WASHINGTON, Sept. 18 (UPI) -- A recently completed 16-year U.S. ground water study shows statistically significant increases in concentrations of nitrates in seven of 24 well networks.
Nitrate is the most common chemical contaminant in the world's ground water, scientists said. Nitrate in drinking water of the United States is regulated by the U.S. Environmental Protection Agency because of health concerns related to infant health and possible cancer risks.
Results of the U.S. Geological Survey study were analyzed to characterize near decade-long trends in nitrate concentrations in ground water between 1988 and 2004 in samples from 495 wells in 24 well networks across the nation.
A well network is a set of about 30 randomly-selected wells designed to examine ground water quality in a particular region. Each network was sampled once between 1988 and 1995 and re-sampled between 2000 and 2004.
"This study highlights the importance of maintaining long-term ground water monitoring programs in the nation, because sustained monitoring provides critical information on changes of our nation's ground water quality, and whether pollution prevention programs are effective in protecting this nation's ground water," said Michael Rupert, a hydrologist with the USGS.
Results from the study appear in the September-October issue of the Journal of Environmental Quality.