Gas power plants could be cheaply retrofitted to generate hydrogen as well as power, chemists say in a Royal Society of Chemistry journal. A catalyst would convert methane into hydrogen gas and combustible coke, allowing the power station to produce hydrogen alongside electricity. Gadi Rothenberg and colleagues at the University of Amsterdam and at IRCE Lyon report in Green Chemistry that the catalyst could be cheaply installed into existing plants.
This kind of technology could ease a transition to a hydrogen economy, reducing the need for heavy investment in large hydrogen-focused plants. Generating hydrogen and power together "is a conceptual change," says Rothenberg. "When you're going to produce hydrogen, you needn't build a huge new power plant to do that. Diverting some of your existing methane feed to produce hydrogen just makes sense." The group tested many new catalysts based on ceria doped with other metals. One nickel-based form shows excellent catalytic activity and would cost only $10 per kilogram.
Study shows drinking water contaminated with potent estrogen Plastic packaging is not without its downsides, and if you thought mineral water was 'clean', it may be time to think again. According to Martin Wagner and Jörg Oehlmann from the Department of Aquatic Ecotoxicology at the Goethe University in Frankfurt am Main, Germany, plastic mineral water bottles contaminate drinking water with estrogenic chemicals. In an analysis1 of commercially available mineral waters, the researchers found evidence of estrogenic compounds leaching out of the plastic packaging into the water. What's more, these chemicals are potent in vivo and result in an increased development of embryos in the New Zealand mud snail. These findings, which show for the first time that substances leaching out of plastic food packaging materials act as functional estrogens, are published in Springer's journal Environmental Science and Pollution Research.
Wagner and Oehlmann looked at whether the migration of substances from packaging material into foodstuffs contributes to human exposure to man-made hormones. They analyzed 20 brands of mineral water available in Germany - nine bottled in glass, nine bottled in plastic and two bottled in composite packaging (paperboard boxes coated with an inner plastic film). The researchers took water samples from the bottles and tested them for the presence of estrogenic chemicals in vitro. They then carried out a reproduction test with the New Zealand mud snail to determine the source and potency of the xenoestrogens. They detected estrogen contamination in 60% of the samples (12 of the 20 brands) analyzed. Mineral waters in glass bottles were less estrogenic than waters in plastic bottles. Specifically, 33% of all mineral waters bottled in glass compared with 78% of waters in plastic bottles and both waters bottled in composite packaging showed significant hormonal activity.
By breeding the New Zealand mud snail in both plastic and glass water bottles, the researchers found more than double the number of embryos in plastic bottles compared with glass bottles. Taken together, these results demonstrate widespread contamination of mineral water with potent man-made estrogens that partly originate from compounds leaching out of the plastic packaging material. The authors conclude: "We must have identified just the tip of the iceberg in that plastic packaging may be a major source of xenohormone* contamination of many other edibles. Our findings provide an insight into the potential exposure to endocrine-disrupting chemicals due to unexpected sources of contamination." *man-made substance that has a hormone-like effect
Reference 1. Wagner M & Oehlmann J (2009). Endocrine disruptors in bottled mineral water: total estrogenic burden and migration from plastic bottles. Environ Sci Pollut Res; [10.1007/s11356-009-0107-7] The full-text article can be provided as a pdf on request or viewed free of charge at http://www.springerlink.com/content/515wg76276q18115/?p=13b47e03f3414b128d9ad2797b775973&pi=0
Fire's potent and pervasive effects on ecosystems and on many Earth processes, including climate change, have been underestimated, according to a new report. "We've estimated that deforestation due to burning by humans is contributing about one-fifth of the human-caused greenhouse effect -- and that percentage could become larger," said co-author Thomas W. Swetnam of The University of Arizona in Tucson. "It's very clear that fire is a primary catalyst of global climate change," said Swetnam, director of UA's Laboratory of Tree-Ring Research. "The paper is a call to arms to earth scientists to investigate and better evaluate the role of fire in the Earth system," he said.
The team also reports that all fires combined release an amount of carbon dioxide into the atmosphere equal to 50 percent of that coming from the combustion of fossil fuels. "Fires are obviously one of the major responses to climate change, but fires are not only a response -- they feed back to warming, which feeds more fires," Swetnam said. When vegetation burns, the resulting release of stored carbon increases global warming. The more fires, the more carbon dioxide released, the more warming -- and the more warming, the more fires. The very fine soot, known as black carbon, that is released into the atmosphere by fires also contributes to warming. "The scary bit is that, because of the feedbacks and other uncertainties, we could be way underestimating the role of fire in driving future climate change," Swetnam said. The report's 22 authors call for the Intergovernmental Panel on Climate Change, or IPCC, to recognize the overarching role of fire in global climate change and to incorporate fire better into future models and reports about climate change. David Bowman, a lead co-author, said, "We're most concerned that fire has not been rigorously and adequately incorporated in the climate models. It's remarkable that such an integral part of the landscape has been so sidelined." Swetnam, Bowman of the University of Tasmania in Hobart, Australia, the other lead co-author Jennifer K. Balch of the National Center for Ecological Analysis and Synthesis in Santa Barbara, Calif. and their colleagues will publish their paper, "Fire in the Earth System," in the April 24 issue of the journal Science. A complete list of authors is at the end of this release.
Because fire on Earth predates humans, its ubiquitous activity is simultaneously accepted and overlooked. Bowman says, "Fire is extraordinarily obvious, but deeply subtle." The article ties together various threads of knowledge about fire from disparate fields including ecology, global modeling, physics, anthropology, environmental history, medicine and climatology. A more complete understanding of how the Earth works requires recognizing how fire is intertwined with and also a driver of human history and the Earth's history, the authors write. Balch said of the article, "This synthesis is a prerequisite for adaptation to the apparent recent intensification of fire feedbacks, which have been exacerbated by climate change, rapid land-cover transformation, and exotic species introductions." She commented about "fires where we don't normally see fires," and pointed to the occurrence of bigger and more frequent fires from the western U.S. to the tropics. Swetnam said that, in addition to the burning in the tropics, huge tracts of the boreal forests of Siberia, Canada and northern Europe burn each year.
"The role of fire in forests in the boreal zone is unappreciated," he said. "Russian forests alone contain more than 50 percent of the carbon stored on land in the Northern Hemisphere," Swetnam wrote in an e-mail, adding that warming is happening fastest at high latitudes. In some recent years, the acreage burned in the forests of Siberia exceeded the size of the U.S. state of Virginia, he said. As the world warms, more of those regions are likely to burn, accelerating the warming. Calling for a holistic fire science, Balch said, "We don't think about fires correctly." "Fire is as elemental as air or water. We live on a fire planet. We are a fire species. Yet, the study of fire has been very fragmented. We know lots about the carbon cycle, the nitrogen cycle, but we know very little about the fire cycle, or how fire cycles through the biosphere."
Analysis of Greenland ice led by Scripps researchers could allay fears about methane 'burp' accelerating current global warming trend An expansion of wetlands and not a large-scale melting of frozen methane deposits is the likely cause of a spike in atmospheric methane gas that took place some 11,600 years ago, according to an international research team led by Scripps Institution of Oceanography at UC San Diego.
The finding is expected to come as a relief to scientists and climate watchers concerned that huge accelerations of global warming might have been touched off by methane melts in the past and could happen again now as the planet warms. By measuring the amount of carbon-14 isotopes in methane from air bubbles trapped in glacial ice, the researchers determined that the surge that took place nearly 12,000 years ago was more chemically consistent with an expansion of wetlands. Wetland regions, which produce large amounts of methane from bacterial breakdown of organic matter, are known to have spread during warming trends throughout history. "This is good news for global warming because it suggests that methane clathrates do not respond to warming by releasing large amounts of methane into the atmosphere," said Vasilii Petrenko, a postdoctoral fellow at University of Colorado, Boulder, who led the analysis while a graduate student at Scripps. The results appear in April 24 editions of the journal Science.
Scientists had long been concerned about the potential for present-day climate change to cause a thawing of Arctic permafrost and a warming of ocean waters great enough to trigger a huge release of methane that would send planetary warming into overdrive. Vast amounts of methane are sequestered in solid form, known as methane clathrate, in seafloor deposits and in permafrost. Cold temperatures and the intense pressure of the deep ocean stabilize the methane clathrate masses and keep methane from entering the atmosphere. Scientists have estimated that a melting of only 10 percent of the world's clathrate deposits would create a greenhouse effect equal to a tenfold increase in the amount of carbon dioxide in the atmosphere. For comparison, the warming trend observed in the last century has taken place with only a 30 percent increase of atmospheric carbon dioxide.
The research team, overseen by Scripps geoscientist and study co-author Jeff Severinghaus, collected what may be the largest ice samples ever for a climate change study. The researchers cut away 15 tons of ice from a site called Pakitsoq at the western margin of the Greenland ice sheet to collect the ancient air trapped within. Methane exists in low concentrations in this air and only a trillionth of any given amount contains the carbon-14 isotope that the researchers needed to perform the analysis. Levels of carbon-14, which has a half-life of 5,730 years, were too high in the methane to have come from clathrates, the researchers concluded. "This study is important because it confirms that wetlands and moisture availability change dramatically along with abrupt climate change," said Severinghaus. "This highlights in a general way the fact that the largest impacts of future climate change may be on water resources and drought, rather than temperature per se." The burst of methane took place immediately after an abrupt transition between climatic periods known as the Younger Dryas and Preboreal. During this event, temperatures in Greenland rose 10° C (18° F) in 20 years. Methane levels over 150 years rose about 50 percent, from 500 parts per billion in air to 750 parts per billion.
In addition to Petrenko and Severinghaus, researchers from the Australian Nuclear Science and Technology Organisation (ANSTO), Oregon State University, the National Institute of Water and Atmospheric Research in New Zealand, the Technical University of Denmark and the Commonwealth Scientific and Industrial Research Organisation in Australia contributed to the report. The work was supported by grants from the National Science Foundation, the Packard Foundation, the American Chemical Society, the ANSTO Cosmogenic Climate Archives of the Southern Hemisphere project and the New Zealand Foundation of Science and Technology.
'Sleep talking' is a green computing advance from UC San Diego and Microsoft Research Personal computers may soon save large amounts of energy by "sleep talking." Computer scientists at UC San Diego and Microsoft Research have created a plug-and-play hardware prototype for personal computers that induces a new energy saving state known as "sleep talking." Normally PCs can be in either awake mode-where they consume power even if they are not being used, or in a low power sleep mode-where they save substantial power but are essentially inactive and unresponsive to network traffic. The new sleep talking state provides much of the energy savings of sleep mode and some of the network-and-Internet-connected convenience of awake mode. UC San Diego computer science Ph.D. student Yuvraj Agarwal presented this work on April 23, 2009 at the USENIX Symposium on Networked Systems Design and Implementation (NSDI 2009). Computer scientists at UC San Diego and Microsoft Research in Redmond, Washington and Cambridge, UK collaborated on this project and the NSDI 2009 paper, "Somniloquy: Augmenting Network Interfaces to Reduce PC Energy Usage.
"Large numbers of people keep their PCs in awake mode even though the PCs are relatively idle for long blocks of time because they want to stay connected to an internal network or the Internet or both," said Agarwal. "I realized that most of the tasks that people keep their computers on for-like ensuring remote access and availability for virus scans and backup, maintaining presence on instant messaging (IM) networks, being available for incoming voice-over-IP (VoIP) calls, and file sharing and downloading-can be achieved at much lower power-use levels than regular awake mode," said Agarwal.
Following this realization, the team built a small USB-connected hardware and software plug-in system that allows a PC to remain in sleep mode while continuing to maintain network presence and run well-defined application functions. It supports instant messaging applications, VoIP, large background web downloads, peer-to-peer file sharing networks such as BitTorrent, and remote access. The computer scientists say their system is easily extensible to support other applications. The computer scientists named their system Somniloquy, which means "the act or habit of talking in one's sleep." In fact, the system allows a PC to appear to "say" to other hosts on the network, "I'm awake and I can perform non-power-intensive tasks"-even though the PC is in sleep mode. If more computational muscle or resources present on the PC such as stored files are required, Somniloquy wakes up the PC. The goal of Somniloquy is to encourage people to put their PCs in sleep mode more often, for example when they are not being used for computationally demanding tasks. "Reducing energy consumed by wall-powered devices, especially computing equipment, offers a huge opportunity to save money and reduce greenhouse gasses," said Agarwal.
"Somniloquy uses a very small low-power computer. It has a low-power processor, some memory, a lightweight operating system, and a small amount of flash to store data. Everything is scaled down and extremely energy efficient," said Agarwal, a self described "computer systems" researcher who uses hardware insights to build better energy-efficient computer systems. Somniloquy's low-power secondary processor functions at the PC's network interface. It runs an embedded operating system and impersonates the sleeping PC to other hosts on the network. Somniloquy will wake up the PC over the USB bus if necessary. For example, during a movie download, when the flash memory fills up, Somniloquy will wake up the PC and transfer the data. When the transfer is complete, it will go back to sleep mode and Somniloquy will again impersonate the computer on the network. The current prototypes work for desktops and laptops, over wired and wireless networks, and are incrementally deployable on systems with an existing network interface. It does not require any changes to the operating system on the PC, to routers or other network infrastructure, or to remote application servers. The researchers evaluated Somniloquy in various settings and say that it consumes 11 to 24 times less power than a PC in idle state, which could translate to energy savings of 60 to 80 percent depending on their use model.
In the future, Somniloquy could be incorporated into the network interface card of new PCs, which would eliminate the need for the prototype's external USB plug-in hardware.
Los Alamos National Laboratory researchers have discovered a potential chink in the armor of fibers that make the cell walls of certain inedible plant materials so tough. The insight ultimately could lead to a cost-effective and energy-efficient strategy for turning biomass into alternative fuels. In separate papers published today in Biophysical Journal and recently in an issue of Biomacromolecules, Los Alamos researchers identify potential weaknesses among sheets of cellulose molecules comprising lignocellulosic biomass, the inedible fibrous material derived from plant cell walls. The material is a potentially abundant source of sugar that can be used to brew batches of methanol or butanol, which show potential as biofuels.
Cellulose is biosynthesized in plant cells when molecules of glucose-a simple sugar-join into long chains through a process called polymerization. The plant then assembles these chains of cellulose into sheets. The sheets are held together by hydrogen bonds-an electrostatic attraction of a positive portion of a molecule to a negative portion of the same or neighboring molecule. Finally, the sheets stack atop one another, sticking to themselves by other types of attractions that are weaker than hydrogen bonds. The plant then spins these sheets into high-tensile-strength fibers of material. Not only are the fibers incredibly strong, but they are incredibly resistant to the action of enzymes called cellulases that can crack the fibers back into their simple-sugar components. The ability to economically and easily break cellulose into sugars is desirable because the sugars can be used to create fuel alternatives. However, due to the tenacity of cellulose fibers, the United States currently lacks an energy-efficient and cost-effective method for turning inedible biomass such as switch grass or corn husks into a sweet source of biofuels.
Working with researchers from the U.S. Department of Agriculture and the Centre de Recherches sur les Macromolécules Végétales in France, Los Alamos researcher Paul Langan used neutrons to probe the crystalline structure of highly crystalline cellulose, much like an X-ray is used to probe the hidden structures of the body. Langan and his colleagues found that although cellulose generally has a well-ordered network of hydrogen bonds holding it together, the material also displays significant amounts of disorder, creating a different type of hydrogen bond network at certain surfaces. These differences make the molecule potentially vulnerable to an attack by cellulase enzymes. Moreover, in this month's Biophysical Journal, Los Alamos researchers Tongye Shen and Gnana Gnanakaran describe a new lattice-based model of crystalline cellulose. The model predicts how hydrogen bonds in cellulose can shift to remain stable under a wide range of temperatures. This plasticity allows the material to swap different types of hydrogen bonds but also constrains the molecules so that they must form bonds in the weaker configuration described by Langan and his colleagues. Most important, Shen and Gnanakaran's model identifies hydrogen bonds that can be manipulated via temperature differences to potentially make the material more susceptible to attack by enzymes that can crack the fibers into sugars for biofuel production. "We have been able to identify a chink in the armor of a very tough and worthy adversary-the cellulose fiber," said Gnanakaran, who leads the theoretical portion of a large, multidisciplinary biofuels project at Los Alamos. "These results are some of the first to come from this team, and eventually could point us toward an economical and viable process for making biofuels from cellulosic biomass," adds Langan, director of the biofuels project.
Funding for the project comes from Laboratory-Directed Research and Development (LDRD), which is the premier source of internally directed research-and-development funding at Los Alamos National Laboratory. The LDRD program invests in high-risk, potentially high-payoff projects at the discretion of the Laboratory Director. Strategic investments of the LDRD program help position Los Alamos to anticipate and prepare for emerging national security challenges.
Plants absorbed carbon dioxide more efficiently under the polluted skies of recent decades than they would have done in a cleaner atmosphere, according to new findings published this week in Nature. The results of the study have important implications for efforts to combat future climate change which are likely to take place alongside attempts to lower air pollution levels. The research team included scientists from the Centre for Ecology & Hydrology, the Met Office Hadley Centre, ETH Zurich and the University of Exeter. Lead author Dr Lina Mercado, from the Centre for Ecology & Hydrology, said, "Surprisingly, the effects of atmospheric pollution seem to have enhanced global plant productivity by as much as a quarter from 1960 to 1999. This resulted in a net 10% increase in the amount of carbon stored by the land once other effects were taken into account."
An increase in microscopic particles released into the atmosphere (known as aerosols), by human activities and changes in cloud cover, caused a decline in the amount of sunlight reaching the Earth's surface from the 1950s up to the 1980s (a phenomenon known as 'global dimming'). Although reductions in sunlight reduce photosynthesis, clouds and atmospheric particles scatter light so that the surface receives light from multiple directions (diffuse radiation) rather than coming straight from the sun. Plants are then able to convert more of the available sunlight into growth because fewer leaves are in the shade. Scientists have known for a long time that aerosols cool climate by reflecting sunlight and making clouds brighter, but the new study is the first to use a global model to estimate the net effects on plant carbon uptake resulting from this type of atmospheric pollution. Co-author Dr Stephen Sitch from the Met Office Hadley Centre (now at the University of Leeds) said, "Although many people believe that well-watered plants grow best on a bright sunny day, the reverse is true. Plants often thrive in hazy conditions such as those that exist during periods of increased atmospheric pollution."
The research team also considered the implications of these findings for efforts to avoid dangerous climate change. Under an environmentally friendly scenario in which sulphate aerosols decline rapidly in the 21st century, they found that by cleaning up the atmosphere even steeper cuts in global carbon dioxide emissions would be required to stabilize carbon dioxide concentrations below 450 parts per million by volume. Co-author Professor Peter Cox of the University of Exeter summed up the consequences of the study, "As we continue to clean up the air in the lower atmosphere, which we must do for the sake of human health, the challenge of avoiding dangerous climate change through reductions in CO2 emissions will be even harder. Different climate changing pollutants have very different direct effects on plants, and these need to be taken into account if we are to make good decisions about how to deal with climate change."
Ice ages are the greatest natural climate changes in recent geological times. Their rise and fall are caused by slight changes in the Earth's orbit around the Sun due to the influence of the other planets. But we do not know the exact relationship between the changes in the Earth's orbit and the changes in climate. New research from the Niels Bohr Institute indicates that there can be changes in the CO2 levels in the atmosphere that suddenly reach a critical turning point and with that trigger the dramatic climate changes. The results are published in the American journal Paleoceanography.
The Earth's climate is essentially contolled by three different cycles (Milankovitch). All three cycles are caused by the pull of the other planets in the solar system on the Earth, and one could say that they control the Earth's climate by causing changes in the Sun's radiation. 1: The Earth's orbit around the sun is not completely circular, but slightly elliptical. The orbit is 'elastic' and contracts and expands in a cycle of 100.000 years. And the closer we are to the Sun, the more solar radiation and the more heat we receive. 2: The Earth's axis has a tilt in relation to the Sun and that is why we have summer and winter. But the tilt is not constant, it swings between 22 degrees and 24 degrees, and the greater the tilt, the greater the difference between summer and winter. This cycle takes 40.000 years. 3: The Earth rotates around on its axis like a top - this gives day and night. But due to the tilt of the Earth and the elliptical orbit the direction changes with a cycle of 20.000 years. This results in varation in to whether the Earth is nearest the Sun during the summer or during the winter. Solar radiation varies in the two hemispheres during the summer due to these cycles in the Earth's tilt and the elliptical orbit and this has profound implications for whether ice caps can build up in the northern hemisphere, where the largest land areas are.
Mysterious changes in ice ages The ice ages have come and gone the last 20 million years and for the last few million years we know with reasonable accuracy how often they come. In the period before about 1 million years ago the ice ages occured around every 40.000 years, then it happened suddenly that the period changed so that it became circa 100.000 years between ice ages. It is a mystery because nothing changed in the behaviour of the Earth's orbit 1 million years ago. It is therefore due to a change that comes from the climate itself. The conventional wisdom around the 100.000 year cycle of the last 10 ice ages is that the 100.000 years variation in the Earth's orbital eccentricity (the measure for how elliptical the orbit is and the half-yearly variation in the Earth's distance from the sun). This variation is still weaker than the variation that occurs with the 40.000 year cycle, so that in itself is a mystery.
Warm, half cold, ice cold With completely new research results geophysicist Peter Ditlevsen, Centre for Ice and Climate at the Niels Bohr Institute, has found part of the explanation for the mystery of the sudden change of the ice ages. He has made model calculations of the climate of the past and compared it to the concrete data from seabed cores, which tell us about the climatic fluctuations of the past. From the results he has been able to construct a diagram over the possible climatic conditions resulting from the variation in solar radiation. It appears that the ice ages and interglacial periods are not a gradual fluctuation between cold and warm climates. What happened 1 million years ago was that the climate system went from a situation where it fluctuated between two states (cold and warm) with a 40.000 year cycle, corresponding to the dominant change in the Sun's radiation. After this period the dynamic changed so that the climate jumped between 3 states, that is to say between a warm interglacial climate like our present climate, a colder climate and a very cold ice age climate. It is still the 40.000 year variation in solar radiation which controls our current fluctuations, but it results in changing climate periods of 80.000 and 120.000 years.
Chaotic dynamic climate?The climate does not become gradually colder or warmer - it jumps from the one state to the other. That which gets the climate to jump is that when the solar radiation changes and reaches a certain threshold - a 'tipping point', the existing climate state, e.g. an ice age, is no longer viable and so the climate jumps over into another state, e.g. a warm interglacial period. In chaos dynamics this phenomenon is called a bifurcation or a 'catastrophe'. In addition to the change in solar radiation there can be random changes in the Earth's weather variations, that contribute to triggering the bifurcation or the 'catastrophe'. Such variations are called 'noise', and a theory is, that the atmosphere's CO2 level can be an important noise-factor. This means that there is the possibility that the 'noise' is a decisive factor for very large climate changes, which can therefore be unpredictable. There is still no explanation for the change in the climate system 1 million years ago, but one theory is that the atmosphere's CO2-level fell to the lowest level ever. If so, the manmade increase in CO2 may result in a return to 40.000 year ice age cycles.
"The new results are an important piece of the puzzle for understanding the ice ages and their climate dynamics. In the manmade climate changes, that we are possibly in the middle of now, one worries a lot about the possible so-called 'tipping points'. The bifurcations that are now identified in the natural climate fluctuations are tipping points, so this is of course an important step in our understanding of climate changes", explains Peter Ditlevsen.
"The bifurcation structure and noise assisted transitions in the Pleistocene glacial cycles": http://www.agu.org/journals/pa/papersinpress.shtml#id2008PA001673
Maintaining a healthy body weight is good news for the environment, according to a study which appears today in the International Journal of Epidemiology. Because food production is a major contributor to global warming, a lean population, such as that seen in Vietnam, will consume almost 20% less food and produce fewer greenhouse gases than a population in which 40% of people are obese (close to that seen in the USA today), according to Phil Edwards and Ian Roberts of the London School of Hygiene & Tropical Medicine's Department of Epidemiology and Population Health. Transport-related emissions will also be lower because it takes less energy to transport slim people. The researchers estimate that a lean population of 1 billion people would emit 1.0 GT (1,000 million tonnes) less carbon dioxide equivalents per year compared with a fat one.
In nearly every country in the world, average body mass index (BMI) is rising. Between 1994 and 2004 the average male BMI in England increased from 26 to 27.3, with the average female BMI rising from 25.8 to 26.9 (about 3 kg - or half a stone - heavier). Humankind - be it Australian, Argentinian, Belgian or Canadian - is getting steadily fatter. 'When it comes to food consumption, moving about in a heavy body is like driving around in a gas guzzler', say the authors. 'The heavier our bodies become the harder and more unpleasant it is to move about in them and the more dependent we become on our cars. Staying slim is good for health and for the environment. We need to be doing a lot more to reverse the global trend towards fatness, and recognise it as a key factor in the battle to reduce emissions and slow climate change', they conclude.
New calculations made by marine chemists from the Monterey Bay Aquarium Research Institute (MBARI) suggest that low-oxygen "dead zones" in the ocean could expand significantly over the next century. These predictions are based on the fact that, as more and more carbon dioxide dissolves from the atmosphere into the ocean, marine animals will need more oxygen to survive. Concentrations of carbon dioxide are increasing rapidly in the Earth's atmosphere, primarily because of human activities. About one third of the carbon dioxide that humans produce by burning fossil fuels is being absorbed by the world's oceans, gradually causing seawater to become more acidic.
However, such "ocean acidification" is not the only way that carbon dioxide can harm marine animals. In a "Perspective" published today in the journal Science, Peter Brewer and Edward Peltzer combine published data on rising levels of carbon dioxide and declining levels of oxygen in the ocean in a set of new and thermodynamically rigorous calculations. They show that increases in carbon dioxide can make marine animals more susceptible to low concentrations of oxygen, and thus exacerbate the effects of low-oxygen "dead zones" in the ocean.
Brewer and Peltzer's calculations also show that the partial pressure of dissolved carbon dioxide gas (pCO2) in low-oxygen zones will rise much higher than previously thought. This could have significant consequences for marine life in these zones. For over a decade, Brewer and Peltzer have been working with marine biologists to study the effects of carbon dioxide on marine organisms. High concentrations of carbon dioxide make it harder for marine animals to respire (to extract oxygen from seawater). This, in turn, makes it harder for these animals to find food, avoid predators, and reproduce. Low concentrations of oxygen can have similar effects.
Currently, deep-sea life is threatened by a combination of increasing carbon dioxide and decreasing oxygen concentrations. The amount of dissolved carbon dioxide is increasing because the oceans are taking up more and more carbon dioxide from the atmosphere. At the same time, ocean surface waters are warming and becoming more stable, which allows less oxygen to be carried from the surface down into the depths. In trying to quantify the impacts of this "double whammy" on marine organisms, Brewer and Peltzer came up with the concept of a "respiration index." This index is based on the ratio of oxygen and carbon dioxide gas in a given sample of seawater. The lower the respiration index, the harder it is for marine animals to respire.
Brewer provides the following analogy, "Animals facing declining oxygen levels and rising CO2 levels will suffer in much the same way that humans in a damaged submarine would suffer, once the concentrations of these gasses reach critical levels. Our work helps define those critical levels for marine animals, and will enable the emerging risk to be quantified and mapped." In the past, marine biologists have defined "dead zones" based solely on low concentrations of dissolved oxygen. Brewer and Peltzer hope that their respiration index will provide a more precise and quantitative way for oceanographers to identify such areas. Tracking changes in the respiration index could also help marine biologists understand and predict which ocean waters are at risk of becoming dead zones in the future. To estimate such effects in the open ocean, the MBARI researchers calculated the respiration index at various ocean depths, for several different forecasted concentrations of atmospheric carbon dioxide. They found that the most severe effects would take place in what are known as "oxygen minimum zones." These are depths, typically 300 to 1,000 meters below the surface, where oxygen concentrations are already quite low in many parts of the world's oceans.
Previously, marine biologists have assumed that the effects of increasing carbon dioxide in the oceans would be greatest at the sea surface, where most of the gas enters the ocean. Such studies have predicted a doubling of pCO2 (from about 280 to 560 micro-atmospheres) at the sea surface over the next 100 years. Brewer and Peltzer's calculations suggest that the partial pressure of carbon dioxide will increase even faster in the deep oxygen minimum zones, with pCO2 increasing by 2.5 times, from 1,000 to about 2,500 micro-atmospheres. Previous studies have indicated that such oxygen minimum zones may expand over the next century. Brewer and Peltzer's research suggests that the effects of this expansion will be even more severe than previously forecast. According to coauthor Peltzer, "The bottom line is that we think it's important to look at both oxygen and carbon dioxide in the oceans, rather than just one or the other." The impact of these chemical changes may be minimal in well-oxygenated ocean areas, but as the authors point out in their paper, "We may anticipate a very large expansion of the oceanic dead zones."
Earth's ozone layer should eventually recover from the unintended destruction brought on by the use of chlorofluorocarbons (CFCs) and similar ozone-depleting chemicals in the 20th century. But new research by NASA scientists suggests the ozone layer of the future is unlikely to look much like the past because greenhouse gases are changing the dynamics of the atmosphere. Previous studies have shown that while the buildup of greenhouse gases makes it warmer in troposphere - the level of atmosphere from Earth's surface up to 10 kilometers (6 miles) altitude - it actually cools the upper stratosphere - between 30 to 50 kilometers high (18 to 31 miles). This cooling slows the chemical reactions that deplete ozone in the upper stratosphere and allows natural ozone production in that region to outpace destruction by CFCs. But the accumulation of greenhouse gases also changes the circulation of stratospheric air masses from the tropics to the poles, NASA scientists note. In Earth's middle latitudes, that means ozone is likely to "over-recover," growing to concentrations higher than they were before the mass production of CFCs. In the tropics, stratospheric circulation changes could prevent the ozone layer from fully recovering. "Most studies of ozone and global change have focused on cooling in the upper stratosphere," said Feng Li, an atmospheric scientist at the Goddard Earth Sciences and Technology Center at the University of Maryland Baltimore County, Baltimore, Md. and lead author of the study. "But we find circulation is just as important. It's not one process or the other, but both."
The findings are based on a detailed computer model that includes atmospheric chemical effects, wind changes, and solar radiation changes. Li's experiment is part of an ongoing international effort organized by the United Nations Environment Programme's Scientific Assessment Panel to assess the state of the ozone layer. Li and colleagues published their analysis in March in the journal Atmospheric Chemistry and Physics. Working with Richard Stolarski and Paul Newman of NASA's Goddard Space Flight Center, Greenbelt, Md., Li adapted the Goddard Earth Observing System Chemistry-Climate Model (GEOS-CCM) to examine how climate change will affect ozone recovery. The team inserted past measurements and future projections of ozone-depleting substances and greenhouse gases into the model. Then the model projected how ozone, the overall chemistry, and the dynamics of the stratosphere would change through the year 2100.
"In the real world, we have observed statistically significant turnaround in ozone depletion, which can be attributed to the banning of ozone-depleting substances," said Richard Stolarski, an atmospheric chemist at Goddard and a co-author of the study. "But making that connection is complicated by the response of ozone to greenhouse gases." The researchers found that greenhouse gases alter a natural circulation pattern that influences ozone distribution. Brewer-Dobson circulation is like a pump to the stratosphere, moving ozone from the lower parts of the atmosphere, into the upper stratosphere over the tropics. Air masses then flow north or south through the stratosphere, away from the tropics toward the poles. In Li's experiment, this circulation pump accelerated to a rate where the ozone flowing upward and outward from the tropics created a surplus at middle latitudes. Though the concentration of chlorine and other ozone-depleting substances in the stratosphere will not return to pre-1980 levels until 2060, the ozone layer over middle latitudes recovered to pre-1980 levels by 2025. The Arctic - which is better connected to mid-latitude air masses than the Antarctic -- benefitted from the surplus in the northern hemisphere and from the overall decline of ozone-depleting substances to recover by 2025. Globally averaged ozone and Antarctic concentrations catch up by 2040, as natural atmospheric production of ozone resumes.
This recovery in the middle and polar latitudes has mixed consequences, Li noted. It might have some benefits, such as lower levels of ultraviolet radiation reaching the Earth's surface and correspondingly lower rates of skin cancer. On the other hand, it could have unintended effects, such as increasing ozone levels in the troposphere, the layer of atmosphere at Earth's surface. The model also shows a continuing ozone deficit in the stratosphere over the tropics. In fact, when the model run ended at year 2100, the ozone layer over the tropics still showed no signs of recovery. In February, researchers from Johns Hopkins University, Baltimore, teamed with Stolarski and other NASA scientists on a similar paper suggesting that increasing greenhouse gases would delay or even postpone the recovery of ozone levels in the lower stratosphere over some parts of the globe. Using the same model as Li, Stolarski, and Newman, the researchers found that the lower stratosphere over tropical and mid-southern latitudes might not return to pre-1980s levels of ozone for more than a century, if ever.
http://www.nasa.gov/topics/earth/features/ozone_recovery.html
Engineers at Oregon State University have discovered a way to use an ancient life form to create one of the newest technologies for solar energy, in systems that may be surprisingly simple to build compared to existing silicon-based solar cells. The secret: diatoms. These tiny, single-celled marine life forms have existed for at least 100 million years and are the basis for much of the life in the oceans, but they also have rigid shells that can be used to create order in a natural way at the extraordinarily small level of nanotechnology.
By using biology instead of conventional semiconductor manufacturing approaches, researchers at OSU and Portland State University have created a new way to make "dye-sensitized" solar cells, in which photons bounce around like they were in a pinball machine, striking these dyes and producing electricity. This technology may be slightly more expensive than some existing approaches to make dye-sensitized solar cells, but can potentially triple the electrical output. "Most existing solar cell technology is based on silicon and is nearing the limits of what we may be able to accomplish with that," said Greg Rorrer, an OSU professor of chemical engineering. "There's an enormous opportunity to develop different types of solar energy technology, and it's likely that several forms will ultimately all find uses, depending on the situation." Dye-sensitized technology, for instance, uses environmentally benign materials and works well in lower light conditions. And the new findings offer advances in manufacturing simplicity and efficiency. "Dye-sensitized solar cells already exist," Rorrer said. "What's different in our approach are the steps we take to make these devices, and the potential improvements they offer." The new system is based on living diatoms, which are extremely small, single-celled algae, which already have shells with the nanostructure that is needed. They are allowed to settle on a transparent conductive glass surface, and then the living organic material is removed, leaving behind the tiny skeletons of the diatoms to form a template.
A biological agent is then used to precipitate soluble titanium into very tiny "nanoparticles" of titanium dioxide, creating a thin film that acts as the semiconductor for the dye-sensitized solar cell device. Steps that had been difficult to accomplish with conventional methods have been made easy through the use of these natural biological systems, using simple and inexpensive materials. "Conventional thin-film, photo-synthesizing dyes also take photons from sunlight and transfer it to titanium dioxide, creating electricity," Rorrer said. "But in this system the photons bounce around more inside the pores of the diatom shell, making it more efficient."
The physics of this process, Rorrer said, are not fully understood - but it clearly works. More so than materials in a simple flat layer, the tiny holes in diatom shells appear to increase the interaction between photons and the dye to promote the conversion of light to electricity, and improve energy production in the process. The insertion of nanoscale tinanium oxide layers into the diatom shell has been reported in ACS Nano, a publication of the American Chemical Society, and the Journal of Materials Research, a publication of the Materials Research Society. The integration of this material into a dye-sensitized solar cell device was also recently described at the fourth annual Greener Nanoscience Conference.
Though greenhouse gases are invariably at the center of discussions about global climate change, new NASA research suggests that much of the atmospheric warming observed in the Arctic since 1976 may be due to changes in tiny airborne particles called aerosols. Emitted by natural and human sources, aerosols can directly influence climate by reflecting or absorbing the sun's radiation. The small particles also affect climate indirectly by seeding clouds and changing cloud properties, such as reflectivity. A new study, led by climate scientist Drew Shindell of the NASA Goddard Institute for Space Studies, New York, used a coupled ocean-atmosphere model to investigate how sensitive different regional climates are to changes in levels of carbon dioxide, ozone, and aerosols. The researchers found that the mid and high latitudes are especially responsive to changes in the level of aerosols. Indeed, the model suggests aerosols likely account for 45 percent or more of the warming that has occurred in the Arctic during the last three decades. The results were published in the April issue of Nature Geoscience.
Though there are several varieties of aerosols, previous research has shown that two types -- sulfates and black carbon -- play an especially critical role in regulating climate change. Both are products of human activity. Sulfates, which come primarily from the burning of coal and oil, scatter incoming solar radiation and have a net cooling effect on climate. Over the past three decades, the United States and European countries have passed a series of laws that have reduced sulfate emissions by 50 percent. While improving air quality and aiding public health, the result has been less atmospheric cooling from sulfates.
At the same time, black carbon emissions have steadily risen, largely because of increasing emissions from Asia. Black carbon -- small, soot-like particles produced by industrial processes and the combustion of diesel and biofuels -- absorb incoming solar radiation and have a strong warming influence on the atmosphere. In the modeling experiment, Shindell and colleagues compiled detailed, quantitative information about the relative roles of various components of the climate system, such as solar variations, volcanic events, and changes in greenhouse gas levels. They then ran through various scenarios of how temperatures would change as the levels of ozone and aerosols -- including sulfates and black carbon -- varied in different regions of the world. Finally, they teased out the amount of warming that could be attributed to different climate variables. Aerosols loomed large. The regions of Earth that showed the strongest responses to aerosols in the model are the same regions that have witnessed the greatest real-world temperature increases since 1976. The Arctic region has seen its surface air temperatures increase by 1.5 C (2.7 F) since the mid-1970s. In the Antarctic, where aerosols play less of a role, the surface air temperature has increased about 0.35 C (0.6 F).
That makes sense, Shindell explained, because of the Arctic's proximity to North America and Europe. The two highly industrialized regions have produced most of the world's aerosol emissions over the last century, and some of those aerosols drift northward and collect in the Arctic. Precipitation, which normally flushes aerosols out of the atmosphere, is minimal there, so the particles remain in the air longer and have a stronger impact than in other parts of the world. Since decreasing amounts of sulfates and increasing amounts of black carbon both encourage warming, temperature increases can be especially rapid. The build-up of aerosols also triggers positive feedback cycles that further accelerate warming as snow and ice cover retreat. In the Antarctic, in contrast, the impact of sulfates and black carbon is minimized because of the continent's isolation from major population centers and the emissions they produce. "There's a tendency to think of aerosols as small players, but they're not," said Shindell. "Right now, in the mid-latitudes of the Northern Hemisphere and in the Arctic, the impact of aerosols is just as strong as that of the greenhouse gases." The growing recognition that aerosols may play a larger climate role can have implications for policymakers. "We will have very little leverage over climate in the next couple of decades if we're just looking at carbon dioxide," Shindell said. "If we want to try to stop the Arctic summer sea ice from melting completely over the next few decades, we're much better off looking at aerosols and ozone."
Aerosols tend to be quite-short lived, residing in the atmosphere for just a few days or weeks. Greenhouses gases, by contrast, can persist for hundreds of years. Atmospheric chemists theorize that the climate system may be more responsive to changes in aerosol levels over the next few decades than to changes in greenhouse gas levels, which will have the more powerful effect in coming centuries. "This is an important model study, raising lots of great questions that will need to be investigated with field research," said Loretta Mickley, an atmospheric chemist from Harvard University, Cambridge, Mass. who was not directly involved in the research. Understanding how aerosols behave in the atmosphere is still very much a work-in-progress, she noted, and every model needs to be compared rigorously to real life observations. But the science behind Shindell's results should be taken seriously. "It appears that aerosols have quite a powerful effect on climate, but there's still a lot more that we need to sort out," said Shindell.
NASA's upcoming Glory satellite is designed to enhance our current aerosol measurement capabilities to help scientists reduce uncertainties about aerosols by measuring the distribution and microphysical properties of the particles.
A tiny microbe can take electricity and directly convert carbon dioxide and water to methane, producing a portable energy source with a potentially neutral carbon footprint, according to a team of Penn State engineers. "We were studying making hydrogen in microbial electrolysis cells and we kept getting all this methane," said Bruce E. Logan, Kappe Professor of Environmental Engineering, Penn State. "We may now understand why." Methanogenic microorganisms do produce methane in marshes and dumps, but scientists thought that the organisms turned hydrogen or organic materials, such as acetate, into methane. However, the researchers found, while trying to produce hydrogen in microbial electrolysis cells, that their cells produced much more methane than expected.
"All the methane generation going on in nature that we have assumed is going through hydrogen may not be," said Logan. "We actually find very little hydrogen in the gas phase in nature. Perhaps where we assumed hydrogen is being made, it is not." Microbial electrolysis cells do require an electrical voltage to be added to the voltage that is produced by bacteria using organic materials to produce current that evolves into hydrogen. The researchers found that the Archaea, using about the same electrical input, could use the current to convert carbon dioxide and water to methane without any organic material, bacteria or hydrogen usually found in microbial electrolysis cells. They report their findings in this week's issue of Environmental Science and Technology. "We have a microbe that is self perpetuating that can accept electrons directly, and use them to create methane," said Logan. Logan, working with Shaoan Cheng, senior research associate; Defeng Xing, post doctoral researcher, and Douglas F. Call, graduate student, environmental engineering, confirmed that the microscopic organisms produced the methane. The researchers created a two-chambered cell with an anode immersed in water on one side of the chamber and a cathode in water, inorganic nutrients and carbon dioxide on the other side of the chamber. They applied a voltage, but recorded only a minute current. The researchers then coated the cathode with the biofilm of Archaea and not only did current flow in the circuit, but the cell produced methane.
"The only way to get current at the voltage we used was if the microbes were directly accepting electrons," said Logan. He notes that the electrochemical reaction takes place without any precious metal catalysts and at a lower energy level than converting carbon dioxide to methane using conventional, non-biological methods. The cells are about 80 percent efficient in converting electricity to methane and because they use carbon dioxide as feed stock, would be carbon neutral if the electricity comes from a non-carbon source such as solar or wind power. "The process does not sequester carbon, but it does turn carbon dioxide into fuel," said Logan. "If the methane is burned and carbon dioxide captured, then the process can be carbon neutral." Logan suggests the method for off peak capture of renewable energy in a portable fuel. Methane is preferred over hydrogen because a large portion of the U.S. infrastructure is already set up to easily transport and deliver methane.
Future stratospheric ozone losses from unregulated launches will eventually exceed ozone losses from CFCs The global market for rocket launches may require more stringent regulation in order to prevent significant damage to Earth's stratospheric ozone layer in the decades to come, according to a new study by researchers in California and Colorado. Future ozone losses from unregulated rocket launches will eventually exceed ozone losses due to chlorofluorocarbons, or CFCs, which stimulated the 1987 Montreal Protocol banning ozone-depleting chemicals, said Martin Ross, chief study author from The Aerospace Corporation in Los Angeles. The study, which includes the University of Colorado at Boulder and Embry-Riddle Aeronautical University, provides a market analysis for estimating future ozone layer depletion based on the expected growth of the space industry and known impacts of rocket launches.
"As the rocket launch market grows, so will ozone-destroying rocket emissions," said Professor Darin Toohey of CU-Boulder's atmospheric and oceanic sciences department. "If left unregulated, rocket launches by the year 2050 could result in more ozone destruction than was ever realized by CFCs." A paper on the subject by Ross and Manfred Peinemann of The Aerospace Corporation, CU-Boulder's Toohey and Embry-Riddle Aeronautical University's Patrick Ross appeared online in March in the journal Astropolitics. Since some proposed space efforts would require frequent launches of large rockets over extended periods, the new study was designed to bring attention to the issue in hopes of sparking additional research, said Ross. "In the policy world uncertainty often leads to unnecessary regulation," he said. "We are suggesting this could be avoided with a more robust understanding of how rockets affect the ozone layer."
Current global rocket launches deplete the ozone layer by no more than a few hundredths of 1 percent annually, said Toohey. But as the space industry grows and other ozone-depleting chemicals decline in the Earth's stratosphere, the issue of ozone depletion from rocket launches is expected to move to the forefront. Today, just a handful of NASA space shuttle launches release more ozone-depleting substances in the stratosphere than the entire annual use of CFC-based medical inhalers used to treat asthma and other diseases in the United States and which are now banned, said Toohey. "The Montreal Protocol has left out the space industry, which could have been included." Highly reactive trace-gas molecules known as radicals dominate stratospheric ozone destruction, and a single radical in the stratosphere can destroy up to 10,000 ozone molecules before being deactivated and removed from the stratosphere. Microscopic particles, including soot and aluminum oxide particles emitted by rocket engines, provide chemically active surface areas that increase the rate such radicals "leak" from their reservoirs and contribute to ozone destruction, said Toohey. In addition, every type of rocket engine causes some ozone loss, and rocket combustion products are the only human sources of ozone-destroying compounds injected directly into the middle and upper stratosphere where the ozone layer resides, he said.
Although U.S. science agencies spent millions of dollars to assess the ozone loss potential from a hypothetical fleet of 500 supersonic aircraft -- a fleet that never materialized -- much less research has been done to understand the potential range of effects the existing global fleet of rockets might have on the ozone layer, said Ross. Since 1987 CFCs have been banned from use in aerosol cans, freezer refrigerants and air conditioners. Many scientists expect the stratospheric ozone layer -- which absorbs more than 90 percent of harmful ultraviolet radiation that can harm humans and ecosystems -- to return to levels that existed prior to the use of ozone-depleting chemicals by the year 2040. Rockets around the world use a variety of propellants, including solids, liquids and hybrids. Ross said while little is currently known about how they compare to each other with respect to the ozone loss they cause, new studies are needed to provide the parameters required to guide possible regulation of both commercial and government rocket launches in the future. "Twenty years may seem like a long way off, but space system development often takes a decade or longer and involves large capital investments," said Ross. "We want to reduce the risk that unpredictable and more strict ozone regulations would be a hindrance to space access by measuring and modeling exactly how different rocket types affect the ozone layer."
The research team is optimistic that a solution to the problem exists. "We have the resources, we have the expertise, and we now have the regulatory history to address this issue in a very powerful way," said Toohey. "I am optimistic that we are going to solve this problem, but we are not going to solve it by doing nothing."
Although adolescent and young adult vegetarians may eat a healthier diet, there is some evidence that they may be at increased risk for disordered eating behaviors. In a study published in the April 2009 issue of the Journal of the American Dietetic Association, researchers observed that adolescent and young adult vegetarians may experience the health benefits associated with increased fruit and vegetable intake and young adults my experience the added benefit of decreased risk for overweight and obesity. However, current vegetarians may be at increased risk for binge eating, while former vegetarians may be at increased risk for extreme unhealthful weight control behaviors.
Using the results of Project EAT-II: Eating Among Teens, researchers from the College of Saint Benedict and Saint John's University, the University of Minnesota, and the University of Texas, Austin, analyzed the diets, weight status, weight control behaviors, and drug and alcohol use of 2,516 adolescents and young adults between the ages of 15 and 23. These participants had been part of Project EAT-I, an earlier survey of middle school and high school students from 31 Minnesota schools using in-class surveys, food frequency questionnaires, and anthropometric measures taken during the 1998-99 academic year. Participants were identified as current (4.3%), former (10.8%), and never (84.9%) vegetarians. Subjects were divided into two cohorts, an adolescent (15-18) group and a young adult (19-23) group. They were questioned about binge eating and whether they felt a loss of control of their eating habits. More extreme weight control behaviors including taking diet pills, inducing vomiting, using laxatives, and using diuretics were also measured.
The authors found that among the younger cohort, no statistically significant differences were found with regard to weight status. Among the older cohort, current vegetarians had a lower body mass index and were less likely to be overweight or obese when compared to never vegetarians. Among the younger cohort, a higher percentage of former vegetarians reported engaging in more extreme unhealthy weight control behaviors when compared to never vegetarians. Among the older cohort, a higher percentage of former vegetarians reported engaging in more extreme unhealthy weight control behaviors when compared to current and never vegetarians. In the younger cohort, a higher percentage of current and former vegetarians reported engaging in binge eating with loss of control when compared to never vegetarians. In the older cohort, a higher percentage of current vegetarians reported engaging in binge eating with loss of control when compared to former and never vegetarians.
Writing in the article, Ramona Robinson-O'Brien, Assistant Professor, Nutrition Department, College of Saint Benedict and Saint John's University, St. Joseph, MN, states, "Study results indicate that it would be beneficial for clinicians to ask adolescents and young adults about their current and former vegetarian status when assessing risk for disordered eating behaviors. Furthermore, when guiding adolescent and young adult vegetarians in proper nutrition and meal planning, it may also be important to investigate an individual's motives for choosing a vegetarian diet."
New research shows that for millions of years carbon dioxide has been stored safely and naturally in underground water in gas fields saturated with the greenhouse gas. The findings - published in Nature today - bring carbon capture and storage a step closer. Politicians are committed to cutting levels of atmospheric carbon dioxide to slow climate change. Carbon capture and storage is one approach to cut levels of the gas until cleaner energy sources are developed. But the risks around the long-term storage of millions of cubic metres of carbon dioxide in depleted gas and oil fields has met with some concern, not least because of the possibility of some of the gas escaping and being released back to the atmosphere. Until now, researchers couldn't be sure how the gas would be securely trapped underground.
Naturally-occurring carbon dioxide can be trapped in two ways. The gas can dissolve in underground water - like bottled sparkling water. It can also react with minerals in rock to form new carbonate minerals, essentially locking away the carbon dioxide underground. Previous research in this area used computer models to simulate the injection of carbon dioxide into underground reservoirs in gas or oil fields to work out where the gas is likely to be stored. Some models predict that the carbon dioxide would react with rock minerals to form new carbonate minerals, while others suggest that the gas dissolves into the water. Real studies to support either of these predictions have, until now, been missing. To find out exactly how the carbon dioxide is stored in natural gas fields, an international team of researchers - led by the University of Manchester - uniquely combined two specialised techniques. They measured the ratios of the stable isotopes of carbon dioxide and noble gases like helium and neon in nine gas fields in North America, China and Europe. These gas fields were naturally filled with carbon dioxide thousands or millions of years ago.
They found that underground water is the major carbon dioxide sink in these gas fields and has been for millions of years. Dr Stuart Gilfillan, the lead researcher who completed the project at the University of Edinburgh said: "We've turned the old technique of using computer models on its head and looked at natural carbon dioxide gas fields which have trapped carbon dioxide for a very long time." "By combining two techniques, we've been able to identify exactly where the carbon dioxide is being stored for the first time. We already know that oil and gas have been stored safely in oil and gas fields over millions of years. Our study clearly shows that the carbon dioxide has been stored naturally and safely in underground water in these fields." Professor Chris Ballentine of the University of Manchester, the project director, said: "The universities of Manchester and Toronto are international leaders in different aspects of gas tracing. By combining our expertise we have been able to invent a new way of looking at carbon dioxide fields. This new approach will also be essential for monitoring and tracing where carbon dioxide captured from coal-fired power stations goes when we inject it underground - this is critical for future safety verification."
Professor Barbara Sherwood Lollar of the University of Toronto and co-author of the study hopes the new data can be fed into future computer models to make modelling underground carbon capture and storage more accurate.
Forum sparks debate on potential range changes in diseases Recent research has predicted that climate change may expand the scope of human infectious diseases. A new review, however, argues that climate change may have a negligible effect on pathogens or even reduce their ranges. The paper has sparked debate in the ecological community. In a forum in the April issue of Ecology, Kevin Lafferty of the U.S. Geological Survey's Western Ecological Research Center suggests that instead of a net expansion in the global range of diseases, climate change may cause poleward range shifts in the areas suitable for diseases as higher latitudes become warmer and regions near the equator become too hot.
The newly suitable areas for diseases will tend to be in more affluent regions where medicines are in widespread use and can more readily combat the diseases, Lafferty says. He cites model estimations that the most dangerous kind of malaria will gain 23 million human hosts outside of its current range by the year 2050, but will lose 25 million in its current range. "The dramatic contraction of malaria during a century of warming suggests that economic forces might be just as important as climate in determining pathogen ranges," Lafferty says. Mercedes Pascual of the University of Michigan sees the situation very differently. Pascual is the lead author of one of five Forum papers published in response to Lafferty. Although she agrees that disease expansion in some areas could be accompanied by retraction in others, she emphasizes that disease range does not always correlate with the number of humans infected. In regions of Africa and South America, for example, humans have historically settled in high latitudes and altitudes. If climate change makes these areas more fit for mosquito breeding and for pathogen development, she writes, then a number of infections could expand. She notes that scientists are already seeing evidence of this pattern. "It would be very unfortunate if the conclusions in Lafferty's paper were taken as evidence that climate change does not matter to infectious diseases," Pascual says. "Range shifts will matter and should be better understood."
Lafferty agrees that range shifts mean there will be winners and losers among human populations. Knowing how disease ranges will shift, instead of assuming a global expansion of diseases, will be the key to distributing resources effectively, he says. Scientists have used the fact that infectious diseases are most prevalent in the tropics to argue that warmer, wetter conditions that might occur under climate change would lead to an increase in infectious disease transmission. However, Lafferty points out that climate change isn't making the whole world warmer and wetter: Warming trends over the last 60 years have led instead to an increase in hot, dry, desert-like climates. Further, he says, infectious diseases don't all increase during warm, wet weather. Meningitis peaks during the tropical dry season, for example, and influenza is an obvious staple of winter weather in temperate climes.
Pascual argues, however, that humans have a history of altering the landscape to suit their needs and thus might unintentionally create better habitat for disease carriers. For example, humans seldom leave accessible arid areas alone; instead, they irrigate them for use as farmlands. According to Pascual, the creation of water sources could provide havens for mosquitoes, and thus malaria parasites, to remain in areas that would otherwise dry out. "We live in a world in which urban and rural areas are increasingly interfacing with each other," says Pascual. "This underscores the challenges for predicting the Earth's changing environment." Lafferty agrees that climate isn't the only issue that affects disease ecology, and maintains that climate may play only a small part in determining disease ranges. "If we over-emphasize the role of climate, which we have little control over, at the expense of other factors that drive disease dynamics, we may be missing the forest for the trees," he says.
For the first time, MIT researchers have shown they can genetically engineer viruses to build both the positively and negatively charged ends of a lithium-ion battery. The new virus-produced batteries have the same energy capacity and power performance as state-of-the-art rechargeable batteries being considered to power plug-in hybrid cars, and they could also be used to power a range of personal electronic devices, said Angela Belcher, the MIT materials scientist who led the research team. The new batteries, described in the April 2 online edition of Science, could be manufactured with a cheap and environmentally benign process: The synthesis takes place at and below room temperature and requires no harmful organic solvents, and the materials that go into the battery are non-toxic. In a traditional lithium-ion battery, lithium ions flow between a negatively charged anode, usually graphite, and the positively charged cathode, usually cobalt oxide or lithium iron phosphate. Three years ago, an MIT team led by Belcher reported that it had engineered viruses that could build an anode by coating themselves with cobalt oxide and gold and self-assembling to form a nanowire.
In the latest work, the team focused on building a highly powerful cathode to pair up with the anode, said Belcher, the Germeshausen Professor of Materials Science and Engineering and Biological Engineering. Cathodes are more difficult to build than anodes because they must be highly conducting to be a fast electrode, however, most candidate materials for cathodes are highly insulating (non-conductive). To achieve that, the researchers, including MIT Professor Gerbrand Ceder of materials science and Associate Professor Michael Strano of chemical engineering, genetically engineered viruses that first coat themselves with iron phosphate, then grab hold of carbon nanotubes to create a network of highly conductive material. Because the viruses recognize and bind specifically to certain materials (carbon nanotubes in this case), each iron phosphate nanowire can be electrically "wired" to conducting carbon nanotube networks. Electrons can travel along the carbon nanotube networks, percolating throughout the electrodes to the iron phosphate and transferring energy in a very short time. The viruses are a common bacteriophage, which infect bacteria but are harmless to humans.
The team found that incorporating carbon nanotubes increases the cathode's conductivity without adding too much weight to the battery. In lab tests, batteries with the new cathode material could be charged and discharged at least 100 times without losing any capacitance. That is fewer charge cycles than currently available lithium-ion batteries, but "we expect them to be able to go much longer," Belcher said. The prototype is packaged as a typical coin cell battery, but the technology allows for the assembly of very lightweight, flexible and conformable batteries that can take the shape of their container. Last week, MIT President Susan Hockfield took the prototype battery to a press briefing at the White House where she and U.S. President Barack Obama spoke about the need for federal funding to advance new clean-energy technologies. Now that the researchers have demonstrated they can wire virus batteries at the nanoscale, they intend to pursue even better batteries using materials with higher voltage and capacitance, such as manganese phosphate and nickel phosphate, said Belcher. Once that next generation is ready, the technology could go into commercial production, she said.
Researchers have developed a critical part of a hydrogen storage system for cars that makes it possible to fill up a vehicle's fuel tank within five minutes with enough hydrogen to drive 300 miles. The system uses a fine powder called metal hydride to absorb hydrogen gas. The researchers have created the system's heat exchanger, which circulates coolant through tubes and uses fins to remove heat generated as the hydrogen is absorbed by the powder. The heat exchanger is critical because the system stops absorbing hydrogen effectively if it overheats, said Issam Mudawar, a professor of mechanical engineering who is leading the research.
"The hydride produces an enormous amount of heat," Mudawar said. "It would take a minimum of 40 minutes to fill the tank without cooling, and that would be entirely impractical." Researchers envision a system that would enable motorists to fill their car with hydrogen within a few minutes. The hydrogen would then be used to power a fuel cell to generate electricity to drive an electric motor. The research, funded by General Motors Corp. and directed by GM researchers Darsh Kumar, Michael Herrmann and Abbas Nazri, is based at the Hydrogen Systems Laboratory at Purdue's Maurice J. Zucrow Laboratories. In February, the team applied for three provisional patents related to this technology. "The idea is to have a system that fills the tank and at the same time uses accessory connectors that supply coolant to extract the heat," said Mudawar, who is working with mechanical engineering graduate student Milan Visaria and Timothée Pourpoint, a research assistant professor of aeronautics and astronautics and manager of the Hydrogen Systems Laboratory. "This presented an engineering challenge because we had to figure out how to fill the fuel vessel with hydrogen quickly while also removing the heat efficiently. The problem is, nobody had ever designed this type of heat exchanger before. It's a whole new animal that we designed from scratch."
The metal hydride is contained in compartments inside the storage "pressure vessel." Hydrogen gas is pumped into the vessel at high pressure and absorbed by the powder. "This process is reversible, meaning the hydrogen gas may be released from the metal hydride by decreasing the pressure in the storage vessel," Mudawar said. "The heat exchanger is fitted inside the hydrogen storage pressure vessel. Due to space constraints, it is essential that the heat exchanger occupy the least volume to maximize room for hydrogen storage." Conventional automotive coolant flows through a U-shaped tube traversing the length of the pressure vessel and heat exchanger. The heat exchanger, which is made mostly of aluminum, contains a network of thin fins that provide an efficient cooling path between the metal hydride and the coolant. "This milestone paves the way for practical on-board hydrogen storage systems that can be charged multiple times in much the same way a gasoline tank is charged today," said Kumar, a researcher at GM's Chemical & Environmental Sciences Laboratory and the GM R&D Center in Warren, Mich. "As newer and better metal hydrides are developed by research teams worldwide, the heat exchanger design will provide a ready solution for the automobile industry."
The researchers have developed the system over the past two years. Because metal hydride reacts readily with both air and moisture, the system must be assembled in an airtight chamber, Pourpoint said. Research activities at the hydrogen laboratory involve faculty members from the schools of aeronautics and astronautics, mechanical engineering, and electrical and computer engineering.
