Geologists Provide New Evidence for Reason Behind Rise of Life in Cambrian Period

PASADENA, Calif.—Geologists have uncovered evidence in the oil fields of Oman that explains how Earth could suddenly have changed 540 million years ago to favor the evolution of the single-celled life forms to the multicellular forms we know today.

Reporting in the December 7 issue of the journal Nature, researchers from MIT, the California Institute of Technology, and Indiana University show that there was a sudden change in the oxygenation of the world's oceans at the time just before the "Cambrian explosion," one of the most significant adaptative radiations in the history of life. With a increased availability of oxygen, the team speculates, single-celled life forms that had dominated the planet for the previous three billion years were able to evolve into the diverse metazoan phyla that still characterize life on Earth.

"The presence of oxygen on Earth is the best indicator of life," says coauthor John Grotzinger, the Fletcher Jones Professor of Geology at Caltech and an authority on sedimentary geology. "But it wasn't always that way. The history of oxygen begins about two and a half billion years ago and occurs in a series of steps. The last step is the subject of this paper."

The key insight was derived when Grotzinger's student Dave Fike, who is lead author of the paper, analyzed core samples and drillings taken at a depth of about three kilometers from oil wells in Oman, which are known to have the oldest commercially viable oil on the planet. The results of carbon and sulfur isotopic analyses from the material led the team to the conclusion that the oceanic conditions that laid down the deposits originally in Oman were quite different from conditions of today.

"You need a very different ocean for these conditions to exist—more like the Black Sea of today, with an upper oxidized layer and lower reduced layer with very little oxygen," says Grotzinger. "The ocean today is pretty well oxidized at all layers, but the ocean before the Cambrian period must have been very different."

When organic matter falls into an ocean that doesn't stir, it becomes deprived of sufficient oxygen and cannot survive as multicellular forms. For this reason, with a limited amount of oxygen, life continued in its single-celled form for the first three billion years.

But about 550 million years ago, according to the team's geologic evidence, the deep ocean began mixing its contents with the shallow ocean, resulting for the first time in a fully oxidized deep ocean.

Characterizing the study as paleoceanography, Grotzinger says the evidence is persuasive because it is so clearly evident in the rock record. Geologists have long believed that the rise of oxygen was a key element involved in the Cambrian radiation, so this discovery really helps solidify that hypothesis.

The oxygen trigger helps account for how life 500 million years ago could have gone from its single-celled existence to the emergence just 10 to 15 million years later of all the metazoan phyla we know today. In short, an abrupt increase in the availability of oxygen may have led to the diversity and complexity of life.

Fike is a graduate student at MIT who is currently in residence at Caltech to work with his professor, Grotzinger, who himself came to Caltech from MIT last year. The other authors of the paper are Lisa Pratt of Indiana University and Roger Summons of MIT.

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Geobiologists Solve "Catch-22 Problem" Concerning the Rise of Atmospheric Oxygen

PASADENA, Calif.—Two and a half billion years ago, when our evolutionary ancestors were little more than a twinkle in a bacterium's plasma membrane, the process known as photosynthesis suddenly gained the ability to release molecular oxygen into Earth's atmosphere, causing one of the largest environmental changes in the history of our planet. The organisms assumed responsible were the cyanobacteria, which are known to have evolved the ability to turn water, carbon dioxide, and sunlight into oxygen and sugar, and are still around today as the blue-green algae and the chloroplasts in all green plants.

But researchers have long been puzzled as to how the cyanobacteria could make all that oxygen without poisoning themselves. To avoid their DNA getting wrecked by a hydroxyl radical that naturally occurs in the production of oxygen, the cyanobacteria would have had to evolve protective enzymes. But how could natural selection have led the cyanobacteria to evolve these enzymes if the need for them didn't even exist yet?

Now, two groups of researchers at the California Institute of Technology offer an explanation of how cyanobacteria could have avoided this seemingly hopeless contradiction. Reporting in the December 12 Proceedings of the National Academy of Sciences (PNAS) and available online this week, the groups demonstrate that ultraviolet light striking the surface of glacial ice can lead to the accumulation of frozen oxidants and the eventual release of molecular oxygen into the oceans and atmosphere. This trickle of poison could then drive the evolution of oxygen-protecting enzymes in a variety of microbes, including the cyanobacteria. According to Yuk Yung, a professor of planetary science, and Joe Kirschvink, the Van Wingen Professor of Geobiology, the UV-peroxide solution is "rather simple and elegant."

"Before oxygen appeared in the atmosphere, there was no ozone screen to block ultraviolet light from hitting the surface," Kirschvink explains. "When UV light hits water vapor, it converts some of this into hydrogen peroxide, like the stuff you buy at the supermarket for bleaching hair, plus a bit of hydrogen gas.

"Normally this peroxide would not last very long due to back-reactions, but during a glaciation, the hydrogen peroxide freezes out at one degree below the freezing point of water. If UV light were to have penetrated down to the surface of a glacier, small amounts of peroxide would have been trapped in the glacial ice." This process actually happens today in Antarctica when the ozone hole forms, allowing strong UV light to hit the ice.

Before there was any oxygen in Earth's atmosphere or any UV screen, the glacial ice would have flowed downhill to the ocean, melted, and released trace amounts of peroxide directly into the sea water, where another type of chemical reaction converted the peroxide back into water and oxygen. This happened far away from the UV light that would kill organisms, but the oxygen was at such low levels that the cyanobacteria would have avoided oxygen poisoning.

"The ocean was a beautiful place for oxygen-protecting enzymes to evolve," Kirschvink says. "And once those protective enzymes were in place, it paved the way for both oxygenic photosynthesis to evolve, and for aerobic respiration so that cells could actually breathe oxygen like we do."

The evidence for the theory comes from the calculations of lead author Danie Liang, a recent graduate in planetary science at Caltech who is now at the Research Center for Environmental Changes at the Academia Sinica in Taipei, Taiwan.

According to Liang, a serious freeze-over known as the Makganyene Snowball Earth occurred 2.3 billion years ago, at roughly the time cyanobacteria evolved their oxygen-producing capabilities. During the Snowball Earth episode, enough peroxide could have been stored to produce nearly as much oxygen as is in the atmosphere now.

As an additional piece of evidence, this estimated oxygen level is also sufficient to explain the deposition of the Kalahari manganese field in South Africa, which has 80 percent of the economic reserves of manganese in the entire world. This deposit lies immediately on top of the last geological trace of the Makganyene Snowball.

"We used to think it was a cyanobacterial bloom after this glaciation that dumped the manganese out of the seawater," says Liang. "But it may have simply been the oxygen from peroxide decomposition after the Snowball that did it."

In addition to Kirschvink, Yung, and Liang, the other authors are Hyman Hartman of the Center for Biomedical Engineering at MIT, and Robert Kopp, a graduate student in geobiology at Caltech. Hartman, along with Chris McKay of the NASA Ames Research Center, were early advocates for the role that hydrogen peroxide played in the origin and evolution of oxygenic photosynthesis, but they could not identify a good inorganic source for it in Earth's precambrian environment.

The paper is available online at the following Web address: http://www.pnas.org/papbyrecent.shtml

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Moore Foundation Gives $6.5 Million to Caltech For Research on Solar-Driven Energy

PASADENA, Calif.—The Gordon and Betty Moore Foundation has awarded $6.5 million to found the Center for Sustainable Energy Research at the California Institute of Technology. The center will conduct research on solar-driven renewable-energy sources. The six-year grant targets various promising technologies that could result in cheap alternatives to fossil fuels.

According to Harry Atwater, the Howard Hughes Professor and professor of applied physics and materials science, the goal of the center is develop the technologies that will transform the industrialized world from one powered by fossil fuels to one that is powered by sunlight. More energy from sunlight strikes the earth in one hour than all of the fossil energy consumed on the planet in a year—so what is missing is not the solar energy, but the science and engineering innovations to use it.

"This new center is the beginning of a major campus effort to address future energy needs," says Atwater, adding that the center will focus on several avenues of research, first taking on technologies pertaining to solar-driven generating methods for fuels such as hydrogen or methanol.

"Splitting water into hydrogen and oxygen using sunlight is a grand challenge because it is the confluence of a number of hard problems," says Atwater. "But success would enable us to either generate and use hydrogen directly as a carbon-free chemical fuel, if society elects to burn the hydrogen by itself, or convert hydrogen to another hydrocarbon fuel like methanol by a carbon-neutral process, if we decide that is the way to go."

Fuel cells using methanol that's made from renewable sources would be carbon-neutral because carbon dioxide would both be consumed and emitted in equal quantities by the reactions for fuel generation and use.

"Which is better? That's the subject of enormous debate," Atwater says. "Currently, we have a liquid-fuel economy, and methanol would have the advantage of being another liquid. However, a hydrogen-as-fuel future would enable us to realize the dream of a fuel that's pollution-free both locally and globally.

"But the biggest challenge is to find a way to split water with sunlight that is robust, efficient, and replaces the platinum catalyst with something that is scalable to terawatts of energy. So platinum is out."

In sum, the Center for Sustainable Energy Research is looking at several technologies to accomplish the goal of providing fossil-fuel alternatives, and several research groups at Caltech are applying their individual expertise to various parts of the problem. Replacing the platinum catalyst, for example, is the goal of Professor of Chemistry Jonas Peters, who has had success with using cobalt as a catalyst. Working on different aspects of solar conversion are Harry Gray, the Arnold O. Beckman Professor of Chemistry, and Nate Lewis, the George L. Argyros Professor and professor of chemistry. Sossina Haile, professor of materials science and chemical engineering, is working on improving fuel cells.

Haile says that society should look toward new possibilities for the future in terms of energy technology rather than scrambling at the last minute when existing options become scarce. "There's an anonymous quote that the Stone Age didn't end because we ran out of stones," she says.

"There is little question that sustainable energy is the grand challenge of our century," Haile adds. "The Moore Foundation has recognized the urgency of the situation. With the foundation's generous support, we will explore radical new ways of addressing all parts of the energy cycle, its generation, its distribution, and its consumption—starting with the basic premise that sunlight provides the planet with more than ample energy to meet our global demands.

"In the fuel-cell portion of the work, we focus on efficient conversion of chemical energy to electricity. And by designing fuel cells that are not restricted to hydrogen as the fuel, we relax the requirement that the world develop a hydrogen storage and delivery infrastructure before the many benefits of fuel cells can be realized."

Atwater says that the Moore Foundation funding is a crucial beginning for the center that could encourage the energy sector to invest more heavily in research and development of alternative sources of energy.

"We hope the center will become a rallying point on campus for work on renewable-energy sources of many kinds," he says. "The solar-driven fuel cycle is our initial effort, but we'll become involved in other promising renewal-energy research opportunities as time goes on."

"I think the story over the next few years will be steady progress on the individual areas of research, guided by the long-term goal of integrating them all together."

The Gordon and Betty Moore Foundation was established in 2000 and seeks to develop outcome-based projects that will improve the quality of life for future generations. It has organized the majority of its grant making around large-scale initiatives and concentrates funding in three program areas: environmental conservation, science, and the San Francisco Bay Area.

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Caltech and BP Team Up to Improve Electricity-Producing Solar Cells

PASADENA, Calif.—The California Institute of Technology has teamed up with the energy company BP to look for better and cheaper ways of producing solar cells. The goal of the program is to make the cost of solar electricity more competitive by increasing the current efficiency levels of solar cells.

The program is to be announced June 27 at the Photovoltaics Summit 2006 in San Diego. For an initial five-year period, researchers at Caltech and BP will explore a method of growing silicon by creating arrays of nanorods rather than by casting ingots and cutting wafers, which is the current conventional way of producing silicon for solar cells. Nanorods are small cylinders of silicon that can be 100 times smaller than a human hair and would be tightly packed in an array like bristles in a brush.

A solar cell made up of an array of nanorods will be able to efficiently absorb light along the length of the rods while also collecting the electricity generated by sunlight more efficiently than a conventional solar cell.

The Caltech solar nanorod program will be directed by Nate Lewis, the George L. Argyros Professor and professor of chemistry, and Harry Atwater, the Howard Hughes Professor and professor of applied physics and materials science. In addition, eight postdoctoral researchers and graduate students will work on the project.

"Nanotechnology can offer new and unique ways to make solar-cell materials that are cheaper yet could perform nearly as well as conventional materials," says Lewis, an expert in surface chemistry and photochemistry.

Lewis's group will investigate uses of nanotechnology to create designer solar-cell materials, from nanorods to nanowires, in order to change the conventional paradigm for solar-cell materials.

"Using nanorods as the active elements opens up very new approaches to design and low-cost fabrication of high-performance solar cells," adds Atwater, an expert in electronic and optoelectronic materials and devices.

Atwater's group will investigate ways of creating silicon-based single-junction and compound semiconductor-multijunction nanorod solar cells using vapor-deposition synthesis methods that are scalable to very large areas.

According to BP officials, the research contract is part of the company's long-term technology strategy and is in keeping with its practice of partnering with the world's leading universities on key technology challenges. The program is also aligned with Alternative Energy, a new business launched by BP in November 2005 that is focused on developing low-carbon options for the power industry.

BP Solar's CEO and president, Lee Edwards, said, "This program represents a significant commitment by BP to the long-term potential of solar energy and complements our existing technology programs with the promise for major breakthroughs in solar technology. "Nanorod technology offers enormous promise. However, like any new technology, challenges remain to be solved to make it commercially viable at scale."

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North Atlantic Corals Could Lead to Better Understanding of the Nature of Climate Change

PASADENA, Calif.—The deep-sea corals of the North Atlantic are now recognized as "archives" of Earth's climatic past. Not only are they sensitive to changes in the mineral content of the water during their 100-year lifetimes, but they can also be dated very accurately.

In a new paper appearing in Science Express, the online publication of the American Association for the Advancement of Science (AAAS), environmental scientists describe their recent advances in "reading" the climatic history of the planet by looking at the radiocarbon of deep-sea corals known as Desmophyllum dianthus.

According to lead author Laura Robinson, a postdoctoral scholar at the California Institute of Technology, the work shows in principle that coral analysis could help solve some outstanding puzzles about the climate. In particular, environmental scientists would like to know why Earth's temperature has been holding so steadily for the last 10,000 years or so, after having previously been so variable.

"These corals are a new archive of climate, just like ice cores and tree rings are archives of climate," says Robinson, who works in the Caltech lab of Jess Adkins, assistant professor of geochemistry and global environmental science, and also an author of the paper.

"One of the significant things about this study is the sheer number of corals we now have to work with," says Adkins, "We've now collected 3,700 corals in the North Atlantic, and have been able to study about 150 so far in detail. Of these, about 25 samples were used in the present study.

"To put this in perspective, I wrote my doctoral dissertation with two dozen corals available," Adkins adds.

The corals that are needed to tell Earth's climatic story are typically found at depths of a few hundred to thousands of meters. Scuba divers, by contrast, can go only about 50 to 75 meters below the surface. Besides, the water is bitter cold and the seas are choppy. And to add an additional complication, the corals can be hard to find.

The solution has been for the researchers to take out a submarine to harvest the coral. The star of the ventures so far has been the deep-submergence vehicle known as Alvin, which is famed for having discovered the Titanic some years back. In a 2003 expedition several hundred miles off the coast of New England, Alvin brought back the aforementioned 3,700 corals from the New England Seamounts.

The D. dianthus is especially useful because it lives a long time, can be dated very precisely through uranium dating, and also shows the variations in carbon-14 (or radiocarbon) due to changing ocean currents. The carbon-14 all originally came from the atmosphere and decays at a precisely known rate, whether it is found in the water itself or in the skeleton of a coral. The less carbon-14 found, the "older" the water. This means that the carbon-14 age of the coral would be "older" than the uranium age of the coral. The larger the age difference, the older the water that bathed the coral in the past.

In a perfectly tame and orderly environment, the deepest water would be the most depleted of carbon-14 because the waters at that depth would have allowed the element the most time to decay. A sampling of carbon-14 content at various depths, therefore, would allow a graph to be constructed, in which the maximum carbon-14 content would be found at the surface.

In the real world, however, the oceans circulate. As a result, an "older" mass of water can actually sit on top of a "younger" mass. What's more, the ways the ocean water circulate are tied to climatic variations. A more realistic graph plotting carbon-14 content against depth would thus be rather wavy, with steeper curves meaning a faster rate of new water flushing in, and flatter curves corresponding to relatively unperturbed water.

The researchers can get this information by cutting up the individual corals and measuring their carbon-14 content. During the animals' 100-year life spans, they take in minerals from the water and use the minerals to build their skeletons. The calcium carbonate fossil we see, then, is a skeleton of an animal that may have just died or may have lived thousands of years ago. But in any case, the skeleton is a 100-year record of how much carbon-14 was washing over the creature's body during its lifetime.

An individual coral can tell a story of the water it lived in because the amount of variation in different parts of the growing skeleton is an indication of the kind of water that was present. If a coral sample shows a big increase in carbon-14 about midway through life, then one can assume that a mass of younger water suddenly bathed the coral. On the other hand, if a huge decrease of carbon-14 is observed, then an older water mass must have suddenly moved in.

A coral with no change in the amount of carbon-14 observed in its skeleton means that things were pretty steady during its 100-year lifetime, but the story may be different for a coral at a different depth, or one that lived at a different time.

In sum, the corals tell how the waters were circulating, which in turn is profoundly linked to climatic change, Adkins explains.

"The last 10,000 years have been relatively warm and stable-perhaps because of the overturning of the deep ocean," he says. "The deep ocean has nearly all the carbon, nearly all the heat, and nearly all the mass of the climate system, so how these giant masses of water have sloshed back and forth is thought to be tied to the period of the glacial cycles."

Details of glaciation can be studied in other ways, but getting a history of water currents is a lot more tricky, Adkins adds. But if the ocean currents themselves are implicated in climatic change, then knowing precisely how the rules work would be a great advancement in the knowledge of our planet.

"These guys provide us with a powerful new way of looking into Earth's climate," he says. "They give us a new way to investigate how the rate of ocean overturning has changed in the past."

Robinson says that the current collection of corals all come from the North Atlantic. Future plans call for an expedition to the area southeast of the southern tip of South America to collect corals. The addition of the second collection would give a more comprehensive picture of the global history of ocean overturning, she says.

In addition to Robinson and Adkins, the other authors of the paper are Lloyd Keigwin of the Woods Hole Oceanographic Institute; John Southon of the University of California at Irvine; Diego Fernandez and Shin-Ling Wang of Caltech; and Dan Scheirer of the U.S. Geological Survey office at Menlo Park.

The Science Express article will be published in a future issue of the journal Science.

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Caltech, MIT Chemists Look for Better Waysto Use Chemical Bonds to Store Solar Energy

PASADENA, Calif.-With gasoline prices hovering at $3 per gallon, probably few Americans need convincing that another energy crisis is imminent. But what precisely is to be done about our future energy needs is still a puzzle. There's talk about a "hydrogen economy," but hydrogen itself poses some formidable challenges.

The key challenge is, of course, how to make the hydrogen in the first place. The best and cheapest methods currently available involve burning coal or natural gas, which means more greenhouse gases and more pollution. Adopting the cheapest method by using natural gas would merely result in replacing our dependence on foreign oil with a dependence on foreign gas.

"Clearly, one clean way to get hydrogen is by splitting water with sunlight," says Harry Gray, who is the Beckman Professor of Chemistry at the California Institute of Technology.

Gray is involved with several other Caltech and MIT chemists in a research program they call "Powering the Planet." The broadest goal of the project is to "pursue efficient, economical ways to store solar energy in the form of chemical bonds," according to the National Science Foundation (NSF). With a new seed grant from the NSF and the possibility for additional funding after the initial three-year period, the Caltech group says they now have the wherewithal to try out some novel ideas to produce energy cheaply and cleanly.

"Presently, this country spends more money in 10 minutes at the gas pump than it puts into a year of solar-energy research," says Nathan S. Lewis, the Argyros Professor and professor of chemistry. "But the sun provides more energy to the planet in an hour than all the fossil energy consumed worldwide in a year."

The reason that Gray and Lewis advocate the use of solar energy is that no other renewable resource has enough practical potential to provide the world with the energy that it needs. But the sun sets every night, and so use of solar energy on a large scale will necessarily require storing the energy for use upon society's demand, day or night, summer or winter, rain or shine.

As for non-renewable resources, nuclear power plants would do the job, but 10,000 new ones would have to be built. In other words, one new nuclear plant would have to come on-line every other day somewhere in the world for the next 50 years.

The devices used in a simple experiment in the high school chemistry lab to make hydrogen by electrolysis are not currently the cheapest ones to use for mass production. In fact, the tabletop device that breaks water into hydrogen and oxygen is perfectly clean (in other words, no carbon emissions), but it requires a platinum catalyst. And platinum has been selling all year for more than $800 per ounce.

The solution? Find something cheaper than platinum to act as a catalyst. There are other problems, but this is one that the Caltech group is starting to address. In a research article now in press, Associate Professor of Chemistry Jonas Peters and his colleagues demonstrate a way that cobalt can be used for catalysis of hydrogen formation from water.

"This is a good first example for us," says Peters. "A key goal is to try to replace the current state-of-the-art platinum catalyst, which is extremely expensive, with something like cobalt, or even better, iron or nickel. We have to find a way to cheaply make solar-derived fuel if we are to ever really enable widespread use of solar energy as society's main power source."

"It's also a good example because it shows that the NSF grant will get us working together," adds Gray. "This and other research results will involve the joint use of students and postdocs, rather than individual groups going it alone."

In addition to the lab work, the Caltech chemists also have plans to involve other entities outside campus--both for practical and educational reasons. One proposal is to fit out a school so that it will run entirely on solar energy. The initial conversion would likely be done with existing solar panels, but the facility would also serve to provide the researchers with a fairly large-scale "lab" where they can test out new ideas.

"We'd build it so that we could troubleshoot solar converters we're working on," explains Gray.

The ultimate lab goal is to have a "dream machine with no wires in it," Gray says. "We visualize a solar machine with boundary layers, where water comes in, hydrogen goes out one side, and oxygen goes out the other."

Such a machine will require a lot of work and a number of innovations and breakthroughs, but Lewis says the future of the planet depends on moving away from fossil fuels.

"If somebody doesn't figure this out, and fast, we're toast, both literally and practically, due to a growing dependence on foreign oil combined with the increasing projections of global warming."

The NSF grant was formally announced August 11 as a means of funding a new group of chemical bonding centers that will allow research teams to pursue problems in a manner "that's flexible, tolerant of risk, and open to thinking far outside the box." The initial funding to the Caltech and MIT group for the "Powering the Planet" initiative is $1.5 million for three years, with the possibility of $2 to $3 million per year thereafter if the work of the center appears promising.

In addition to Gray, Lewis, and Peters, the other Caltech personnel include Jay Winkler and Bruce Brunschwig, both chemists at Caltech's Beckman Institute. The two faculty members from MIT involved in the initiative are Dan Nocera and Kit Cummins.

Jonas Peters's paper will appear in an upcoming issue of the journal Chemical Communications. In addition to Peters and Lewis, the other authors are Brunschwig, Xile Hu, a postdoctoral researcher in chemistry at Caltech, and Brandi Cossairt, a Caltech undergraduate.

 

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Caltech wins Energy Star Award

PASADENA, Calif. - The Caltech community can take comfort in knowing that the fuel used to generate electricity is spent wisely and is environmentally friendly.

That's what the Combined Heat and Power (CHP) Partnership, a division of the Environmental Protection Agency (EPA), concluded last month when it bestowed, on behalf of the EPA and the Department of Energy, the 2004 Energy Star CHP Award to Caltech.

"Through the recovery of otherwise waste heat for campus cooling and heating, Caltech has demonstrated leadership in energy use and management," the award's announcement letter read. "Caltech's CHP system is a great example for other facilities across the nation."

Caltech's CHP system can boast an efficiency of 73 percent, which means that the system uses approximately 30 percent less fuel than equivalent separate heat and power systems.

The Institute's aging 6 megawatt CHP system was replaced in 2003 with a highly efficient, natural-gas-burning 12.5 megawatt system that not only reduces polluting emissions by 15 percent but is also able to generate up to 90 percent of the energy consumed on campus.

The new system will help the City of Pasadena avoid the dreaded rolling blackouts and brownouts California has seen in prior years.

MEDIA CONTACT: Mark Wheeler (626) 395-8733 wheel@caltech.edu

Visit the Caltech media relations website: http://pr.caltech.edu/media

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Size Does Matter - When it Comes to Reducing Environmental Pollution

PASADENA, Calif.-When it comes to mitigating the harmful impacts of environmental pollution--size does matter . . . or, at least, that's the hypothesis that California Institute of Technology professors Janet Hering and Richard Flagan will be testing.

Hering is professor of environmental science and engineering executive officer for Keck Laboratories. Flagan is executive officer of chemical engineering Irma and Ross McCollum professor of chemical engineering and professor of environmental science and engineering.

In a study funded by the Camille and Henry Dreyfus Foundation, Hering and Flagan will examine whether the effectiveness of iron nanoparticles in pollution remediation is influenced by their size. The $120,000 grant, under the Dreyfus Foundation's 2004 Postdoctoral Program in Environmental Chemistry, will be used to recruit a postdoctoral scientist to conduct research in environmental chemistry.

Specifically, the researchers will utilize this grant to examine effective strategies for reduction and mitigation of environmental pollutants in aquatic ecosystems. Ultimately, the study seeks to help provide viable, cost-effective commercial technologies for the remediation of certain contaminants, including groundwater contaminants, chlorinated solvents, nitrates, pesticides, various chemical by-products, residue created in manufacturing, and other industrial or inorganic contaminants.

The study, "Use of Vapor-Phase Synthesized Iron Nanoparticles to Examine Nanoscale Reactivity," will investigate whether reactivity and effectiveness of iron nanoparticles, in pollution mitigation, are influenced by their size. The study will compare particles in different size classes to determine whether nanoparticles exhibit enhanced reactivity in the reduction of organic substrates based on their size when surface area effects are accounted for.

Elemental iron [Fe(0)], or zero-valent iron, has been demonstrated to be an effective reductant for a wide range of environmental contaminants, including both organic and inorganic contaminants. Upon reaction with Fe(0), some contaminants can be transformed to products that are non-toxic or immobile. Fe(0) can be delivered to the subsurface environment by injection of Fe(0) nanoparticles.

If research results yield a conclusion that the size of Fe(0) nanoparticles does make a difference in their reactivity or effectiveness, then this finding will have a significant effect on the application of Fe(0) materials in environmental remediation and will provide insight into the fundamental chemical properties and behavior of nanoparticles in these applications.

Created in 1946, the Camille and Henry Dreyfus Foundation bears the names of modern chemistry pioneers Drs. Camille Dreyfus and his brother Henry. The foundation's mandate is "to advance the science of chemistry, chemical engineering, and related sciences as a means of improving human relations and circumstances throughout the world." The foundation directs much of its resources to the support of excellence in teaching and research by outstanding chemistry faculty at universities and colleges.

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Unexpected Changes in Earth's Climate Observed on the Dark Side of the Moon

PASADENA, Calif.—Scientists who monitor Earth's reflectance by measuring the moon's "earthshine" have observed unexpectedly large climate fluctuations during the past two decades. By combining eight years of earthshine data with nearly twenty years of partially overlapping satellite cloud data, they have found a gradual decline in Earth's reflectance that became sharper in the last part of the 1990s, perhaps associated with the accelerated global warming in recent years. Surprisingly, the declining reflectance reversed completely in the past three years. Such changes, which are not understood, seem to be a natural variability of Earth's clouds.

The May 28, 2004, issue of the journal Science examines the phenomenon in an article, "Changes in Earth's Reflectance Over the Past Two Decades," written by Enric Palle, Philip R. Goode, Pilar Montañes Rodríguez, and Steven E. Koonin. Goode is distinguished professor of physics at the New Jersey Institute of Technology (NJIT), Palle and Montañes Rodríguez are postdoctoral associates at that institution, and Koonin is professor of theoretical physics at the California Institute of Technology. The observations were conducted at the Big Bear Solar Observatory (BBSO) in California, which NJIT has operated since 1997 with Goode as its director. The National Aeronautics Space Administration funded these observations.

The team has revived and modernized an old method of determining Earth's reflectance, or albedo, by observing earthshine, sunlight reflected by the Earth that can be seen as a ghostly glow of the moon's "dark side"—or the portion of the lunar disk not lit by the sun. As Koonin realized some 14 years ago, such observations can be a powerful tool for long-term climate monitoring. "The cloudier the Earth, the brighter the earthshine, and changing cloud cover is an important element of changing climate," he said.

Precision earthshine observations to determine global reflectivity have been under way at BBSO since 1994, with regular observations commencing in late 1997.

"Using a phenomenon first explained by Leonardo DaVinci, we can precisely measure global climate change and find a surprising story of clouds. Our method has the advantage of being very precise because the bright lunar crescent serves as a standard against which to monitor earthshine, and light reflected by large portions of Earth can be observed simultaneously," said Goode. "It is also inexpensive, requiring only a small telescope and a relatively simple electronic detector."

By using a combination of earthshine observations and satellite data on cloud cover, the earthshine team has determined the following:

= Earth's average albedo is not constant from one year to the next; it also changes over decadal timescales. The computer models currently used to study the climate system do not show such large decadal-scale variability of the albedo.

= The annual average albedo declined very gradually from 1985 to 1995, and then declined sharply in 1995 and 1996. These observed declines are broadly consistent with previously known satellite measures of cloud amount.

= The low albedo during 1997-2001 increased solar heating of the globe at a rate more than twice that expected from a doubling of atmospheric carbon dioxide. This "dimming" of Earth, as it would be seen from space, is perhaps connected with the recent accelerated increase in mean global surface temperatures.

= 2001-2003 saw a reversal of the albedo to pre-1995 values; this "brightening" of the Earth is most likely attributable to the effect of increased cloud cover and thickness.

These large variations, which are comparable to those in the earth's infrared (heat) radiation observed in the tropics by satellites, comprise a large influence on Earth's radiation budget.

"Our results are only part of the story, since the Earth's surface temperature is determined by a balance between sunlight that warms the planet and heat radiated back into space, which cools the planet," said Palle. "This depends upon many factors in addition to albedo, such as the amount of greenhouse gases (water vapor, carbon dioxide, methane) present in the atmosphere. But these new data emphasize that clouds must be properly accounted for and illustrate that we still lack the detailed understanding of our climate system necessary to model future changes with confidence." Goode says the earthshine observations will continue for the next decade. "These will be important for monitoring ongoing changes in Earth's climate system. It will also be essential to correlate our results with satellite data as they become available, particularly for the most recent years, to form a consistent description of the changing albedo. Earthshine observations through an 11-year solar cycle will also be important to assessing hypothesized influences of solar activity on climate."

Montañes Rodríguez says that to carry out future observations, the team is working to establish a global network of observing stations. "These would allow continuous monitoring of the albedo during much of each lunar month and would also compensate for local weather conditions that sometimes prevent observations from a given site." BBSO observations are currently being supplemented with others from the Crimea in the Ukraine, and there will soon be observations from Yunnan in China, as well. A further improvement will be to fully automate the current manual observations. A prototype robotic telescope is being constructed and the team is seeking funds to construct, calibrate, and deploy a network of eight around the globe.

"Even as the scientific community acknowledges the likelihood of human impacts on climate, it must better document and understand climate changes," said Koonin. "Our ongoing earthshine measurements will be an important part of that process."

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Robert Tindol
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Atmospheric scientists still acquire samples the old-fashioned way--by flying up and getting them

PASADENA, Calif.—Just as Ishmael always returned to the high seas for whales after spending time on land, an atmospheric researcher always returns to the air for new data.

All scientific disciplines depend on the direct collection of data on natural phenomena to one extent or another. But atmospheric scientists still find it especially important to do some empirical data-gathering, and the best way to get what they need is by taking up a plane and more or less opening a window.

At the California Institute of Technology, where atmospheric science is a major interest involving researchers in several disciplines, the collection of data is considered important enough to justify the maintenance of a specially equipped plane dedicated to the purpose. In addition to the low-altitude plane, several Caltech researchers who need higher-altitude data are also heavy users of the jet aircraft maintained by NASA for its Airborne Science Program--a longstanding but relatively unsung initiative with aircraft based at the Dryden Flight Research Center in California's Mojave Desert.

"The best thing about using aircraft instead of balloons is that you are assured of getting your instruments back in working order," says Paul Wennberg, professor of atmospheric chemistry and environmental engineering science. Wennberg, whose work has been often cited in policy debates about the human impact on the ozone layer, often relies on the NASA suborbital platforms (i.e., various piloted and drone aircraft operating at mid to high altitudes) to collect his data.

Wennberg's experiments typically ride on the high-flying ER-2, which is a revamped reconnaissance U-2. The plane has room for the pilot only, which means that the experimental equipment has to be hands-free and independent of constant technical attention. Recently, Wennberg's group has made measurements from a reconfigured DC-8 that has room for some 30 passengers, depending on the scientific payload, but the operating ceiling is some tens of thousands of feet lower than that of the ER-2.

"The airplane program has been the king for NASA in terms of discoveries," Wennberg says. "Atmospheric science, and certainly atmospheric chemistry, is still very much an observational field. The discoveries we've made have not been by modeling, but by consistent surprise when we've taken up instruments and collected measurements."

In his field of atmospheric chemistry, Wennberg says the three foundations are laboratory work, synthesis and modeling, and observational data--the latter being still the most important.

"You might have hoped we'd be at the place where we could go to the field as a confirmation of what we did back in the lab or with computer programs, but that's not true. We go to the field and see things we don't understand."

Wennberg sometimes worries about the public perception of the value of the Airborne Science Program because the launching of a conventional jet aircraft is by no means as glamorous or romantic as the blasting off of a rocket from Cape Canaveral. By contrast, his own data-collection would appear to most as bread-and-butter work involving a few tried-and-true jet airplanes.

"If you hear that the program uses 'old technology,' this refers to the planes themselves and not the instruments, which are state-of-the-art," he says. "The platforms may be old, but it's really a vacuous argument to say that the program is in any way old.

"I would argue that the NASA program is a very cost-effective way to go just about anywhere on Earth and get data."

Chris Miller, who is a mission manager for the Airborne Science Program at the Dryden Flight Research Center, can attest to the range and abilities of the DC-8 by merely pointing to his control station behind the pilot's cabin. On his wall are mounted literally dozens of travel stick-ons from places around the world where the DC-8 passengers have done research. Included are mementos from Hong Kong, Singapore, New Zealand, Australia, Japan, Thailand, and Greenland, to name a few.

"In addition to atmospheric chemistry, we also collect data for Earth imaging, oceanography, agriculture, disaster preparedness, and archaeology," says Miller. "There can be anywhere from two or three to 15 experiments on a plane, and each experiment can be one rack of equipment to half a dozen."

Wennberg and colleagues Fred Eisele of the National Center for Atmospheric Research and Rick Flagan, who is McCollum Professor of Chemical Engineering, have developed special instrumentation to ride on the ER-2. One of their new instruments is a selected-ion- chemical ionization mass spectrometer, which is used to study the composition of the atmospheric aerosols and the mechanisms that lead to its production.

Caltech's Nohl Professor and professor of chemical engineering, John Seinfeld, conducts an aircraft program that is a bit more down-to-earth, at least in the literal sense.

Seinfeld is considered perhaps the world's leading authority on atmospheric particles or so-called aerosols--that is, all the stuff in the air like sulfur compounds and various other pollutants not classifiable as a gas. Seinfeld and his associates study primarily atmospheric particles, their size, their composition, their optical properties, their effect on solar radiation, their effect on cloud formation, and ultimately their effect on Earth's climate.

"Professor Rick Flagan and I have been involved for a number of years in an aircraft program largely funded by the Office of Naval Research, and established jointly with the Naval Postgraduate School in Monterey. The joint program was given the acronym CIRPAS," says Seinfeld, explaining that CIRPAS, the Center for Interdisciplinary Remotely Piloted Aircraft Studies, acknowledges the Navy's interest in making certain types of environmental research amenable for drone aircraft like the Predator.

"The Twin Otter is our principal aircraft, and it's very rugged and dependable," he adds. "It's the size of a small commuter aircraft, and it's mind-boggling how much instrumentation we can pack in this relatively small aircraft."

Caltech scientists used the plane in July to study the effects of particles on the marine strata off the California coast, and the plane has also been to the Canary Islands, Japan, Key West, Florida, and other places. In fact, the Twin Otter can essentially be taken anywhere in the world.

One hot area of research these days, pardon the term, is the interaction of particulate pollution with radiation from the sun. This is important for climate research, because, if one looks down from a high-flying jet on a smoggy day, it becomes clear that a lot of sunlight is bouncing back and never reaching the ground. Changing atmospheric conditions therefore affect Earth's heat balance.

"If you change properties of clouds, then you change the climatic conditions on Earth," Seinfeld says. "Clouds are a major component in the planet's energy balance."

Unlike the ER-2, in which instrumentation must be contained in a small space, the Twin Otter can accommodate onboard mass spectrometers and such for onboard direct logging and analysis of data. The data are streamed to the ground in real time, which means that the scientists can sit in the hangar and watch the data come in. Seinfeld himself is one of those on the ground, leaving the two scientist seats in the plane to those whose instruments may require in-flight attention.

"We typically fly below 10,000 feet because the plane is not pressurized. Most of the phenomena we want to study occur below this altitude," he says.

John Eiler, associate professor of geochemistry, is another user of the NASA Airborne Research Program, particularly the air samples returned by the ER-2. Eiler is especially interested these days in the global hydrogen budget, and how a hydrogen-fueled transportation infrastructure could someday impact the environment.

Eiler and Caltech professor of planetary science Yuk Yung, along with lead author Tracey Tromp and several others, issued a paper on the hydrogen economy in June that quickly became one of the most controversial Caltech research projects in recent memory. Using mathematical modeling, the group showed that the inevitable leakage of hydrogen in a hydrogen-fueled economy could impact the ozone layer.

More recently Eiler and another group of collaborators, using samples returned by the ER-2 and subject to mass spectroscopy, have reported further details on how hydrogen could impact the environment. Specifically, they capitalized on the ER-2's high-altitude capabilities to collect air samples in the only region of Earth where's it's simple and straightforward to infer the precise cascade of reactions involving hydrogen and methane.

Though it seems contradictory, the Eiler team's conclusion from stratospheric research was that the hydrogen-eating microbes in soils can take care of at least some of the hydrogen leaked by human activity.

"This study was made possible by data collection," Eiler says. "So it's still the case in atmospheric chemistry that there's no substitute for going up and getting samples."

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RT
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