News
Researchers Discover Bacterium that Detoxifies Chlorinated Pollutants
A bacterium discovered by scientists at the Georgia Institute of Technology may open the door for designing more efficient and successful bioremediation strategies for thousands of sites.
Scientists and engineers have struggled for years with the cleanup of groundwater and subsurface environments contaminated decades ago by unregulated use of the common solvents tetrachloroethene (PCE) and trichloroethene (TCE). These toxic compounds are primarily used in dry cleaning operations and degreasing of metal components. Complicating the situation are natural biotic and abiotic processes that transform these solvents to intermediate substances, such as toxic dichloroethenes, and cancer-causing agents, such as vinyl chloride.
But in a step forward, the Georgia Tech scientists successfully used a naturally occurring bacterium, designated Dehalococcoides strain BAV1, in a pilot study conducted at the Bachman Road residential area, a location contaminated with PCE by a former dry cleaning operation in Oscoda, Mich. The result was complete dechlorination of PCE to ethene within six weeks.
According to lead researcher Frank Loeffler, an assistant professor in the School of Civil and Environmental Engineering, bioaugmentation previously had a rather poor reputation for success. "Now, we have a good example of bioaugmentation at work," he said. "It is a viable option, especially at sites with this type (chlorinated solvents) of contamination. So there's a lot of excitement about this. People have spent a lot of money to clean up those sites without success. Now there's a new hope."
Thousands of similar contaminated sites exist, including military installations where PCE and TCE were once used unregulated as degreasing agents.
Georgia Tech researchers plan to conduct larger-scale studies of BAV1.
"Organisms like BAV1 have an enormous potential to help detoxify chlorinated pollutants," Loeffler said. "But we're just at the beginning of understanding their function, distribution and ecology in the environment."
The Georgia Tech researchers' findings are reported in the July 3, 2003, issue of the journal Nature in an article titled "Detoxification of Vinyl Chloride to Ethene Coupled to Growth of an Anaerobic Bacterium."
Low Costs May Hinder Water Conservation
While others barter for silver and gold, people in the arid West United States may eventually find water to be more valuable.
A study conducted by two professors from the University of New Mexico (UNM) found that low costs of water prevent customers from embracing conservation, according to a Rocky Mountain News article.
"Our thinking hasn't really caught up with the economic good," associate economics professor Janie Chermak said in the article.
To save water during multi-year droughts, many Western cities and utilities have boosted rates and added surcharges to discourage waste. But with water rates still only slightly above those of the 1950s, UNM economics professor David Brookshire said the low cost provides residents little incentive to conserve.
According to the article, Brookshire and Chermak's research shows that a 10-minute shower uses about 15 gallons of water and costs only 3.8 cents in Denver, which equates to about $1.16 per month. Denver's average rainfall is 15 inches a year. The researchers reported that the same daily shower costs $1.09 a month in Albuquerque, N.M., which receives an average of 9 inches of rain each year. In comparison, a month of daily showers costs $2.24 in Minneapolis, which gets 28 inches of rain each year.
Despite the differences in average rainfall, Brookshire said the cost differences are really due to a calculation of what it costs to deliver the water. He said utilities establish rates to break even on costs rather than on the availability of water.
"There's no reason why the price of water couldn't go up and go down just as electric and gas bills go up and down," Brookshire said in the Rocky Mountain News article.
The national average cost of water is $1.50 per 1,000 gallons, according to Jack Hoffbuhr, executive director of the American Water Works Association. "There's not much you can buy in today's economy for that."
Don Wojcik, water policy analyst for the conservation group Land and Water Fund of the Rockies said people are still more likely to respond to a combination of conservation measures, including rebates for low-flow toilets and other water savers. "Every customer has a different motivation. Some are motivated by rate; some are motivated by education," he said.
Manure Management Rules Could Cost Farms More Than $1 Billion
According to a U.S. Department of Agriculture (USDA) study released in June 2003, efforts to comply with new manure management rules designed to reduce water pollution could cost livestock and poultry farms more than $1 billion in annual net income.
The study, conducted by the agency's Economic Research Service (ERS), also found that meeting nutrient application standards will require concentrated animal feeding operations (or CAFOs) to spread manure over a much larger land base than they are currently using. For example, only 18 percent of large hog farms and 23 percent of large dairies are currently applying manure on enough cropland to meet a nitrogen nutrient plan.
"Competition for land on which to spread manure could be severe in regions with high concentrations of animals," the study's authors note.
Crop producers' reluctance to use manure as a fertilizer is a serious impediment to reducing farmers' manure management costs and securing better water quality, according to the researchers. Research to find ways to overcome what crop producers see as the drawbacks of using manure, education on manure's benefits and financial assistance for crop growers willing to use more manure could help, the ERS economists suggest.
In a July 9, 2003, statement, Dr. William J. Weida of the Global Resource Action Center for the Environment, a nonprofit environmental group, said, "There's an obvious, cost-effective solution to the problem, which is to reduce the density of animals in large confined operations, leading to less manure and lower costs. However, what we are likely to see in the short run, as enforcement gets underway, is a regional shift to areas where manure disposal costs are cheaper or to less developed countries that have not enacted environmental regulations."
USDA's study, "Manure Management for Water Quality: Costs to Animal Feeding Operations of Applying Manure Nutrients to Land," is available online at www.ers.usda.gov/publications/aer824/aer824.pdf.
More information on the U.S. Environmental Protection Agency's (EPA) new CAFO rule, which requires large animal farms to improve manure management, is available at cfpub.epa.gov/npdes/afo/cafofinalrule.cfm.
Sea Salt Findings Aid in Climate Modeling
A new scientific study has revealed that tiny, wind-blown sea salt particles drifting into the atmosphere participate in a chemical reaction that may have impacts on climate and acid rain.
The study, by scientists at the Department of Energy's Pacific Northwest National Laboratory and the University of California, Irvine, and published in the July 3, 2003, online issue of Science Express, found that sea salt particles absorb more sulfur dioxide and convert it to sulfuric acid more rapidly than previously thought.
Sulfur dioxide, a form of sulfur, is a byproduct of burning fossil fuels containing sulfur and also is formed when naturally emitted sulfur-containing compounds react in the atmosphere. Once in the air, sulfur dioxide is converted to sulfuric acid, a major component of acid rain and a contributor to haze in the atmosphere. The resulting haze particles can affect clouds, playing an important role in climate.
In the lab, the team of scientists simulated an ocean spray in which wind carries tiny sea salt particles into the atmosphere. They then exposed the salt particles to ozone, water vapor and light, three elements found in the atmosphere. The reaction caused the salt particles to change from a neutral to a base.
"Climate modelers have assumed that the sea salt particles rapidly become acidic in the atmosphere and therefore their climate impact was underestimated," said Alexander Laskin, first author of the Science Express paper and senior research scientist at PNNL. "We now know that under certain conditions they remain basic during the day and therefore their role must be reconsidered."
After struggling for years to understand the effects of sulfur chemistry in climate models, the PNNL-UCI study should provide climate experts with a new understanding of sea salt's role in atmospheric chemistry, allowing them to better predict and capture that information in models used to predict climate change.
"The chemistry discovered in these experiments is not currently included in models of sulfuric acid formation in air, but could help to resolve discrepancies between model predictions and measurements of sulfur dioxide and sulfuric acid, which is essential for understanding the role of these compounds in acid deposition and global climate," said Barbara Finlayson-Pitts, a professor of chemistry at UC-Irvine who participated in the study.
Coral Bleaching Indicative of Stressful Conditions
Coral bleaching recently discovered at all seven of the World Wildlife Fund's (WWF) research sites in the U.S. territory of American Somoa may be a result of global warming-related increases in annual sea surface temperatures, according to an article in the July/August 2003 issue of the organization's publication, Focus.
WWF scientists found that up to 30 percent of the coral reef at the Maloata Bay community reserve has been bleached. Most other sites, including reefs within the U.S. National Park of American Samoa and the Fagatele Bay National Marine Sanctuary experienced between 10 percent and 20 percent bleaching.
Corals "bleach," or lose the colorful symbiotic algae that are necessary to their continued health and survival, when exposed to stressful conditions, commonly increases in sea temperatures.
"The bleaching that we're seeing at WWF research sites in American Samoa's protected areas is further evidence that with the threat of climate change, reef conservation will require ever more innovative responses," said Lara Hansen, a primary investigator for the WWF Climate Change program research project, in the Focus article. "Marine reserves are essential -- they protect reefs from destructive fishing and collecting practices -- but they can't prevent global warming. Climate change-related stresses have to be approached in other ways. WWF's research here will help us assess what steps we can take to conserve coral reefs in the face of climate change."
While beautiful to look at, coral reefs are also home to many oceanic species, serving as a resource for human food supplies and economies.
Study Documents Ocean Mixing on Hawaiian Ridge
Scientists are gaining new understanding of ocean mixing, complex motions of seawater that span large-scale phenomena down to small turbulence that serve a key role in redistributing heat throughout the oceans, and how the mixing process occurs.
Researchers representing six institutions, including Scripps Institution of Oceanography at the University of California, San Diego, describe ocean mixing in unprecedented detail, capturing intriguing phenomena such as undersea waves that spanned nearly 1,000 feet in a research paper published in the July 18 issue of Science. Using an array of technologies and instruments, scientists in the Hawaii Ocean-Mixing Experiment (HOME), an $18 million National Science Foundation-sponsored project, focused on pinpointing, dissecting and analyzing ocean mixing.
The researchers chose to study the Hawaiian Ridge, a 1,600-mile largely submerged volcanic mountain chain that stretches from the Big Island of Hawaii to Midway Island, due to its rough topography, including large underwater mountains and valleys. Such areas are sometimes referred to as the "stirring rods" of the oceans. Prior to the HOME project, areas like the Hawaiian Ridge were thought to be a major energy pathway for ocean mixing and turbulence. Traveling across the Pacific, oceanic tides crash upon the ridge and dissipate. To help explain how such areas mix warm, low-latitude waters and cool polar waters, HOME investigators undertook a comprehensive survey to track ocean energy and turbulence.
"Understanding where, when and how turbulent mixing takes place in the ocean is one of the most outstanding problems in oceanography," said Eric Itsweire, director of NSF's physical oceanography program, which funded the research. Even small mixing processes, occurring at centimeter scales, largely account for ocean stratification and affect climate.
"Places like the Hawaiian Ridge are thought to be hot spots for ocean mixing. HOME was designed to understand how energy from tides is dissipated in the abyssal ocean through complex interactions with the rough-bottom topography associated with mid-ocean ridges," Itsweire said.
Using the research vessel Roger Revelle, the towed instrument SeaSoar, a new Doppler sonar developed by Scripps scientist Robert Pinkel, and a variety of other instruments and equipment, the scientists found that the Hawaiian Ridge is indeed a site with increased ocean mixing. They documented undersea internal wave energy that was enhanced 10 times as compared with normal open ocean areas.
"One of the triumphs of the HOME experiment was being able to measure the cascade from thousands of meters down to centimenter scales," said Dan Rudnick, an oceanographer at Scripps and lead author of the Science paper. "I don't think this effort is rivaled in terms of measuring detailed dissipation over a topographic feature."
With the details of the cascading processes described in the Science paper, the co-authors helped further close the gap of how energy is dissipated in ocean mixing. Still, the paper notes that the energy puzzle is not completely solved with these results. More energy for ocean mixing must be found elsewhere.
"Our conclusion is interesting because we found that there was certainly a lot of energy loss occurring at the Hawaiian Ridge, but much of it propagates away and doesn't get dissipated at the ridge. So we're approaching closure of this phenomenon," said Rudnick. "But until we have a firmer understanding of this process, until we get a better handle on mixing, climate models will be of limited use."
Planning for the HOME project began in 1996. The final field phases of the project were concluded last month. Scientific analysis of the data set is planned through 2005.
WWF Report: U.S./Canada Fail to Regulate Salmon Farming
Nearly a decade after the United States and Canada agreed to regulate salmon farming and protect the species, a new report released in May by the World Wildlife Fund (WWF) and the Atlantic Salmon Federation indicates that neither country has addressed the environmental impacts of salmon farming nor helped reverse the decline of wild Atlantic salmon, according to an article in WWF's July/August 2003 issue of Focus.
Documenting the failures of all seven of the world's largest salmon-producing countries, the report gave the countries an average score of two, on a scale from one to ten, based upon their efforts to live up to the agreement to regulate the industry and safeguard threatened wild salmon populations. The United States was ranked second to last in the study, while Canada was ranked third overall. The five other countries included in the report were Norway, Scotland, Ireland, Iceland and the Faroe Islands of Denmark.
Fish farming, also known as salmon aquaculture, produces nearly 240 million pounds of fish each year in the United State and Canada. Farmed fish now outnumber wild fish 48 to one in the North Atlantic Ocean.
Emerging as a lucrative business in the early 1990s, expansion of fish farming industries has generated new biological threats to the species, particularly when farmed fish escape and carry disease and parasites to wild salmon. Combined with overfishing, these biological threats are heavily impacting the species and causing worry as to its survival. In the 1980s, an estimated 800,000 Atlantic sea winter salmon returned to the eastern United States and Canada each year to spawn in rivers. Today, only about 80,000 make it back, indicating a decline of more than 90 percent.
Yet WWF scientists are optimistic that quick proactive steps could reverse the trend. "With continued support and action by WWF activists, and through science-based research, we can work with governments and industries to help stem the decline in wild Atlantic salmon stocks," Grasso said in the Focus article.
While some species have been put on the Endangered Species List in Oregon, Washington and Northern California, most Pacific salmon species are not endangered, a trend the WWF hopes to see continue.
In 2002, Alaska's statewide commercial salmon fisheries program became the first "sustainable" fishery certified by the Marine Stewardship Council (MSC), and independent certifier founded by WWF and Unilever, one of largest commercial buyers of seafood. Reaching all the way to the consumer, an MSC label on a seafood product shows that it comes from a fishery that uses ocean-friendly methods. To date, more than 100 major seafood processors, traders and retailers have pledged their support of the MSC certification program. A major California salmon fishery hopes to become the second MSC-certified fishery in the United State later this year.
Texas Researchers Aid Residents with OSSFs
In a region where many rural residents rely both on individual wells for drinking water and the use of on-site wastewater treatment systems to treat and dispose of domestic wastes, researchers with the Texas A&M University (TAMU) System and the Texas Water Resources Institute (TWRI) are working to improve training and continuing education among residents using on-site sewage facilities (OSSFs).
In one of several applied research and demonstration projects that examine the performance of OSSFs, Bruce Lesikar of the Cooperative Extension and the Biological and Agricultural Engineering Department and Suresh Pillai recently completed a study to examine the extent to which OSSFs treat and remove specific microbial pathogens from the waste stream. The study tested how well a sand filter and a constructed wetland might lower levels of Salmonella spp. and bacteriophages. A conservative tracer, bromide, was used to understand the fate and transport of these contaminants with these OSSFs.
The researchers found that viruses were reduced by 3-logs in the constructed wetland and 2-logs in the sand filter. Still, results of the tracer tests suggest that the removal of bacterial pollutants may vary greatly depending on site-specific conditions that influence such processes as adsorption, desorption and the inactivation of microorganisms.
Rick Weaver, a researcher in the TAMU Soil and Crop Sciences Department, also is working with OSSF issues. He is currently studying the extent to which constructed wetlands may be a viable strategy for on-site wastewater treatment, as well as examining the role of microbes in successfully treating domestic wastewater. With assistance from TWRI, Weaver and Amanda Richmond Richter, a graduate student, sampled water quality at several East Texas sites where constructed wetlands have been used for on-site wastewater treatment. Richter's graduate research examined both the effects of using various substrates to line wetland beds (gravel and other media), as well as whether non-traditional disinfection methods (ultraviolet light) could be effective in treating effluents.
Also working extensively with OSSFs, John Jacob, a TWRI Associate and a scientist with Cooperative Extension and the Texas Sea Grant Program, developed a series of detailed geographic information systems that allow regulators, homeowners and industry professionals to screen specific sites within counties that may be poor locations for septic systems. Sites are evaluated based on the slope and the depth to groundwater. Jacob also has created a Web-based class that provides instruction about how to evaluate sites and soils to determine if they are suitable for OSSFs. More information is available at www.urban-nature.org.
TWRI has developed a wealth of resources dealing with on-site wastewater treatment on its Web site at twri.tamu.edu.
This news section originally appeared in the September/October 2003 issue of Water & Wastewater, Volume 3, Number 5.
This article originally appeared in the 09/01/2003 issue of Environmental Protection.