New USGS groundwater studies explain what, when, and how contaminants may reach public-supply wells.

All wells are not equally vulnerable to contamination because of differences in three factors: the general chemistry of the aquifer, groundwater age, and direct paths within aquifer systems that allow water and contaminants to reach a well.

More than 100 million people in the United States receive their drinking water from public groundwater systems, which can be vulnerable to naturally occurring contaminants such as radon, uranium, arsenic, and man-made compounds, including fertilizers, septic-tank leachate, solvents and gasoline hydrocarbons.

The USGS tracked the movement of contaminants in groundwater and in public-supply wells in four aquifers in California, Connecticut, Nebraska and Florida. The importance of each factor differs among the various aquifer settings, depending upon natural geology and local aquifer conditions, as well as human activities related to land use and well construction and operation. Findings in the four different aquifer systems can be applied to similar aquifer settings and wells throughout the nation.

Complete findings, fact sheets, maps and decision support tools are available.

"Our findings can help public-supply well managers protect drinking water sources by prioritizing their monitoring programs and improving decisions related to land use planning, well modifications or changes in pumping scenarios that might help to reduce movement of contaminants to wells," said Sandra Eberts, USGS groundwater study team leader.

Research on the vulnerability of public-supply wells began in 2001. The USGS has also been working since 1991 to study the occurrence of more than 600 naturally occurring and man-made chemicals from more than 1,100 wells used for public supply across the nation. Scientists found that chemicals are frequently detected, often in mixtures, but seldom at concentrations likely to affect human health.

The quality of drinking water from the nation’s public-water systems is regulated by the U.S. Environmental Protection Agency under the Safe Drinking Water Act. Related links to sources of information on public-supply wells are available. USGS studies are intended to complement drinking water monitoring required by federal, state and local programs, which focus primarily on post-treatment compliance monitoring.

Highlights on the four studies:

In the Central Valley aquifer system near Modesto, Calif., the USGS found that agricultural and urban development have enabled uranium to move from sediments to water in the upper part of the aquifer. This water can drain down the well when it is not pumping and enter the lower aquifer. When pumping resumes, contaminant concentrations can be temporarily elevated in water pumped from the well. As a result of USGS findings, public-supply well managers have changed their pumping schedule, which has reduced the amount of contaminated water pumped from the well.

In the glacial aquifer system in Woodbury, Conn., the USGS found that the young age of the water throughout the aquifer makes it vulnerable to contamination from man-made compounds. The USGS also found that dry wells used in Woodbury to capture storm water runoff reroute the potentially contaminated water directly into the aquifer used as a drinking water source. This direct transfer prevents soil and unsaturated sediments near the land surface from filtering out some of the contaminants.

In the High Plains aquifer near York, Neb., the USGS found some contaminants in a public-supply well that seems protected by overlying clay. Nearby irrigation wells have allowed water containing nitrate and volatile organic compounds to leak down from an overlying shallow aquifer into the aquifer that serves as the drinking water source for the public-supply well.

In the Floridan aquifer system near Tampa, Fla., the USGS found that a large percentage of young water and contaminants from a shallow sand aquifer travels quickly along natural conduits until it reaches a supply well in a lower rock aquifer that serves as a drinking water source. Because of these natural conduits, the supply well is vulnerable to the man-made contaminants in the upper aquifer, and the mixing of waters from the two aquifers has caused arsenic concentrations to increase in water reaching the supply well.

Source: USGS

Additional, suggested searches:

Learn more about the California study.

Learn more about the Connecticut study.

Learn more about the Nebraska study.

Learn more about the Florida study.

Learn more about public-supply well contamination in a USGS video podcast.

Bibliography.

Related Products.

More about this topic at Andinia.com.

Debates about this in our forum.

Related games and entertainment.

WASHINGTON - Will 2010 be the warmest year on record? How do the recent U.S. "Snowmageddon" winter storms and record low temperatures in Europe fit into the bigger picture of long-term global warming? NASA has launched a new web page to help people better understand the causes and effects of Earth's changing climate.

The new "A Warming World" page hosts a series of new articles, videos, data visualizations, space-based imagery and interactive visuals that provide unique NASA perspectives on this topic of global importance.

The page includes feature articles that explore the recent Arctic winter weather that has gripped the United States, Europe and Asia, and how El Nino and other longer-term ocean-atmosphere phenomena may affect global temperatures this year and in the future. A new video, "Piecing Together the Temperature Puzzle," illustrates how NASA satellites monitor climate change and help scientists better understand how our complex planet works.

The new web page is available on NASA's Global Climate Change Web site at: http://climate.nasa.gov/warmingworld

For more information about NASA and agency programs, visit: http://www.nasa.gov

Source: NASA

Additional, suggested searches:

Bibliography.

Related Products.

More about this topic at Andinia.com.

Debates about this in our forum.

Related games and entertainment.

A disinfection solution presently used for salmon eggs also prevents transmission of the virus that causes viral hemorrhagic septicemia or VHS - one of the most dangerous viral diseases of fish - in other hatchery-reared fish eggs, according to new U.S. Geological Survey-led research.

VHS has caused large fish kills in wild fish in the U.S., especially in the Great Lakes region, where thousands of fish have died from the virus over the last few years. The disease causes internal bleeding in fish, and although in the family of viruses that includes rabies, is not harmful to humans. Thus far, the virus has been found in more than 25 species of fish in Lakes Michigan, Huron, Erie, St. Clair, Superior and Ontario, as well as the Saint Lawrence River and inland lakes in New York, Michigan and Wisconsin.

Read more...

Source: USGS

Additional, suggested searches:

Bibliography.

Related Products.

More about this topic at Andinia.com.

Debates about this in our forum.

Related games and entertainment.