News this Week

Science  01 Aug 2008:
Vol. 321, Issue 5889, pp. 620
  1. CHEMISTRY

    New Catalyst Marks Major Step in the March Toward Hydrogen Fuel

    1. Robert F. Service

    Climate change concerns, high gas prices, and a good deal of international friction would fade if scientists could learn a trick every houseplant knows: how to absorb sunlight and store its energy in chemical bonds. What's needed are catalysts capable of taking electricity and using it to split water to generate hydrogen gas, a clean fuel. Unfortunately, the catalysts discovered so far work under harsh chemical conditions, and the best ones are made from platinum, a rare and expensive metal.

    No more. This week, researchers at the Massachusetts Institute of Technology (MIT) in Cambridge led by chemist Daniel Nocera report online in Science a new water-splitting catalyst that works under environmentally friendly conditions (www.sciencemag.org/cgi/content/abstract/1162018). More important, it's made from cobalt and phosphorus, fairly cheap and abundant elements. The new catalyst needs improvements before it can solve the world's energy problems, but several outside researchers say it's a crucial development.

    “This is a great result,” says John Turner, an electrochemist and water-splitting expert at the National Renewable Energy Laboratory in Golden, Colorado. Thomas Moore, a chemist at Arizona State University in Tempe, goes further. “It's a big-to-giant step” in the direction of powering industrial societies with renewable fuels, he says. “I'd say it's a breakthrough.” Meanwhile, on pages 671 and 676, other groups report related advances—a cheap plastic fuel cell catalyst that converts hydrogen to electricity, and a solid oxide fuel cell catalyst that operates at lower temperatures—that affect another vital component of any future solar hydrogen system.

    English chemists first used electricity to split water more than 200 years ago. The reaction requires two separate catalytic steps. The first, the positively charged electrode, or anode, swipes electrons from hydrogen atoms in water molecules. The result is that protons (hydrogen atoms minus their electrons) break away from their oxygen atoms. The anode catalyst then grabs two oxygen atoms and welds them together to make O2. Meanwhile, the free protons drift through the solution to the negatively charged electrode, or cathode, where they hook up with electrons to make molecular hydrogen (H2).

    Water power.

    Cobalt-phosphorus catalyst opens the way to using sunlight to extract hydrogen from water.

    CREDIT: JOSEPH SOHM/VISIONS OF AMERICA/CORBIS

    The hard part is finding catalysts that can orchestrate this dance of electrons and protons. The anode, which links oxygens together, has been a particularly difficult challenge. Platinum works but is too expensive and rare to be viable on an industrial scale. “If we are going to use solar energy in a direct conversion process, we need to cover large areas,” Turner says. “That makes a low-cost catalyst a must.” Other metals and metal oxides can do the job but not at a neutral pH—another key to keeping costs down. In 2004, Nocera's team reported in the Journal of the American Chemical Society a cobalt-based catalyst that did the reverse reaction, catalyzing the production of water from O2, protons, and electrons. “That told us cobalt could manage multielectron and proton-coupled reactions,” Nocera says.

    Unfortunately, cobalt is useless as a standalone water-splitting anode because it dissolves in water. Nocera and his Ph.D. student Matthew Kanan knew they couldn't get over this hurdle. So they went around it instead. For their anode, they started with a stable electrode material known as indium tin oxide (ITO). They then placed their anode in a beaker of water, which they spiked with cobalt (Co2+) and potassium phosphate. When they flipped on the current, this created a positive charge in the ITO. Kanan and Nocera believe this initially pulls electrons from the Co2+, turning it first to Co3+, which pairs up with negatively charged phosphate ions and precipitates out of solution, forming a film of rocklike cobalt phosphate atop the ITO. Another electron is yanked from the Co3+ in the film to make Co4+, although the mechanism has not yet been nailed down. The film forms the critical water-splitting catalyst. As it does so, it swipes electrons from hydrogen atoms in water and then grabs hold of lone oxygen atoms and welds them together. In the process, the Co4+ returns to Co2+ and again dissolves into the water, and the cycle is repeated.

    The catalyst isn't perfect. It still requires excess electricity to start the water-splitting reaction, energy that isn't recovered and stored in the fuel. And for now, the catalyst can accept only low levels of electrical current. Nocera says he's hopeful that both problems can be solved, and because the catalysts are so easy to make, he expects progress will be swift. Further work is also needed to reduce the cost of cathodes and to link the electrodes to solar cells to provide clean electricity. A final big push will be to see if the catalyst or others like it can operate in seawater. If so, future societies could use sunlight to generate hydrogen from seawater and then pipe it to large banks of fuel cells on shore that could convert it into electricity and fresh water, thereby using the sun and oceans to fill two of the world's greatest needs.

  2. RISK ASSESSMENT

    Regulators Seek to Redefine 'Working Life'

    1. David Malakoff*
    1. David Malakoff is a science writer living in Alexandria, Virginia.

    Figuring out if millions of American workers are at risk from on-the-job exposure to hazardous chemicals has long been a thorny scientific problem. Last week, it became a prickly political issue too. Two senior Democrats in Congress demanded that the Bush Administration kill a proposal to change how the Department of Labor conducts the risk assessments that underpin worker safety regulations. Senator Edward Kennedy (D-MA) and Representative George Miller (D-CA), who lead Congress's labor committees, charged that a leaked draft of the proposal shows that the Administration is rushing to “slip through a rule that may have profound negative impacts on worker safety” before leaving office in January.

    Labor Department officials reject the charge, saying that the changes they're proposing—including one that could reduce a worker's estimated exposure to dangerous substances—are designed to make risk assessments more “consistent, reliable, and transparent.” And they say that if the new guidelines move forward, there will be plenty of time to hash out scientific issues.

    Critics are skeptical. “There certainly could be an interesting and worthwhile debate about the technical assumptions that go into risk assessment, but you don't do that by shoving new guidelines out at the last minute,” says David Michaels, an epidemiologist and worker safety advocate at George Washington University in Washington, D.C.

    Sparks fly.

    Before leaving office, the Bush Administration wants to change rules for calculating exposure to chemicals in the workplace, a key factor in risk calculations that underlie health regulations.

    CREDIT: NATALIE FOBES/CORBIS

    The Administration had not publicly released the proposal as Science went to press. But the draft leaked to The Washington Post calls for several changes in how two agencies, the Occupational Safety and Health Administration (OSHA) and the Mine Safety and Health Administration, approach risk assessments. One is bureaucratic: It would require the agencies to do more to notify the public—a move critics claim is designed to entangle new rules in red tape.

    Another more controversial section calls for altering how regulators calculate a key risk measure called “working life.” Currently, in most cases the agencies assume that a person works for 45 years (from age 20 to 65) and use that span to calculate potential total exposure to hazardous substances. From that, they estimate how many workers might get sick or die.

    But that approach likely overstates risks, the draft says, because few workers stay in the same job for 45 years. To back that view, it includes statistics showing that less than 5% of American workers stay with the same employer for even 35 years. “Thus, the actual exposure of the overwhelming majority of workers will likely be substantially less” than current methods estimate, according to the proposal. Instead, it calls for basing assessments on studies of how long workers actually work each day, and how long they stay in the same industry.

    That may not be a bad idea—but it's not good enough to dump the 45-year assumption, says Adam Finkel, a former OSHA regulator who now teaches at the University of Medicine and Dentistry of New Jersey in Piscataway. For one thing, regulators often don't have the time or money to collect such detailed information—if it actually exists, he says. And just because workers change jobs doesn't necessarily mean that their exposure risks go down, he adds. “Sandblasters who report a change of employer very often remain sandblasters, and are unlikely to become stockbrokers,” he wrote in a 2002 paper in the journal Human and Ecological Risk Assessment. Finally, he says regulators will always need some yardstick for comparing risks. “The EPA [Environmental Protection Agency] uses 70 years,” he notes, “and while you can argue whether 45 years is the right number, it's not a bad one if you want to err on the side of safety.”

    The proposal also fails to make transparent exactly what “cookbook” the government will follow in developing the assumptions that go into every risk assessment, says toxicologist Joseph Rodricks, head of health sciences at ENVIRON, an Arlington, Virginia-based consulting firm. “To do this correctly, you'd need to lay out all the science and then say how you are going to navigate the maze,” he says. “This doesn't.”

    Even if the new risk rules are adopted, experts point out that they won't be the last word on worker safety regulations. Historically, they say OSHA has loosened the exposure limits suggested by risk assessments if the government decides industry can't afford to meet them or the technology doesn't exist. Finkel says “that's exactly what happened” in developing the only major new workplace rule written by the Bush Administration, which limits exposure to the carcinogen hexavalent chromium produced by welding, electroplating, and other industrial processes. “They looked at the risk assessment number,” he says, “and then pretty much ignored it.”

  3. LINO BARAÑAO INTERVIEW: New Minister Raises Expectations for Science in Argentina

    1. Jocelyn Kaiser,
    2. Eliot Marshall

    Last December, Argentina created a new ministry of science with an independent budget. The driving force behind this move—the new president, Cristina Fernández de Kirchner—then named cell biologist Lino Barañao, 54, the nation's first science minister. The elevation of science and the promotion of an active researcher are signs that life is looking up for researchers in Argentina 6 years after a devastating currency crash. During that crisis, grants went unpaid and talented researchers fled the country for jobs abroad. Now, a fellowship program designed to encourage young Argentine scientists to come home is celebrating its 400th recruit.

    CREDIT: GREG SCHALER

    Expectations for science under Barañao are booming. “He's one of us. This is the first time we've had a real scientist reach such a position. We want him to succeed,” says University of Buenos Aires (UBA) molecular biologist Alberto Kornblihtt.

    Barañao, a faculty member at UBA, served simultaneously until last year as director of the country's main research grant-funding body, the Agencia Nacional de Promoción Científica y Tecnológica. (Another agency, CONICET, pays salaries and stipends.) As newly appointed science chief, Barañao has announced a plan to upgrade and build new research facilities—easing a severe space crunch, scientists say—and has pledged to increase science and technology spending from roughly 0.65% to 1% of gross domestic product for both basic and applied research by 2010. In addition, he supports corporate tax breaks for investing in research and development (R&D). Some researchers say they're hoping that CONICET under the new regime will raise scientists' salaries 20% to 30%. Barañao, though not giving details on possible salary changes, says he plans to target funds for fields with industrial promise, including biotechnology, nanotechnology, and computing.

    Indeed, the country's scientific leaders, including Kornblihtt, have long argued that boosting basic science and getting companies in Argentina to invest in research would help build a more independent and stable economy. Barañao himself has worked with industry: He served as an adviser to an Argentine biotech company that created the country's first transgenic cattle in 2002 to make human growth hormone and other therapeutic proteins. That seemed daring at the time, he says, as many university scientists were afraid that an association with industry could hurt their careers.

    Barañao shared his thoughts on Argentina's ambitions in a brief interview with Science last month.

    On Argentine attitudes

    L.B.:We have a strong background in terms of basic science. We are the only Latin American country that has produced three Nobel Prize winners. … Usually, people associate science with a kind of cultural value. Now we have to show that this accumulation of knowledge can lead to an accumulation of wealth.

    Luring scientists to industry

    L.B.: [Most scientists are government employees.] The average amount they receive is up to $30,000 per year for equipment and supplies. [Under a new universityindustry collaborative program], they can receive four times more; they can have more students. … When we opened a call for applicants 2 years ago, we were not very optimistic; we thought it would be difficult to have people from different institutions and different cultures working together. But we received 120 proposals. … So there has been a change in the way people think about this. They know they have to cooperate, … and they have to work with companies.

    Targeted investment

    L.B.: Technology-based enterprises in Argentina are very small; they do not have significant amounts of money. It is more like Italy than the United States. They see it as the government's role to put money in high-risk development. We have some multinational companies operating in Argentina, but they run most of their R&D out of headquarters. But what we are seeing now is that [multinationals] are considering outsourcing of R&D. Big pharma, for example, … is buying small companies or creating new platforms within the company to produce growth. … One example in Argentina is a company called Delta Biotech that developed a new method for vitamin D production based on funding from our agency. It has been growing at 400% a year, and now investments are coming from all over Europe. The oldest member of this company is 35 years old. That shows the potential for small companies to grow and be competitive.

    Living up to expectations

    L.B.: My son said to me, “For 4 years, you will be the best minister of science we have ever had.” It's a big challenge. … I know the qualities and pitfalls of the scientific community. I'm confident that we will have some concrete results. We won't change everything right away, but to show that we have solved some particular problems, to develop a few successful companies, to have many students enrolled in interdisciplinary programs … will send a signal that changes are occurring.

  4. PALEONTOLOGY

    Is Dinosaur 'Soft Tissue' Really Slime?

    1. Carl Zimmer*
    1. Carl Zimmer is the author of Microcosm: E. coli and the New Science of Life.

    In 2005, researchers made headlines when they reported that they had found intact blood vessels from a 68-million-year-old Tyrannosaurus rex. The discovery raised hopes that paleontologists could get their hands on the flesh and blood of vanished animals. This week, however, other scientists challenged the results, arguing that the dinosaur flesh was in fact just coatings of young bacteria. But the original researchers stand by their results, calling the new argument weak. “There really isn't a lot new here,” says Mary Schweitzer of North Carolina State University in Raleigh.

    In 2003, a crew led by Jack Horner of the Museum of the Rockies in Bozeman, Montana, dug up an exquisitely preserved T. rex fossil. Schweitzer dissolved a fragment in weak acid. With the bone gone, transparent vessels were left behind (Science, 25 March 2005, p. 1852). Other fossils yielded branched tubes, spheres that resembled blood cells, and what appeared to be bone-forming cells known as osteocytes. Later, Schweitzer and colleagues isolated what they identified as collagen proteins from the T. rex and from a mastodon fossil. The sequence of amino acids in the mastodon collagen was closest to that of elephants; the T. rex collagen was most similar to that of birds, its closest living relatives.

    These results inspired Thomas Kaye, a research associate at the Burke Museum of Natural History and Culture in Seattle, Washington, to look for soft tissue. He set out to use scanning electron microscopes to find it without having to dissolve the fossils first. “I thought, ‘We'll just crack the bones open and take a look,’” he says.

    The researchers selected a well-preserved turtle fossil and quickly found cell-like balls that turned out to be located in tubes. “We actually did a happy dance,” he said.

    But the happiness turned to suspicion when Kaye kept finding the spheres in other fossils, even in badly degraded ones. “It was clear they weren't blood cells,” he says. He and his colleagues suspect that the balls are geological formations called framboids.

    Schweitzer's tubes and osteocytes, they argue, are not blood vessels or cells but biofilms formed by bacteria that invaded the fossils after death. In a paper published Monday in the journal PLoS ONE, Kaye and colleagues report that carbon dating of one sample shows that the tubes are at most a few decades old and that their infrared spectra give a closer match to bacterial biofilms than to collagen. Troughs in the walls of the tubes resemble the track a microbe would make crawling through a biofilm, they note. “We think that's one of the smoking guns,” Kaye says.

    “This piece of work demonstrates just how careful we have to be when attempting to analyze fossil bones for traces of original molecules or biomarker molecules,” says David Martill of the University of Portsmouth, U.K., a paleobiologist not involved in either study. Other researchers are less impressed. “There are a number of misinterpretations and lack of basic data in this paper,” says Frances Westall, the director of the Centre de Biophysique Moléculaire-CNRS in Orléans, France.

    Cell-out?

    Researchers mistook “framboids” in dinosaur fossils for corpuscles, a new paper contends.

    CREDIT: T. G. KAYE ET AL., PLOS 3, 7 (JULY 2008)

    Schweitzer says she welcomes skepticism but that Kaye and his team “only address aspects of our study that fit conveniently with their preconceived ideas.” They did not explain how proteins from a bacterial biofilm could be similar to bird or elephant proteins, for example. “They pick and choose what to focus on,” Schweitzer says, arguing that a rebuttal of her work must account for all of her evidence. She also doubts that bacteria could have formed the tubes.

    Martill, however, thinks that the tubes might well be biofilms. He says his own experience shows how aggressively bacteria and fungi can invade fossils. Still, he considers Schweitzer's research “incredibly impressive” and believes that at least some of the dinosaur material is genuine collagen. “This is why we should not abandon hope,” he says.

  5. SCIENCE AT THE OLYMPICS

    Will Beijing's Dirty Air Hurt Performance?

    1. Erik Stokstad
    CREDIT: ILLUSTRATIONS BY PETER AND MARIA HOEY

    Neuroimaging, high-tech materials, new asthma meds, detection-eluding drugs, thermoregulation—will all these make athletes stronger and faster at the 2008 Summer Games in Beijing? Science investigates

    Will performance suffer if athletes hit a wall of hot, polluted air in Beijing? Probably, say experts, although there may be some surprising twists.

    Among those chasing medals, perhaps the biggest fear is a pollution-induced asthma attack in someone who isn't normally asthmatic. On the other hand, some speculate that asthmatics—who take medicine as a precaution against pollution and other triggers—might actually have an advantage during a bad air day.

    Asthma is more common among elite athletes than in the general population, especially in endurance sports. Common symptoms—wheezing and shortness of breath—afflict perhaps up to 20% of elite athletes, because they spend so much time training outside. (Swimmers suffer from breathing air with chlorine.) Moreover, acute asthma attacks called exercise-induced bronchoconstriction (EIB) strike widely: up to 33% of swimmers, for example, even those without chronic asthma.

    Precautions.

    A masked runner in an April 2008 long-distance race in Beijing.

    CREDIT: FREDERIC J. BROWN/AFP/GETTY IMAGES

    The attacks happen because top athletes breathe in more than 150 liters of air per minute—through their mouths rather than their noses. “You can't pull out the pollen and the particulate matter, and they go directly into the lungs,” says Timothy Craig of Pennsylvania State University College of Medicine in Hershey. By the time the air reaches the airways, it is also irritatingly dry. In response, the airway membranes inflame, muscles tighten, and mucus accumulates—all quickly constricting the passageways in the lungs and making it hard to breathe.

    EIB is impossible to prevent entirely, but inhaled corticosteroids and β2 agonists can help. The International Olympic Committee (IOC) allows these drugs, given medical proof of asthma. Using the drugs could potentially give medicated asthmatics an advantage over other athletes in terms of averting an attack, says Kenneth Rundell, a physiologist at Marywood University in Scranton, Pennsylvania. Recently, however, the U.S. Food and Drug Administration approved another asthma drug, montelukast sodium, for preventing EIB. Because it is not known to enhance performance, the IOC hasn't banned it and any athlete can take it.

    Aside from the risk of EIB, little is known about the subtler impact of pollution on athletic performance. One exception is a study of 15 college ice-hockey players who didn't have asthma. Rundell asked them to pedal an exercise bike as hard as they could for 6 minutes. Compared with breathing clean air, total power output fell roughly 5% when the athletes breathed soot particles in concentrations similar to air near a busy highway. Rundell thinks the power loss, reported in the January issue of the Journal of Strength and Conditioning Research, is due to inflammation driven by pollution. In another study, published in Inhalation Toxicology in 2005, Rundell showed that montelukast sodium guards against pollution-induced EIB: “Where the pollution is very high, one could probably benefit quite a bit.”

    National teams have prepared for Beijing by screening athletes for asthma to get IOC permission for restricted drugs. And to reduce the amount of time athletes spend breathing polluted air, some teams will arrive in Beijing just before an event. The USOC even designed carbon-filter masks that its athletes can wear.

    The IOC, in turn, may reschedule endurance events if the air quality is bad. But IOC officials note that in test events conducted last August in Beijing, there were no complaints from national teams about the polluted air. A look back at the 1984 Olympics, in smoggy Los Angeles, suggests they may have a point: 67 asthmatic members of the U.S. team won a total of 41 medals.

    Even so, Olympic officials have conceded that pollution may mean that fewer world records are broken in Beijing than in past Olympics.

    GASPING FOR AIR

    Former U.K. gold medalist

    Steve Ovett collapsed from

    asthma after an 800-meter race

    in the 1984 Los Angeles games.

    He finished fourth, spent 2 days

    in hospital, and blamed pollution.

  6. SCIENCE AT THE OLYMPICS

    Can Ice Vests Provide a Competitive Chill?

    1. Adrian Cho

    At the 2004 Athens games, 30 minutes before the women's marathon, Deena Kastor of the United States began her “warm-up.” Instead of jogging in the 35°C heat, she donned an ice-filled vest, sat down, and waited for the start of the 42.2-kilometer run. More than 2 hours later, staying cool seemed to pay off. A kilometer from the finish, Kastor pulled into third place to secure a bronze medal. “The vest definitely helps performance because I am delaying the point in the race in which I overheat,” says Kastor, who will race in Beijing.

    The logic seems unimpeachable. As body temperature climbs to 40°C, strength and endurance evaporate. So cooling off before competition should enable an athlete to push harder and longer. Runners, rowers, cyclists, and others are already using ice vests. But how much does “precooling” help, and for which events? “It definitely lowers body temperature,” says Iain Hunter, an exercise scientist at Brigham Young University (BYU) in Provo, Utah. “The question is, does it improve performance? And that's a lot less clear.”

    Since the 1970s, numerous studies have shown that precooling can dramatically affect some measures of athletic output. A 1995 study of 14 male runners found that if they were first chilled for 30 minutes in a chamber at 5°C, they could run on a treadmill at a certain level of exertion for an average of 26.4 minutes, a whopping 3.8 minutes longer than they averaged otherwise.

    Chilled.

    Australian Olympic marathoner Lee Troop models an ice vest, 2004.

    CREDIT: AP PHOTO/ROB GRIFFITH

    Olympic events are typically races over fixed distances, however, and the few studies of race times show much smaller improvements. In 2005, BYU's Hunter and colleagues studied 18 female cross-country runners, who had ingested encapsulated thermometers, as they participated in 4- and 5-kilometer races. Some wore ice vests for an hour before their race, and, on average, their core body temperatures were half a degree lower than those who did not, even at the ends of the races. But the researchers found only an insignificant difference of a few seconds in the two groups' average times.

    Similarly, Kirk Cureton and colleagues at the University of Georgia, Athens, put nine male and eight female runners through simulated 5-kilometer races on treadmills. When the runners wore ice vests during a 38-minute warm-up of jogging and stretching, they finished the time trial 13 seconds faster on average than when they warmed up without them. That was a 57-meter lead over their warmer selves, and “even if it was 10 meters it would be important,” Cureton says.

    But Cureton and colleagues found that temperature differences vanished by race's end, suggesting that precooling is less valuable for long races like the marathon. It likely helps for races lasting between a minute and an hour, Cureton says. It definitely hurts in sprint events.

    How it works is a mystery. When the skin is cool, less blood flows to it to carry away heat, leaving more to course through the muscles. Precooling may also change the input from the body's heat sensors to the brain, which regulates pacing, enabling the athlete to push harder, says Rob Duffield, an exercise physiologist at Charles Sturt University in Bathurst, Australia.

    This much is certain: Using an ice vest won't make an athlete unbeatable. Paula Radcliffe of the United Kingdom, the world record holder for the women's marathon, wore one before the Athens race. She overheated and dropped out 6 kilometers from the finish.

  7. SCIENCE AT THE OLYMPICS

    What's Age Got to Do With It?

    CREDIT: SOURCES INCLUDE: OFFICIAL OLYMPICS WEB SITE, SPORTS REFERENCE, MENZIESERA.COM, GYMNASTICS ZONE

    Medalists span the decades

    11 Italy's Luigina Giavotti, 11, won silver in gymnastics in 1928.

    13 Marjorie Gestring, 13, of the U.S. won gold in diving in 1936—the youngest gold medalist ever.

    14 Hungarian swimmer Krisztina Egerszegi, 14, won gold in 1988.

    15 U.S. runner Pearl Jones, 15, won gold in the 4 × 100-m relay in 1952.

    33 U.S. swimmer Dara Torres, 33, won two gold and three bronze medals in 2000. Now 41, she is swimming in Beijing.

    34 U.K. sprinter Kelly Holmes, 34, won gold in the 800-and 1500-m events in 2004.

    46 Ethel Seymour, 46, won a bronze medal on Great Britain's gymnastics team in 1928.

    59 Bill Northam of Australia, 59, won gold in yachting in 1964.

    72 Swedish shooter Oscar Swahn, 72, won silver in the team double-shot running deer event in 1920.

  8. SCIENCE AT THE OLYMPICS

    Do New Materials Make the Athlete?

    1. Andrea Lu

    In 1960, Ethiopian marathoner Abebe Bikila earned an Olympic gold medal without wearing any shoes. But bare feet on the Olympic track these days are passé, as athletes slip into ever more high-tech gear. Shoes, swimsuits, and clothing are getting lighter and stronger, adhering like glue to athletes' bodies and moving more fluidly through air and water.

    In Beijing, U.S. track and field athletes will be wearing Nike shoes and clothing that incorporate threads made of Vectran, a superstrong liquid crystal polymer that withstands high temperatures. The result, according to Nike, is lighter, stiffer shoes to reduce friction and clothes that reduce drag by 7% compared with the Nike outfits worn at the 2004 games in Athens.

    Sprinters will also benefit from even tighter compression garments. In theory, these improve performance because of proprioception, that unconscious ability that enables you to pinpoint your nose when your eyes are closed. Physiologist Russ Tucker of the University of Cape Town, South Africa, says that because runners need to contract muscles precisely—at the proper angle, velocity, and time—tight-fitting garments help the brain identify where in space the limb is poised so they know when to activate the muscle.

    In the water, the Speedo LZR Racer suit, which debuted in March 2008, is all the buzz. Swimmers donning the suit have broken 46 world records so far. The suit includes polyurethane panels placed strategically around parts of the torso, abdomen, and lower back that experience high amounts of drag in the pool. It also incorporates a corset-like structure that keeps the body in a streamlined position. Raúl Arellano, a biomechanist at the University of Granada, Spain, says the LZR Racer suit could benefit older athletes like 41-year-old Dara Torres of the United States, especially in areas where fat tends to accumulate.

    Some of the technologies needed to develop the suit “didn't really exist 10 years ago,” says Jason Rance, head of Aqualab in Nottingham, U.K., the division of Speedo that designed the suit. Those include ultrasonic welding that eliminated the need for seams, and technology that allowed parts of the suit to be finely sanded and a water-repellent substance added to prevent water from leaking in.

    But the suit has raised eyebrows. “Who's going to win the gold medal, the swimmer or the technician?” asks Huub Toussaint, a biomechanist at the Free University in Amsterdam, who worries that the suit gives swimmers an unfair edge, although the international body governing the sport approved it.

    For all the hype surrounding space-age shoes and clothing, there's a flip side: Any boost to performance could just be psychological. South Africa's Tucker, who races for fun, says the compression garments make him feel powerful and secure. Such a superhero aura might give any competitor a mental edge. “It doesn't really matter if the advantages are physically real or not,” he says, “as long as the athlete gets some benefit.”

    NAKED TRUTH

    Swimming goggles were first allowed in 1976.

    Some of the first known spiked track shoes were invented by Joseph William Foster in the early 1890s.

    Greek athletes usually competed nude. According to one ancient writer, Pausanias, a competitor deliberately lost his shorts so that he could run more freely during the race in 720 B.C.E., and clothing was then abolished. Other explanations abound.

  9. SCIENCE AT THE OLYMPICS

    Can Neuroscience Provide a Mental Edge?

    1. Greg Miller

    For Olympic athletes, physical strength, speed, and stamina are a given. But when elite competitors go head to head, it can be the mind as much as the muscles that determines who wins. A collaboration between sports psychologists and cognitive neuroscientists is trying to figure out what gives successful athletes their mental edge.

    Positive thinking.

    Canadian swimmer Brittany Reimer.

    CREDIT: JERRY LAMPEN/REUTERS/CORBIS

    One focus is why some athletes rebound better than others after a poor performance. Even at the Olympic level, it's not uncommon for an athlete to blow a race early in a meet and then blow the rest of the meet, says Hap Davis, the team psychologist for the Canadian national swim team. To investigate why—and what might be done about it—Davis teamed up with neuroscientists including Mario Liotti at Simon Fraser University in Burnaby, Canada, and Helen Mayberg at Emory University in Atlanta, Georgia.

    The researchers used functional magnetic resonance imaging (fMRI) to monitor brain activity in 11 swimmers who'd failed to make the 2004 Canadian Olympic team and three who made the team but performed poorly. The researchers compared brain activity elicited by two video clips: one of the swimmer's own failed race and a control clip featuring a different swimmer. Watching their own poor performance sparked activity in emotional centers in the brain similar to that seen in some studies of depression, the researchers reported in June in Brain Imaging and Behavior. Perhaps more tellingly, the researchers found reduced activity in regions of the cerebral cortex essential for planning movements. Davis speculates that the negative emotions stirred up by reliving the defeat may affect subsequent performances by inhibiting the motor cortex.

    Davis and neuroscientist Dae-Shik Kim at Boston University (BU) School of Medicine are now using diffusion tensor imaging to visualize the connections between emotion and motor-planning brain regions. Kim hypothesizes that these connections might differ in athletes who are better able to shake off a bad performance. So far his team has scanned about a dozen BU athletes. Meanwhile, Davis and collaborators have been looking for interventions that would perk up the motor cortex. Additional fMRI studies, as yet unpublished, suggest that positive imagery—imagining swimming a better race, for example—boosts motor cortex activity, even when athletes see a videotaped failure. Jumping exercises have a similar effect, Davis says.

    The work has already changed the Canadian team's poolside strategy, he says: “We pick up on [any negativity] right away and intervene.” Davis has the swimmers review a video of a bad performance within half an hour and think about how they would fix it. Anecdotally, it seems to be working, he says. “We're seeing more people turn it around.”

    The fMRI findings suggest that quick, positive intervention helps athletes bounce back, says Leonard Zaichkowsky, a sports psychologist at BU who collaborates with Davis and Kim. But coaches often take a different approach with athletes. “Typically what happens is they've got hard-assed coaches reaming them out for a bad performance,” he says. “It's the opposite of what they should be doing.”

  10. SCIENCE AT THE OLYMPICS

    Does Doping Work?

    1. Martin Enserink

    It depends on how much proof you want. By the tough standards of modern medicine, there's little hard evidence for the efficacy of dozens of compounds on the list of the World Anti-Doping Agency (WADA). They are rarely tested in placebo-controlled trials; for most, the evidence is what medical researchers would call “anecdotal.”

    Many substances on the list are probably useless, most researchers say, if not outright detrimental for athletic prowess. “The science behind it is pretty weak,” concedes Swedish oncologist Arne Ljungqvist, a former Olympic high jumper who chairs WADA's Health, Medical & Research Committee.

    Not that we don't know anything about what works. Decades ago, double-blind trials for amphetamines and other stimulants showed that they can enhance performance in short, explosive activities, such as sprinting. Anabolic steroids have been proved beyond any doubt to increase muscle mass and enhance performance among male athletes in sports that require strength, such as weightlifting and shot-putting; in women, they appear to work for endurance sports as well. History provides more circumstantial evidence: In many sports, the amazing rise in performances came to a halt after the crackdown on anabolic steroids began in earnest in the 1980s, and some records have not been broken since then.

    But for many other compounds the evidence is thin, says Harm Kuipers, a physician and former speed-skating world champion who studies doping at Maastricht University in the Netherlands. One of the hottest substances of the moment, erythropoietin (EPO), has been tested for performance enhancement in only four double-blind trials, Kuipers says; they showed that it increased maximum oxygen uptake and performance, but apparently for short durations only.

    Data are lacking because rigorous trials are expensive, and there's little incentive to fund them. The drugs' target population, top athletes, usually can't be recruited into studies because it might ruin their careers. Also, the list of substances and combinations is endless; cyclists once used a cocktail of strychnine, cognac, and cocaine, for instance. And the risk of side effects can make ethics panels frown.

    Still, some say WADA should promote more efficacy studies. The agency is currently spending millions of dollars to improve detection of human growth hormone, a banned substance that appears to be very popular and is very hard to detect. Yet, the “science on efficacy is really soft,” says Donald Catlin, who until 2007 led a major antidoping lab at the University of California, Los Angeles. “I'd prefer to have true evidence before we go after it.”

    If WADA, created in 1999, had a more scientific attitude, it would drop many drugs from the list, which it inherited from the International Olympic Committee, says Kuipers, who sat on the panel for several years. Countless substances—such as beta-agonists, corticosteroids, and narcotics—are listed simply because athletes used them, or were rumored to use them, even though they are widely believed to be useless.

    A spot on the list may actually encourage athletes to experiment with a substance, Kuipers says: “The doping list is a shopping list for some.” Such experiments can be dangerous. In healthy people, for instance, an overdose of insulin—another listed substance that few believe does athletes any good—can lead to a fatal drop in blood sugar levels.

    Ljungqvist takes the opposite view: Removing substances from the list would signal that it's okay to use them, he says. And WADA wants to protect athletes from any drug they don't need, if only to send a message to their young fans. Ljungqvist agrees that this means that practically anything can end up on WADA's list—and that athletes risk ending their careers by taking something that doesn't bring them one bit closer to a gold medal.

  11. SCIENCE AT THE OLYMPICS

    Gender Balance

    Early player.

    British tennis Olympian Charlotte Sterry, 1908.

    CREDIT: HULTON ARCHIVE/GETTY IMAGES
  12. CHINA'S ENVIRONMENTAL CHALLENGES

    Three Gorges Dam: Into the Unknown

    1. Richard Stone

    A marvel of engineering, the Three Gorges Dam will start operating at full capacity later this year. Already under way is an epic experiment on how a dam impacts the environment.

    A marvel of engineering, the Three Gorges Dam will start operating at full capacity later this year. Already under way is an epic experiment on how a dam impacts the environment

    Pulling out all the stops.

    Three Gorges is generating loads of electricity—and concern.

    CREDIT: COURTESY OF WANG DING

    YICHANG, CHINA—For millions of people along the Yangtze River, the turbid waters of Asia's longest river have long provided an abundance of fish, including one kind that locals are especially fond of: carp. But Yangtze fisheries are harvesting less than half the carp they were 5 years ago. Thanks in no small measure to the completion of the Three Gorges Dam, the world's biggest dam, the outlook for the prized fish is grim.

    The Yangtze's four major carp species—bighead, black, grass, and silver—spawn when water levels rise during the summer monsoon rains. “They need this stimulation,” says Liu Huanzhang, an ecologist at the Institute of Hydrobiology (IHB) of the Chinese Academy of Sciences (CAS) in Wuhan. Three Gorges reservoir, a 660-kilometer-long serpentine lake that began to fill in 2003, has subtly altered seasonal variations in water levels below the dam. Recent IHB surveys have found a sharp decline in carp eggs and larvae downstream. “It's a very bad sign,” Liu says.

    CREDIT: DU HUAJU/XINHUA PRESS/CORBIS

    Carp are not the only Yangtze species on the ropes. Fishers are hauling in anything with fins and gills that they can net or lay hooks on, including the tiniest of fish to feed aquaculture species such as catfish or mandarin fish, IHB has documented. The central government bans fishing on the Yangtze for 3 months each year, during spawning. But with vast stretches of the river in danger of being fished out, one of China's senior ecologists, IHB's Cao Wenxuan, last month made a bold public plea for a 10-year moratorium for the entire Yangtze.

    Other troubles sapping the Yangtze's vitality include industrial effluents, raw sewage, and heavy boat traffic. But by greatly altering ecosystems on the Yangtze's middle reaches, the Three Gorges Dam, which operators plan to bring to full capacity by the end of the year, will complicate attempts to prevent a mighty river from becoming inhospitable to some aquatic life forms.

    The Three Gorges Dam is one of several huge projects that are transforming China's environment. They include the recent completion of the world's highest railway across the Tibetan Plateau and a plan to divert billions of cubic meters of water each year from the Yangtze and other southern rivers to China's parched north (Science, 25 August 2006, p. 1034). But perhaps no endeavor has generated more debate on the economic and environmental tradeoffs of megaprojects than the $25 billion Three Gorges venture in Yichang.

    The main justification is flood control. By regulating water flow, the dam is designed to prevent disastrous floods that have occurred every decade or so; the worst in the last century was a flood in 1931 that the government says killed 145,000 people and left 28 million homeless. (Unofficial tallies put the death toll at 3 million people or more.) Also on the plus side, the dam's hydropower station is expected to generate 84.7 billion kilowatt-hours per year of electricity, an amount equal to that produced by burning 50 million tons of coal. And Three Gorges has eased navigation as the rising waters have eliminated treacherous shoals upstream. For these and other reasons, the State Council Three Gorges Project Construction Committee (CTGPC) has hailed the dam as “greatly beneficial” to the environment. According to CTGPC vice director Li Yong'an, “the project has brought more ecological benefit than harm.”

    But to many critics, Three Gorges is a bête noire. Besides worsening the plight of fish, the dam has fragmented habitats in a biodiversity hot spot, and it could erode inhabited islands in the Yangtze River delta. The impoundment of 39.3 billion cubic meters of water has destabilized slopes, heightening risk in a landslide-prone region, while the sheer weight of all that water has heaped strain on seismic faults. The rising waters have also uprooted more than 1 million people and submerged entire communities. Another 4 million of the 16 million people living in the reservoir area may have to be relocated in coming years, officials revealed last fall.

    In China, public debate about the dam's dark side is muted. But for scientists, the myriad effects of Three Gorges are fair game. The government has sanctioned an ambitious program to monitor the Yangtze and the Three Gorges reservoir area, which at 58,000 square kilometers is bigger than Switzerland. “We're studying the changing landscape,” says Wu Bingfang, whose team at CAS's Institute of Remote Sensing Applications (IRSA) in Beijing is using satellite imagery to follow how the dam impacts its surroundings. They also intend to estimate how much methane and other greenhouse gases the reservoir area emits as submerged vegetation rots.

    “Now that the dam is a reality, I hope we can manage it well,” says Niu Wenyuan, chief scientist of China's sustainable development strategy program and a counselor of the State Council. A wealth of data on the Yangtze's fragile condition has been posted to a CTGPC-run Web site, http://www.tgenviron.org/. The findings are expected to guide priorities of a $7.3 billion monitoring and mitigation program over the next 12 years.

    “Humanity deserves the opportunity to learn some lessons from this engineering exercise,” says Chen Jiquan, a landscape ecologist at the University of Toledo in Ohio. In 2000, Chen led a 12-person delegation from the Society for Conservation Biology to China to assess Three Gorges. The group offered recommendations to a dozen bodies in China and at the United Nations but did not receive a single response. “It was a sad story,” says Chen.

    Well bred.

    A female jiangzhu and her two babies at IHB.

    Chinese scientists insist they are open to outside views and determined to confront the colossal project's mixed legacy. “Researchers want to tell the truth,” says Wu.

    A fading pulse

    In the 1930s, engineers identified the picturesque Three Gorges region straddling Hubei and Sichuan provinces as an ideal spot for a dam to dwarf all others. The original idea was to tame the Yangtze's periodic floods, but planning sputtered until the early 1980s, when China's energy needs grew more intense. “They thought this large dam would solve a lot of problems,” says Chen. Then-Premier Li Peng, a water engineer by training, pushed hard for Three Gorges, and in 1984 CAS began an environmental impact assessment. After weighing the pros and cons, the 8-yearlong review gave Three Gorges the thumbs-up. Construction started in 2003—to the dismay of many scientists. “I felt there were serious problems. My opinion was to wait 20 or 30 years,” says Niu.

    In May 2006, some 26,000 workers completed a Great Wall for the Yangtze: a concrete barrier 185 meters tall and 2.3 kilometers long. The reservoir had begun filling 3 years earlier and has risen from its original low water mark of 62 meters to the present 156 meters. By December, engineers expect to have finished installing the last five of 26 hydropower turbines.

    For ships to move upstream, they must traverse five locks stacked like a staircase at the dam's northern end that raise craft more than 100 meters. Migratory fish don't have a chance. “There was serious debate about whether to build a passage for fish,” says Liu. In the end, he says, authorities abandoned the idea because migratory fish can't pass the Gezhouba Dam spanning the Yangtze just 38 kilometers downstream, and it would have been “impossible” to build a big enough passage for the primary species that would have benefited from it, the Chinese sturgeon (Acipenser sinensis).

    It turns out, however, that Chinese sturgeon may still have a future on the Yangtze. The ancient species spends much of its life at sea, migrating upriver to spawn. The original sturgeon spawning areas were hundreds of kilometers upstream of Three Gorges. The fish has been blocked from reaching those areas since Gezhouba Dam rose in 1981. But the sturgeon is now observed to spawn downstream of Gezhouba, and fishing for it is banned in China.

    Although millions of lab-bred fingerlings have been released into the Yangtze in the past 2 decades, most young sturgeon captured in the Yangtze delta are wild, suggesting that the wild population is coping reasonably well, Liu says. Over the past 3 years, the Yangtze River Fisheries Research Institute in Jingzhou has released sturgeon into the Three Gorges reservoir to see if the fish can thrive exclusively in fresh water. Early results are discouraging, says the institute's Wei Qiwei, because the reservoir ecosystem is changing as the river slows and silt accumulates. “The lake now is not suitable for a benthic feeder,” he says. Such upheavals threaten 40 other endemic fish species, IHB and other researchers say. “Species that cannot adapt to the reservoir will gradually disappear,” says Liu.

    Subtle changes to Yangtze hydrology have had unforeseen effects. “These changes hit the carp on several fronts,” says Brian Murphy, a fisheries researcher at Virginia Polytechnic Institute and State University in Blacksburg. In April and May, Three Gorges Dam operators dump water from the reservoir to make room for summer monsoon rain surges. The modest spike in flow stimulates adult carp to leave floodplain lakes and start spawning runs before they have stored enough energy and before eggs have matured, says Murphy. The colder water they encounter on the river further retards egg maturation and suppresses hatching rates and development of fry. Dam operations in the fall reduce water flow, stimulating carp to migrate back to the floodplain earlier than normal, again reducing their chances to accumulate energy stores, Murphy says. Drift sampling at Jianli, 350 kilometers downriver from the dam, has revealed a precipitous fall from an estimated 2.5 billion eggs and larvae in 1997 to 100.5 million in 2005, Murphy, Xie Songguang of IHB, and others reported in Fisheries in July 2007.

    It's unlikely that the carp can adapt to the new regime. “It seems that any such adaptation could only occur over many generations, and the severe nature of the present spawning reduction yields very few fish for selection to act upon,” Murphy says.

    For some declining species, it's hard to untangle the dam's impact from other ills. “I doubt that there are enough good ‘before and after’ data to determine which species have been most affected, nor would it be easy to separate declines due to pollution and overfishing from the dam's effects,” says David Dudgeon, an aquatic ecologist at the University of Hong Kong.

    A case in point is the Chinese paddlefish (Psephurus gladius), a monster known to reach 7 meters in length. Scientists haven't spotted one in years (Science, 22 June 2007, p. 1684), suggesting that the fate of this dying breed was sealed long before Three Gorges bisected the Yangtze. Fishers report occasional sightings upstream of the dam, so Wei says he has not given up on the possibility of 11th-hour heroics—artificial breeding—to prolong the species' survival if individuals can be captured.

    Two high-profile victims of the Yangtze's many ills are mammals: the river dolphin, or baiji (Lipotes vexillifer), and the finless porpoise, or jiangzhu (Neophocaena phocaenoides asiaorientalis). A 2006 survey along 1700 kilometers of the Yangtze failed to spot a single baiji, suggesting that the cetacean is down to several dozen individuals and functionally extinct (Science, 22 December 2006, p. 1860). CTGPC has claimed that the baiji can be saved and has designated a reserve on the Xinluo stretch of the Yangtze. Experts say CTGPC's plan is either woefully out of date or wishful thinking.

    CREDIT: ZHOU YUEMIN/IRSA

    There's still hope for the jiangzhu. Although the 2006 survey recorded fewer than 300 sightings, indicating a maximum population of 1800, IHB's Wang Ding and his colleagues are keeping the species on life support at IHB, where a jiangzhu was born in 2005—the first freshwater cetacean born in captivity in the world. Wang's group is also nurturing a small population in Tian-e-Zhou Reserve, an oxbow of the Yangtze about 250 kilometers east of Three Gorges. But the dam's long shadow may reach there as well. Because water released through the dam tends to carry little silt, the “sour” downstream flow eats away at banks and scours the bottom. Wang's group is monitoring whether erosion will deepen the Yangtze near Tian-e-Zhou. That could sever the connection between river and reserve and prevent water exchange that's critical to the jiangzhu.

    To give the Yangtze's aquatic denizens a fair shot at survival, authorities will have to make serious progress in reducing the river's pollution. On an autumn 2000 cruise from Wuhan to Chongqing, a city of 9 million people at the reservoir area's western end, Chen's delegation observed scores of factories and small enterprises “discharging a lot of effluent directly into the river,” Chen says. In Chongqing, officials showed off a sophisticated model of water flow—for determining how much waste they could get away with dumping in the Yangtze. “We were speechless,” says Chen. “We didn't know if they were joking.” It was no joke: That evening, Chen and colleagues saw “mountains of trash” near the Yangtze. “I hope they aren't dumping it anymore,” he says.

    Perhaps not, after pollution limits and enforcement tightened in 2002. Since then, CTGPC has spent nearly $5 billion on sewage treatment plants and garbage disposal centers. To supplement this effort, the State Environmental Protection Agency last February announced that it will spend $3.3 billion over the next 3 years on 460 projects to improve Yangtze water quality. Despite such measures, the amount of sewage and effluent dumped in the Yangtze in 2006 (the last year for which numbers are available) was nearly 30 billion tons, or more than 4.5 million tons for every kilometer of the river. Experts spar over whether the water is improving or actually getting worse. “People are always fighting, arguing over the data,” says one CAS scientist.

    By slowing the flow of the Yangtze and nearby tributaries, Three Gorges saps the rivers' ability to detoxify and flush out pollutants. Last week, environmental authorities revealed that they are battling a bloom of blue-green algae along a 25-kilometer stretch of the Xiangxi River—the first outbreak of its kind in the reservoir area. They blamed the bloom on a buildup of pollutants from upstream phosphor mines and chemical plants. In the absence of strict pollution controls, Chen and others fear that the reservoir could become a giant cesspool.

    A warped environment

    In the rolling hills above Yichang, two graduate students unearth and examine the data recorder of a seismometer buried near a farmhouse. A team led by geophysicists Zhou Hua-wei of Texas Tech University in Lubbock and Xu Yixian of China University of Geosciences in Wuhan installed a network of 60 seismometers in the vicinity of Three Gorges Dam in mid-May, a few days after the devastating magnitude-7.9 Wenchuan earthquake centered 350 kilometers to the west. They are using recordings of thousands of aftershocks that rippled through the land here to map in detail the local geological structure and the strain placed on it by the reservoir.

    The dam's location was carefully chosen in a section of crust called the Huangling core, an upwelling of granitic rock in a sea of unstable limestone. “This is called a weak seismic zone,” says Zhou. “But I'm not so convinced.” A key unknown is the deep structure of two fault systems skirting the edge of the Huangling core: one 20 kilometers to the west, and one less than 60 kilometers to the east. It's not clear, he says, whether stress propagates between the fault systems and whether the faults link up with each other deep below the surface, beneath the dam. Zhou expects to have preliminary results by the end of the year.

    Although the risk of an earthquake powerful enough to bring down Three Gorges Dam is remote, the reservoir's impoundment has undeniably wrought massive changes on its surroundings. Currently, 632 square kilometers of terrain are under water. By the end of the year, engineers plan to begin raising the reservoir from 156 meters to its maximum capacity of 175 meters, which will submerge roughly 400 more square kilometers.

    One immediate hazard is landslides. At a forum in Wuhan last fall, Huang Xuebin, chief of the Three Gorges' office of geological disaster prevention and control, said that landslides into the reservoir had produced towering waves that crashed into the shore, according to the official Xinhua News Agency. “Frequent geological disasters” threaten lives, Huang argued.

    “We are concerned about what will happen when the reservoir level reaches 175 meters,” says Qiao Jianping, a geophysicist at CAS's Institute of Mountain Hazards and Environment in Chengdu who has studied landslides in the Three Gorges area. The reservoir's rising waters have weakened slopes by saturating the soil. Qiao's team is developing a method to forecast slides a few days in advance by combining landslide hazard maps and rainfall data, as most slides are triggered by heavy rains. He expects to have a workable system in 2 or 3 years. In the meantime, the government has spent about $2 billion to stabilize landslide zones in the reservoir area by driving steel rods into the ground and building concrete retaining walls. “This work has enlarged the habitable areas along the river,” Qiao says.

    That's vital, considering that authorities in the past decade have relocated 1.2 million people to newly built towns and cities in the reservoir area. (Another 200,000 were moved to more distant locations.) Last fall, a Chongqing official told Xinhua that another 4 million people may have to be moved in the next 10 to 15 years.

    Slim pickings.

    IHB researchers collect carp eggs and larvae near Chongqing.

    CREDIT: LIU HUANZHANG

    The Chinese press has featured stories of resolute citizens starting life anew. To get a more systematic view on how people are coping, IRSA has hired a polling firm, Horizon Research Consultancy Group, to interview the displaced. “We want to find out how different generations are responding to the rapid changes,” says Wu. The government has allotted $22 billion for resettlement and poverty alleviation in the reservoir area over the next 12 years.

    People aren't the only creatures having to move out of harm's way. Scientists have mounted an operation to rescue two evergreen plants found only along the Yangtze's banks in the Three Gorges area. Much of the habitat of a shrub, Myricaria laxiflora, and that of a fern, Adiantum reniforme var. sinense, was lost when the reservoir's level rose to 156 meters. CTGPC funded a team led by Xie Zongqiang of CAS's Institute of Botany in Beijing to uproot more than 10,000 of the plants before the waters rose and replant them at four conservation centers.

    One story only beginning to unfold is how ecosystems will respond to extensive habitat fragmentation after the reservoir's rising waters flooded valleys and turned several dozen hilltops into islands (Science, 23 May 2003, p. 1239). Xie and his colleagues are studying how communities of species are changing on several of the islands. They expect to see rapid biodiversity loss. “Such changes may test theories of island biogeography,” says Xie. On the plus side, he says, the government has established several new nature reserves in the reservoir area.

    A big wildcard is what will happen as silt builds up behind the dam—and as sedimentation is reduced downstream. In the second half of the 20th century, the Yangtze deposited about 40 million tons of sediment in its delta, forming the largest alluvial islands on Earth. Chongming Island, which started out as a sandbar 1400 years ago, now covers more than 1000 square kilometers and has a population of 650,000.

    In 1979, authorities sought to consolidate these gains by planting on tidal mud flats Spartina alterniflora, a grass native to salt marshes in the southeastern United States. But the invader has spread rapidly and now threatens the Yangtze delta's ecological diversity, Chen and colleagues reported in the June Journal of Plant Ecology. Reduced sedimentation is expected to erode the alluvial islands, Chen says. At the same time, filling the Three Gorges reservoir and diverting water to other potential projects in the north will decrease the flow and allow more saltwater intrusion into the delta—spurring Spartina's spread.

    The biggest fear of all is a dam breach. “The dam's failure would result in one of the worst disasters in history,” says Zhou. Some 75 million people live directly downstream of Three Gorges. One possible—albeit improbable—trigger could be an earthquake that's off the scale for the region. Another potential strain would be huge pulses of water from sustained heavy precipitation or sudden melting of glaciers that feed the Yangtze. “If any catastrophe happens,” Chen says, “I'm not sure China—or any nation—could handle it.”

    A more likely scenario is that some decades from now, the Yangtze and the Three Gorges reservoir area will achieve an ecological equilibrium and the mammoth dam will become a monument to the profound transformation of the land around it.

  13. CHINA'S ENVIRONMENTAL CHALLENGES

    Fears Over Western Water Crisis

    1. Richard Stone

    Dramatic reductions in water flow in the Tarim River, the lifeblood of Xinjiang Province, mean provincial authorities must act fast to conserve water and find alternative water sources.

    ÜRÜMQI, CHINA—The Tarim River is the lifeblood of Xinjiang Province, providing more than half the irrigation water for this Alaska-sized region in western China. The largest inland river in Asia, the Tarim is also a green-fringed stockade keeping the vast Takla Makan Desert from advancing northward into rugged grasslands and fertile oases inhabited by the majority of the province's 20 million people. With Xinjiang's fortunes riding on the Tarim, officials watched with growing dismay last winter as the river's volume fell 28% below average and 300 kilometers of its 1321-kilometer-long course ran dry. After enjoying 2 decades of robust flow, water managers in May ordered strict rationing through September.

    One group of researchers saw the crisis coming. Based on past flow rates and weather conditions anticipated for 2007–08, Chen Yaning and colleagues at the Chinese Academy of Sciences' Xinjiang Institute of Ecology and Geography in Ürümqi forecast a sharp drop in runoff feeding the Tarim. Their report in the 20 March issue of Hydrological Processes predicted that the river will bounce back this coming winter. But if their numbers are correct, another—and worse—crisis will happen in 2009–10, when the Tarim's inputs are predicted to be 12% less than the past year's poor flow. “Most farms will not be able to irrigate their crops,” says Chen, who calls the looming threat “a big conflict between ecology and the economy.”

    The long-term prognosis is cloudier. On one hand, Xinjiang has been getting wetter over the past half-century, and models suggest that precipitation will continue to increase, says Ye Qian, a climate expert at the National Center for Atmospheric Research in Boulder, Colorado. But as the world warms, glaciers in the Tian Shan and Kunlun mountain ranges encircling the Tarim Basin are retreating, and the Tarim's fate is tied to its glacier-fed tributaries. “If the glaciers disappear, so will the source of the Tarim's water,” says Liu Changming, a hydrologist at the Institute of Geographical and Natural Resources Research in Beijing. Rising temperatures will also increase freshwater loss through evaporation.

    This is not the first water crisis to grip Xinjiang. In recent decades, the Tarim's nine historical tributaries have dried up one by one, leaving just three: the Aksu, the Yarkand, and the Hotan rivers. (Last winter, the Yarkand and Hotan stopped flowing altogether, only resuming in May with spring runoff.) Worried by the high evaporation rates as the Tarim neared its terminus, Chinese engineers in the early 1970s dammed the river to create the Daxihaizi Reservoir. The amputation dried up the Tarim's final 321 kilometers, turning villages downstream into ghost towns. In the meantime, the “green corridor”—a marshy vegetation belt extending 800 or so meters on either side of the Tarim—began to wilt as water diversion to Daxihaizi and smaller reservoirs drew down the water table. Since 2000, the central government has spent roughly $15 million shoring up this line of defense against the Takla Makan.

    All signs indicate that provincial authorities must act fast to conserve water. Unbridled irrigation in the Tarim's upper reaches, Chen says, sucked the life from tributaries and caused rampant salinization that has ruined 1.1 million hectares of farmland, a quarter of Xinjiang's total. Water-saving steps could include switching from ditch irrigation to drip irrigation and moving away from water-intense crops.

    The grand challenge is to find alternative water sources. Chen's group plans to team up with Wang Chi-Yuen of the University of California, Berkeley, to hunt for hidden aquifers. As a first step, they will chart features—such as limestone karst formations—likely to hold water. “There must be large aquifers in the mountains,” Chen says. Xinjiang's future may depend on it.

    Thin green line.

    The Tarim River keeps the Takla Makan Desert at bay and irrigates much of Xinjiang's cropland.

    CREDIT: CHEN YANING
  14. CHINA'S ENVIRONMENTAL CHALLENGES

    A Green Fervor Sweeps the Qinghai-Tibetan Plateau

    1. Hao Xin

    In a controversial venture, officials plan to halt open grazing, eradicate rodents, restore "degraded" grasslands, improve wetlands, and plant many trees and shrubs.

    In a controversial venture, officials plan to halt open grazing, eradicate rodents, restore “degraded” grasslands, improve wetlands, and plant many trees and shrubs

    Farmward bound.

    Livestock that have grazed on these high grasslands are being moved into fenced areas, and nomadic herders are being settled in villages.

    CREDIT: JULIA KLEIN/COLORADO STATE UNIVERSITY

    XINING, CHINA—No detail seems too small these days for officials working on environmental issues in western China's Qinghai Province. The chief of tree planting in the forestry bureau can attest to this. Leaving the telephone, he told a recent visitor that he had just had a surprising call: Qinghai's governor had noticed some unhealthy trees on her way to the airport. Her office wanted him to investigate.

    Tending to sick trees is at one end of an array of government-led initiatives here that include some monumental undertakings as well. All have been deployed in the past decade in pursuit of a single goal. Government officials say that over several decades, human activities have left the grasslands of Qinghai in a “degraded” condition. Rivers and lakes are declining as well, according to this view, and environmental restoration is needed across the plateau, a fragile area that is the source of several major Asian rivers and is considered an ecological resource for eastern China. The central government has offered to share the costs, which helps to explain the enthusiasm for environmental reclamation in this province.

    In May, Qinghai's governor announced the launch of the latest initiative, a 10-year plan to restore the region's crown jewel—Lake Qinghai, or Qinghai Hu—and surrounding lands. Embracing 30,000 square kilometers, the project includes a slew of tasks: to curtail grazing on grasslands, control rodents and insect pests that damage alpine meadows, protect wetlands, curb desertification, plant trees and shrubs, protect biodiversity, and construct small towns in which nomadic herders and their livestock would be settled in accord with “ecological migration.”

    Jewel in the crown.

    Lake Qinghai, affected by large agricultural projects in the past, is the focus of an environmental remediation program.

    CREDIT: LI XIAO-YAN/BEIJING NORMAL UNIVERSITY

    This sweeping program has been promised $227 million from the central government—about half the amount initially sought. It comes on the heels of a larger conservation effort begun in 2005 in the plateau's Sanjiangyuan region, the headwaters of the Yellow, Yangtze, and Lancang (Mekong) rivers. This plan covers 320,000 square kilometers and has been promised $1 billion in central government funds over 6 years.

    Many welcome the government's green initiatives. Some also have reservations. Julia Klein, a global change researcher from Colorado State University in Fort Collins who is collaborating with Chinese researchers, gives a mixed review: “The protection of Lake Qinghai is an important endeavor,” she says. “Some of the proposed actions, such as wetlands protection, are useful and practical objectives.” However, she notes that other proposals, such as halting grazing, “may be ineffective or potentially harmful.”

    “Sanjiangyuan and Qinghai Hu are very good projects with huge investments,” says Zhao Xinquan, director of the Northwest Institute of Plateau Biology of the Chinese Academy of Sciences (CAS) in Xining, “but they should be guided by science.” A proposed scientific component of the Qinghai Hu project was dropped, and scientists say that so far they have had little input.

    Better benchmarks

    Both Chinese and U.S. scientists say more research is needed to understand the fundamental changes taking place in the area known as the Qinghai-Tibetan Plateau, sometimes called the “water tower of Asia.” To begin with, there are no agreed-upon standards to measure environmental degradation, says Andrew Smith, a conservation biologist at Arizona State University in Tempe, who first visited Qinghai Hu in 1984. “Chinese officials characterize the plateau in broad terms,” he says, “but it is huge—constituting 25% of the land area of China—and very diverse. One cannot say the entire plateau is degraded.”

    Unlikely villains.

    Experts disagree on whether pikas (inset) deserve the blame for creating “black sands” areas within grasslands.

    CREDITS: ANDREW SMITH/ARIZONA STATE UNIVERSITY, TEMPE

    Cai Yanjun, a researcher at the CAS Institute of Earth Environment in Xi'an, agrees that clearer benchmarks are needed. But some exist: Grasslands are degraded, he notes, “if ground vegetative cover, biomass production, and quality of forage have decreased.” A key issue, says Cai, is to determine if alterations are the result of global climate change or are caused by local human activities, such as overgrazing, that could be better regulated.

    There's wide agreement that human activities over half a century can be blamed for some of the environmental damage around Qinghai Hu. Under Mao Zedong, grasslands along the shores of Lake Qinghai were plowed for crops. Mao's government also sited dozens of labor camps in Qinghai, to which a quarter of a million criminals and political prisoners were banished. Later, as commerce boomed in the 1980s, mineral prospectors and medicinal plant hunters gouged the area.

    The pattern changed in 1999, when the Beijing government pushed for environmental improvement after a 1998 Yangtze River flood killed thousands of people. Many thought deforestation upstream in Sichuan and Qinghai contributed to the severity of the flood. The government launched the “grain to green” program to return farmlands not suitable for agriculture to forests or grasslands. In 2001, 12 military-owned farms around Qinghai Hu were returned to local civilian governments, and about 80% of tillage on shores developed in the 1950s has been returned to grass.

    But critics worry that simple engineering solutions aren't adequate; they could lead to the same kind of brute-force, monolithic strategies that caused trouble in the first place. Many officials who advocate ecological improvement, Smith asserts, “do no science, utter proclamations, and spend ferociously to engage in activities that are totally unproven.”

    Fencing the plateau

    Provincial officials often cite overgrazing as a major cause of land degradation on the Qinghai-Tibetan Plateau. According to the province's forestry bureau, grasslands around Qinghai Hu can support a maximum livestock equivalent of 3.65 million sheep, but the equivalent of 6 million sheep now graze there. The Qinghai Hu and Sanjiangyuan conservation plans calls for sealing off from grazing 854,700 hectares of grassland, resettling 881 households (4157 persons) away from the lake, and reducing livestock by the equivalent of 1 million sheep.

    Resettlement has already been carried out in the Sanjiangyuan region on a larger scale, depopulating part of the plateau. Although the government provided $7000 to $12,000 per household to build houses and fences, herders have found it hard to live on this level of support, says Zhao. Smith is concerned about the social consequences; he claims that the low-status jobs and crime in resettlement villages have caused resentment.

    The consequences of long-term overgrazing on the plateau are not clear, but removal of grazing entirely, as the Qinghai Hu conservation plan calls for, may be harmful, argues Klein. Since 1997, Klein has been simulating warming and grazing to observe the effects on grasslands in field experiments in Haibei county north of Qinghai Hu. She and her colleagues found that warming reduces plant biodiversity and alpine meadow biomass, but grazing helps to slow down the loss of species. When livestock are completely removed from rangeland, dried grass left over from the previous year stunts new growth, keeping grass yellow even at the height of the growing season. The Tibetan Plateau “is a system that has evolved with grazing; the removal of grazing from the system could have profound ecological consequences,” says Klein.

    Fencing off grasslands also may pose a threat to the critically endangered Przewalski's gazelle (Procapra przewalskii). This species, which is endemic to China, used to roam the dry western grasslands but is now found in small populations only in the vicinity of Lake Qinghai, according to the International Union for the Conservation of Nature, which in 1996 put Przewalski's gazelle on its Red List of Endangered Species. The last population survey conducted in 2003 counted about 600 gazelles, less than half the number of wild pandas.

    Wang Dajun, a conservationist, and his grad students at Peking (Beijing) University have been conducting a new population survey since January 2008. Grad student Zhang Lu says that even though gazelles can jump over fences separating pastures, the barriers are dangerous to young or pregnant animals. Every year, there is news of a gazelle dying on a fence, says Zhang, and fences make it more difficult for gazelles to escape predators such as wolves.

    Taking out a keystone

    The Qinghai wolves' major food source—small native mammals including plateau pikas (Ochotona curzoniae), voles (Microtus brandti), and zokors (Myospalax baileyi)—have been blamed for causing grassland degradation as well and are targeted for eradication under the conservation plans. They are thought to compete for forage with livestock, and their burrows damage plant roots. Agriculture and animal husbandry agencies lump them together as rodents.

    For more than 4 decades, local government agencies have been trying to control plateau pika populations using various rodenticides, including Compound 1080 and Fussol; both have since been discontinued because of environmental contamination and collateral damage to predators. Now the primary chemicals are Gophacide and Zinophos and anticoagulants, according to Smith and J. Marc Foggin, founding director of Plateau Perspectives, an organization in the provincial capital Xining that supports conservation and sustainable development. (Foggin did research on mammals and birds in Qinghai as a grad student at Arizona State University in the 1990s.)

    The pika eradication effort could have unintended consequences for other species, Foggin and Smith wrote in what is considered the definitive study in Animal Conservation in 1999. Pikas are a keystone species, providing many ecosystem functions to the Tibetan Plateau, they wrote. The animals are a major food source not just for wolves but for brown bears and most of the large predatory birds of the plateau, and many nesting bird species use pika burrows as shelters for breeding. Where pikas have been poisoned, bird populations are also low, they found. But Smith claims that “for all the money spent, there is little evidence to show [that poisoning is] effective.” Adds Wang: “The main causes for grassland degradation are overgrazing and climate change; killing native wild animals will not solve the problem.”

    Water level rebounds

    A fundamental—and critically important—rationale for remediation efforts in Qinghai is to protect the wetlands and prevent lakes from declining. A growing body of evidence, however, suggests that climate change is more important than human activity in changing water levels in Qinghai—and that water levels may be rebounding.

    The earliest measurement of Lake Qinghai's water level was taken in 1908 by a Russian explorer. Since then and for almost the entire century afterward, the lake has been dropping. But that could be changing.

    Using data from 1959 to 2000, Li Xiao-Yan and his colleagues at Beijing Normal University have studied water balances of Qinghai Hu. They found that the lake water level dropped at an average rate of 8 cm per year during this period, primarily from evaporation losses and reduced precipitation. They estimated that crop irrigation and livestock watering were less significant factors, amounting to only 1% of evaporation.

    Li Shijie, a researcher at the CAS Nanjing Institute of Geography and Limnology, had observed high-altitude lakes decline for more than 2 decades. But in 2006, when he went back to Zigetang Co, a small saline lake fed primarily by surface discharges in northern Tibet, he “was very surprised” to find that its level had increased by 1.8 meters since 2002. Meteorological and hydrological data indicated that annual precipitation had increased since 2000 compared with the 1980s, at least over the southern part of the Qinghai-Tibetan Plateau. Some Chinese scientists had argued that climate warming would first make the plateau drier as land temperatures rose, but that later, as ocean temperatures caught up, heavier summer monsoons from the Indian Ocean would bring more rainfall to the plateau.

    Rare sight.

    Critics say that a plan to fence in some wild areas could make life more difficult for the endangered Przewalski's gazelle.

    CREDIT: WANG FANG/BEIJING UNIVERSITY

    Li obtained data for four catchments near Qinghai Hu and applied the Soil and Water Assessment Tool developed by the U.S. Department of Agriculture to model the lake's water balances. Fitting past meteorology and hydrology to the model, he and his colleagues predicted that water levels in Qinghai Hu likely will fluctuate from 2006 to about 2010 and then rebound.

    Remote sensing and weather data so far seem to bear out Li Shijie's modeling. According to Li Fengxia, director of the Qinghai Institute of Meteorological Science, the lake's surface area has fluctuated since 2005 and was 9.75 square kilometers larger in July 2005 than it was in July 2004. Several monitoring dates in July 2006 showed lake area increase as well. She attributes the trend to two factors: increased precipitation and increased snow melting feeding runoffs into the lake.

    Although some say it's too early to tell whether this fluctuation is temporary or a turning point for lake water level, one thing is clear: The ecological issues affecting the Qinghai Hu basin are complex. “We are just beginning to understand how different drivers—such as climate change, large herbivore grazing, and small mammals—interact to affect the Tibetan Plateau grasslands and the water balance in this system,” says Klein.

    “The situation in the Qinghai Lake region illustrates how climate change can have some of its greatest impacts on subsistence-oriented communities who are tightly coupled to their natural resource base,” says Klein. Although many problems require mitigation at a global scale, “local policies should enhance the herders' and the ecosystem's resilience and adaptation to these and future ecosystem changes. Herder relocation and its associated consequences will likely be counter to these goals.”

    Both Chinese and American scientists are planning more research in the area. The U.S. National Science Foundation recently approved a $1 million, 5-year project to study the social and ecological dimensions of pastoralism in Qinghai, says Smith, who is a co-principal investigator of the study, which involves researchers from several U.S. institutions.

    The Chinese Ministry of Science and Technology wants to pick up the tab to support the scientific research left out of the Qinghai Hu conservation plan to help guide the engineering endeavor; the project's budget of $4.4 million is awaiting final approval by the finance ministry.

  15. CHINA'S ENVIRONMENTAL CHALLENGES

    Beijing's Marathon Run to Clean Foul Air Nears Finish Line

    1. Richard Stone

    Drastic measures have brought down levels of some pollutants; a return to business as usual after the Olympics could be bad for health.

    Drastic measures have brought down levels of some pollutants; a return to business as usual after the Olympics could be bad for health

    Bad air day.

    Beijing's smog is notorious.

    CREDIT: GUANG NIU/GETTY IMAGES

    BEIJING—Looking south from the roof of the Institute of Remote Sensing Applications (IRSA) in Beijing, the new Olympic Stadium known as the Bird's Nest shimmers on a hazy horizon. IRSA may not have a ringside seat for the competition that begins here next week, but it is on the frontlines of an Olympian struggle now reaching a climax: the grueling effort to clean Beijing's air.

    Since 1 June, instruments perched atop IRSA—one of 14 stations in the Beijing region run by a team from six Chinese Academy of Sciences (CAS) institutes—have been monitoring gases and particulate matter around the clock. The stakes are high: In 2001, Beijing Olympics organizers vowed that concentrations of four of the worst pollutants—sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide, and particulate matter less than 10 micrometers in diameter (PM10)—would meet World Health Organization (WHO) guidelines by 2008. Since then, the goalposts have shifted. In 2004, Beijing officials said that concentrations of PM10 would be reduced to levels comparable with other major cities in developing countries and that tropospheric ozone—a corrosive molecule that sunlight shears off from NO2, volatile organic compounds, and other precursors—would meet China's air standard, which is more lenient than WHO's.

    According to Beijing's Environmental Protection Bureau (EPB), last year SO2 concentrations were 60.8% lower than in 1998, NO2 was down 10.8%, and PM10 had declined 17.8%. “No doubt, there has been a great improvement in air quality,” says Liu Wenqing, director of the Anhui Institute of Optics and Fine Mechanics and leader of the CAS monitoring team. But much of the gains were achieved between 1998 and 2001, when hundreds of noxious coal-fired plants were closed or fitted with scrubbers. Steven Q. Andrews, an environmental consultant in Washington, D.C., who has scrutinized Beijing's air-quality data, contends that gains in recent years are illusory. “Pollution levels have not decreased at all,” he asserts.

    The big question is whether aggressive measures over the past several months to further stem pollution, including shuttering hundreds of factories in Beijing and surrounding provinces, are having a substantial effect. The CAS team says so: As Science went to press, their data show dramatic reductions in SO2 and NO2 levels from this time last year—so much so that these two pollutants are now well under WHO limits. PM10 and ozone are still problems. An edict removing a million cars from Beijing's streets for the next 2 months should beat down these pollutants. CAS data show PM10 concentrations throughout Beijing at less than 150 micrograms per cubic meter (μg/m3)—China's standard—but above WHO's limit of 50 μg/m3. Ozone levels remain high. While most countries have tightened regulations in recent years, China raised its hourly ozone standard from 160 to 200 μg/m3 in 2000; WHO's 8-hour average is 100 μg/m3.

    Eye on the birdie.

    Wang Yuesi at CAS's monitoring site near the Bird's Nest.

    CREDIT: R. STONE/SCIENCE

    Indeed, air quality during the Olympics will be a matter of luck, says Kenneth Rahn Sr., an atmospheric chemist at the University of Rhode Island, Narragansett, who works with colleagues in China. A few times each summer, winds from the northwest flush out pollution—and everyone is pulling for such weather during the games. “The doomsday scenario,” Rahn says, is a high-pressure system settling in and trapping pollutants.

    Long, hard slog

    The force majeure behind the miasma is rapid growth. Beijing's population has swelled from 11 million to 16 million in 7 years, and in that time the number of vehicles has doubled to 3.3 million. Some 1200 cars and trucks are being added to the streets each day. That's a huge burden, as vehicle emissions contribute as much as 70% of the city's air pollutants, says CAS team member Wang Yuesi of the Institute of Atmospheric Physics in Beijing.

    Beijing is not the first Olympics host city beset by foul air. Nor will it be the most polluted: Imagine the air quality in London in 1948, Tokyo in 1964, or Mexico City in 1968. “Until the 1980s, Olympics organizers didn't pay much attention to the environment,” says Liu. When they did wake up to pollution, they took aim at ozone. During the 1984 games in Los Angeles, the marathon course hugged the seaside to avoid downtown smog. High ozone levels also bedeviled Atlanta in 1996 and Athens in 2004.

    But if there was a gold medal for bad air, Beijing would be hard to be beat. According to the World Bank, 16 of the 20 cities with the worst air pollution in the world are in China—including Beijing. Particularly alarming are PM10 levels, which last year in Beijing averaged 141 μg/m3—nearly three times the WHO standard. The Chinese Academy for Environmental Planning blamed air pollution for 411,000 premature deaths in China in 2003. “In Beijing, some days are really terrible for health and quality of life,” says Guy Brasseur, director of the Earth and Sun Systems Laboratory at the National Center for Atmospheric Research in Boulder, Colorado.

    Beijing is a prisoner of geography: Mountains to the west and north trap emissions, CAS researchers say. (Rahn says he is “unconvinced” that the mountains exert a trapping effect.) Air quality deteriorates in spring and summer, when temperatures and humidity soar and the prevailing winds pile on pollutants from industrialized regions to the south. “We think that other areas contribute 30% to 40% of Beijing's pollution,” says Wang. In the warm months, the city often stews in acrid haze until rain or cleansing winds from Mongolia offer a brief reprieve. “In Beijing, air quality mostly depends on meteorology,” says Liu. By early winter, air improves with more frequent Mongolian winds—although in the spring, these same winds can also usher in Beijing's infamous dust storms.

    To cure Beijing of its ills, city officials, after winning the bid to host the 2008 games, promised to spend $12 billion on environmental cleanup to stage a “Green Olympics.” Furnaces in tens of thousands of homes were converted from coal to gas and scores of coal-hungry factories were relocated to other provinces. That eased SO2 levels considerably, as coal burning is the main source of that pollutant. But concentrations of nitrogen oxides and volatile organic compounds—precursors of ozone—rose from 2000 to 2005. The tide began to turn that year, when strict Euro IV emissions standards started to bite, says Wang, and since then levels of those pollutants have begun to taper off.

    To consolidate these gains and tackle the big bugbear, PM10, 19 industries around Beijing late last year were ordered to cut 2008 emissions by 30%. In March, new vehicle emissions standards came into effect that are expected to reduce PM10 emissions in Beijing in 2008 by 330 million tons, 27% less than last year. “In the past 5 years, the local government has done its best,” says Liu. Rahn agrees. “I'm in their corner,” he says. “They're doing all the right things.”

    But was their best good enough? Beijing EPB thinks so. Its Air Quality Index scales pollution levels from 0 to 500 on any given day; 100 or below is a “Blue Sky Day.” Last year, Beijing had a record 246 Blue Sky Days (see table), and through the first half of 2008, precisely half of 2007's total—123 Blue Sky Days. But in the current issue of Far Eastern Economic Review, Andrews alleges that Blue Sky Days are a “misinformation campaign.” Last year, he notes, Beijing reported 57 days when the index was between 96 and 100, and only 5 days between 101 and 105. Liu notes that EPB's equipment is not as advanced as CAS's and only measures air pollution at ground level at specific sites—not as pollutants mix over a large urban area. Nevertheless, Liu says his team's data largely vindicate EPB's.

    View this table:

    Each of CAS's Beijing regional stations has a suite of instruments, including flux towers equipped with a scanning differential optical absorption spectrometer (DOAS), to measure pollutants in the air column. IRSA's rooftop is one of three “super” monitoring sites with additional instrumentation. CAS researchers also cruise Beijing's ring roads in a van equipped with DOAS and lidar. Data are being integrated with satellite imagery. Besides observing whether Beijing is living up to its clean-air vows, the team is probing questions such as how weather patterns influence regional pollution, and they are refining models of how pollutants move. The monitoring work will be repeated in Shanghai, which will host the World Expo in 2010.

    CAS put a prototype of its network through its paces last August, including a 4-day period when Beijing ordered cars with license plates ending in even numbers off the street one day and odd numbers the next. During the test, which idled up to 1.3 million cars a day, NO2 concentrations fell 26%—to levels lower than in the surrounding countryside, says Liu. SO2 and PM10 also declined, but ozone levels rose—a disturbing phenomenon seen in other cities that have brought pollution levels down, Brasseur says.

    In a less encouraging assessment, Wang Wen-xing and colleagues at the Chinese Research Academy of Environmental Sciences in Beijing, during a monitoring campaign in Beijing from 7 August to 30 September 2007, measured ozone and PM10 levels that were “much higher” than China's standards, they reported in the June issue of Air Quality, Atmosphere & Health. “This study is a bombshell,” says Andrews, in that the observed pollution levels “vary drastically” from what EPB reported: for example, 50% higher for PM10 and 33% higher for SO2.

    Business as usual?

    Looking beyond the Olympics, scientists predict that hard-won improvements will go up in smoke when traffic returns to normal and industries rev back up after the Paralympics end here in September. Beijing's air quality tends to worsen in autumn, when high-pressure air can linger for days on end, potentially amplifying a rebound effect. “We will be watching if the pollution comes back again,” says Wang Yuesi.

    “Clearly, China needs to establish a long-term plan,” says Brasseur. A good first step would be a thorough analysis of the chemical composition of Beijing's pollutants, he says: “Every megacity has a different spectrum.” Once the ingredients of the witches' brew are known, CAS scientists hope Beijing can follow the trajectory of Los Angeles, which has tamed its once fearsome smog. “We want to learn from L.A.,” says Wang Yuesi. Getting there, for starters, will take huge reductions in auto and industrial emissions. But CAS, with a mandate limited to analyzing pollution levels, cannot compel municipalities to adopt control measures.

    In the meantime, all eyes are on how the athletes cope with the smog. On 20 July, in a final push to bring down PM10 levels before the Olympics opening ceremony on 8 August, nonessential industries in Beijing ground to a halt and the odd-even license-plate prohibition came into force. Reliable weather forecasts will come only a few days before the big event. “We hope the wind will be coming from the northwest,” says Wang Yuesi. Or, as Rahn puts it, “It's time to start praying to the Mongolian weather gods.”

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