News briefs from the frontiers of science

Tree discovery yields clues on ancient forests; why ethanol may not be a pollution solution.

Tree yields clues on ancient forests

Paleontologists combing through a New York State quarry have found the remark­ably well-preserved remains of one of the most ancient trees known. It thrived some 360 to 380 million years ago, stood about 30 feet tall, and sported a feather-duster array of foliage at the top instead of sprouting branches with leaves or needles.

In 2004, a team of US and British scientists uncovered a crown from the tree species, known as Wattieza. A year later, the team uncovered a 28-foot trunk nearby. Wattieza is the oldest known example of a shape that appears repeatedly over the evolutionary history of trees and still appears today in modern palms and tree ferns.

Fossilized stumps of the trees were first discovered in the 1870s near Gilboa, N.Y. Fossilized crowns appeared in places as diverse as Belgium and Venezuela.

The team says the tree holds critical clues to what the forest's ecosystem might have been like. For example, the tree species apparently shed foliage repeatedly as it grew. The large amount of tree litter covering the forest floor would have encouraged the evolution of four-legged foragers, the team speculates. The results appear in today's issue of the journal Nature.

Ethanol: not a pollution solution

Ethanol-based fuel may help wean the United States from foreign oil, but it may not do much to clean the air, according to a study from Stanford University. In some places, air quality may get worse, the research suggests. The study is an early attempt to gauge the effects on pollution and public health of a large-scale shift from gasoline to biofuels.

Mark Jacobson, an associate professor at Stanford, used an advanced pollution and weather forecasting model, along with data on population growth and detailed estimates of future types and amounts of emissions for the US and for key air-pollution hot spots like Los Angeles. Then he compared the effects in 2020 of running the entire US fleet of autos, trucks, and motorcycles with gasoline versus the effect of using a blend of 85 percent ethanol and 15 percent gasoline.

In Los Angeles and regions like the Northeast, smog increased when ethanol replaced gasoline. In the Southeast, smog concentrations fell. The difference in smog levels was the result of differences in weather patterns, the background level of other smog ingredients, and the levels of hydrocarbons and oxides of nitrogen in the two fuels.

The study projects that by 2020, cases of ozone-related health problems would be 4 percent higher nationally, while in some areas, such as Los Angeles, cases would be 9 percent higher than if drivers fueled up with gasoline. The results suggest that to get the best balance of air quality and reduced levels of greenhouse gases, plug-in hybrid cars or those powered by fuel cells might be better options. The study appeared in the April 18 issue of the journal Environmental Science and Technology.

Ocean ridges need to vent

Undersea ridges, where Earth's crust spreads and renews itself, are hot spots for marine biologists and geologists alike. Now, Chinese and US researchers exploring the bottom of the southwest Indian Ocean say they have discovered a large field of hydrothermal vents along an ultra-slow spreading ridge, a type of ridge long thought to be too cool to host them.

Hints that this type of ridge could be a geological and biological hothouse first came from the Gakkel Ridge in the Arctic Ocean, the slowest-spreading ridge on the planet. During a 2001 expedition aboard the US Coast Guard icebreaker Healy, researchers found nine vents, twice as many as theories predicted.

The Indian Ocean team, which included scientists from the Woods Hole (Mass.) Oceanographic Institution, gathered the data in February and March during a Chinese-led expedition aboard the country's research vessel Dayang 1. Sensors aboard robotic undersea vehicles detected plumes of the hot, mineral-laden water the vents spew, and the team used sonar to map the extent of the vent field, which covers an area somewhat larger than a football field. The vent site is one of the largest yet discovered, the scientists say.

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