In the Lab

• By Jim DiPeso
• Apr 01, 2001

Aggravating land loss

Agricultural lands face an enormous challenge to provide food for the expected population surge of 1.5 billion people over the next 20 years.

World food production is at risk from farming methods that have degraded soils, parched aquifers, polluted waters and caused the loss of animal and plant species, according to a study by the International Food Policy Research Institute (IFPRI) and the World Resources Institute (WRI). Soil degradation has dramatically reduced crop productivity, with consequences for poor, heavily populated countries.

Using analysis of satellite-derived data, digital maps and new ways of mapping global agriculture, this study has become the first comprehensive audit report of the world agriculture's ability to provide sufficient food, goods and services that are vital for sustaining human life. The report is called Pilot Analysis of Global Ecosystems: Agroecosystems. It revels that:

• Soil degradation, including nutrient depletion, erosion and salinization, is widespread;
• Twenty to 30 percent of the world's forest areas have been converted to agriculture, resulting in extensive species and habitat loss. Agriculture is encroaching on many national parks and other protected areas; and
• Agriculture consumes 70 percent of the freshwater withdrawn annually by humans. Irrigation is draining more water than is being replenished by rainfall, causing water tables to fall. Moreover, many water sources are being polluted by excessive use of fertilizers and pesticides.

"We must find ways to increase food production to sustain growing populations in developing countries. But this challenge must be accomplished without major increases in the amount of new land under cultivation, which would further threaten forests and biodiversity, and without resorting to unstable farming practices," said Ian Johnson, chairman of the Consultative Group on International Agricultural Research (CGIAR) and a World Bank Vice President.

The report is part of a series of five technical reports that also cover fresh water coastal, forest and grassland ecosystems. Taken together, these reports are the first such comprehensive assessment of the state of the world's ecosystems. The reports set the stage for the Millenium Ecosystems Assessment (MEA) that will be launched this year (see In the Lab, Dec. '00). The MEA is expected to fill in the data gaps identified by these reports through the participation of hundreds of the world's leading scientists who will be mobilized by this $20 million, four-year effort.

"We must not continue to take nutrients out of the soil faster than we replace them. We must not continue to deplete water resources faster than they can be replenished," said Per Pinstrup-Anderson, Director General of IFPRI. "By analogy, you cannot continue to take more out of your bank account than you put in. Sooner or later, you'll run out of money."

The World Bank contributed to this report.

Mixing oil and water

A team of researchers from Texas A&M University are trying to take some of the tremendous amounts of water created in oil and gas production and put it to use to restore rangelands and ecosystems.

The scientists were brought together by a faculty incubator grant provided by the Texas Water Resources Institute (TWRI). The idea of this program is to create teams of interdisciplinary researchers to address critical water resources and environmental issues. The grants provide start-up funds for teams of scientists to get together, develop proposals for comprehensive research projects, conduct literature searches, and meet with funding agencies to discuss ideas.

Roughly seven barrels of water are produced for each barrel of oil that comes out of the ground in mature West Texas oil fields where more than 400 million gallons of water are produced daily. Once the oil has been recovered, something has to be done with this water or brine. To date, the management strategy has been to dispose of the water in underground injection wells.

One of the researchers, David Burnett, said "We want to learn how we can take this significant volume of water and use it to improve the environment, especially in parts of West Texas where water is scarce. This means we will have to learn about the chemistry of pollutants in produced waters, the water quality we need to put brines to beneficial uses, and how we can treat these waters so they can be suitable for irrigation and revitalizing ecosystems."

About 75,000 barrels of water are produced at the Marathon Oil Company's Yates Well Field near Fort Stockton. Burnett hopes the efforts of this team will be able to find ways to treat and reuse roughly 10 percent of the water produced. Getting a team with such mixed areas of expertise and points of view yield insights into a number of areas which need to be explored.

The next step in the process, Burnett says, is to have the individual scientists and engineers develop specific research proposals, which they may want to pursue as part of this project. Soon, the team hopes to present this issue and the expertise of individual members to potential sources of funding.

For more information, visit the TWRI web site at twri.tamu.edu.

Fern Fills Up With Arsenic

A common fern has been found to soak up extraordinary amounts of arsenic without any ill effects, potentially offering a natural way of cleaning up polluted soil and water.

The plant, known as the brake fern, grows naturally in the Southeast and California.

"It looks lush green,'' said Lena Ma, a soil chemist who led the research at the University of Florida at Gainesville. "When I take people to my greenhouse to look at a fern with 8,000 parts per million of arsenic, they can't imagine it's toxic waste."

The brake fern, whose scientific name is Pteris vittata, is the first plant known to accumulate arsenic in extremely high concentrations and still flourish, scientists said.

Ma said that, unlike many ferns, this one likes the sun. It could potentially be cultivated in water and act as a natural arsenic filter. And the fern's arsenic-loving genes could potentially be spliced into other plants.

"The fact that it can take something that is toxic at extremely low concentration and accumulate it at high concentrations is very useful," said Stephen Ebbs, a plant researcher at Southern Illinois University.

Some plants are already used to remove other pollutants from the environment, a process known as phytoremediation. But the plants do not concentrate the toxins as strongly as the brake fern.

Additional powerful accumulators are being tested, but these plants are generally small and thus collect chemicals in very small amounts.

By contrast, the brake fern collects the arsenic in fronds that grow up to five feet long. Unlike roots - where some plants accumulate pollutants - the fronds are easy to harvest when it is time to clear away the arsenic.

Scientists said more work is needed on how to dispose of the plants.

The report of the fern's special properties comes at a time of intensified worry about arsenic in drinking water. Last year, a World Health Organization study said that up to 77 million of Bangladesh's people are at risk of poisoning from naturally occurring arsenic in drinking water.

Recently, U.S. Environmental Protection Agency (EPA) announced a much tighter standard for arsenic in American drinking water, forcing about 3,000 communities to take stronger action.

The Florida researchers were looking for a plant that could take in soil arsenic in high concentrations and then be hauled away. They tested 14 species from an abandoned lumber yard contaminated by arsenic in Archer, Fla. Their tests showed that the brake ferns growing there concentrated up to 200 times the arsenic level in the soil. In other tests, the researchers spiked soil with varying levels of arsenic and found that brake ferns absorbed the poison at 10 to 64 times the original concentrations.

It is unclear if the fern is taking in arsenic as a nutrient or for some other reason.

Edenspace, a company in Dulles, Va., bought rights and has already begun to market the fern commercially.

The Associated Press and Nature journal contributed to this report.

The Contamination Isn't Mine

Potential contamination from mine sites is a large environmental liability for the mining industry and a constant threat to the purity of the land and water adjacent to mines.

A network of small oxygen probes could avert acid damage to the environment and save mining companies millions of dollars. The developers of this probe, the Commonwealth Scientific Industrial Research Organisation (CSIRO), a branch of the Australian government, believe they could change the way mining companies monitor the rehabilitation of mine sites, especially where acidic mine wastes are present.

The presence of oxygen in sulphidic mine wastes results in oxidation of the sulphide minerals and with water forms sulphuric acid. The resulting acid mine drainage causes contamination of surface and groundwater. To reduce or eliminate this contamination, the mineral wastes are commonly covered with earth or synthetic covers.

The CSIRO probe has provided a detailed and accurate assessment of the long-term stability and effectiveness of these covers to prevent oxygen reaching the mineral wastes. The probes can be used at remote sites and the data can be retrieved using mobile phones and modems. Placed at various depths in the earth cover and buried waste, the oxygen probes monitor the effectiveness of the cover by detecting the amount of oxygen present. No oxygen means the covers are doing their job.

"Acid mine drainage caused by the oxidation of sulphidic mining waste is one of the biggest environmental problems faced by the mining industry," says Dr. Brad Patterson, an environmental chemist with CSIRO Land and Water who has worked on the probes for over five years.

Despite concerns about the long term effectiveness of earth coverings, this method is one of the few cost effective solutions to preventing acid leaching from the mine waste into the environment.

Conventional sampling of the tailings for oxygen is done manually and infrequently because taking samples is time consuming and costly. In remote locations, this sampling may only occur two or three times a year. "A lot can happen between sampling done this way," Dr. Patterson says. "The CSIRO probes constantly monitor oxygen levels, giving an accurate interpretation of any changes in oxygen concentration over time. Any failings of the earth cover can be immediately discovered and action taken. Once set up, it is inexpensive to continue long term monitoring."

Dr. Patterson says the probe was tested at an old tailings site in western Australia with high levels of pyrite, iron sulphide, which was covered with a synthetic cover to prevent atmospheric oxygen oxidizing the pyrite and producing acid mine drainage.

"We are confident the probes are sufficiently robust to withstand conditions found in most mine sites around the world," Dr. Patterson said.

Acid mine drainage is a serious problem worldwide, and the CSIRO team hopes that mines in other countries take up this technology.

Environmental News Service contributed to this report.

This article originally appeared in the April 2001 issue of Environmental Protection, Vol. 12, No. 4, p. 10.

This article originally appeared in the 04/01/2001 issue of Environmental Protection.