Human Activity, the Nitrogen Cycle, and Global Issues
As with the carbon and water cycles, human activity can tip the balance in these natural cycles. Some examples are: manipulation of crops to enhance nitrogen content of soils; excess fertilizer runoff, which enhances stream and river algal and plant growth; and by-products of technology that produce nitrogen compounds which become pollutants in high concentrations. You may have your students investigate these real-world phenomena, apply their knowledge of not only the nitrogen cycle but the water and carbon cycles as well, and thereby, demonstrate knowledge of the complexity of the problems by explaining the causes, effects and possible solutions.
This lesson is aimed at high school students; however, you may modify it as a whole class activity. Students act as environmental engineers to understand the requirements that allow soil-dwelling bacteria to remove nitrates from polluted groundwater at a hog farm. This two-week-long lesson introduces students to the real-life applications of bioremediation. Students design and then analyze their results from an experiment that uses microcosms in jars containing simulated soil and water samples. Instructions on how to prepare solutions, along with sources of the nitrate test kits, are provided for the teacher. A Cornell Science Inquiry Partnerships Fellow created and piloted this activity. MSP
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This self-contained lesson could be done by middle school students in pairs. In this social approach to learning, students can help each other understand the content and share their interpretations and reactions. The module is from a larger series on water quality investigations. It provides background information on nitrates and how they affect water quality. It also contains a pre-test and a post-test, a laboratory investigation, and a self-study game. The purpose of the site is to help students understand and describe the sources of nitrates and the role they play in an ecosystem and the effects of excess nitrates on water quality and human health. Students will also learn how to measure, graph, and interpret the direct and indirect effects of nitrates on fish. MSP full record
One of the promises of genetically modified (GM) food is that it helps minimize the need for pesticides and fertilizers, and may help reduce the threat to future food supplies. But opponents of GM food say that solution poses more problems than it solves. In the third installment of a series on GM food, a science reporter visited a farm where agroecology is being tested. MSP full record
Gases trapped in ice cores show the dramatic impact that human activities have had on the planet since the Industrial Revolution. This graph, from the web site accompanying the Frontline/NOVA special "What's Up with the Weather?," reveals how atmospheric carbon dioxide, methane, and nitrous oxides from coal- and oil-burning power plants, cars, and other fossil-fuel-burning sources have climbed along with the world population, with as yet unknown effects on the climate system. MSP full record
This lesson is part of a larger environmental science curriculum developed for Maryland teachers. A recommended grade level is not identified, but with some modification the lesson can be adapted to middle school students. There are four separate activities, any of which can stand alone. MSP full record
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Copyright
July 2007 — The Ohio State University. This material is based upon work
supported by the National Science Foundation under Grant No. 0424671. Any
opinions, findings, and conclusions or recommendations expressed in this
material are those of the author(s) and do not necessarily reflect the views of
the National Science Foundation.
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