• Water runs downhill. If humans put it on the land, or in the air, it will likely end up in the water eventually.
• The worst problems with pollution in this country come not from industrial discharge pipes, but from “non-point sources” such as agricultural and urban runoff, and contaminated precipitation.

This lesson is about how ecosystems purify water and what kinds of things humans do that alter these processes. It also discusses the value of the natural water purification service to humans. The take-home message is that the key to maintaining water purification services is to protect and restore the ecosystems that provide these services. “

Link:  http://www.sciencenetlinks.com/lessons.cfm?BenchmarkID=11&DocID=275