In Brief, continued from page 24 ECOLOGY Asteroids on the Inside Scientists have long looked far afield for A World Aflame asteroids. Now they have found one cir- cling the sun inside the earth’s orbit. very year fire scorches some 71 million hectares (175 million acres) of forest and David J. Tholen Egrassland. In 1997 drought brought on by El Niño exacerbated fires, many of and graduate which were deliberately set, the world over. In Indonesia, for instance, the devastation

student Robert was particularly extreme because of the worst drought the country had seen in 50 )

Earth map 1998 DK36 Whiteley of the years. According to the World Wildlife Fund’s 1997 report The Year the World Caught Fire, Venus University of Indonesia lost two million hectares to flame. A satellite image from last year shows the AM (

Sun OGR Hawaii spotted extent of the damage (red in image at right). A composite of data from 1992 to 1995 (at Mercury the object, left) shows fires in the region in red and purple. Fires this year in the Amazon, Mexico, named 1998 Florida and elsewhere promise to make 1998 another record year. The National Aero- TELLITE PR

Mars AL SA Asteroid Belt DK36, using a nautics and Space Administration has teamed up VID J. THOLEN OGIC

DA with the National Oceanic and Atmospher- specialized cam- OL era on the 2.24-meter telescope atop ic Administration to provide weekly up- Mauna Kea in February. Preliminary cal- dates on fires around the world. In- culations show that nearly 1.3 million formation can be found at http:// DEFENSE METEOR ; modarch.gsfc.nasa.gov/fire_ ) kilometers always separate the earth e

atlas/fires.html on the World glob from the asteroid as it passes through (

the daytime sky—good news, given Wide Web. —Sasha Nemecek eam that DK36 appears to be 40 meters in diameter. The asteroid that devastated the Tunguska region of Siberia in 1908 isualization T was about the same size. d EOS AM-1 V ddar Phone Home o Still no sign of extraterrestrial life, ac- NASA G cording to SERENDIP III, the most sensitive sky survey to date. The INDONESIA OCKLI ON/ST search, led by Stuart C. Bowyer of the T University of California at Berkeley, used a detector mounted on the world’s largest radio telescope in Arecibo, Puer- SIMMON/SUT to Rico. Starting in 1992, the instrument analyzed 500 trillion signals, looking in a radio band centered on a wavelength of 70 centimeters—a region typically BIOLOGY patches of algae and masses of filamen- reserved for communications. No luck. tous fungi abound. “Each time we go But the team hasn’t given up hope. there we find something new,” says Ri- SERENDIP IV, now in the works, should RIVER OF VITRIOL cardo Amils, director of the laboratory be 40 times more sensitive than its pre- The Rio Tinto in Spain abounds in of applied microbiology at the Center for Molecular Biology at the Autonomous decessor; it will simultaneously examine acid—and unexpected organisms 168 million frequency channels every University in Madrid, who discovered 1.7 seconds. the river’s wild ecosystem in 1990. “We have now collected about 1,300 forms Just Add Water gainst the dark stand of pine of life living here, including bacteria, The wonders of modern science never trees, the waters of the Rio Tinto yeast, fungi, algae and protists. But the cease. Ryuzo Yanagimachi and col- A appear even more vividly red real number is surely much higher.” leagues at the University of Hawaii have than usual. Here, near its headwaters in Before Amils and his colleagues stud- produced live mice from dead sperm. southwest Spain, the strong smell of sul- ied the 93-kilometer (58-mile) river, it The workers added water back to freeze- fur overwhelms even the fragrance of was assumed that the acidic waters were dried sperm and injected it into mouse the dense forest. The crimson river—in- purely the result of the Rio Tinto copper eggs using a procedure called intracy- famous for its pH of two, about that of mine, one of the world’s largest and old- toplasmic sperm injection (ICSI). They sulfuric acid, and for its high concentra- est. The microbiologist now believes that found that freeze-drying had preserved tion of heavy metals—seems dead, a pol- industry—in particular, the sulfuric acid the genetic information in the sperm luted wasteland and a reminder of the associated with copper mining and the well enough to regenerate healthy ecological devastation mining can entail. discarded metal tailings—is not entirely mice. The tactic is expected to be an im- Yet the remarkable Rio Tinto is hardly responsible for the condition of the wa- provement on previous methods of lifeless, as scientists have discovered in ter. He has found that historical records storing genetic information from mice the past several years. Even in parts of refer to the river’s long-standing acidity. used in research. —Kristin Leutwyler the river where the pH falls below two— Amils postulates that the river’s strange

SA and the water is painful to touch—green chemistry led its first miners—the Tar-

26 Scientific American September 1998 News and Analysis Copyright 1998 Scientific American, Inc. tessians in 3000 B.C.—to in- stood for the time being—ap- vestigate the banks for de- pear to feed on the immense posits. Soon after, the Ro- deposits of metal sulfides, cre- mans, who extracted great ating the sulfuric acid that, quantities of gold and silver, together with oxidized iron, called the river Urbero, Phoe- produces the very conditions nician for “river of fire.” And that lead to heavy metals in the Arab name for it was solution. “river of sulfuric acid.” The most abundant organ- Amils’s argument is bol- isms in the river appear to be stered by other observations. algae, which produce oxy- The low pH and high con- gen in champagnelike bub- centration of metals—includ- bles that the researchers ing iron, arsenic, copper, cad- watch float to the surface. mium and nickel—is consis- How algae work in this acid tent throughout the entire inferno, however, has the sci- river, becoming less acidic entists mystified. “We need where the Rio Tinto meets more research to explain how the Atlantic Ocean. Typical- algae can collect light and ly, waterways that receive produce organic matter and mining waste have acidic oxygen in such conditions,” concentrations only near the Amils notes. source of pollution. Strong One possibility is that some rains also cannot seem to re- of the Rio Tinto algae and duce the acidity of the river. fungi have established cer- To explain how this amaz- tain symbiotic associations. A ing condition came about— “Through evolution we can and is perpetuated—the re- see that symbionts can thrive searchers point to what they successfully in a habitat that UIS MIGUEL ARIZ have learned about the spe- L otherwise would be inhos- cies found there. They are RED WATERS pitable,” explains Lynn Mar- convinced that the extreme and high acidity of the Rio Tinto do not deter a wealth gulis, a biologist at the Uni- conditions are produced by of microscopic life, including blooms of algae. versity of Massachusetts at bacteria. Thiobacillus ferro- Amherst. “Long-term associ- oxidans, for example, is abundant in dans. Evidence of its corrosive capabili- ation can create new species through the river. This microorganism is capable ty sits on the banks, where abandoned symbiogenesis.” of oxidizing sulfur and iron—thereby railroad cars were flooded with river Understanding this symbiosis—if it is giving the Rio Tinto its red hue and water. In service just 15 years ago, these present in the Rio Tinto—could help name. Amils and his colleagues recently cars now appear as skeletons, devoured Margulis, Amils and others understand documented the presence of another by the Rio Tinto microbes. “These bac- the development of early life on the bacterium, Leptospirillum ferrooxidans, teria are a kind of metallic piranha,” earth. “In my view, the river is a better which feeds exclusively on iron and is Amils says. model for the life that flourished in the even more abundant than T. ferrooxi- Other bacteria—not as well under- Proterozoic, with an abundance of oxy- gen and algae, than it is for the anoxic Archean eon,” Margulis says. During the Proterozoic—between 2.5 billion and 600 million years ago—anaerobic and aerobic organisms survived in ex- treme conditions, perhaps assisting one id another. adr The Rio Tinto could also offer further y of M insights. Perhaps Amils and his crew ersit niv are seeing the kind of life that thrived on Mars millions of years ago. The ver- onomous U satility of these bacteria—particularly ut A

A those that work in anoxic conditions on

CHILL mineral substrates such as iron sulfides—

EZ-AR make them good candidates for a model of extraterrestrial life. “I cannot say that Martians were like this, but Mars would ANABEL LÓP be a perfect bite for many bacteria liv- DIATOMS ing here, that is for sure,” Amils says. from the Rio Tinto are among the 1,300 species found to live there. —Luis Miguel Ariza in Madrid

28 Scientific American September 1998 News and Analysis Copyright 1998 Scientific American, Inc.