Drink What You Drive
DB: This is Earth and Sky. Nitrogen is the most common gas in Earth’s atmosphere.
JB: A process called “nitrogen fixation” makes this gas suitable for use . . . for example, by plants which use chemically fixed nitrogen compounds as fertilizers.
DB: But some portion of the nitrates applied to fields and lawns ultimately ends up in our drinking water – where it’s known to cause health problems. Nitrates also enter the water supply from other sources – one source is automobile tailpipes. And nitrogen compounds are a major component of smog and acid rain.
JB: Recently, researchers collected water samples from 22 pristine mountain streams in the San Bernardino and Angeles National Forests, downwind of Los Angeles freeways. The Federal government limits nitrates in drinking water to 10 parts per million. These researchers found nitrate levels up to 6 parts per million. The nitrate levels tail off with increased distance from Los Angeles. A similar trend was found near Mexico City.
DB: The researchers think that airborne nitrates collect on the surfaces of plants, then wash off in rain. Other airborne nitrates probably fall with snow and enter streams with the spring melt. We have links to more information on nitrates – come to today’s show at earthsky.com. Special thanks today to the National Fish and Wildlife Foundation. We’re Block and Byrd for Earth and Sky.
The following individuals were interviewed for today’s show. Our thanks to:
Dr. Tom Meixner
Department of Environmental Sciences
University of California
Riverside, CA
Dr. Mark Fenn
Pacific Southwest Research Station
USDA Forest Service
Dr. Eric Betterton
Department of Atmospheric Sciences
University of Arizona
Dr. Jeffrey Collett
Atmospheric Science Department
Colorado State University
Colorado State University Cooperative Extension: Nitrates in Drinking Water
Washington State Department of Health: Nitrates in Drinking Water Position Paper
Illinois Department of Public Health Division of Environmental Health Fact Sheet: Nitrates in Drinking Water
The University of Georgia College of Agricultural & Environmental Sciences Cooperative Extensive Service: Your Drinking Water – Nitrates
Additional Teacher Resources
U.S. National Park Service, Wind Cave National Park: Water Pollution Quiz
This site contains an interactive quiz for students covering simple concepts concerning watershed and groundwater pollution as well as its causes and repercussions.
Michigan Department of Environmental Quality: Nitrate in Drinking Water
Large amounts of nitrate in drinking water can cause serious illness in infants less than six months of age. This report answers questions students may have about this possible problem.
U.S. Environmental Protection Agency, Ground Water & Drinking Water: Consumer Fact-Sheet on Nitrates
This fact-sheet covers questions students may have concerning the chemical nitrate that may be found in some public or private drinking water supplies. It can cause health problems if found in amounts greater than the health standard set the U.S. Environmental Protection Agency.
