In the lab

Reducing groundwater pollution

Toxic chemicals are contaminating groundwater on every inhabited continent, endangering the world's most valuable supplies of freshwater, reports a study from the Worldwatch Institute, a Washington, DC-based research organization. This first global survey of groundwater pollution shows that a toxic brew of pesticides, nitrogen fertilizers, industrial chemicals and heavy metals is fouling groundwater everywhere.

"Groundwater contamination is an irreversible act that will deprive future generations of one of life's basic resources," said Payal Sampat, author of Deep Trouble: The Hidden Threat of Groundwater Pollution.

Some 97 percent of the planet's liquid freshwater is stored in underground aquifers. Nearly one third of all humanity relies almost exclusively on groundwater for drinking, including the residents of some of the largest cities in the developing world, such as Jakarta, Dhaka, Lima and Mexico City. Almost 99 percent of the rural U.S. population, and 80 percent of India's villagers, depend on groundwater for drinking.

"Groundwater pollution is essentially permanent," said Sampat. Water recycles extremely slowly underground, too slowly to flush out or dilute toxic chemicals. Water that enters an aquifer remains there for an average of 1,400 years, compared to only 16 days for rivers. Thus Londoners, for example, may be drinking water that fell as rain as long ago as the last Ice Age.

The urgency of preventing groundwater contamination is highlighted by the costs of cleanup efforts. Water utilities in the midwestern United States, a region that is highly dependent on groundwater, spend $400 million each year to treat water for just one chemical, the pesticide atrazine. According to the U.S. National Research Council, initial cleanup of contaminated groundwater at some 300,000 sites in the United States could cost up to $1 trillion over the next 30 years.

"To preserve this valuable resource, we need to make systematic changes in the way we grow our food, manufacture goods and dispose of waste," Sampat said.

The report proposes retooling industrial agriculture to reduce farm runoff, a leading source of groundwater pollution. The U.S. Environmental Protection Agency (EPA) estimates that cutting agricultural pollution could eliminate the need for at least $15 billion worth of additional advanced water treatment facilities.

Farmers from Indonesia to Kenya are learning how to use fewer chemicals while boosting yields. Since 1998, all the farmers in China's Yunnan Province have eliminated their use of fungicides, while doubling rice yields, by planting more diverse varieties of the grain. Water utilities in Germany now pay farmers to switch to organic operations because it costs less than removing farm chemicals from water supplies.

Companies also need to take greater responsibility for their toxic discharges. Sixty percent of the most hazardous liquid waste in the United States -- 34 billion liters per year of solvents, heavy metals, and radioactive materials -- is injected directly into deep groundwater via thousands of "injection wells." Although EPA requires that these effluents be injected below the deepest source of drinking water, some have entered underground water supplies in Florida, Texas, Ohio and Oklahoma.

Manufacturers can reduce groundwater pollution by reusing materials and chemicals-thus reducing leakages from landfills. Companies are building "industrial symbiosis" parks in which the unusable wastes from one firm become the input for another. Such waste exchanges help an industrial park in Kalundborg, Denmark, to keep more than 1.3 million tons of effluent out of landfills and septic systems each year.

Manufacturers can also switch to less toxic alternatives. In Sweden, where chlorinated solvents were entirely phased out by the end of 2000, some firms already report economic savings from switching to water-based solvents derived from biochemical sources such as citrus fruits, corn, soybeans and lactic acid.

For more information, visit www.worldwatch.org.

More eco-friendly manure

In the United States, swine produce more than 15 million tons of manure each year containing an estimated 460,000 tons of phosphorus -- phosphorus that can, when in high enough concentrations, lead to environmental disaster if a manure spill occurs. However, a researcher at the University of Missouri-Columbia has found a way to reduce the risk of phosphorus pollution using biotechnology.

Swine nutritionist Gary Allee explained that hogs need a certain amount of phosphorus in their diet, but that most of the phosphorus in corn and soybeans is in a form, known as phytate phosphorus, that hogs cannot digest. So, producers add mineral supplement containing phosphorus to the hogs' diets. Although this provides hogs with the necessary phosphorus, the undigested phytate phosphorus is still excreted.

"We realize that what we put into an animal affects what comes out, so we changed what we're putting in," he said. "Rather than attempting to treat the current phosphorus levels in manure, our approach is to reduce the levels before we reach the treatment process."

To accomplish this, Allee started feeding hogs genetically modified (GM) corn developed by Pioneer Hi-Bred International Inc. This variety is modified to contain higher levels of phosphorus that hogs can digest.

"Only 10 to 15 percent of the phosphorus in standard varieties of corn is digestible by pigs," Allee said. "However, about 60 percent of the phosphorus in the genetically modified variety is digestible by pigs, which allows producers to supplement less inorganic phosphorus. The result is less phosphorus ends up in the manure."

Results from testing -- in both a laboratory setting and at commercial hog farms in Missouri and Iowa -- show the use of "low-phytate" corn can reduce phosphorus excretion by 30 to 40 percent. Performance testing also shows that hogs on this diet do as well as hogs on traditional diets supplemented with phosphorus. The Journal of Animal Science published these results.

"This new variety of corn also can be used to reduce phosphorus excretion in poultry," Allee said. "We can make significant strides to protect the environment by improving the digestibility of naturally occurring phosphorus."

Research on low-phytate corn is part of a cooperative project involving a number of research institutions including North Carolina State University, Purdue University, Michigan State University and Oklahoma State University.

For more information, visit www.missouri.edu/~news.

Light shines on contamination

A Scottish university has developed organisms that produce their own light and "go out" when exposed to contaminated soil.

The organisms, developed through genetic engineering, are being put to use to detect pollutants in soil. The organisms signal when they are endangered by a toxin, said Anne Glover, professor of microbiology at the University of Aberdeen.

"When they're happy, they glow," Glover said. "When they're unhappy, they stop glowing."

Exposure to contaminants causes the organisms to cease the biochemical reaction that produces light, Glover said.

The organisms can be used as an "integrated detector" of contaminants, she said. Unlike traditional chemical detection methods that may miss contaminants, the Aberdeen bioluminescent organisms can tell if any contaminants are present, she said. "They're like a safety net."

Different types of the organisms developed by the university can detect different types of contamination, Glover said. Some of the organisms react in the presence of volatile organic chemicals, such as organophosphates. Still others detect heavy metals.

In addition, Glover said, the organisms can identify the presence of toxins that may be dangerous to either plants or animals. Bacteria developed by the university can identify toxins harmful to the environment generally, while bioluminescent yeast detects contaminants more toxic to animals.

Glover said the organisms were developed by transferring genes from a bioluminescent marine bacterium called photobacterium. The light results from an enzyme reaction in the organisms, she said.

The University of Aberdeen helped create a company, Remedios Ltd., in 1999 to commercialize the technology. The company uses the technology to develop a map of toxic contamination.

Glover said the technology is already in use in Europe, where a large number of contaminated sites has created a huge market for cleanup technologies.

In addition to detecting contamination, the company helps design cleanup strategies using the information it gathers about the nature and extent of contamination, Glover said.

Widely employed by the United States, bioremediation is becoming more popular in Europe because it uses naturally occurring soil organisms to break down contamination, often yielding nothing more than water and carbon dioxide as end products, Glover said.

For more information, visit www.remedios.uk.com.

This article originally appeared in the 02/01/2001 issue of Environmental Protection.

About the Author

Jim DiPeso is communications director at the Pacific Northwest Pollution Prevention Resource Center, Seattle.

comments powered by Disqus