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Wednesday, September 17, 2014

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University Launches Dynamic, Interactive Information Website UMD Right Now

December 4, 2012
Contacts: 

Crystal Brown 301-405-4618 crystalb@umd.edu

College Park, Md. – Today, the University of Maryland launched a brand-new multimedia news and information portal, UMD Right Now, which provides members of the media and the public with real-time information on the university and its extended community.

UMD Right Now replaces Newsdesk, which previously served as the university’s news hub and central resource for members of the media. The new site is aimed at reaching broader audiences and allows visitors to keep up with the latest Maryland news and events, view photos and videos and connect with the university across all of its social media platforms.

“We designed UMD Right Now to be a comprehensive, vibrant site where visitors can find new and exciting things happening at Maryland,” said Linda Martin, executive director, Web and New Media Strategies. “Through social media, video, photos and news information, we hope to engage visitors and compel the community to explore all that Maryland has to offer.”

The new website, umdrightnow.umd.edu, contains up-to-date news releases and announcements, facts and figures about the university, a searchable database of faculty and staff experts, information highlighting innovation and entrepreneurship at UMD, additional resources for news media and other campus and athletics news.

“UMD RightNow is the place to go to find out all the things happening on and around campus on any given day,” said Crystal Brown, chief communications officer. “This website brings real-time news, events and information right to your fingertips.”

For more information and contact information for the Office of University Communications, please visit umdrightnow.umd.edu.

New Research Unveils Population Patterns of U.S. Immigrants from Mexico

September 17, 2014
Contacts: 

Michael S. Rendall, mrendall@umd.edu

UMD and CIDE researchers uncover new phenomenon: U.S. immigrants from Mexico come disproportionately from areas with less-educated populations

COLLEGE PARK, Md. – Mexican immigration dwarfs migratory flows into the United States from other countries. Studies of Mexican immigrants in the United States have emphasized their low average level of education compared with other immigrant populations as well as with Mexicans who remain at home.

A new study published in Population and Development Review, “Two Decades of Negative Educational Selectivity of Mexican Migrants to the United States,” by Michael S. Rendall, professor of sociology and director of the Maryland Population Research Center at the University of Maryland and Susan W. Parker, professor of economics, Centro de Investigation y Docencia Economicas (CIDE), Mexico, helps to explain this phenomenon. 

“Immigration has commonly been considered to be selective of healthier more able individuals with higher levels of schooling than the population as a whole, motivated by greater opportunities in the destination country,” according to Rendall. “Yet in this case, Mexican migrants have lower education, on average, than Mexicans who remain at home. Why?  By looking carefully at place-size data we find that a disproportionate share of Mexican migrants came from rural and small-urban areas (population less than 20,000) through the 1990s and 2000s. Because these areas have lower schooling levels than medium- to larger-sized urban areas of Mexico, the result is that migrants have lower education than the overall Mexican population at the most common migration ages.”  

Migrants who completed primary school are the most over-represented group relative to the Mexican population aged 18-54, and migrants who completed any upper secondary education are the most under-represented group. The study concludes that the geographic factor is the major cause of the apparently anomalous negative educational selectivity of migration from Mexico to the United States.

This phenomenon is significant not only because education affects migrants’ labor market prospects and impacts in the United States but because it also affects outcomes for their children, i.e. second-generation immigrants.

Rendall adds, “The restrictive U.S. immigration policy that has been in place throughout the 1990s and 2000s does not appear to have had the intended effect of deterring unauthorized migration overall. It may, however, have had a greater deterrent effect on higher-educated migrants than on lower-educated migrants.”

New Detector Captures Unprecedented Range of Light Waves

September 17, 2014
Contacts: 

Kathryn Tracey 443-340-2299

UMD Research Opens Door to Future Applications in Medicine and Security

COLLEGE PARK, Md. - New research at the University of Maryland could lead to a generation of light detectors that can see below the surface of bodies, walls, and other objects.

Using the special properties of graphene, a two-dimensional form of carbon that is only one atom thick, a prototype detector is able to see an extraordinarily broad band of wavelengths. Included in this range is a band of light wavelengths that have exciting potential applications but are notoriously difficult to detect: terahertz waves, which are invisible to the human eye.

Top-down view of broadband, ultra-fast graphene detector capable of detecting terahertz frequencies at room temperature. Credit: Thomas Murphy
A research paper about the new detector was published in Nature Nanotechnology.  Lead author Xinghan Cai, a University of Maryland physics graduate student, said a detector like the researchers' prototype "could find applications in emerging terahertz fields such as mobile communications, medical imaging, chemical sensing, night vision, and security."

The light we see illuminating everyday objects is actually only a very narrow band of wavelengths and frequencies. Terahertz light waves' long wavelengths and low frequencies fall between microwaves and infrared waves. The light in these terahertz wavelengths can pass through materials that we normally think of as opaque, such as skin, plastics, clothing, and cardboard. It can also be used to identify chemical signatures that are emitted only in the terahertz range.

Few technological applications for terahertz detection are currently realized, however, in part because it is difficult to detect light waves in this range. In order to maintain sensitivity, most detectors need to be kept extremely cold, around 4 degrees Kelvin, or -452 degrees Fahrenheit. Existing detectors that work at room temperature are bulky, slow, and prohibitively expensive.

The new room temperature detector, developed by the University of Maryland team and colleagues at the U.S. Naval Research Lab and Monash University, Australia, gets around these problems by using graphene, a single layer of interconnected carbon atoms. By utilizing the special properties of graphene, the research team has been able to increase the speed and maintain the sensitivity of room temperature wave detection in the terahertz range.

Using a new operating principle called the "hot-electron photothermoelectric effect," the research team created a device that is "as sensitive as any existing room temperature detector in the terahertz range and more than a million times faster," says Michael Fuhrer, professor of physics at the University of Maryland and Monash University, Australia.

Graphene, a sheet of pure carbon only one atom thick, is uniquely suited to use in a terahertz detector because when light is absorbed by the electrons suspended in the honeycomb lattice of the graphene, they do not lose their heat to the lattice but instead retain that energy.

The concept behind the detector is simple, says University of Maryland Physics Professor Dennis Drew. "Light is absorbed by the electrons in graphene, which heat up but don't lose their energy easily. So they remain hot while the carbon atomic lattice remains cold." These heated electrons escape the graphene through electrical leads, much like steam escaping a tea kettle. The prototype uses two electrical leads made of different metals, which conduct electrons at different rates. Because of this conductivity difference, more electrons will escape through one than the other, producing an electrical signal.

This electrical signal detects the presence of terahertz waves beneath the surface of materials that appear opaque to the human eye – or even x-rays. You cannot see through your skin, for example, and an x-ray goes right through the skin to the bone, missing the layers just beneath the skin's surface entirely. Terahertz waves see the in-between. The speed and sensitivity of the room temperature detector presented in this research opens the door to future discoveries in this in-between zone.

Closest-Ever Orbiter Sends Data on "Rubber Ducky" Comet

September 16, 2014
Contacts: 

Heather Dewar 301-405-9267
Lee Tune 301-405-4679

UMD astronomers see comet's surprising shape in far-ultraviolet light

COLLEGE PARK, Md. - As the spacecraft Rosetta approaches a "rubber ducky" shaped comet for the closest comet observations ever made, the spacecraft's instruments are already gathering data that may lead to new insights about how these heavenly bodies form, and how they evolve in their repeated orbits around the sun, says University of Maryland astronomer Lori Feaga.

A camera aboard the comet-orbiting spacecraft Rosetta took this photo of comet 67P/Churyumov-Gerasimenko, known as C-G, from a distance of about 79 kilometers, or 49 miles. on August 19, 2014. Credit: ESA/Rosetta/NAVCAMRosetta, an international mission launched by the European Space Agency in 2004, is slated to become the first spacecraft to orbit a comet up close and observe it in detail as it travels towards the sun. After a ten-year journey, including nearly three years in deep-space hibernation, Rosetta is now about 60 kilometers (37 miles) from its target, comet 67P/ Churyumov-Gerasimenko, known to mission investigators as C-G. The comet is hurtling through an ice-cold region of space some 525 million kilometers (326 million miles) from the sun, and will make its closest approach to the sun in August 2015.

Rosetta is due to come within 10 kilometers (6.2 miles) of C-G in November, when it will attempt to drop a lander for the first-ever observation of a comet from its own surface. The orbiter and lander are carrying 20 specialized instruments, and the mission is designed to observe C-G for a year or more.

Feaga, a UMD associate research scientist, and Michael A'Hearn, an astronomy professor, are co-investigators working with an instrument called Alice, an ultraviolet spectrograph that is sending back the first observations ever made of a comet's surface in far-ultraviolet radiation, which cannot be detected by telescopes that rely on visible light. Developed by Southwest Research Institute (SwRI) in Boulder, Colo., Alice is providing sensitive, high-resolution data from the comet's surface.  By viewing a comet up close in far-ultraviolet light, investigators hope to gain new information about this comet's gases and ices, and to learn more about the evolution of comets in general. 

Sometimes referred to as "dirty snowballs," comets are primordial fragments of the materials that formed our sun and its planets. First discovered in 1969, C-G has orbited the sun many times and has already burned off much of its original gas and icy material, says Feaga. Earlier observations revealed C-G's size, about 3.5 by 4 kilometers (2.2 by 2.5 miles). But since July, when Alice and other instruments began mapping the comet's surface daily, it has become apparent that C-G has "two distinct lobes, shaped like the head and the body of a duck," says Feaga.

Astronomers used to think that bi-lobed comets, the product of two comets colliding or of geologic processes similar to erosion, were rare. But as researchers observe more comets with better instruments, "we're seeing more of these bi-lobed shapes," Feaga says, "and we're realizing how many close encounters comets have had with each other over time."

As Rosetta gets closer to C-G, Alice and other instruments will show whether there are any variations in color between the two lobes. A color comparison "will show us whether C-G is made of two pieces that formed at the same time in the same place, and were fused together in some cosmic collision back in the early stages of the solar system," Feaga said, "or whether they formed much further apart and collided gradually, later on, without any great catastrophe."

Alice's mapping has shown that the comet's surface is unusually dark, deeper than charcoal-black, when seen in the ultraviolet spectrum. Because C-G is too far away for the sun's warmth to turn its water into vapor, researchers would expect to see water in the form of patchy ice on the comet's surface. But so far, Alice has not detected large patches of ice made from water on the surface.

"We're a bit surprised at how little evidence of observed water-ice it shows," says Alan Stern, an associate vice president of SwRI's Space Science and Engineering Division and Alice's principal investigator. Alice is one of three NASA-funded instruments aboard Rosetta, and NASA's Jet Propulsion Laboratory is managing the U.S. contribution to the international mission.

Hydrogen & Solar Power Boosted by New Ability to Shape Nanostructures

September 15, 2014
Contacts: 

Lee Tune 301-405-4679

Findings promise wide-ranging advances from clean energy to new sensors

COLLEGE PARK, Md. – New nanotechnology findings from physicists at the University of Maryland have moved us significantly closer to a "holy grail" of clean energy research – the efficient, cost effective generation of  clean hydrogen fuel from sunlight.

The UMD team created a fundamentally new synthesis strategy for hybrid nanostructures that they and other scientists say make possible new nanostructures and nanotechnologies with huge potential applications ranging from clean energy and quantum computing advances to new sensor development. 

The team demonstrated the power of their method by creating a photocatalyst that is almost 15 times more efficient in using solar energy to split water (H2O) into hydrogen and  oxygen than conventional photocatalysts. Photocatalysts are substances that use light to boost chemical reactions. Chlorophyll is a natural photocatalyst used by plants.

"The ingenious nano-assemblies that Professor Ouyang and his collaborators have fabricated, which  include the novel feature of a silver-gold particle that super-efficiently harvests light, bring us a giant step nearer to the so-far elusive goal of artificial photosynthesis: using sunlight to transform water and carbon dioxide into fuels and valuable chemicals," says Professor Martin Moskovits of the University of California at Santa Barbara, a recognized expert in this area of research and not affiliated with the paper.

Lighting the Way to Clean, Efficient Power 

Hydrogen fuel cell has long been considered a tremendously promising, clean alternative to gasoline and other carbon based (fossil) fuels that are currently used for cars, electrical generation and most other energy applications. A fuel cell combines stored hydrogen gas with oxygen from the air to produce electricity that can power vehicles, homes and businesses. The only byproduct of hydrogen fuel cells is water. Combustion of gasoline and other carbon-based fuels emit pollutants, including carbon dioxide, the principle greenhouse gas contributing to climate change.

Solar Water Splitting: A Step Towards Carbon-Free Energy and Environment.  Credit: Md. Golam Kibria, McGill University. Montreal, Quebec, Canada.

Solar Water Splitting: A Step Towards Carbon-Free Energy and Environment.
Credit: Md. Golam Kibria, McGill University. Montreal, Quebec, Canada.

It's expected that in 2015, American consumers will finally be able to purchase fuel cell cars from Toyota and other manufacturers. Although these will be zero-emissions vehicles, most of the hydrogen fuel to power them currently is made from natural gas, a fossil fuel that contributes to climate change and increasingly is being produced by the controversial process known as fracking.

The cleanest way to produce hydrogen fuel is using solar energy to split water into hydrogen and oxygen. However, decades of research advances have not yielded photocatalytic methods with sufficient energy efficiency to be cost effective for use in large scale water splitting applications. Efficient creation of hydrogen fuel from sunlight is also critical to development of large scale solar energy plants because hydrogen fuel is an ideal way to store for later use, the energy generated by such facilities.

The UMD team's work advances the efficiency of photocatalysts and lays the foundation for much larger future advances by more fully realizing a light-generated nanoparticle effect first used by ancient Romans to create glass that changes color based on light. This effect, known as surface plasmon resonance, involves the generation of high energy electrons using light.

UMD team leader Min Ouyang, an associate professor in the department of physics and the Maryland NanoCenter., explains that plasmon resonance is the generation of a collective oscillation of low energy electrons by light. The light energy stored in such a "plasmonic oscillator" then can be converted to energetic carriers (i.e., "hot" electrons) for use in photocatalysis and many other applications.

"Using our new modular synthesis strategy, our UMD team created an optimally designed, plasmon-mediated photocatalytic nanostructure that is an almost 15 times more efficient than conventional photocatalysts," says Ouyang.

In studying this new photocatalyst, Min and his colleagues identified a previously unknown "hot plasmon electron-driven photocatalysis mechanism with an identified electron transfer pathway."

It is this new mechanism that makes possible the high efficiency of the UMD team's new photocatalyst. And it is a finding made possible by the precise materials control allowed by the team's new general synthesis method.

The UMD team says their findings hold great promise for future advances to make water splitting cost effective for large-scale use in creating hydrogen fuel. And the team's newly-discovered mechanism for creating hot (high energy) electrons should also be applicable to research involving other photo-excitation processes.

A Fundamental Nanotechnology Advance

The findings of Min and his colleagues were published recently in Nature Communications. Their primary discovery is a fundamentally new synthesis strategy for hybrid nanostructures that uses a connector, or "intermedium," nanoparticle to join multiple different nanoparticles into nanostructures that would be very difficult or perhaps even impossible to make with existing methods. The resultant mix and match modular component approach avoids the limitations in material choice and nanostructure size, shape and symmetry that are inherent in the crystalline growth (epitaxial) synthesis approaches currently used to build nanostructures.

"Our approach makes it possible to design and build higher order [more complex and materially varied] nanostructures with a specifically designed symmetry or shape, akin to the body's ability to make different protein oligomers each with a specific function determined by its specific composition and shape," says Ouyang. "Such a synthesis method is the dream of many scientists in our field and we expect researchers now will use our approach to fabricate a full class of new nanoscale hybrid structures," he says.

One of the many scientists excited about the new UMD method is the University of Delaware's Matt Doty, an associate professor of materials science and engineering, physics, and electrical and computer engineering and associate director of the UD Nanofabrication Facility. "The work of Weng and coauthors provides a powerful new tool for the 'quantum engineering' of complex nanostructures designed to implement novel electronic and optoelectronic functions. [Their] new approach makes it feasible for researchers to realize much more sophisticated nanostructure p designs than were previously possible." he says.

Support for this research was provided by the Office of Naval Research, the U.S. Department of Energy, the National Science Foundation, and the Research Corporation for Science Advancement. 

Hierarchical synthesis of non-centrosymmetric hybrid nanostructures and enabled plasmon-driven photocatalysis, Lin Weng, HuiZhang, Alexander O. Govorov and Min Ouyang. Nature Communications; Article number: 4792; doi:10.1038/ncomms5792

UMD Innovations in Virtual Reality Boosted by New NSF Grant

September 15, 2014
Contacts: 

Tom Ventsias 301-405-5933

COLLEGE PARK, Md. – UMD development of virtual and augmented reality technologies – such as visualization tools that allow a surgeon to "see through" a patient during surgery – just got a big boost through a $600,000 research grant from the National Science Foundation (NSF).

UMD development of virtual and augmented reality technologies – such as visualization tools that allow a surgeon to "see through" a patient during surgery – just got a big boost through a $600,000 research grant from the National Science Foundation (NSF).The NSF Major Research Instrumentation grant will support UMD research in virtual reality (VR), which either mimics real-world settings or creates fantasy worlds; and in augmented reality (AR), which embeds digital information into real-world settings. Both fields are expected to expand exponentially in the near future in applications tied to scientific visualization, entertainment, military uses, architecture, navigation, education, prototyping, collaborative communication, and more.

The grant will be used to purchase new equipment and provide infrastructure support for a 1,000-square-foot "augmentarium" now under construction. This Virtual and Augmented Reality Laboratory will feature interactive projection displays, robotic mounts and high-speed computing clusters that, university officials say, will position UMD as a leader for the effective visualization of large and complex data.

When launched later this year, the interactive lab will bring together researchers from across campus and beyond to explore ideas and technologies that combine real-time data within virtual settings and backdrops.

"These technologies will engage our faculty and students to explore new pathways of discovery that can have far-reaching scientific and societal benefits," says Jayanth Banavar, dean of the College of Computer, Mathematical, and Natural Sciences (CMNS).

The equipment and capabilities of the new Virtual and Augmented Reality Laboratory will be used to support many UMD research and education projects. These include research to advance understanding of large-scale astronomy data, weather and climate prediction, data visualization for cybersecurity and characterization of stem cells. Other research will study how people interact with VR and AR technologies, and how they can best be used in an educational setting. And it's expected that the lab will support workshops developed by the Maryland Center for Women in Computing to encourage middle school and high school girls to participate in VR and AR projects.

The virtual and augmented reality lab will also take advantage of several cross-institutional partnerships supported by MPowering the State, which joins scientists at the University of Maryland with physicians, clinicians and other health experts at the University of Maryland, Baltimore.

"We look forward to further collaboration with our colleagues in Baltimore to identify opportunities and leverage our combined strengths in computing power and clinical expertise," says Amitabh Varshney, director of the University of Maryland Institute for Advanced Computer Studies and principal investigator of the NSF grant.

Researchers from both institutions envision specialized headgear that surgeons can wear in an operating room, providing real-time patient and surgical data that is "overlaid" on top of a patient during surgery.

Initial seed funding for the UMD virtual and augmented reality lab came from CMNS, with additional support from the university's Division of Research and the provost's office.

To view illustrations of several virtual and augmented reality projects under development at UMD, go here.

UMD Announces Largest Gift in University History

September 12, 2014

The University of Maryland announced today a gift of $31 million from Oculus VR co-founder and CEO and UMD alumnus, Brendan Iribe – the largest gift in the university's history. The majority of the gift, $30 million, will help fund construction of the Brendan Iribe Center for Computer Science and Innovation, and the remaining $1 million will establish the Brendan Iribe Scholarship in Computer Science.

Brendan Iribe, Oculus CEO, Gives $31M for New UMD Computer Science Building

September 12, 2014
Contacts: 

Katie Lawson 301-405-4622

Largest Gift in University History Set to Transform Computer Science Education

COLLEGE PARK, Md. – The University of Maryland announced today a gift of $31 million from Oculus co-founder and CEO and UMD alumnus Brendan Iribe – the largest gift in the university's history. The majority of the gift, $30 million, will help fund construction of the Brendan Iribe Center for Computer Science and Innovation, a new computer science building designed for cutting-edge work in virtual reality, augmented reality, computer vision, robotics and future computing platforms. The remaining $1 million of the gift will establish the Brendan Iribe Scholarship in Computer Science.

"The University of Maryland was an inspiration for me, and the relationships I made there have lasted a lifetime," says Iribe. "I've always wanted to give back to the school and public education system, and I hope this building will shape the future of computer science students at the university. The space is designed for hackers, makers and engineers, which will help give rise to future breakthroughs, products and startups that will transform the way we live and interact with the world around us."

In addition, Oculus chief software architect and co-founder and 2003 UMD graduate Michael Antonov is making a gift of $4 million to the university. Most of this gift, $3.5 million, will support construction of the building, and $500,000 will fund scholarships. An additional gift of $3 million from Elizabeth Iribe, Brendan's mother, will establish two endowed chairs in the Department of Computer Science.

Brendan Iribe"I've been passionate about computer science my whole life, and my experience at the University of Maryland fed that passion even more," says Antonov. "My hope is that this gift will give UMD students access to world-class resources and facilities for computer science that enables them to achieve the seemingly impossible."

"The transformative vision and support of Brendan, together with the exceptional commitment of his mother, Liz, and his UMD classmate Michael, will create a unique space where students from all disciplines can imagine, build, collaborate, and succeed together," says University of Maryland President Wallace Loh. "This is truly a space that will mold future innovators and entrepreneurs and spark economic vitality in Maryland and beyond."

The new, state-of-the-art facility will be a hub for cutting-edge computer science research and an incubator for technology and innovation. The building's design encourages collaboration, with an emphasis on hacker/maker spaces and team breakout areas.

"The Iribe Center will feature state-of-the-art maker spaces with access to new equipment and resources that enable students and faculty to bring their ideas to life in ways that were previously inaccessible," says Jayanth Banavar, dean of the College of Computer, Mathematical, and Natural Sciences. "It's exciting to be working on the cutting-edge of the field, alongside Brendan, Michael, and the team at Oculus, and I'm looking forward to seeing what our community creates."

Brendan Iribe speaks with UMD studentsSpecialized labs will support groundbreaking research in virtual reality, augmented reality, artificial intelligence, robotics, computer vision and human interaction. Students will have the opportunity to learn in classrooms designed specifically for interactive, collaborative and active learning. Hands-on training will successfully prepare them for the growing technology workforce.

"This is the beginning of a long-term commitment toward transforming education -- many of my best memories and relationships came from the University of Maryland, and I hope this gift fosters more life-changing friendships and partnerships like the one between Michael and me," says Iribe. "I truly believe virtual reality is the future of computing, with an impact that will be as big, if not bigger, than the jump to 3-D graphics or mobile devices. This gift positions Maryland to be one of the leading institutions for virtual reality in the world."

This gift will support the university's growing computer science department, which recently ranked 17th in the Academic Ranking of World Universities and 15th in the U.S. News & World Report rankings of graduate programs. Undergraduate enrollment in the department has more than doubled in the past eight years to over 2,000 students and more than 200 students are pursuing graduate degrees.

Photo credit: Mike Morgan

Ecosystems of U.S. Cities Show "Urban Evolution" Patterns

September 11, 2014
Contacts: 

Heather Dewar 301-405-9267

Urban waters record the salt in our food, cement in our sidewalks, UMD scientist says

This stream restoration project in Baltimore, Maryland is in an early stage of evolution towards sustainability. A concrete channel that enclosed the stream has been removed, and native tree seedlings have been planted along its banks. Credit: Tamara Newcomer Johnson, University of MarylandCOLLEGE PARK, Md. - Most people think of city landscapes as simpler, diminished versions of the wild forests and free-flowing streams found in remote places. But in a series of studies published Sept. 10, 2014 in a special issue of the journal Biogeochemistry, scientists specializing in urban ecosystems say just the opposite is true. Urban landscapes are more complex than they seem, and from coast to coast these ecosystems can work in surprisingly similar ways, regardless of local conditions. And they have the potential to change quickly – for better or worse – depending on how people manage them.

In 14 studies, scientists from across the U.S. examined the impacts of human actions on the geology, chemistry and biology of urban ecosystems. The studies were carried out in a broad range of climates from Boston and Baltimore to San Juan, Puerto Rico, Tucson, Arizona and Southern California, including sites in the National Science Foundation's Long Term Ecological Research (LTER) network. Results were published in a special issue of Biogeochemistry exclusively devoted to urban ecosystems, edited by University of Maryland geologist Sujay Kaushal and University of New Hampshire ecologists William McDowell and Wilfred Wollheim.

"Urban ecosystems change relatively quickly in response to human activities," says Kaushal. "These changes can result in rapid losses of ecosystem functions, like flood protection and pollution filtration, or they can result in progress toward ecological health and productivity. The difference depends in large part on how they are managed."

In an overview article, Kaushal, McDowell and Wollheim point out some key factors that affect the evolution of urban ecosystems. For example, the streams, lakes and land surfaces that make up cities' watersheds show consistent patterns of change over time:

  • They are becoming saltier, partly due to road salt used for de-icing, and partly because the salt that people eat ends up in urban streams. Excess salt in the human diet is excreted in human waste, and captured by sewer systems. Crumbling sewage pipes leak this chloride-laden waste into groundwater, where it eventually mingles with surface water, say the authors of the overview paper. The researchers propose that one way to track the spread of urbanization is by looking at the chloride content of cities' freshwater rivers and streams.
  • They carry the chemical signature of dissolving concrete, a major building material in urban areas since the mid-20th century. Most concrete contains cement made of powdered limestone, which weathers easily when exposed to acid rain or chemicals. The authors say many cities now have their own human-made geology: concrete surfaces that mimic a type of limestone called karst. This "urban karst" is constantly breaking down into its constituent elements, including calcium and carbonate minerals, which flow into urban streams and affect their pH content, and therefore their ability to sustain aquatic life.
  • Urban ecosystems develop "hot spots," like road crossings where automobile exhaust, litter, de-icing salt and other human-made substances can sharply alter downstream water quality. They also experience "hot moments," such as heavy rainstorms that wash large pulses of organic matter and manufactured chemicals into streams, or cause sewage overflows. These hot moments can suddenly change water chemistry in ways that shock natural systems. 
  • The networks that supply cities with water evolve and expand over time, including not just surface waters, but also storm drains, leaking water and sewer pipes, roofs and gutters, groundwater, and waste water that humans bring into the area from other watersheds. The boundaries between nearby cities' watersheds are blurring, making it hard to define, study and manage them.

Eroding stream banks and aging sewer lines contribute to evolving water pollution problems in cities. In this photo from Baltimore, Maryland, a sewage pipe that was originally placed in a stream bed developed leaks, and is now surrounded by a concrete casing. Credit: Tamara Newcomer Johnson, University of Maryland "There is a lot of good urban restoration work underway," says McDowell, "but often it only has a short-term effect, because urban watersheds follow their own evolutionary paths. For example, utility managers may build a stormwater retention pond to capture polluted runoff, such as excess nitrogen from urban runoff. And it may work very well for a few years. But then it fills in with sediment, and becomes a wetland, and it's no longer working the way the engineers designed it to work."

"We hope scientists, managers and citizens will work together to make decisions that allow for what we call 'urban evolution,' – that is, changes in the ecology of cities over time, " says Kaushal. "If we do that, we can find effective ways to understand and manage the trajectory of urban ecosystems, from decline towards sustainability."

"This synthesis brings the power of evolutionary biology to understanding ecosystem processes in urban environments, some of the most rapidly changing habitats globally," says Saran Twombly, NSF's LTER program director.  "Merging evolutionary biology with ecosystem sciences is an exciting frontier for long-term ecological research, beginning with this issue on biogeochemical cycles."

Pages

September 17
A new survey of the Iranian public finds that the majority of Iranians would support their government making a deal on... Read
September 17
UMD and CIDE researchers uncover new phenomenon: U.S. immigrants from Mexico come disproportionately from areas with... Read
September 17
New research at the University of Maryland could lead to a generation of light detectors that can see below the surface... Read
September 16
As the spacecraft Rosetta approaches a "rubber ducky" shaped comet, the spacecraft's instruments are already gathering... Read