Tuesday, April 22, 2014

Environmentally compatible organic solar cells in the future

Date:
April 16, 2014 - SCIENCE DAILY
Source:
Karlsruhe Institute of Technology
Summary:
Environmentally compatible production methods for organic solar cells from novel materials are in the focus of “MatHero”. The new project aims at making organic photovoltaics competitive to their inorganic counterparts by enhancing the efficiency of organic solar cells, reducing their production costs and increasing their life-time.

Environmentally compatible production methods for organic solar cells from novel materials are in the focus of "MatHero." The new project coordinated by Karlsruhe Institute of Technology (KIT) aims at making organic photovoltaics competitive to their inorganic counterparts by enhancing the efficiency of organic solar cells, reducing their production costs and increasing their life-time. "Green" processes for materials synthesis and coating play a key role. "MatHero" is funded by the European Commission with an amount of EUR 3.5 million.

Organic solar cells will open up entirely new markets for photovoltaics. These "plastic solar cells" have several advantages: They are light-weight, mechanically flexible, can be produced in arbitrary colors, and hence allow a customized design for a variety of applications. Moreover, organic solar cells can be produced by printing processes with a low consumption of materials and energy, enabling the inexpensive production of high numbers of solar cells. In order to become competitive in established markets, various challenges still have to be mastered. The energy conversion efficiency has to be improved to more than ten percent. Costs of materials synthesis have to be reduced. The life-time of the materials and modules has to be enhanced to more than ten years.
To reach these objectives, the European project consortium of "MatHero" studies environmentally compatible processes for materials synthesis, coating and printing. All novel printable materials are formulated using non-chlorinated solvents. "The use of environmentally compatible solvents is a major prerequisite for cost reduction, as complex safety measures on the industrial scale will no longer be required," Dr. Alexander Colsmann of KIT's Light Technology Institute (LTI) explains. Together with Christian Sprau, Colsmann coordinates the project.
"MatHero -- New materials for highly efficient and reliable organic solar cells" covers the complete value chain of organic solar cell fabrication: From the design and synthesis of the polymers used to assemble the solar cells to the fabrication and characterization of the modules to the assessment of device stability. The project goal is an environmentally compatible printed organic solar module initially for off-grid applications. In the consortium, physicists, chemists, materials scientists, and engineers cooperate in an interdisciplinary project team in order to study fundamental scientific and product development aspects. The KIT scientists develop new solar cell architectures and analyze process up-scaling, focusing on enhancing solar cell efficiencies as well as on using environmentally compatible solvents.
"MatHero" is funded by the EC under the 7th framework programme with an amount of EUR 3.5 million. Besides KIT, the research institutions Fraunhofer Institute for Applied Polymer Research (IAP), Potsdam, the Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA) in France, and Acondicionamiento Tarrasense (LEITAT) in Spain participating in the project. The industry partners are Advent Technologies SA (Greece), and Arkema (France) and Eight19 Ltd (UK). The project started in early 2014 and is scheduled for a duration of three years.

Story Source:
The above story is based on materials provided by Karlsruhe Institute of TechnologyNote: Materials may be edited for content and length.

Cite This Page:
Karlsruhe Institute of Technology. "Environmentally compatible organic solar cells in the future." ScienceDaily. ScienceDaily, 16 April 2014. .



Endemic in pork industry: Will new tests prevent it?

Date:
April 14, 2014 - SCIENCE DAILY
Source:
Kansas State University
Summary:
Tests to identify pig viruses have been developed in hopes of preventing the further spread of diseases that have already killed almost 6 million pigs. "Enteric disease in pigs has turned into a huge, huge problem and we're developing all kinds of new tests to address the old problems but also to address the new diseases that are just destroying everything," said a veterinarian.

Pork products cost about 10 percent more than they did last year, according to the U.S. Bureau of Labor Statistics, and economists expect the prices to continue rising because of diarrhea viruses currently devastating the pork industry.

That's why researchers at the Kansas State Veterinary Diagnostic Laboratory at Kansas State University have developed new tests they hope will mitigate the spread of these viruses.
"Enteric disease in pigs has turned into a huge, huge problem and we're developing all kinds of new tests to address the old problems but also to address the new diseases that are just destroying everything," said Dick Hesse, director of diagnostic virology at the lab and professor of diagnostic medicine and pathobiology.
Hesse says there are at least three viruses with similar symptoms affecting pigs, two of which have entered the United States for the first time -- porcine epidemic diarrhea virus and delta coronavirus. Swine specialists and molecular diagnosticians at the Kansas State Veterinary Diagnostic Laboratory have developed tests to detect which virus is infecting the pigs.
"If you know what they've been exposed to and how high the immunity is, you can make adjustments on how you treat the virus," Hesse said.
Porcine epidemic diarrhea virus has already killed an estimated 6 million pigs. The Kansas State University laboratory is one of only four in the United States with the new tests to identify these diseases. The researchers hope the tests will stop the spread of these diseases before they become endemic.
"They're management tools," Hesse said. "With enough information, you can make informed decisions and minimize the impact of the disease."
Story Source:
The above story is based on materials provided by Kansas State University. The original article was written by Lindsey Elliott. Note: Materials may be edited for content and length.

Cite This Page:
Kansas State University. "Endemic in pork industry: Will new tests prevent it?." ScienceDaily. ScienceDaily, 14 April 2014. .

Result of slow degradation on environmental pollutants

Date:
April 14, 2014 - SCIENCE DAILY 
Source:
ETH Zurich
Summary:
Why do environmental pollutants accumulate in the cold polar regions? This may not only be due to the fact that many substances are less volatile at low temperatures, as has been long suspected, but also to their extremely slow natural degradation. Although persistent environmental pollutants have been and continue to be released worldwide, the Arctic and Antarctic regions are significantly more contaminated than elsewhere. The marine animals living there have some of the highest levels of persistent organic pollutant (POP) contamination of any creatures.

Although persistent environmental pollutants have been and continue to be released worldwide, the Arctic and Antarctic regions are significantly more contaminated than elsewhere. The marine animals living there have some of the highest levels of persistent organic pollutant (POP) contamination of any creatures. The Inuit people of the Arctic, who rely on a diet of fish, seals and whales, have also been shown to have higher POP concentrations than people living in our latitudes.

Today, the production and use of nearly two dozen POPs and several ozone-depleting substances have been greatly restricted by two international agreements: the Stockholm Convention and the Montreal Protocol. It is not entirely clear why POPs released mainly during the second half of the 20th century, after being distributed all over the globe by air and ocean currents, have become concentrated in the polar regions. It is therefore difficult to make accurate predictions about the long-term fate of these pollutants. Researchers from ETH Zurich are currently investigating the underlying physical and chemical processes that control the dynamics of these pollutants.
Simulation of real and hypothetical substances
Thus far, discussions have focused primarily on two factors affecting pollutant accumulation, both of which are related to the cold conditions of the polar regions. At low temperatures, chemical compounds are less volatile. Experts have long suspected that these physical (thermodynamic) properties are the main reason for the higher concentrations. Based on this understanding, the concentrations found in the polar regions are the result of the long-term global distribution of POPs, governed by physics. The second factor is that chemical and microbiological degradation of substances is temperature-dependent as well: what are already poorly degradable environmental pollutants degrade even more slowly than they would in the warmer regions of the world. However, this factor was thought to be less influential.
A team of researchers led by Martin Scheringer, group leader in the Safety and Environmental Technology Group, part of the Department of Chemistry and Applied Biosciences (D-CHAB), has now compared the two effects. The scientists developed a computer model and simulated the persistence of about a dozen actual and several hundred theoretical environmental pollutants. In addition to geographical components such as ocean and air currents, the model took into account the tendency of the substances to occur in water, soil and air, and the speed at which they degrade in these environments.
Only volatile substances reach equilibrium
In their study, the scientists have shown that the theory that posits thermodynamic properties as the key factor applies only to highly volatile substances, which accumulate in the atmosphere, such as chlorofluorocarbons (CFCs), formerly used for coolants, and tetrachloromethane, formerly used in fire extinguishers. "Highly volatile substances are so mobile that they quickly achieve a geographical distribution that is controlled by their thermodynamic properties," says Scheringer.
This is not the case for substances that accumulate mainly in water, soil and the fatty tissues of living organisms, such as the notorious insecticide DDT or the polychlorinated biphenyls (PCBs) used for electrical insulators and joint sealants. "Their pattern of distribution in the environment is determined by slower degradation in cold regions and faster degradation in warm regions," explains Scheringer. They do not reach a thermodynamic equilibrium.
Model calculations offer advantages
"Our model calculation offers advantages over the analysis of concentrations measured in the field," says Scheringer. Although patterns and certain mechanisms are also evident in the measurements, the analysis is affected by measurement uncertainties and substantial background noise. A model calculation, on the other hand, is idealised, making it possible to eliminate the background noise. It also has the advantage of making future projections possible.
Scheringer realises that even if the physical reasons behind the higher concentrations are known, this will not directly change much for the affected inhabitants of the polar regions. "We can no longer take these substances back out of the environment. All we can do is stop releasing them," he said. This is precisely the goal of the Stockholm Convention.
Story Source:
The above story is based on materials provided by ETH Zurich. The original article was written by Fabio Bergamin. Note: Materials may be edited for content and length.

Journal Reference:
  1. Sebastian Schenker, Martin Scheringer, Konrad Hungerbühler. Do Persistent Organic Pollutants Reach a Thermodynamic Equilibrium in the Global Environment? Environmental Science & Technology, 2014; 140408064408002 DOI: 10.1021/es405545w

Cite This Page:
ETH Zurich. "Result of slow degradation on environmental pollutants." ScienceDaily. ScienceDaily, 14 April 2014. .

House windows that double as solar panels? Shiny quantum dots brighten future of solar cells

Date:
April 14, 2014 -  SCIENCE DAILY
Source:
DOE/Los Alamos National Laboratory
Summary:
A house window that doubles as a solar panel could be on the horizon, thanks to recent quantum-dot work. Scientists have demonstrated that superior light-emitting properties of quantum dots can be applied in solar energy by helping more efficiently harvest sunlight.

A house window that doubles as a solar panel could be on the horizon, thanks to recent quantum-dot work by Los Alamos National Laboratory researchers in collaboration with scientists from University of Milano-Bicocca (UNIMIB), Italy. Their project demonstrates that superior light-emitting properties of quantum dots can be applied in solar energy by helping more efficiently harvest sunlight.

"The key accomplishment is the demonstration of large-area luminescent solar concentrators that use a new generation of specially engineered quantum dots," said lead researcher Victor Klimov of the Center for Advanced Solar Photophysics (CASP) at Los Alamos.
Quantum dots are ultra-small bits of semiconductor matter that can be synthesized with nearly atomic precision via modern methods of colloidal chemistry. Their emission color can be tuned by simply varying their dimensions. Color tunability is combined with high emission efficiencies approaching 100 percent. These properties have recently become the basis of a new technology -- quantum dot displays -- employed, for example, in the newest generation of the Kindle Fire ™ e-reader.
Light-harvesting antennas
A luminescent solar concentrator (LSC) is a photon management device, representing a slab of transparent material that contains highly efficient emitters such as dye molecules or quantum dots. Sunlight absorbed in the slab is re-radiated at longer wavelengths and guided towards the slab edge equipped with a solar cell.
Klimov explained, "The LSC serves as a light-harvesting antenna which concentrates solar radiation collected from a large area onto a much smaller solar cell, and this increases its power output."
"LSCs are especially attractive because in addition to gains in efficiency, they can enable new interesting concepts such as photovoltaic windows that can transform house facades into large-area energy generation units," said Sergio Brovelli, who worked at Los Alamos until 2012 and is now a faculty member at UNIMIB.
Because of highly efficient, color-tunable emission and solution processability, quantum dots are attractive materials for use in inexpensive, large-area LSCs. One challenge, however, is an overlap between emission and absorption bands in the dots, which leads to significant light losses due to the dots re-absorbing some of the light they produce.
"Giant" but still tiny, engineered dots
To overcome this problem the Los Alamos and UNIMIB researchers have developed LSCs based on quantum dots with artificially induced large separation between emission and absorption bands (called a large Stokes shift).
These "Stokes-shift" engineered quantum dots represent cadmium selenide/cadmium sulfide (CdSe/CdS) structures in which light absorption is dominated by an ultra-thick outer shell of CdS, while emission occurs from the inner core of a narrower-gap CdSe. The separation of light-absorption and light-emission functions between the two different parts of the nanostructure results in a large spectral shift of emission with respect to absorption, which greatly reduces losses to re-absorption.
To implement this concept, Los Alamos researchers created a series of thick-shell (so-called "giant") CdSe/CdS quantum dots, which were incorporated by their Italian partners into large slabs (sized in tens of centimeters) of polymethylmethacrylate (PMMA). While being large by quantum dot standards, the active particles are still tiny -- only about hundred angstroms across. For comparison, a human hair is about 500,000 angstroms wide.
"A key to the success of this project was the use of a modified industrial method of cell-casting, we developed at UNIMIB Materials Science Department" said Francesco Meinardi, professor of Physics at UNIMIB.
Spectroscopic measurements indicated virtually no losses to re-absorption on distances of tens of centimeters. Further, tests using simulated solar radiation demonstrated high photon harvesting efficiencies of approximately 10% per absorbed photon achievable in nearly transparent samples, perfectly suited for utilization as photovoltaic windows.
Despite their high transparency, the fabricated structures showed significant enhancement of solar flux with the concentration factor of more than four. These exciting results indicate that "Stokes-shift-engineered" quantum dots represent a promising materials platform. It may enable the creation of solution processable large-area LSCs with independently tunable emission and absorption spectra.
Story Source:
The above story is based on materials provided by DOE/Los Alamos National LaboratoryNote: Materials may be edited for content and length.

Journal Reference:
  1. Francesco Meinardi, Annalisa Colombo, Kirill A. Velizhanin, Roberto Simonutti, Monica Lorenzon, Luca Beverina, Ranjani Viswanatha, Victor I. Klimov, Sergio Brovelli. Large-area luminescent solar concentrators based on ‘Stokes-shift-engineered’ nanocrystals in a mass-polymerized PMMA matrixNature Photonics, 2014; DOI: 10.1038/nphoton.2014.54

Cite This Page:
DOE/Los Alamos National Laboratory. "House windows that double as solar panels? Shiny quantum dots brighten future of solar cells." ScienceDaily. ScienceDaily, 14 April 2014. .

Making dams safer for fish around the world

Date:
April 14, 2014 - SCIENCE DAILY
Source:
DOE/Pacific Northwest National Laboratory
Summary:
The pressure changes that many fish experience when they travel through the turbulent waters near a dam can seriously injure or kill the fish. Scientists from around the world, including areas like Southeast Asia and Brazil where huge dams are planned or under construction, are working together to protect fish from the phenomenon, known as barotrauma.

Think of the pressure change you feel when an elevator zips you up multiple floors in a tall building. Imagine how you'd feel if that elevator carried you all the way up to the top of Mt. Everest -- in the blink of an eye.

That's similar to what many fish experience when they travel through the turbulent waters near a dam. For some, the change in pressure is simply too big, too fast, and they die or are seriously injured.
In an article in the March issue of the journal Fisheries, ecologists from the Department of Energy's Pacific Northwest National Laboratory and colleagues from around the world explore ways to protect fish from the phenomenon, known as barotrauma.
Among the findings: Modifying turbines to minimize dramatic shifts in pressure offers an important way to keep fish safe when passing through dams. The research is part of a promising body of work that aims to reduce such injuries by improving turbine designs in dams around the world.
PNNL researchers are working with officials and scientists from Laos, Brazil, and Australia -- areas where hydropower is booming -- to apply lessons learned from experience in the Pacific Northwest, where salmon is king and water provides about two-thirds of the region's power. There, billions of dollars have been spent since 1950 to save salmon endangered largely by the environmental impact of hydropower.
"Hydropower is a tremendous resource, often available in areas far from other sources of power, and critical to the future of many people around the globe," said Richard Brown, a senior research scientist at PNNL and the lead author of the Fisheries paper.
"We want to help minimize the risk to fish while making it possible to bring power to schools, hospitals, and areas that desperately need it," added Brown.
Harnessing the power of water flowing downhill to spin turbines is the most convenient energy source in many parts of the world, and it's a clean, renewable source of energy to boot.
In Brazil, several dozen dams are planned along the Amazon, Madeira and Xingu rivers -- an area that teems with more than 5,000 species of fish, and where some of the largest hydropower projects in the world are being built. In southeastern Australia, hydropower devices are planned in the area drained by the Murray-Darling river system. And in Southeast Asia, hundreds of dams and smaller hydro structures are planned in the Lower Mekong River Basin.
The authors say the findings from a collaboration that spans four continents improve our understanding of hydropower and will benefit fish around the globe. New results about species in the Mekong or Amazon regions, for instance, can inform fish-friendly practices in those regions of the United States where barotrauma has not been extensively studied.
To 'Everest' and back in an instant
Dams vary considerably in the challenges they pose to migrating fish, and the challenges are magnified when a fish must pass through more than one dam or hydro structure. At some, mortality is quite high, while at others, such as along the Columbia River, most fish are able to pass over or through a single dam safely, thanks to extensive measures to keep fish safe. Some fish spill harmlessly over the top, while others pass through pipes or other structures designed to route fish around the dam or steer them clear of the energy-producing turbines.
Still, at most dams, the tremendous turbulence of the water can hurt or disorient fish, and the blades of a turbine can strike them. The new study focuses on a third problem, barotrauma -- damage that happens at some dams when a fish experiences a large change in pressure.
Depending on its specific path, a fish traveling through a dam can experience an enormous drop in pressure, similar to the change from sea level to the top of Mt. Everest, in an instant. Just as fast, as the waters swirl, the fish suddenly finds itself back at its normal pressure.
Those sudden changes can have a catastrophic effect on fish, most of which are equipped with an organ known as a swim bladder -- like a balloon -- to maintain buoyancy at a desired depth. When the fish goes deeper and pressures are greater, the swim bladder shrinks; when the fish rises and pressure is reduced, the organ increases in size.
For some fish, the pressure shift means the swim bladder instantly expands four-fold or eight-fold, like an air bag that inflates suddenly. This rapid expansion can result in internal injuries or even death.
Factors at play include the specific path of a fish, the amount of water going through a turbine, the design of the turbine, the depth of water where the fish usually lives, and the physiology of the fish itself.
"To customize a power plant that is the safest for the fish, you must understand the species of fish in that particular river, their physiology, and the depth at which they normally reside, as well as the tremendous forces that the fish can be subjected to," said Brown.
PNNL scientists have found that trying to keep minimum pressure higher in all areas near the turbine is key for preventing barotrauma. That reduces the amount of pressure change a fish is exposed to and is a crucial component for any turbine that is truly "fish friendly." Preventing those extremely low pressures also protects a turbine from damage, reducing shutdowns and costly repairs.
Lower Mekong River Basin
Brown and PNNL colleague Zhiqun (Daniel) Deng have made several trips to work with scientists in Southeast Asia, where dozens of dams are planned along the Mekong River and its tributaries. The Mekong starts out high in Tibet and travels more than 2,700 miles, touching China, Myanmar, Laos, Thailand, Cambodia, and Vietnam. The team estimates more than 1,200 species of fish make their home in the Mekong, including the giant Mekong catfish and the giant freshwater stingray, as well as the endangered Irrawaddy dolphin.
The scientists estimate that the region's fish account for almost half of the protein in the diet of the people of Laos and nearly 80 percent for the people of Cambodia. Four out of five households in the region rely heavily on fish for food, jobs, or both.
"Many people in Southeast Asia rely on fish both for food and their livelihood; it's a huge issue, crucial in the lives of many people. Hydropower is also a critical resource in the region," said Deng, a PNNL chief scientist and an author of the paper.
"Can we reduce the impact of dams on fish, to create a sustainable hydropower system and ensure the food supply and livelihoods of people in these regions? Can others learn from our experiences in the Pacific Northwest? This is why we do research in the laboratory -- to make an impact in the real world, on people's lives," added Deng.
The same team of scientists just published a paper in the Journal of Renewable and Sustainable Energy, focusing broadly on creating sustainable hydro in the Lower Mekong River Basin. The paper discusses the potential for hydropower sources in the region (30 gigawatts), migratory patterns of its fish, the importance of fish-friendly technology, and further studies needed to understand hydro's impact on fish of the Mekong.

Story Source:
The above story is based on materials provided by DOE/Pacific Northwest National Laboratory. The original article was written by Tom Rickey. Note: Materials may be edited for content and length.

Journal Reference:
  1. Richard S. Brown, Alison H. Colotelo, Brett D. Pflugrath, Craig A. Boys, Lee J. Baumgartner, Z. Daniel Deng, Luiz G. M. Silva, Colin J. Brauner, Martin Mallen-Cooper, Oudom Phonekhampeng, Garry Thorncraft, Douangkham Singhanouvong.Understanding Barotrauma in Fish Passing Hydro Structures: A Global Strategy for Sustainable Development of Water ResourcesFisheries, 2014; 39 (3): 108 DOI: 10.1080/03632415.2014.883570

Cite This Page:
DOE/Pacific Northwest National Laboratory. "Making dams safer for fish around the world." ScienceDaily. ScienceDaily, 14 April 2014.

Air pollution over Asia influences global weather and makes Pacific storms more intense

Date:
April 14, 2014 -SCIENCE DAILY
Source:
Texas A&M University
Summary:
In the first study of its kind, scientists have compared air pollution rates from 1850 to 2000 and found that anthropogenic (human-made) particles from Asia impact the Pacific storm track that can influence weather over much of the world.

In the first study of its kind, scientists have compared air pollution rates from 1850 to 2000 and found that anthropogenic (human-made) particles from Asia impact the Pacific storm track that can influence weather over much of the world.

The team, which includes several researchers from Texas A&M University, has had its work published in the current issue of Proceedings of the National Academy of Sciences (PNAS).
Yuan Wang, Yun Lin, Jiaxi Hu, Bowen Pan, Misti Levy and Renyi Zhang of Texas A&M's Department of Atmospheric Sciences, along with colleagues from Pacific Northwest National Laboratory, the University of California at San Diego and NASA's Jet Propulsion Laboratory, contributed to the work.
The team used detailed pollution emission data compiled by the Intergovernmental Panel on Climate Change and looked at two scenarios: one for a rate in 1850 -- the pre-Industrial era -- and from 2000, termed present-day.
By comparing the results from an advanced global climate model, the team found that anthropogenic aerosols conclusively impact cloud formations and mid-latitude cyclones associated with the Pacific storm track.
"There appears to be little doubt that these particles from Asia affect storms sweeping across the Pacific and subsequently the weather patterns in North America and the rest of the world," Zhang says of the findings.
"The climate model is quite clear on this point. The aerosols formed by human activities from fast-growing Asian economies do impact storm formation and global air circulation downstream. They tend to make storms deeper and stronger and more intense, and these storms also have more precipitation in them. We believe this is the first time that a study has provided such a global perspective."
In recent years, researchers have learned that atmospheric aerosols affect the climate, either directly by scattering or absorbing solar radiation, and indirectly by altering cloud formations. Increasing levels of such particles have raised concerns because of their potential impacts on regional and global atmospheric circulation.
In addition, Zhang says large amounts of aerosols and their long-term transport from Asia across the Pacific can clearly be seen by satellite images.
The Pacific storm track represents a critical driver in the general global circulation by transporting heat and moisture, the team notes. The transfer of heat and moisture appears to be increased over the storm track downstream, meaning that the Pacific storm track is intensified because of the Asian air pollution outflow.
"Our results support previous findings that show that particles in the air over Asia tend to affect global weather patterns," Zhang adds.
"It shows they can affect the Earth's weather significantly."
Yuan Wang, who conducted the research with Zhang while at Texas A&M, currently works at NASA's Jet Propulsion Laboratory as a Caltech Postdoctoral Scholar.
The study was funded by grants from NASA, the Department of Energy, Texas A&M's Supercomputing facilities and the Ministry of Science and Technology of China.

Story Source:
The above story is based on materials provided by Texas A&M UniversityNote: Materials may be edited for content and length.

Journal Reference:
  1. Yuan Wang, Minghuai Wang, Renyi Zhang, Steven J. Ghan, Yun Lin, Jiaxi Hu, Bowen Pan, Misti Levy, Jonathan H. Jiang, and Mario J. Molina. Assessing the effects of anthropogenic aerosols on Pacific storm track using a multiscale global climate modelPNAS, April 14, 2014 DOI: 10.1073/pnas.1403364111

Cite This Page:
Texas A&M University. "Air pollution over Asia influences global weather and makes Pacific storms more intense." ScienceDaily. ScienceDaily, 14 April 2014. .

Plugging an ozone hole: Extreme Antarctic ozone holes have not been replicated in Arctic

Date:
April 14, 2014 - SCIENCE DAILY
Source:
Massachusetts Institute of Technology
Summary:
Since the discovery of the Antarctic ozone hole, scientists, policymakers, and the public have wondered whether we might someday see a similarly extreme depletion of ozone over the Arctic. But a new study finds some cause for optimism: Ozone levels in the Arctic haven’t yet sunk to the extreme lows seen in Antarctica, in part because international efforts to limit ozone-depleting chemicals have been successful.

Since the discovery of the Antarctic ozone hole, scientists, policymakers, and the public have wondered whether we might someday see a similarly extreme depletion of ozone over the Arctic.

But a new MIT study finds some cause for optimism: Ozone levels in the Arctic haven't yet sunk to the extreme lows seen in Antarctica, in part because international efforts to limit ozone-depleting chemicals have been successful.
"While there is certainly some depletion of Arctic ozone, the extremes of Antarctica so far are very different from what we find in the Arctic, even in the coldest years," says Susan Solomon, the Ellen Swallow Richards Professor of Atmospheric Chemistry and Climate Science at MIT, and lead author of a paper published this week in the Proceedings of the National Academy of Sciences.
Frigid temperatures can spur ozone loss because they create prime conditions for the formation of polar stratospheric clouds. When sunlight hits these clouds, it sparks a reaction between chlorine from chlorofluorocarbons (CFCs), human-made chemicals once used for refrigerants, foam blowing, and other applications -- ultimately destroying ozone.
'A success story of science and policy'
After the ozone-attacking properties of CFCs were discovered in the 1980s, countries across the world agreed to phase out their use as part of the 1987 Montreal Protocol treaty. While CFCs are no longer in use, those emitted years ago remain in the atmosphere. As a result, atmospheric concentrations have peaked and are now slowly declining, but it will be several decades before CFCs are totally eliminated from the environment -- meaning there is still some risk of ozone depletion caused by CFCs.
"It's really a success story of science and policy, where the right things were done just in time to avoid broader environmental damage," says Solomon, who made some of the first measurements in Antarctica that pointed toward CFCs as the primary cause of the ozone hole.
To obtain their findings, the researchers used balloon and satellite data from the heart of the ozone layer over both polar regions. They found that Arctic ozone levels did drop significantly during an extended period of unusual cold in the spring of 2011. While this dip did depress ozone levels, the decrease was nowhere near as drastic as the nearly complete loss of ozone in the heart of the layer seen in many years in Antarctica.
The MIT team's work also helps to show chemical reasons for the differences, demonstrating that ozone loss in Antarctica is closely associated with reduced levels of nitric acid in air that is colder than that in the Arctic.
"We'll continue to have cold years with extreme Antarctic ozone holes for a long time to come," Solomon says. "We can't be sure that there will never be extreme Arctic ozone losses in an unusually cold future year, but so far, so good -- and that's good news."
The paper is the first to use observational evidence to confirm the chemical processes in polar stratospheric clouds that lead to ozone loss, says Brian Toon, a professor of atmospheric and oceanic sciences at the University of Colorado at Boulder and an expert on stratospheric ozone loss. Previous studies have used computer models or theories to explain the connection between nitric acid in these clouds and ozone depletion.
"It is an excellent example of the relatively rare paper that is clever and insightful," says Toon, who was not involved in this most recent study. "[It] goes beyond complex computer calculations to demonstrate from observations an important process occurring in the atmosphere."
Story Source:
The above story is based on materials provided by Massachusetts Institute of Technology. The original article was written by Audrey Resutek. Note: Materials may be edited for content and length.

Journal Reference:
  1. Susan Solomon, Jessica Haskins, Diane J. Ivy, and Flora Min. Fundamental differences between Arctic and Antarctic ozone depletionPNAS, April 14, 2014 DOI: 10.1073/pnas.1319307111

Cite This Page:
Massachusetts Institute of Technology. "Plugging an ozone hole: Extreme Antarctic ozone holes have not been replicated in Arctic." ScienceDaily. ScienceDaily, 14 April 2014. .

'Problem wells' source of greenhouse gas at unexpected stage of natural gas production

Date:
April 14, 2014 -SCIENCE DAILY
Source:
Purdue University
Summary:
High levels of the greenhouse gas methane were found above shale gas wells at a production point not thought to be an important emissions source. The findings could have implications for the evaluation of the environmental impacts from natural gas production. The study, which is one of only a few to use a so-called "top down" approach that measures methane gas levels in the air above wells, identified seven individual well pads with high emission levels during the drilling stage.

High levels of the greenhouse gas methane were found above shale gas wells at a production point not thought to be an important emissions source, according to a study jointly led by Purdue and Cornell universities. The findings could have implications for the evaluation of the environmental impacts from natural gas production.

The study, which is one of only a few to use a so-called "top down" approach that measures methane gas levels in the air above wells, identified seven individual well pads with high emission levels and established their stage in the shale-gas development process.
The high-emitting wells made up less than 1 percent of the total number of wells in the area and were all found to be in the drilling stage, a preproduction stage not previously associated with significant emissions.
"These findings present a possible weakness in the current methods to inventory methane emissions and the top-down approach clearly represents an important complementary method that could be added to better define the impacts of shale gas development," said Paul Shepson, a professor of chemistry and earth atmospheric and planetary sciences at Purdue who co-led the study with Jed Sparks, a professor of ecology and evolutionary biology at Cornell. "This small fraction of the total number of wells was contributing a much larger large portion of the total emissions in the area, and the emissions for this stage were not represented in the current inventories."
The researchers flew above the Marcellus shale formation in southwestern Pennsylvania in the Purdue Airborne Laboratory for Atmospheric Research, a specially equipped airplane. The aircraft-based approach allowed researchers to identify plumes of methane gas from single well pads, groups of well pads and larger regional scales and to examine the production state of the wells.
"It is particularly noteworthy that large emissions were measured for wells in the drilling phase, in some cases 100 to 1,000 times greater than the inventory estimates," Shepson said. "This indicates that there are processes occurring -- e.g. emissions from coal seams during the drilling process -- that are not captured in the inventory development process. This is another example pointing to the idea that a large fraction of the total emissions is coming from a small fraction of shale gas production components that are in an anomalous condition."
The bottom-up inventories have been produced from industry measurements of emissions from individual production, transmission and distribution components and then scaling up to create an estimate of emissions for the region. However, with thousands of wells, and a complex processing and transmission system associated with each shale basin, obtaining a representative data set is difficult, he said.
A paper detailing the results will be published in the Proceedings of the National Academy of Sciences on Monday (April 14). The David R. Atkinson Center for a Sustainable Future at Cornell University funded this research.
"We need to develop a way to objectively measure emissions from shale gas development that includes the full range of operator types, equipment states and engineering approaches," Shepson said. "A whole-systems approach to measurement is needed to understand exactly what is occurring."

Story Source:
The above story is based on materials provided by Purdue University. The original article was written by Elizabeth K. Gardner. Note: Materials may be edited for content and length.

Journal Reference:
  1. Dana R. Caulton, Paul Shepson, Renee L. Santoro, Jed P. Sparks, Robert W. Howarth, Anthony R. Ingraffea, Maria O. L. Cambaliza, Colm Sweeney, Anna Karion, Kenneth J. Davis, Brian H. Stirm, Stephen A. Montzka, and Ben R. Miller.Toward a better understanding and quantification of methane emissions from shale gas developmentPNAS, 2014 DOI: 10.1073/pnas.1316546111


Cite This Page:
Purdue University. "'Problem wells' source of greenhouse gas at unexpected stage of natural gas production." ScienceDaily. ScienceDaily, 14 April 2014. .

Moth study suggests hidden climate change impacts

Date:
April 15, 2014 - SCIENCE DAILY 
Source:
University of Michigan
Summary:
A 32-year study of subarctic forest moths in Finnish Lapland suggests that scientists may be underestimating the impacts of climate change on animals and plants because much of the harm is hidden from view. Researchers used advanced statistical techniques to examine the roles of different ecological forces affecting the moth populations and found that warmer temperatures and increased precipitation reduced the rates of population growth.

A 2-year study of subarctic forest moths in Finnish Lapland suggests that scientists may be underestimating the impacts of climate change on animals and plants because much of the harm is hidden from view.

The study analyzed populations of 80 moth species and found that 90 percent of them were either stable or increasing throughout the study period, from 1978 to 2009. During that time, average annual temperatures at the study site rose 3.5 degrees Fahrenheit, and winter precipitation increased as well.
"You see it getting warmer, you see it getting wetter and you see that the moth populations are either staying the same or going up. So you might think, 'Great. The moths like this warmer, wetter climate.' But that's not what's happening,'' said ecologist Mark Hunter of the University of Michigan.
Hunter used advanced statistical techniques to examine the roles of different ecological forces affecting the moth populations and found that warmer temperatures and increased precipitation reduced the rates of population growth.
"Every time the weather was particularly warm or particularly wet, it had a negative impact on the rates at which the populations grew," said Hunter, the Henry A. Gleason Collegiate Professor in the U-M Department of Ecology and Evolutionary Biology.
"Yet, overall, most of these moth populations are either stable or increasing, so the only possibility is that something else other than climate change -- some other factor that we did not measure -- is buffering the moths from substantial population reductions and masking the negative effects of climate change."
The findings have implications that reach beyond moths in Lapland.
If unknown ecological forces are helping to counteract the harmful effects of climate change on these moths, it's conceivable that a similar masking of impacts is happening elsewhere. If that's the case, then scientists are likely underestimating the harmful effects of climate change on animals and plants, Hunter said.
"We could be underestimating the number of species for which climate change has negative impacts because those effects are masked by other forces," he said.
Hunter and six Finnish colleagues report their findings in a paper scheduled for online publication April 15 in the journal Global Change Biology.
The study was conducted at the Värriö Strict Nature Reserve, 155 miles north of the Arctic Circle and less than four miles from the Finnish-Russian border. The nearest major road is more than 60 miles away.
Between 1978 and 2009, Finnish scientists used light traps at night to catch 388,779 moths from 456 species. Eighty of the most abundant species were then analyzed.
Hunter used a statistical technique called time series analysis to examine how various ecological forces, including climate, affected per capita population growth.
Scientists want to know how climate change will impact insects because the six-legged creatures play key roles as agricultural pests, pollinators, food sources for vertebrates, vectors of human disease, and drivers of various ecosystem processes.
Researchers believe that butterflies and moths may be particularly susceptible to population fluctuations in response to climate change -- especially at high latitudes and high elevations.
Most recent studies of moth abundance have shown population declines. So Hunter and his colleagues were surprised to find that 90 percent of the moth species in the Lapland study were either stable or increasing.
On one level, the results can be viewed as a good news climate story: In the face of a rapid environmental change, these moths appear to be thriving, suggesting that they are more resilient than scientists had expected, Hunter said.
But the other side of that coin is that unknown ecological forces appear to be buffering the harmful effects of climate change and hiding those impacts from view. The results also demonstrate that "simple temporal changes in population abundance cannot always be used to estimate effects of climate change on the dynamics of organisms," the authors conclude.
"The big unknown is how long this buffering effect will last," Hunter said. "Will it keep going indefinitely, or will the negative effects of climate change eventually just override these buffers, causing the moth populations to collapse?"
Another big unknown: What ecological forces are currently buffering the Lapland moths from the negative effects of a warming climate?
Finnish team members who've been collecting moths at the Värriö reserve for decades say they have noticed a gradual increase in tree and shrub density, increased rates of tree growth, and a rise in the altitude of the tree line.
Trees provide food and shelter for moths, and leaf litter offers overwintering sites and resting areas away from predators. Perhaps the observed vegetation changes are helping to offset the negative effects of warmer temperatures and increased precipitation. That possibility was not analyzed in the current study.

Story Source:
The above story is based on materials provided by University of MichiganNote: Materials may be edited for content and length.
Journal Reference:
  1. Mark D. Hunter, Mikhail V. Kozlov, Juhani Itämies, Erkki Pulliainen, Jaana Bäck, Ella-Maria Kyrö, Pekka Niemelä. Current temporal trends in moth abundance are counter to predicted effects of climate change in an assemblage of subarctic forest mothsGlobal Change Biology, 2014; DOI: 10.1111/gcb.12529

Cite This Page:
University of Michigan. "Moth study suggests hidden climate change impacts." ScienceDaily. ScienceDaily, 15 April 2014. .