Environmental News - American Chemical Society


Environmental News - American Chemical Societypubs.acs.org/doi/pdf/10.1021/es053271oby KS Betts - ‎2005May 15, 2005 -...

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Environmental ▼ News Budget cuts raise questions about U.S. DOE priorities

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THE UNIVERSIT Y OF GEORGIA SAVANNAH RIVER ECOLOGY L ABORATORY

wo potential casualties of tal Research (BER) section of DOE’s funding the lab was transferred to the Department of Energy’s Office of Science. “Our budget has BER. SREL was then faced with the (DOE) proposed fiscal year been flat, which means that our task of restructuring its programs 2006 (FY ’06) budget are funding budget has been decreasing when so that they aligned “with the very for the Savannah River Ecology you factor in the cost of living,” exnarrowly focused mission of [BER’s] Laboratory (SREL) and research plains Aristides Patrinos, BER’s diEnvironmental Remediation Sciinto surficial science—a new area rector. We’re not left with any fat ence division,” Bertsch explains. of study for DOE that focuses on rawhatsoever. We are now trimming Nevertheless, SREL was “very dionuclide behavior and has been meat and bone.” willing and flexible to make trandeemed important by scisitions and shifts” to acentists inside and outside commodate BER’s needs, the agency. Both cuts are Patrinos says. Both Patriraising concerns from envinos and Bertsch say that ronmental scientists as well SREL came out “very well” as policy makers. in the two BER-sponsored “SREL is a valuable napeer reviews. tional resource and, in my DOE’s FY ’06 budget also opinion, one of the premier has no funding for surficial ecological research organiscience, which focuses on zations in the world,” says the behavior of radionuBrian Looney, an advisory clide contaminants at and scientist with the Savannah near the surface, Patrinos River National Laboratory, says. BER had been gearing a separate facility. SREL up to broaden its research The Tims Branch–Steed Pond system at the Department of scientists have “an incrediportfolio by studying surfiEnergy’s Savannah River reservation is a top candidate for ble record of pioneering recial contaminants, and the DOE research into the effects of surficial contamination, search and are recognized Tims Branch–Steed Pond which puts wildlife at risk. However, DOE’s FY ‘06 budget by the frequent use of their system at the Savannah has no funding for the Savannah River Ecology Laboratory or surficial science. research [books and paRiver site was a top candipers] in the ecology classdate for SREL funding. SedSREL is operated by the Unirooms of universities everywhere,” iments in the river system, which is he adds. If DOE’s FY ’06 budget is versity of Georgia, which requires subject to episodes of both flooding approved by Congress, it would end DOE’s support to keep the lab runand drying, remain contaminated nearly 54 years of federal funding ning, says SREL’s director, Paul with ~70% of the 48.4 tons of urathat began with the Atomic Energy Bertsch. nium left over from fuel fabrication Commission, which eventually was Bertsch and Patrinos agree that operations in the 1950s and 1960s, subsumed by DOE. SREL’s funding problems are part according to SREL. The sediments Funding SREL makes good sense of the fallout of DOE’s shifting priare also contaminated with nickel, as part of DOE’s research portfolio orities. DOE’s Office of Environcadmium, copper, chromium, and because the Savannah River site mental Management funded SREL lead, Bertsch points out. has contamination in the surface from its founding in 1989 until FY Surficial contaminants actuwaters, which is unique in terms ’03, paying for research into phyally pose a more immediate risk of DOE’s problem areas, adds Jim toremediation, bioremediation, than the subsurface contaminaTiedje, a distinguished professor of and in situ stabilization. But when tion that DOE has focused on fundcrop and soil sciences and of microEnvironmental Management’s mising, Bertsch contends. The topic biology and molecular genetics at sion was revised to concentrate fits well with the emerging area of Michigan State University. on accelerating cleanups of concoupled hydrobiogeochemical proThe decision to eliminate SREL taminated, Cold-War-era weapons cesses, he explains. emerged from the 10% hit imposed sites (Environ. Sci. Technol. 2002, “Processes controlling radioon the Biological and Environmen36, 136A–137A), responsibility for nuclide fate are highly dependent 216A ■ ENVIRONMENTAL SCIENCE & TECHNOLOGY / MAY 15, 2005

© 2005 American Chemical Society

such research at the Savannah River site, adds Tiedje, who was on the subcommittee charged with studying the issue. Patrinos says he recognizes that surficial science is important for DOE, but he adds that the risk posed by any pollutants depends on their toxicity. At present, DOE has no set timetable for when it may tackle surficial contaminants. Like many of the intractable issues whose timetables were reset by the move to accelerated cleanups, they may not be addressed until 2020 or 2030, Bertsch says. These are just the kinds of difficult issues that rely on the longer-term basic ecological research that managers at the Savannah River site see as very important but that does not fit with BER’s mission of basic science, Bertsch says. —KELLYN S. BETTS

Diet controls methylmercury in fish eggs

PAUL DRE VNICK

A fish’s diet before she spawns— not, as previously assumed, the amount of methylmercury stored in her body—controls the amount of methylmercury in her eggs. This finding means that the concentration of methylmercury in fish eggs is highly sensitive to seasonal changes in dietary methylmercury, according to research published in this issue of ES&T (pp 3585–3591).

Researchers found that methylmercury in these fathead minnow eggs comes directly from the mother fish’s diet, not from the mercury stored in her body.

Little is known about the toxicological effects of methylmercury on the early developmental stages of fish, explains lead author Chad Hammerschmidt at the University of Connecticut, Groton. However, James Wiener, a fisheries biologist at the University of Wisconsin, says recent studies show that methylmercury in adult fish has adverse effects at lower levels than expected. This new finding suggests that the egg, “a handful of cells that undergoes profound neurological changes, might be vulnerable to the developmental effects of methylmercury, a neurotoxin,” he adds. The new insight might eventually have practical implications, says author Mark Sandheinrich at the University of Wisconsin, La Crosse. For example, reservoir managers may be prompted to time water releases to minimize methylmercury levels just before spawning season.

News Briefs Gloom . . . with a window of opportunity

Approximately 60% of the earth’s ecosystem services—the term ecologists use for the processes required to support life, including fresh water, soil loss, nutrient cycles, and biodiversity—are being degraded or used unsustainably, according to the Millennium Ecosystem Assessment Synthesis Report, which was released in late March. The report was put together by the UN Environment Programme (UNEP) with the aid of more than 1300 social and natural scientists from 95 countries, the largest body of experts ever assembled to assess knowledge in this area. They collectively warn that the harmful consequences of this degradation could grow significantly worse over the next 50 years. However, “it is still possible to ease the strain on our planet by making significant changes in policies, institutions, behavior, technology, and knowledge,” says Timothy Wirth, president of the UN Foundation, one of the major funders of the assessment. To view the report, go to www.millenniumassessment.org.

Plant lacks typical pathogen defense

Most plants have natural mechanisms to fend off infection, but David Salt and his colleagues at Purdue University have shown that the alpine flower Thlaspi does not have those mechanisms and instead accumulates metals to resist pathogens, according to research published in Plant Physiology (2005, 137, 1082–1091). Thlaspi thrives in nickel-containing soil, and this insight may help researchers to develop crops for phytoremediation.

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on the nature of the local biogeochemical environment,” says Jon Chorover, associate professor of environmental chemistry at the University of Arizona, Tucson. “Since it is present in a humid, forested system, radionuclide contamination at [the Savannah River site] is subjected to significant interaction with the resident biota and organic matter. . . . Although biology likely plays an important role in contaminant fate throughout the DOE complex, it is paramount at [Savannah River] where the tight coupling between hydrologic dynamics and the activities of plants and microbes strongly impact geochemical cycling.” Surficial research also costs less to carry out than research into the deeper subsurface. This is one of the reasons that a subcommittee of BER’s Advisory Committee recommended in April 2004 conducting

Environmental▼ News Hammerschmidt and Sandheinrich fed diets contaminated with methylmercury to young fathead minnows, the “lab rats” of fish studies. When the fish matured, some were fed a diet spiked with different concentrations of methylmercury. The methylmercury of eggs from minnows that were fed the spiked food reflected the food concentrations, not the minnows’ body burdens. Some field data support the lab results, says Sandheinrich. The methylmercury budget of Max Lake in Wisconsin dropped in 1991 because of a change in water chemistry. Mean levels of total mercury in the fish carcasses were the same before and after the water change. But methylmercury concentrations in the eggs of fish collected beforehand were almost twice those in

eggs collected afterward, he notes. “This is the kind of information that investigators couldn’t tease out of a field study,” says Wiener. “Now we know that early life exposure may depend on the abundance of methylmercury in the maternal diet. Methylmercury in lakes systematically varies from peaks to valleys. The timing of spawning could make a difference to what’s in the eggs,” he adds. In the past, fish were mainly viewed as a pathway for mercury exposure to people and wildlife. Biologists only recently started to study the effects of methylmercury on fish, Wiener points out. Hammerschmidt, Sandheinrich, and their colleagues previously showed that exposure to methylmercury at environmentally relevant levels affects the reproductive success of

fish by reducing the production of testosterone and estrogen. Subsequently, this reduces the number of fish that spawn, increases the time it takes them to spawn, and decreases egg production (Environ. Sci. Technol. 2002, 36, 877–883; 2003, 37, 4390–4396). Hammerschmidt cautions that changes in the amount of methylmercury transferred to the eggs will not directly affect the body burden in fish as they grow. This is because egg concentrations are far lower than fish body burdens. For example, eggs contain picogram quantities of methylmercury, whereas oneyear-old fish can accumulate microgram levels. However, the data do show that some important aspects of aquatic systems respond quickly to changes in methylmercury loadings, he says. —REBECCA RENNER

The densities of key neurotransmitter receptors in mammalian brains may be a good early warning of neurotoxic damage from methylmercury (MeHg), according to research in this issue of ES&T (pp 3580–3584). The findings are based on a Canadian study examining neurotoxic effects in wild river otters (Lontra canadensis), who are exposed to low levels of MeHg throughout their lives because of their exclusive fish diet. However, researchers seem to be seeing opposite effects in other species. Above a certain threshold, MeHg poisoning causes focal lesions in specific regions of adult mammals’ brains, such as the cerebral cortex. In developing fetuses, the effects are even more severe. Brain lesions are more widespread, and damage occurs to the central nervous system, as was observed in children of mothers exposed to high levels of MeHg in Japan in the early 1970s. In the new study, researchers looked at the responses to MeHg in the brains of wild river otters before they showed any obvious signs of neural injury. “What we have

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Early warning sign of methylmercury poisoning?

Studies of wild river otters, whose fish diets expose them to low levels of methylmercury, indicate that the density of neurotransmitters in the brain may be an early warning of injury.

seen was more a continuous effect, rather than a typical threshold response,” says Laurie Chan, corresponding author and associate professor at the Centre for Indigenous Peoples’ Nutrition and Environment at McGill University (Canada). Chan and his colleagues analyzed the mercury content in the brains of wild river otters trapped in Nova Scotia and Ontario. Because lake characteristics in Nova Scotia favor mercury methylation, otters from this region had significantly higher MeHg burdens than those from Ontario—2.78 versus 0.94 micrograms per gram in the cerebal cortex. The higher MeHg levels correlate with lower

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densities of two different neurotransmitter receptors in the cerebral cortex. These receptors belong to the dopaminergic and cholinergic systems, which are linked to key neural functions, such as cognition, learning and memory, and motor control. “Even if we don’t know yet exactly in what ways the functioning of the central nervous system is modified, densities of neurotransmitter receptors are relevant physiological parameters,” says Teresa Coccini, a toxicologist studying molecular mechanisms underlying MeHg neurotoxicity at the Salvatore Maugeri Foundation (Italy). “If these densities are found to be altered [in wild animals], this for sure tells us something. It is therefore important to know when these parameters change,” she adds. Earlier work from Chan and colleagues on minks also found that with increasing MeHg levels, densities of dopaminergic receptors drop, but those of cholinergic receptors increase, even though these animals inhabit the same regions as the otters. However,

minks do not exclusively live on fish. “It is very interesting to compare the responses of different species,” says Chan. With that in mind, Chan plans to quantify possible neurochemical changes in marine mammals because they can bioaccumulate even higher concentrations of persistent neurotoxicants. Coccini’s own studies with rats in the lab also found an increase of cholinergic receptors in the brain and in blood, where lymphocytes also express these receptors, following exposure to MeHg (Environ. Health Perspect. 2000, 108,

29–33). Although measurements such as those performed by Chan and colleagues may prove useful as biological markers to assess environmental health, Coccini cautions that careful validation studies and a better understanding of the functional role of changes in receptor densities are still needed. Nevertheless, Chan is convinced that their new data challenge the longheld concept of a fixed-threshold response to MeHg. “In the future, we will be in a better position to frame risk-assessment paradigms.” —ORI SCHIPPER

A significant improvement in leather processing

J. R AGHAVA R AO

In research published in this issue of ES&T (pp 3776–3783), scientists from India’s Central Leather Research Institute (CLRI), the largest institution of its kind in the world, describe an important step forward in reducing the water pollution from leather processing. Because the technology is green and shows potential for increasing the economic value of leather, experts believe it has real promise.

The Central Leather Research Institute’s new technology for dehairing hides results in larger pieces of leather.

Typically, sodium sulfide and lime are used to remove hair from cowhides in the production of leather. The hair is completely degraded by the process, but a sludge is left behind, says Dennis Shelly, the director of the Leather Research Institute at Texas Tech University. This protein-rich sludge is the top pollution problem of the industry

and is a much bigger concern than wastes that contain the chromium used in leather tanning, he says. “From a waste-loading perspective, the dehairing issue is a larger magnitude,” explains Gary Sayler, director of the University of Tennessee at Knoxville’s Center for Environmental Biotechnology. “You must remember that many of the very active countries in tanning are developing countries with much more limited capacity for treatment, let alone advanced waste treatment.” CLRI’s new enzyme-based technology preserves the hair, and this should significantly decrease the environmental impact of leather processing, Shelly says. “If you can save the hair without dissolving it, you will reduce the [chemical] oxygen demand of the waste stream. And that’s moving in the right direction,” Shelly explains. CLRI says that the process, which uses the commercially available enzyme Biodart, reduces the chemical oxygen demand of the resulting wastewater by 53% and total solids by 26%. “Solid waste management [is] the need of the hour in the tanning industry,” says Md. Rafiq, director of KKSK Leather Processors, Ltd., an Indian firm that has been field-testing CLRI’s new technology and deems it promising. “Ever since the [Indian] Supreme Court ordered the closure of more than

News Briefs Potent neurotoxin found in blue-green algae

For the first time, researchers have found that unrelated species of cyanobacteria produce a toxin associated with neurodegenerative diseases, according to a paper published in the April 5 Proceedings of the National Academy of Sciences (2005, 102, 5074–5078). The researchers say that “the ubiquity of cyanobacteria in terrestrial, as well as freshwater, brackish, and marine environments, suggests a potential for widespread human exposure.” The researchers found that, given the right conditions, all known types of cyanobacteria produce the neurotoxin -N-methylamino-L-alanine (BMAA), which has been found in the brains of people with Alzheimer’s and a paralytic disease similar to Parkinson’s. Because eutrophication and rising global temperatures could trigger increases in the extent and duration of algal blooms in waters worldwide, the researchers recommend monitoring BMAA concentrations in drinking waters contaminated by cyanobacterial blooms.

Climate-change scientists share prize

The 2005 Tyler Prize for Environmental Achievement was awarded in April to two scientists whose pioneering work set the stage for climate-change science. C. David Keeling, a professor at Scripps Institution of Oceanography, has been collecting data since 1958 that show the gradual buildup of CO2. He also developed techniques for measuring atmospheric CO2 concentrations. Lonnie Thompson, a professor of geological sciences at Ohio State University, was the first scientist to study the tiny samples of ancient atmospheres preserved in the glaciers in tropical areas. By collecting these samples, Thompson has documented the rapid pace at which tropical glaciers are disappearing. For more information, go to www.usc.edu/dept/LAS/tylerprize.

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Environmental▼ News 500 tanneries in and around Tamil Nadu [in 1996], the tanners in India are really looking for ‘greener’ leather processing,” says Jonnalagadda Raghava Rao, the paper’s corresponding author. “Development and commercialization of clean and green leather processing is a major thrust of our group, as well as [the] institute’s top priority,” he adds. Only China’s leather industry is larger than India’s, Shelly says. He estimates that the leather industry is worth at least $1 trillion worldwide, annually. The new technology helps sidestep some of what Rao calls “do–undo” approaches in leather processing. For example, the conventional approach uses lime to swell hides, then removes the compound to reduce the swelling. CLRI’s new enzymatic technology avoids this step. Moreover, it can be coupled

with an enzyme-based fiber-opening step so that the process “completely avoids ‘undoing’ steps,” Rao says. KKSK Leather Processors is also testing this enzyme-based fiber-opening technology. CRLI’s new dehairing process also uses significantly less production water—“practically none,” Sayler notes. “I believe this is an approach that can be used many places where bulk production proteases are available. These enzymes are cheap and easy to make and are very stable,” he says. For all of these reasons, that technology “will be easier to put in place than chromium alternatives,” he says. An important side benefit of the enzymatic dehairing process is that it leaves more product, increasing the area of the leather by 8% compared with conventional processes, according to Rao. He estimates that

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tanners could get the equivalent of about U.S.$265 for each metric ton of raw hides they process. An increase of 8% is significant, Shelly agrees. The technology is also likely to be marketable because a growing number of automotive and furniture manufacturers, particularly in Europe, are demanding that leathers be produced using the greenest possible technologies, he says. “There are companies, like Mercedes, that require a nonchrome tanned leather,” he points out. CLRI is also actively investigating alternatives to the chromium used in conventional tanning, Rao says. The institute has developed a method based on vegetable tannins (Environ. Sci. Technol. 2004, 38, 871–879) that they are testing as part of an entirely “bio-based” method of leather processing, he says. —KELLYN S. BETTS