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Forest fires fuel Pollution crisis

Asia is suffocating under growing clouds of smog spewed out bycars, industry and household stoves

FRED PEARCE AND ROB EDWARDS

FOREST fires raging across Indonesian Borneo and its neighbour Sumatra are threatening to intensify toxic smog and pollution hanging over South-East Asia, which the United Nations identified this week as one of the world's niost pernicious environmental hazards. The pollution kills hundreds of thousands of people every year, and is disrupting the region's climate, says the UN. 'I'he fires have been spreading since mid-July. Researchers in the area now fear they could spark a repeat of the pollution crisis in 1997, when a thick, cliokiiig sniog spread over neiglibouring countries. Then, as now, fires were sparked by plantation companies setting alight tinder-dry forest during a drought triggered by the 1997-98 El Niiio. Agronomist Suwido Limill at the University of Palangka Raya, the capital of Central Kalimantan province of Indonesian Borneo, says he has halted teaching and research in a last-ditch attempt to control the fires. He and his students are desperately trying to create fire breaks by digging deep wells, hoping to tap groundwater that could dampen the dry, peaty soil and inake it less flammable. Limin says the Indonesian government is failing to support his efforts, and he is appealing to the international community for eniergency funds to help control the fires. "Millions of dollars have been spent investigating the fires Of 1997 and the damage they did," says jack Rieley of Nottingham University, who is researching the peat bogs of Kaliniantan. "But no one is putting any dollars into tackling the causes of these fires and fighting them when they occur." Palangka Raya is already full of smoke and airports are being closed, says Limin. "]'he conditions are terrible and many children will become ill." Such fires contribute to a continent-wide pollution that a report by the UN Environment Programme (UNEP) says is making millions of people ill with respiratory diseases, and causing hundreds of thousands of premature deaths each year. Smoke from forest fires combines with that spilling out from millions of small, inefficient cookers burning wood, cow dung and other natural fuels, says UNEP. At certain times of year, say scientists from the US, India and Germany, this combines with emissions from vehicles, factories and power stations to form clouds of pollution that can affect many million square kilometres of Afghanistan, Pakistan, India, Nepal, Burma and south-east China. "These initial findings clearly indicate that this growing cocktail of soot, particles, aerosols and other pollutants is becoming a major environmental hazard for Asia," says Klaus T6pfer, UNEP's executive director. Some 6o per cent of the world's 6 billion people live in Asia, and the population is growing rapidly. Yet the World Health Organization safety limits for air pollution are exceeded in all 23 Indian cities with more than a million inhabitants. A. P. Mitra, one of the report's main authors from the National Physical Laboratory in New Delhi, says that the brown cloud is also cutting the amount of sunlight reaching the Earth's surface. This could reduce evaporation and lead to a decline in rainfall, threatening scarce water supplies.

"No one is putting any dol la rs into tackling the causes of these fires and fighting them as they occur"

Agriculture is likely to stiffer, too. Already there is evidence from India that the loss of sunlight may be cutting winter rice harvests by as much as lo per cent. "The report is a warning," Mitra told New Scien tist. It's time to take action." The Indonesian forest fires, and the scale of the continent's wider pollution problem, highlights the dilemma facing the 170 countries gathering at the World Summit in johannesburg next week: how to achieve economic growth without sacrificing the health of the planet. Even if they agree on some future economic miracle, forest fires in the region will still have a massive impact. Some 1.7 billion tonnes of carbon were released from peat bogs burning in Borneo during the blazes Of 1997, says Limin.'Fhat's equivalent to almost a third of the global emissions that year from fossil-fuel burning. 0

Weeds do well out of modified crops

ANDYC0GHLAN

WEEDS have been shown for the first time to become stronger and fitter by cross-breeding with genetically engineered crops, in this case sunflowers. And at the same time, a team in France has demonstrated how easily weeds might be able to swap genes with the GM strains of sugar beet already in field trials. The findings emphasise the need for developers of GM crops to be cautious about which traits they introduce into plants, in case they spread irreversibly to weeds. They also strengthen the case for using technologies that would prevent gene spread altogether, argues Jeremy Sweet of the National Institute for Agricultural Botany in Cambridge. "if you're worried about a gene which alters the fitness of wild populations, then stopping the GM plant breeding has got to be a good thing," he says. Allison Snow's team at Ohio State University has shown in controlled tests that wild sunflowers, considered a weed by many farmers in the US, become hardier and produce So per cent more seeds if they are crossed with a GM sunflower resistant to seed-nibbling moth larvae. "We were shocked," says Snow. However, Pioneer Hi-Bred of Iowa, which developed the GM sunflower, says it has no plans to sell the strain commercially. Snow, whose results were presented to a conference last week, cautions against overstating the significance of the results. "It doesn't prove all GM crops are dangerous," she says. "I just think we need to be careful because genes can be very valuable for a weed and persist for ever once they're out there." Pioneer Hi-Bred spokesman Doyle Karr adds that existing GM crops such as soybeans and maize don't have any wild relatives in the US. And although GM canola, or oilseed rape, is related to wild mustard, the only spread of genes so far has been to commercial non- GM rape, especially in Canada. "It's all gene- and crop-specific," he says. "You ask beforehand what the implications are if there's crossover, and that's been true all along." However, various companies are developing GM sugar beets. Studies of normal beet fields by Henk van Dijk and his colleagues at the University of Lille in France suggest that they have underestimated the likelihood of GM beets swapping genes with the beet weeds that grow among them. "We found gene flow to be possible between all forms," they say in the Journal of Applied Ecology (vOl 39, p 56i). The situation with beet is particularly complicated because there is a two-way flow, with weed genes often polluting farm strains and reducing yields. The beet weeds could become even more of a nuisance to farmers if they pick up herbicide-resistance genes. Van Dijk says that while tricks such as doubling the number of chromosomes in GM strains could reduce the chance of gene spread, they would not eliminate it. "It's almost inevitable," he says. But despite the risk, he still believes GM strains could help farmers.

US may set up certification scheme for GM-free products

IN A bid to appease overseas buyers, maize and soybean exports from the US may soon come with a government stamp verifyingthatthey have been kept separate from genetically modified products. The US Department of Agriculture announced lastweekthat it is consider'ingsetting up a voluntary certification scheme to help exporters trade with the European Union and other countries that oppose GM crops or require labelling of GM products.

Some suppliers already have segregation procedures in place, but under the proposed system USI)A ofFicials would inspect suppliers to guarantee they are meeting standards. "We're not going to saythatthe product doesn't contain any GMO," says USDA spokesman Jerry Redding. "We'll only be certifyingthe process." The idea is that suppliers will be able to hire federal inspectors to review their methods for excluding GM materials, a process which would go all the way from planting through to harvesting, processing and transport. Earlier this year, the European Parliament voted for a far stricter and more elaborate system that would require suppliers to trace food from its source. Attacked by many as costly and impractical, itwon't become law unless it passes a furthervate. Anti-GM activistjeremy Rifkin believes the USDA's certification system will be of little consequence to suppliers or European importers. But he sees the move as the agency's first official admission that separating GM craps is both feasible and worth doing. "The USDA has been fightingthis idea of segregation all along," he says. "It's a big concession. They're realisingthat you can't force someone to eat somethiAg they don't want to eat.11 Tom Slunecka, the director of development for the National Com Growers Association, believes suppliers will find a certification system useful, though he's not convinced the USDA should get involved. "But the concept of standardising, we believe, is a good waytogo." Robin Orwant 41

US military wakes up to asteroid risk

JEFF HECHT, BOSTON

WHILE media attention has focused on the dangers of a giant asteroid hitting the Earth, debate is hotting up over the risk from smaller rocks, like the one that exploded above the Tunguska region of Siberia in igo8. Experts are coming up with dramatically different estimates of the risk from small asteroids, those about 50 or 6o metres across. An astronomer at NASA's jet Propulsion Laboratory (JPL) in Pasadena, California, estimates only one impact every iooo years, but a senior official at the US government's Space Command says this figure is too low. He claims that during the past century alone, there were two further strikes besides Tunguska. He wants a military centre specifically to watch the skies and warn of impending impacts. Small asteroids do not threaten global devastation, but can cause extensive local damage. I'he blast from the 6o-metre Tuiiguska object flattened about 2000 square kilometres of forest when it exploded 8 kilometres above the ground. There is little evidence of how often such events occur, as small asteroids are hard to spot in space and once they've hit leave no craters. History records only one undisputed event, Tunguska. Extrapolations of the risk from larger objects imply infrequent strikes. Lunar craters imply only two strikes every lo,ooo years, and asteroid surveys suggest one every several liundred years, says Alan Harris of IPL. He estimates one strike every iooo years. But Doug ReVelle of the Los Alaiiios National Laboratory in New Mexico says military records of smaller meteor explosions near the top of the atinospliere suggest Tunguska-like events occur about every 120 years. Simon Worden of US Space Coniniaiid gives an even more unsettling estimate - three events in loo years. He says he has evidence that a'Funguska-sized asteroid hit the Amazon in the 1930s, while another exploded over central Asia in the 1940S. Civilian astronomers give little credence to these events, which are based on scattered human reports. But military analysts are taught to worry about poorly defined threats. At a Senate lunch last month, Worden warned of a catastrophe if such an asteroid hit a populated area, and urged the Pentagon's surveillance centre in Colorado to take on about io people just to watch for asteroids. Astronomers are happy for the Pentagon to use early-warning satellites to monitor small atmospheric blasts, and Worden promises to speed up the release of data, which security rules currently delay by weeks. But they are not happy about the idea of an impact warning centre in military hands. "Impacts are an international problem," says Brian Marsden, head of the Minor Planet Center at the Harvard-Smithsonian Center for Astrophysics, which coordinates asteroid observations.

Sex changes on the brain

THE most widely used herbicide in the US, and another chemical found in many household cleaning products, skew the sexual development of zebrafish. But, surprisingly, they do it by affecting their brains, not their gonads. This adds to a growing body of evidence suggesting that pollutants don't have to mimic oestrogen to have a "gender- bending" effect, and that many more chemicals than we thought could be triggering the increasingly widespread feminisation and masculinisation of fish in rivers around the world. Until now, the received wisdom has been that gender-bending chemicals work by docking with the cell receptor normally reserved for oestrogen. But John Trant and his team at the University of Maryland Biotechnology Institute have discovered that common pollutants affect sexual development in a different way, by disrupting a brain enzyme called aromatase that converts testosterone into oestrogen. Trant exposed juvenile zebrafish in the lab to a dozen common pollutants at levels typically found in US waterways. Some compounds increased the amount of aromatase, some decreased it. Two had a large impact - the herbicide atrazine, and nonylphenol, a surfactant found in household products. With nonylphenol "we saw 270- fold increases in brain aromatase in undifferentiated larval fish, at the point just before they become males or females." Atrazine boosted levels of the enzyme by a factor Of 200, Trant told a Society for the Study of Reproduction meeting in Baltimore last month. He suspects that changing levels of aromatase alters the amounts of testosterone and oestrogen in the fish's brains, in turn influencing their sexual development. Chris Kirk, who studies gender-bending chemicals at the University of Birmingham, agrees. "Aromatase is an important enzyme in oestrogen synthesis in fish and people," he says. "If you disrupt it early in life, it's quite plausible that it could have an impact on sexual development." To measure the enzyme levels, Trant had to kill his zebrafish larvae before they had a chance to become male or female. But he now plans to repeat the experiment over three months, giving the fish enough time to reach sexual maturity. That should allow him to spot whether changes in aromatase levels in the fish correlate with sex changes seen in the wild. Andy Coghlan

Key enzyme changes balance of sex hormones

0 Young zebrafish exposed to pollutant

0 Pollutant suspected of Increasing activity of gene coding for aromatase, to that more of the enzyme is produced In the brain

0 Aromatase changes testosterone in brain to oestrogen, having a 'gender-bending" effect on the fish

Adult fish become masculinised

Fish flounder in shrinking gene pool

OVERFISHING is leading to a massive decline in genetic diversity in some fisheries, potentially robbing them of their best chance of recovery. A research team in New Zealand has discovered that in one stock of snapper fish, just one in every 10,000 produces a large number of surviving offspring, and that the gene pool has shrunk dramatically in the past 50 years. Until now scientists thought overfishing posed little threat to genetic diversity, assuming that even small numbers of fish could still produce millions of offspring. Recent research has also revealed that small fractions of each stock produce most offspring, but the genetic implications of this were unclear. Now an international team led by Lorenz Hauser from the University of Hull has found a unique way to tackle this question. They took DNA samples from the scales of New Zealand snapper kept in archive colledions. They chose fish from two populations - one huge fishery that has sustained commercial fishing for loo years, and a smaller stock that began to dwindle about 50 years ago after becoming a commercial target. They analysed a specific section of the DNAfrom each scale. For the larger, stable population they found genetic diversity had remained relatively constant. But with the smaller population they made two startling discoveries. First, the number of different alleles in the section of DNA plummeted over the years as the population decreased. Second, using calculations based on this decreasing genetic diversity, they estimated that just one in every 10,000 fish had a large number of offspring that survived (Proceedings of the Notional Academy of Sciences, DOI: 10JOT3/pnas.172242899). "That was the biggest surphse," says team member Peter Smith, a fisheries scientist at the University of Melbourne in Victoria. Smith says it is not clear yet exactly why so few fish breed successfully. But in a small population, it becomes more likely that the few effective breeders will also end up in a fishing net, leading to further declines in the genetic diversity of the stock. 'if we lose diversity," Smith says, 'then it's gone forgood." MarkSchrope

Satellites paint a far more rosy picture of forest loss

RAINFORESTS aren't disappearing as fast as we thought. The first global survey of high-resolution satellite images focusing on deforested hotspots indicates almost 25 per cent less deforestation during the iggos than would be expected from the widely used figures compiled by the UN's Food and Agriculture Organization. The FAO collects information from individual countries, which use satellites or local reports to estimate the amount and kinds of forest within their borders. With the help of additional satellite data, the FAO then calibrates this information and comes up with a global total. These figures are considered to be the best estimates available, and are routinely used by the Intergovernmental Panel on Climate Change and researchers who want to calculate how much carbon dioxide is being released into the atmosphere. But Hugh Eva from the European Commission's Global Vegetation Monitoring Unit in Ispra, Italy, points out that many countries, especially those embroiled in political conflict, find it difficult to compile accurate national figures. And each country has a slightly different definition of what a "forest" actually is. That, as well as other factors, mean there is a huge error in the FAO's estimates - up to 50 per cent in some cases. So Eva, Fredric Achard and their team collaborated with environmental experts from Latin America, Africa, South-East Asia and India to identify areas where deforestation is particularly bad. They selected ioo sites over the three continents, covering 6.5 percent of the total forest, and tracked down high-resolution satellite images taken over these areas between iggo and 1997. They found that, on average, 4.9 million hectares of rainforest were lost each year to factors such as clear-cutting, fire and conversion to farmland. That is 23 per cent less deforestation than the 6.4 million hectares estimated by the FAO (Science, VOI 297, P 999). If the researchers are right, that would mean that less CO, than we thought has been released as those trees rot or are burnt. A spokesman for the FAO says that Eva and Achard are relying on a relatively small set of data, which still leaves room for a large margin of error. But a further review of the world's tropical forests happening as part of NASA's Landsat Pathfinder project should help resolve any discrepancies. Rather than focusing on deforestation hotspots, the Pathfinder satellite is taking images and data from coast to coast across each continent. Nicola Jones

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