Module 7: What Is in Your Water?
The goal of Module 7, What Is in Your Water?, is to lead students to a better but basic understanding of freshwater chemistry, natural and human contaminants, and impacts of certain practices on human and ecosystem health. After completing the module, students will be able to:
- calculate the concentration of contaminant in a reservoir;
- apply government drinking water regulatory standards to identify contaminant levels that might be harmful to human health;
- analyze concentration vs. time data for various dissolved components of river water and groundwater;
- infer the processes responsible for seasonal trends in compounds of natural and human origin;
- propose and evaluate methods for mitigating human impacts on water quality;
- evaluate the trade-off between agricultural productivity and water quality as a result of fertilizer usage and runoff.
Context for Use
Description and Teaching Materials
All materials for students are available online using the Student Materials link below. These can be implemented entirely in the context of distance learning, with students completing any discussion questions in the form of a blog or discussion group. In a traditional or blended classroom setting, students can complete the online unit as homework, using class time to address the discussion questions and for the Summative Assessment.
Teaching Notes and Tips
Module 7 primarily deals with the chemistry of natural waters. Most students are unfamiliar with modes of expressing concentration, so we begin this module with a brief exposé of concentration equivalences and calculations and an "Activate Your Learning" exercise. Most students successfully performed the unit conversions and calculations and were able to use this skill in Module 7 Formative Assessments. Students seemed to have no trouble with either of the two Formative Assessments and responded well to Formative Assessment 2 in particular. They provided mostly very thoughtful responses in that formative assessment regarding balancing agricultural production in the Midwest against fisheries health and production in the Gulf Coast region—not everyone agreed on solutions, which was of interest to us.What students found difficult
One challenge was helping students relate the general material presented in the module to specific water bodies and understand how water quality information is used in practice. Case studies in the formative assessments help with this, but instructors may choose to present (or have students research) TMDLs for local water bodies. TMDL reports are fairly easy to find from the relevant state agencies and/or Environmental Protection Agency (EPA) website. Reflections
To provide additional context, instructors may choose to go into detail about the history and evolution of the Clean Water Act. Also, useful and up-to-date information can be gleaned from the EPA National Water Quality Inventory Report to Congress (305b) or the EPA webpage on TMDLs.
The Module 7 Summative Assessment requires access to computers, and the instructor should ask students to bring theirs to class. A list of contaminants for "fact sheet" construction is provided, and students are divided into groups of two to work on them (see References and Resources section below). They are required to cite peer-reviewed literature and/or government websites in support of their "facts." Students were given access to all fact sheets and asked to study them for a brief discussion. As an alternative, instructors may choose to ask students to prepare the contaminant fact sheets prior to coming to class and use class time to present/discuss findings. For larger classes, it may be helpful to expand the list of contaminants.
Summative AssessmentThe Summative assessment for this module involves Constructing a Contaminant Fact Sheet.
References and Resources
- Readings from Student Materials — Module 7: What Is in Your Water?
- The Big Thirst: The Secret Life and Turbulent Future of Water by Charles Fishman: Chapter 8
Fact Sheets and other examples for students:
- Cyanobacteria and Cyanotoxins: Information for Drinking Water Systems EPA Factsheet (Acrobat (PDF) 78kB Nov11 15)
- Atrazine Chemical Summary from the EPA (Acrobat (PDF) 120kB Nov11 15)
- Diethyltoluamide (DEET) Chemical Summary from the EPA (Acrobat (PDF) 136kB Nov11 15)
- Selenium in Drinking-water, a 2011 report from the World Heath Organization
- The Environmental Impacts of Glycophosphate, a June 2013 report from Friends of the Earth Europe
- Benotti, Mark J., Rebecca A. Trenholm, Brett J. Vanderford, Janie C. Holady, Benjamin D. Stanford and Shane A. Snyder. (2009) Pharmaceuticals and Endocrine Disrupting Compounds in U.S. Drinking Water. Environmental Science and Technology, 43, 3, pp. 597-603.