February 2008, Vol. 20, No.2


Ethanol Demand Could Increase ‘Dead Zone’ in Gulf

The Gulf of Mexico “dead zone” — currently the size of New Jersey — likely will grow in coming years unless federal policies to control it change. This is due in part to the demand for corn-based ethanol fuels, according to scientists at the University of Michigan (Ann Arbor).

Fertilizer runoff from as far away as the midwestern Corn Belt states is largely blamed for the annual low-oxygen, or hypoxic, event, which threatens the $500 million Gulf Coast fishery, explained University of Michigan researcher Donald Scavia in a university news release.

"We have made no progress in controlling it,” said Scavia, a natural resources and environment scientist who led the first federal integrated assessment of the Gulf dead zone in 2000. “And if we continue to put more land into corn because of the ethanol craze, then there’ll be more nitrogen and larger dead zones.”

In an article in the journal Environmental Science & Technology, Scavia and University of Michigan researcher Kristina Donnelly conclude that the best way to shrink the dead zone is to reduce amounts of nitrogen and phosphorus that flow down the Mississippi River and into the gulf. Previous efforts focused only on cutting nitrogen, which is used to make crop fertilizer.

Scavia and Donnelly took new U.S. Geological Survey estimates of nutrient levels entering the Mississippi River and entered them into a university computer model that projects the future of gulf hypoxia.

The study, according to the news release, shows that reducing phosphorus alone — a course advocated by some in the agricultural industry — could trigger the growth of even bigger dead zones in the waters of the western gulf.

“We understand what needs to be done, and the technology needed to do it is available,” Scavia said. “All we really need is the political will and the funding.”

The 2000 assessment concluded that excess nitrogen from fertilizers fueled the gulf dead zone’s growth in the 1970s. In 2001, a Hypoxia Action Plan was delivered to the U.S. Congress and the president. Its goal was to shrink the dead zone by reducing nitrogen runoff into waterways. 

Environmental Discussions on the Go

With the debut of its “Green Scene” podcasts, the U.S. Environmental Protection Agency (EPA) has a new medium for reaching out to the general public and exploring timely environmental issues.

Green Scene, which can be viewed online or downloaded as a podcast, features agency officials discussing environmental topics of concern while providing the public with useful tips and information on how to make a difference in local communities, according to EPA. The discussions — roughly 5 minutes in length — run biweekly.

The agency’s first podcast, which ran in November, featured George Gray, EPA’s chief researcher, talking about America Recycles Day. A December podcast featuring Maria Vargas with EPA’s Energy Star Program focused on making energy-efficient choices when selecting holiday decorations and gifts.

The Green Scene podcast box is accessible from EPA’s home page — www.epa.gov — and all discussions are archived and posted at www.epa.gov/newsroom/greenscene

Where’s the Runoff?

Cattle produce much more than beef: A typical 1000-head feedlot can generate as much as 254 Mg (280 tons) of manure in a week, according to the U.S. Agricultural Research Service (ARS). Safely managing the runoff from such feedlots can be a challenge, but ARS scientists have developed a new method for storing runoff that is designed to improve upon current practices.

Feedlot runoff often is stored in a large pond or basin and then is distributed as nutrient-rich irrigation water or processed for safe disposal. This method — approved by the U.S. Environmental Protection Agency (EPA) — is far from perfect, ARS reports. Over time, nutrients can percolate through the soil into groundwater, and pond maintenance is expensive and difficult, according to ARS.

Research leader John Nienaber from the Environmental Management Research Unit of the U.S. Meat Animal Research Center (Clay Center, Neb.) worked with agricultural engineers Roger Eigenberg and Bryan Woodbury to design an alternative system in which runoff containing manure solids enters temporary storage basins at the base of the sloped feedlot.

The basin is large enough to hold runoff for several hours to allow the solid waste to settle to the bottom. The remaining liquid is then drained through distribution tubes that provide even dispersal over a grassy field or “vegetative treatment area,” also known as a VTA. The system, conditionally approved by EPA, has many benefits, according to ARS. It requires minimal management, significantly reduces waste storage time, eliminates the need for runoff pumping, and removes standing water. The technology could also be applied to other livestock.

Read more about the research in the November–December 2007 issue of Agricultural Research magazine at www.ars.usda.gov/is/AR/archive

Acid Rain Sources May Hail From Afar

Nitrate found in precipitation occurring in rural areas of the northeastern and midwestern United States is primarily caused by emissions from stationary sources located hundreds of miles away, according to a new U.S. Geological Survey (USGS) study.

A USGS news release reports that stationary sources include coal-burning power plants and other industrial facilities, and while vehicles are the single largest emission source of nitrogen oxides in these regions, distant stationary sources may have a greater impact on nitrate found in rain and snow.

“These results demonstrate that we have a new chemical analysis tool for tracing the influence of emissions from stationary sources,” said Emily Elliott, former USGS scientist and current assistant professor at the University of Pittsburgh. “This could be a powerful method for monitoring the effects of stationary source emission reductions slated for this region over the next 8 years.”

The study, published in the journal Environmental Science and Technology, presents the first large-scale investigation of nitrogen isotopes in precipitation. The authors analyzed stable nitrogen isotopes at 33 long-term National Atmospheric Deposition Program (NADP) monitoring sites, according to USGS. NADP is a cooperative nationwide program that measures air pollutant concentrations in rain and snow at more than 250 stations across the United States, most of which are deliberately located in relatively rural settings away from urban, industrial, or agricultural centers.

Power plants and other stationary sources emit pollutants high in the atmosphere that can be transported for long distances before falling to the ground, while vehicles emit pollutants through tailpipes close to the ground, where they are more likely to be deposited over shorter distances near roadways, USGS reports. Further, a portion of emissions from all sources may be deposited on the landscape in gaseous forms, such as aerosols and particles, in addition to precipitation.

The abstract of the article is available at pubs.acs.org/journals/esthag/index.html, under the “Articles ASAP” tab. The full text of the article can be obtained from Michael Bernstein by contacting him at m_bernstein@acs.org

NSF Science and Technology Center Recognized

The U.S. National Science Foundation (NSF) Science and Technology Center for Sustainability of Semi-Arid Hydrology and Riparian Areas (SAHRA) is one of two institutions to win the 2007 International Great Man-Made River Prize, according to an NSF news release.

The prize — awarded by the United Nations Education, Science, and Culture Organization (commonly known as UNESCO) — “rewards remarkable scientific research work on water usage in arid areas as well as areas subject to drought and also for the development of agriculture for the benefit of humanity and the environment,” the news release states. The other institution to win the 2007 prize was the Center for Hydrometeorology and Remote Sensing at the University of California–Irvine.

SAHRA, headquartered at the University of Arizona (Tucson), comprises several institutions, including universities, government agencies, and national laboratories.

“The award … reflects our numerous contributions to the hydrology of semiarid and arid regions of the world and the level of international respect for the work we do,” SAHRA Director Jim Shuttleworth said. “We carry out state-of-the-art science and engineering in the water arena and, by building strong relationships with water professionals, make sure the resulting understanding gets used effectively and quickly.”

For more information on SAHRA, see www.sahra.arizona.edu