Nitrate is the most common chemical contaminant in the world’s ground water, including in aquifers used for drinking-water supply. Nitrate in drinking water of the United States is regulated by the U.S. Environmental Protection Agency (USEPA) because of concerns related to infant health and possible cancer risks.
Use of man-made synthetic fertilizers has steadily increased since World War II, raising the potential for increased nitrate contamination of the nation’s ground water, despite efforts in recent decades to improve land-management practices. Monitoring nitrate trends in ground water through time is important in determining how quickly ground-water systems respond to changes in chemical use and best management practices.
One of the first nationwide studies of nitrate trends in ground water of the United States was recently completed by scientists at the U.S. Geological Survey (USGS), as part of that agency’s federally-funded National Water-Quality Assessment (NAWQA) Program. In particular, monitoring data collected by NAWQA across the country in multiple aquifers were analyzed to characterize near-decadal trends in nitrate concentrations in ground water between 1988 and 2004. Results from the study were published in a companion supplement to the September-October issue of the Journal of Environmental Quality.
Decadal-scale changes of nitrate concentrations were evaluated in ground water samples collected from 495 wells in 24 well networks across the United States in predominantly agricultural areas. A well network is a set of about 30 randomly-selected wells designed to examine ground-water quality in a particular region. Each well network was sampled once during 1988–1995 and resampled once during 2000–2004.
Findings show statistically significant increases in concentrations of nitrate in 7 of the 24 well networks. Median nitrate concentrations of three of those seven well networks increased above the USEPA maximum contaminant level of 10 parts per million. Concentrations decreased in one network located in the Willamette Valley of Oregon. The study included estimates of the age of the ground water (that is, time since the water recharged to the aquifer); nitrate concentrations in ground water increased in response to the increased use of fertilizers since World War II.
“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.
The USGS implemented the NAWQA Program in 1991 to support national, regional, state, and local information needs and decisions related to water-quality management and policy (http://water.usgs.gov/nawqa). The NAWQA Program is designed to answer: What is the condition of our Nation’s streams and ground water, and how are conditions changing over time? In the second decade of the Program (2001–2012), a major focus is on regional assessments of water-quality conditions and trends at sites that have been consistently monitored for more than a decade.
The full article is available for no charge for 30 days following the date of this summary. View the abstract at http://jeq.scijournals.org/cgi/content/abstract/37/5_Supplement/S-240.
The Journal of Environmental Quality, http://jeq.scijournals.org is a peer-reviewed, international journal of environmental quality in natural and agricultural ecosystems published six times a year by the American Society of Agronomy (ASA), Crop Science Society of America (CSSA), and the Soil Science Society of America (SSSA). The Journal of Environmental Quality covers various aspects of anthropogenic impacts on the environment, including terrestrial, atmospheric, and aquatic systems.
The American Society of Agronomy (ASA) http://www.agronomy.org, is a scientific society helping its 8,000+ members advance the disciplines and practices of agronomy by supporting professional growth and science policy initiatives, and by providing quality, research-based publications and a variety of member services.
Successful calculation of human and natural influence on cloud formation
04.11.2016 | Goethe-Universität Frankfurt am Main
Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
08.12.2016 | Life Sciences
08.12.2016 | Physics and Astronomy
08.12.2016 | Materials Sciences