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  • richardmitnick 12:48 pm on April 14, 2017 Permalink | Reply
    Tags: , Fog harvesting, , Water, water everywhere … even in the air   

    From MIT: “Water, water everywhere … even in the air” 

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    MIT News

    April 14, 2017
    David Chandler

    This proof-of-concept device, built at MIT, demonstrates a new system for extracting drinking water from the air. The sequence of images at right shows how droplets of water accumulate over time as the inside temperature increases while exposed to the sun. Images courtesy of the researchers

    Scientists discover a way to harvest fresh water from air, including in arid regions.

    Severe water shortages already affect many regions around the world, and are expected to get much worse as the population grows and the climate heats up. But a new technology developed by scientists at MIT and the University of California at Berkeley could provide a novel way of obtaining clean, fresh water almost anywhere on Earth, by drawing water directly from moisture in the air even in the driest of locations.

    Technologies exist for extracting water from very moist air, such as “fog harvesting” systems that have been deployed in a number of coastal locations. And there are very expensive ways of removing moisture from drier air. But the new method is the first that has potential for widespread use in virtually any location, regardless of humidity levels, the researchers say. They have developed a completely passive system that is based on a foam-like material that draws moisture into its pores and is powered entirely by solar heat.

    The findings are reported in the journal Science by a team including MIT associate professor of mechanical engineering Evelyn Wang, MIT postdoc Sameer Rao, graduate student Hyunho Kim, research scientists Sungwoo Yang and Shankar Narayanan (currently at Rensselaer Polytechnic Institute), and alumnus Ari Umans SM ’15. The Berkeley co-authors include graduate student Eugene Kapustin, project scientist Hiroyasu Furukawa, and professor of chemistry Omar Yaghi.

    Fog harvesting, which is being used in many countries including Chile and Morocco, requires very moist air, with a relative humidity of 100 percent, explains Wang, who is the Gail E. Kendall Professor at MIT. But such water-saturated air is only common in very limited regions. Another method of obtaining water in dry regions is called dew harvesting, in which a surface is chilled so that water will condense on it, as it does on the outside of a cold glass on a hot summer day, but it “is extremely energy intensive” to keep the surface cool, she says, and even then the method may not work at a relative humidity lower than about 50 percent. The new system does not have these limitations.

    For drier air than that, which is commonplace in arid regions around the world, no previous technology provided a practical way of getting water. “There are desert areas around the world with around 20 percent humidity,” where potable water is a pressing need, “but there really hasn’t been a technology available that could fill” that need, Wang says. The new system, by contrast, is “completely passive — all you need is sunlight,” with no need for an outside energy supply and no moving parts.

    In fact, the system doesn’t even require sunlight — all it needs is some source of heat, which could even be a wood fire. “There are a lot of places where there is biomass available to burn and where water is scarce,” Rao says.

    The key to the new system lies in the porous material itself, which is part of a family of compounds known as metal-organic frameworks (MOFs). Invented by Yaghi two decades ago, these compounds form a kind of sponge-like configuration with large internal surface areas. By tuning the exact chemical composition of the MOF these surfaces can be made hydrophilic, or water-attracting. The team found that when this material is placed between a top surface that is painted black to absorb solar heat, and a lower surface that is kept at the same temperature as the outside air, water is released from the pores as vapor and is naturally driven by the temperature and concentration difference to drip down as liquid and collect on the cooler lower surface.

    Tests showed that one kilogram (just over two pounds) of the material could collect about three quarts of fresh water per day, about enough to supply drinking water for one person, from very dry air with a humidity of just 20 percent. Such systems would only require attention a few times a day to collect the water, open the device to let in fresh air, and begin the next cycle.

    What’s more, MOFs can be made by combining many different metals with any of hundreds of organic compounds, yielding a virtually limitless variety of different compositions, which can be “tuned” to meet a particular need. So far more than 20,000 varieties of MOFs have been made.

    “By carefully designing this material, we can have surface properties that can absorb water very efficiently at 50 percent humidity, but with a different design, it can work at 30 percent,” says Kim. “By selecting the right materials, we can make it suitable for different conditions. Eventually we can harvest water from the entire spectrum” of water concentrations, he says.

    Yaghi, who is the founding director of the Berkeley Global Science Institute, says “One vision for the future is to have water off-grid, where you have a device at home running on ambient solar for delivering water that satisfies the needs of a household. … To me, that will be made possible because of this experiment. I call it personalized water.”

    While these initial experiments have proved that the concept can work, the team says there is more work to be done in refining the design and searching for even more effective varieties of MOFs. The present version can collect water up to about 25 percent of its own weight, but with further tuning they think that proportion could be at least doubled.

    “Wow, that is an amazing technology,” says Yang Yang, a professor of engineering at the University of California at Los Angeles, who was not involved in this work. “It will have a tremendous scientific and technical impact on renewable and sustainable resources, such as water and solar energy.”

    The work was supported in part by ARPA-E, a program of the U.S. Department of Energy.

    See the full article here .

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  • richardmitnick 10:13 am on September 9, 2016 Permalink | Reply
    Tags: , , , Water   

    From Physics Today: “Water flows freely through carbon nanotubes” 

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    Physics Today

    08 September 2016
    Andrew Grant

    A new experiment confirms the slipperiness of the minuscule carbon cylinders but not their boron nitride counterparts.

    Despite the frenzy of research into carbon nanotubes (CNTs) over the past few decades (see, for example, Physics Today, June 1996, page 26), there isn’t much experimental evidence for one of the tiny structures’ most talked-about superpower­s: the ability to funnel water with nearly zero friction. The problem has been achieving the sensitivity to measure water transport rates as feeble as a femtoliter a second. Now Lydéric Bocquet and his colleagues at École Normale Supérieure in Paris have confirmed the slipperiness of CNTs by directly measuring water flow through individual nanotubes whose bores ranged from 15 nm to 50 nm. The researchers stuck a multiwalled CNT inside a small pipette and essentially turned the nanotube into the needle of a syringe. Pressure applied inside the pipette caused water to flow through the CNT and into a tank of water. Rather than tracking the water as it flowed through the tube, Bocquet and his team analyzed the motion of suspended polystyrene nanobeads in the tank to deduce the strength of the jet emerging from the CNT (see image below, which shows the response at various pressures). The results verify that CNTs allow water to flow extremely efficiently. Bocquet’s team also confirmed its 2010 prediction that the flow rate would increase as the tube’s radius decreased, although the dependence turned out to be roughly quadratic rather than quartic. The biggest surprise came when the researchers replaced the CNTs with nanotubes of boron nitride. Although the BN tubes are nearly structurally identical to their carbon counterparts (see Physics Today, November 2010, page 34), they proved far more resistant to water flow. The finding seems to suggest that electronic properties—CNTs are conductors; boron nitride nanotubes are insulators—play a role in hydrodynamics at very small scales. Bocquet and his team plan to investigate that possibility as they explore the nanotubes’ potential for applications such as water distillation and filtration. (E. Secchi et al., Nature 537, 210, 2016.)


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  • richardmitnick 6:59 am on July 26, 2016 Permalink | Reply
    Tags: 2001: Mars Odyssey spacecraft, , , , Water   

    From phys.org: “Digging deeper into Mars” 


    July 25, 2016
    No writer credit

    Water is the key to life on Earth. Scientists continue to unravel the mystery of life on Mars by investigating evidence of water in the planet’s soil. Previous observations of soil observed along crater slopes on Mars showed a significant amount of perchlorate salts, which tend to be associated with brines with a moderate pH level. However, researchers have stepped back to look at the bigger picture through data collected from the 2001: Mars Odyssey, named in reference to the science fiction novel by Arthur C. Clarke, “2001: A Space Odyssey,” and found a different chemical on Mars may be key. The researchers found that the bulk soil on Mars, across regional scales the size of the U.S. or larger, likely contains iron sulfates bearing chemically bound water, which typically result in acidic brines. This new observation suggests that iron sulfates may play a major role in hydrating martian soil.

    Global map of Mars sulfur concentration (as percentage by mass) derived from the 2001: Mars Odyssey Gamma Ray Spectrometer spectra. Overlay shows qualitatively what types of hydrated sulfates are consistent with the variations seen in sulfur and water across the latitudes. Upright triangles indicate peaks in possible sulfate type abundance while the inverted triangles show less prominent values. Credit: Nicole Button, LSU Planetary Science Lab

    This finding was made from data collected by the 2001: Mars Odyssey Gamma Ray Spectrometer, or GRS, which is sensitive enough to detect the composition of Mars soil up to one-half meter deep. This is generally deeper than other missions either on the ground or in orbit, and it informs the nature of bulk soil on Mars. This research was published recently in the Journal of Geophysical Research: Planets.

    2001: Mars Odyssey robotic spacecraft, in service since April 7, 2001

    “This is exciting because it’s contributing to the story of water on Mars, which we’ve used as a path for our search for life on Mars,” said Nicole Button, LSU Department of Geology and Geophysics doctoral candidate and co-author in this study.

    The authors expanded on previous work, which explored the chemical association of water with sulfur on Mars globally. They also characterized how, based on the association between hydrogen and sulfur, the soil hydration changes at finer regional scales. The study revealed that the older ancient southern hemisphere is more likely to contain chemically bound water while the sulfates and any chemically bound water are unlikely to be associated in the northerly regions of Mars.

    The signature of strong association is strengthened in the southern hemisphere relative to previous work, even though sulfates become less hydrated heading southwards. In addition, the water concentration may affect the degree of sulfate hydration more than the sulfur concentration. Limited water availability in soil-atmosphere exchange and in any fluid movement from deeper soil layers could explain how salt hydration is water-limited on Mars. Differences in soil thickness, depth to any ground ice table, atmospheric circulation and sunshine may contribute to hemispheric differences in the progression of hydration along latitudes.

    The researchers considered several existing hypotheses in the context of their overall observations, which suggest a meaningful presence of iron-sulfate rich soils, which are wet compared to Mars’ typically desiccated soil. This type of wet soil was uncovered serendipitously by the Spirit Rover while dragging a broken wheel across the soil in the Paso Robles area of Columbia Hills at Gusev Crater. Key hypotheses of the origin of this soil include hydrothermal activity generating sulfate-rich, hydrated deposits on early Mars similar to what is found along the flanks of active Hawaiian volcanoes on Earth. Alternatively, efflorescence, which creates the odd salt deposits on basement walls on Earth, may have contributed trace amounts of iron-sulfates over geologic time. A third key hypothesis involves acidic aerosols released at volcanic sites, such as acid fog, dispersed throughout the atmosphere, and interacting subsequently with the finer components of soil as a source of widespread hydrated iron-sulfate salts.

    Among these hypotheses, the researchers identify acid fog and hydrothermal processes as more consistent with their observations than efflorescence, even though the sensitivity of GRS to elements, but not minerals, prevents a decisive inference. Hydrothermal sites, in particular, are increasingly recognized as important places where the exchange between the surface and deep parts of Earth’s biosphere are possible. This hypothesis is significant to the question of martian habitability.

    “Our story narrows it to two hypotheses, but emphasizes the significance of all of them,” said LSU Department of Geology and Geophysics Assistant Professor Suniti Karunatillake, who is a fellow lead author. “The depth and breadth of these observation methods tell us about global significance, which can inform the big question of what happened to the hydrologic cycle on Mars.”

    See the full article here .

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  • richardmitnick 1:15 pm on July 1, 2016 Permalink | Reply
    Tags: , , , Water   

    From Astrobites: “Water worlds – self-arrests, thermostats and long-term climate stability” 

    Astrobites bloc


    Title: Water On -and In- Terrestrial Planets
    Authors: Cowan, Nicolas B.
    First Author’s Institution: McGill University, Montreal, Canada
    Status: To appear in Proceedings of the Comparative Climates of Terrestrial Planets II conference

    Earth features a unique surface among Solar System planets; it is composed of both liquid water oceans and large continents. The continents float on top of the mantle rock material, while the water is continuously recycled by subducting slabs in the dynamic system of plate tectonics. The stability of the average sea level and the permanent flux of water in the tectonic system is by far not self-explanatory. That the continents are exposed proves to be quite good circumstances for us — they could very well reside below the ocean surface, which would prohibit any land-based life as we know it. For a deeper understanding of this conundrum we have to involve not only the study of our own planet, but we need to see its formation and evolution in comparison with other terrestrial planets and moons in the Solar System and even the galaxy.

    Long-term climate stability — self-regulation or runaway?

    Earth’s climate stability seems to be regulated by the carbonate-silicate cycle, during which rocks are transformed by weathering, sedimentation and magmatism. This process dictates the pace of carbon release from the interior to the atmosphere and is crucial in regulating the global temperature (which is why excess release of, among others, carbon dioxide is generally considered to be a bad idea…). A good indication that the process works (on million year timescales!) is that we did have liquid water on the surface ~4.5 billion years ago, even though the Sun was much fainter than today and Earth should have been in a global snowball state at that time.

    Such a self-regulation effect is a neat mechanism, as it might allow extrasolar planets to harbour liquid water in a relatively broad zone of separations to their host star – the so called habitable zone. However, the temperature thermostat of Earth’s climate stability not only depends on plate tectonics, but the exposure of land and the resulting weathering of rocks is crucial to this process. Therefore, on pure water worlds (which might be frequent), where the whole surface is covered with oceans, we might run into problems….

    How to get rid of too much water?

    Hypothetically, waterworlds can enter a state of “self-arrest” if they do not feature a thermostat as discussed above: their host-star continually brightens and therefore the planet will heat up over time. Eventually, it will enter a stage where water vapour can be held in the atmosphere, which will subsequently be destroyed by UV light from the star. This process continues until continents are exposed to the atmosphere, at which point the planet enters a climate cycle as Earth. Hypothetically.

    Obviously, we do not have any evidence that such a process can act and we do not understand the complicated interactions of the atmosphere and stellar irradiation well enough to make detailed predictions. However, if losing water through the atmosphere would not work, maybe terrestrial planets can incorporate more water into their mantles. As the author of today’s paper suggested in a former work, it is possible that the exact amount of water incorporated into the planetary interior crucially depends on the pressure at the seafloor. Earth’s mantle harbours ~3-11 oceans, thus there is much more water in the interior than exposed on the surface, and in general it could absorb even more – it just does not do it. So maybe we face a self-regulation here again.

    Columbus for exo-worlds

    Nothing will probably resolve this enigma until we will be able to actually *see* land on other worlds, we could make a census of planetary properties and compare the results with the predictions by various theories. This might sound like wild science fiction, and so far it is. However, the author lists recent ideas of how observations of continents on other terrestrial planets could be done in the not-so-distant future. We’re talking about 10-30 years with new space facilities, which will give us high enough spectral resolution to decipher changes in brightness and color of the observed planets. These estimates can be converted into very rough ideas of how the surface of a planet looks like.

    Another option is to analyse the pieces of shattered worlds which fall onto the surfaces of white dwarfs, dead stars at the end of their life cycles. This is actually done already and gives us clues about the elemental abundances in the broken-up pieces of former terrestrial planets around these stars. With further technical and theoretical development we might one day be able to understand the distribution of water in the universe — the no. 1 element important for complex chemistry and thus life.

    See the full article here .

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    Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
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    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
    Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

  • richardmitnick 3:55 pm on May 23, 2016 Permalink | Reply
    Tags: , , Water, Water-Energy Nexus New Focus of Berkeley Lab Research   

    From LBL: “Water-Energy Nexus New Focus of Berkeley Lab Research” 

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    Berkeley Lab

    May 23, 2016
    Julie Chao
    (510) 486-6491

    Water banking, desalination, and high-resolution climate models are all part of the new Berkeley Lab Water Resilience Initiative. (California snowpack photo credit: Dan Pisut/ NASA)

    Billions of gallons of water are used each day in the United States for energy production—for hydroelectric power generation, thermoelectric plant cooling, and countless other industrial processes, including oil and gas mining. And huge amounts of energy are required to pump, treat, heat, and deliver water.

    This interdependence of water and energy is the focus of a major new research effort at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). With the twin challenges of population growth and climate change adding to the resource pressures, Berkeley Lab’s Water Resilience Initiative aims to use science and technology to optimize coupled water-energy systems and guide investments in such systems.

    “Considering water and energy as separate issues is passé,” said Berkeley Lab scientist Robert Kostecki, one of the three leads of the initiative. “Now the two are becoming critically interdependent. And both the energy and water sectors are expected to experience serious stresses from extreme climate events. However the problem on each side is dealt with, there needs to be an understanding of possible implications on the other side.”

    The Initiative has three main goals: hydroclimate and ecosystem predictions, revolutionary concepts for efficient and sustainable groundwater systems, and science and technology breakthroughs in desalination. The goals can be viewed as analogous to energy distribution, storage, and generation, says Susan Hubbard, Berkeley Lab’s Associate Lab Director for Earth and Environmental Sciences.

    “We consider improved hydroclimate predictions as necessary for understanding future water distribution,” Hubbard said. “We are exploring water banking as a subsurface strategy to store water that is delivered by snowmelt or extreme precipitation. To remain water resilient in other locations and to take advantage of seawater through brackish inland produced waters, Berkeley Lab is performing fundamental investigations to explore new approaches to desalinate water, ideally leading to cost and energy efficient approaches to generate water.”

    Climate: the Source of All Water

    The climate, ultimately, is the source of all water, and in places like California, where the snow pack plays an important role, climate change will have a big impact on how much water there will be and when it will come. The goal of the climate focus of the Initiative, led by Berkeley Lab climate scientist Andrew Jones, is to develop approaches to predict hydroclimate at scales that can be used to guide water-energy strategies.

    “Historically we’ve developed climate models that are global models, developed to answer global science questions,” Jones said. “But there’s an increasing demand for information at much finer spatial scales to support climate adaptation planning.”

    Ten years ago, Berkeley Lab scientists helped develop global climate models with a resolution of 200 kilometers. By 2012, the most advanced models had 25 km resolution. Now a project is underway to develop a regional climate model of the San Francisco Bay Area with resolution of 1 km, or the neighborhood level.

    “We’ll be looking at the risk of extreme heat events and how that interacts with the microclimates of the Bay Area, and additionally, how change in the urban built environment can exacerbate or ameliorate those heat events,” Jones said. “Then we want to understand the implications of those heat events for water and energy demands.”

    The eventual goal is to transfer this model for use in other urban areas to be able to predict extreme precipitation events as well as drought and flood risk.

    Subsurface: Storage, Quality, and Movement of Water Underground

    Another Initiative focus, led by Peter Nico, head of Berkeley Lab’s Geochemistry Department, studies what’s happening underground. “We have a lot of expertise in understanding the subsurface—using various geophysical imaging techniques, measuring chemical changes, using different types of hydrologic and reactive transport models to simulate what’s happening,” he said. “So our expertise matches up very well with groundwater movement and management and groundwater quality.”

    Groundwater issues have become more important with the drought of the last four years. “California has been ‘overdrafting’ water for a long time, especially in the San Joaquin Valley, where we’re pulling more water out than is naturally infiltrating back in,” Nico said. “With the drought the use of groundwater has gone up even more. That’s causing a lot of problems, like land subsidence.”

    While there is already a lot of activity associated with groundwater management in California, Nico added, “we still can’t confidently store and retrieve clean water in the subsurface when and where we need it. We think there’s a place to contribute a more scientific chemistry- and physics-based understanding to efficient groundwater storage in California.”

    For example, Berkeley Lab scientists have expertise in using geophysical imaging, which allows them to “see” underground without drilling a well. “We have very sophisticated hydrologic and geochemical computer codes we think we can couple with imaging to predict where water will go and how its chemistry may change through storage or retrieval,” he said.

    Berkeley Lab researchers are helping test “water banking” on almond orchards. (Courtesy of Almond Board of California)

    They have a new project with the Almond Board of California to determine the ability to recharge over-drafted groundwater aquifers in the San Joaquin Valley by applying peak flood flows to active orchards, known as “water banking.” The project is part of the Almond Board’s larger Accelerated Innovation Management (AIM) program, which includes an emphasis on creating sustainable water resources. Berkeley Lab scientists will work with existing partners, Sustainable Conservation and UC Davis, who are currently conducting field trials and experiments, and contribute their expertise on the deeper subsurface, below the root zone of the almond trees, to determine what happens to banked water as it moves through the subsurface.

    Another project, led by Berkeley Lab researcher Larry Dale, is developing a model of the energy use and cost of groundwater pumping statewide in order to improve the reliability of California’s electric and water systems, especially in cases of drought and increase in electricity demand. The project has been awarded a $625,000 grant by the California Energy Commission.

    Desalination: Aiming for Pipe Parity

    Reverse osmosis is the state-of-the-art desalination technology and has been around since the 1950s. Unfortunately, there have been few breakthroughs in the field of desalination since then, and it remains prohibitively expensive. “The challenge is to lower the cost of desalination of sea water by a factor of five to achieve ‘pipe parity,’ or cost parity with water from natural sources,” said Kostecki, who is leading the project. “This is a formidable endeavor and it cannot be done with incremental improvements of existing technologies.”

    To reach this goal, Kostecki and other Berkeley Lab researchers are working on several different approaches for more efficient desalination. Some are new twists on existing technologies—such as forward osmosis using heat from geothermal sources, graphene-based membranes, and capacitive deionization—while others are forging entirely new paradigms, such as using the quantum effects in nanoconfined spaces and new nano-engineered materials architectures.

    “The reality is that if one is shooting for a 5X reduction in the cost of desalination of water, then this requires a completely new way of thinking, new science, new technology—this is what we are shooting for,” said Ramamoorthy Ramesh, Associate Lab Director for Energy Technologies.

    Some of these projects are part of the U.S./China Clean Energy Research Center for Water Energy Technologies (CERC-WET), a new $64-million collaboration between China and the United States to tackle water conservation in energy production and use. It is a cross-California collaboration led on the U.S. side by Berkeley Lab researcher Ashok Gadgil and funded primarily by the Department of Energy.

    “Berkeley Lab is ideally suited to take on the water-energy challenge,” said Ramesh. “As a multidisciplinary lab with deep expertise in energy technologies, computational sciences, energy sciences as well as earth and climate sciences, we have the opportunity to develop and integrate fundamental insights through systems-level approaches. Relevant to California, we are focusing on developing scalable water systems that are resilient in an energy-constrained and uncertain water future.”

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  • richardmitnick 11:13 am on January 3, 2016 Permalink | Reply
    Tags: , , Water   

    From Nautilus: “Five Things We Still Don’t Know About Water” June 2015 but Important 



    June 11, 2015 [Just found this]
    Richard Saykally
    Illustration by Jackie Ferrentino

    Temp 1

    From steam to ice, water continues to mystify.

    “What could we not know about water? It’s wet! It’s clear. It comes from rain. It boils. It makes snow and it makes ice! Does our government actually spend taxpayer money for you to study water?”

    This excerpt is from one of the last conversations I had with my dear late mother, who passed away some seven years ago, still remarkably frugal at age 99. Her words reflect a view seemingly held by half the world’s population: Water is boring.

    The other half of the world, though, fanned by pseudoscience and new-age gurus, seems to buy into magical properties like homeopathy, structured water, polywater, and water memory.

    The truth lies somewhere in the middle. Yes, water is common—in fact, it is the third most common molecule in the universe. But, contrary to Mother’s views, it is also deceptively complex. Here are just a few of the scientific problems related to water that remain open today:

    1. How Many Kinds of Ice Are There?

    At latest count, there are 17 different crystalline forms of solid water. However, only one form—Ice Ih—exists commonly on Earth outside of the laboratory. A second crystalline form called Ice Ic is present in very minor amounts in the upper atmosphere, and another 15 forms occur only at very high pressures. (There is also a lot of water in interstellar space, but it is usually an amorphous, non-crystalline, glassy ice frozen onto dust grains.)

    The remarkable variety of crystalline ice forms results from the tetrahedral network of strong hydrogen bonds formed among neighboring water molecules.

    Regular Tetrahedron

    In the condensed phases of water, each molecule optimizes its hydrogen bonding capacity by forming four hydrogen bonds at near-tetrahedral angles. The hydrogen bonds inside Ice Ih form an open, three-dimensional structure with a low density.

    Big Ice: Liquid water (left) is composed of hydrogen (white) and oxygen (red) atoms arranged in a nearly tetrahedral structure. Common ice, or Ice Ih (right), shows a three-dimensional network that is less dense, explaining why ice floats on water.Wikimedia

    The application of pressure to tetrahedral substances, including crystalline ice, elemental carbon, silicon, and phosphorus, can collapse low-density solid forms into a variety of structures of sequentially higher density, presumably until the close-packed limit is reached. This produces the 17 forms of crystalline ice we have observed so far. Are there more to discover?

    2. Are There Two Kinds of Liquid Water?

    Several decades ago, Japanese scientists claimed to have observed transitions between two phases of amorphous ice under high pressure. Since we believe that amorphous ice is essentially a frozen snapshot of the corresponding liquid, this observation implied that two types of liquid water must exist: normal, low-density water, and a compact high-density form analogous to high-pressure amorphous ice.

    Subsequent simulations have supported this claim. They investigated water whose temperature was below freezing, but above its “homogeneous nucleation temperature” (the temperature below which liquid water cannot exist). In this so-called “deeply supercooled” region, scientists saw evidence for a phase transition between two liquid forms of water.

    However, other scientists argue that these results are artifacts, and that such transitions are unlikely to occur, based on principles of statistical mechanics. The fact that they occur so far away from equilibrium makes them difficult to observe and model—in fact, behavior far away from equilibrium is a current frontier of condensed matter theory.

    3. How Does Water Evaporate?

    The rate of evaporation of liquid water is one of the principal uncertainties in modern climate modeling. It determines the size distribution of water droplets in clouds, which, in turn, determines how clouds reflect, absorb, and scatter light.

    But the exact mechanism for how water evaporates isn’t completely understood. The evaporation rate is traditionally represented in terms of a rate of collision between molecules, multiplied by a fudge factor called the evaporation coefficient, which varies between zero and one. Experimental determination of this coefficient, spanning several decades, has varied over three orders of magnitude. Theoretical calculations have been hampered by the fact that evaporation is an extremely rare event, requiring prohibitively long and large computer simulations.

    Together with his colleagues, David Chandler, of the University of California, Berkeley, used a theory capable of describing such rare events, called transition path sampling, to calculate the water evaporation coefficient. They arrived at a value near one. This corresponds fairly well to recent liquid microjet experiments that produce a value of 0.6 for both normal water and heavy water.

    However, there are a couple of wrinkles. For one thing, it remains unclear why experiments performed under more atmospherically relevant conditions yield much lower values. Also, the transition path sampling simulations suggest that evaporation relies on an anomalously large capillary wave running along the liquid’s surface, which strains and weakens the hydrogen bonds holding on to an evaporating water molecule. The addition of salts to water raises the surface tension and suppresses the capillary wave amplitude, and so should reduce the evaporation rate. But experimental studies show little or no effect when salts are added.

    4. Is the Surface of Liquid Water Acidic or Basic?

    Temp 2
    Image Source: Unknown at http://www.tourist-destinations.net/2013/09/niagara-falls-canada.html


    There is something remarkable about the mist surrounding Niagara Falls: The individual droplets move as if they are negatively charged. The same is true for most waterfalls. This has long been interpreted as evidence for the accumulation of negative hydroxide (OH-) ions at the droplet surfaces, which would mean that the surfaces are basic—with a pH value greater than the 7 of neutral water. In fact, this thinking has become dogma within the community of colloid scientists.

    The surface of liquid water contains a larger number of broken hydrogen bonds, which produce a rather different chemical environment than that found in the bulk. But recent experiments and calculations suggest that hydrated protons (H+) actually dominate the liquid water surface, producing an acidic (less than 7) pH and a positively charged surface, rather than a basic, negatively charged surface.

    Many important processes in chemistry and biology, like atmospheric aerosol–gas exchanges, enzyme catalysis, and transmembrane proton transport, involve proton exchanges at the water surface, and explicitly depend on the pH at the water’s surface—a quantity which is currently unknown.

    5. Is Nanoconfined Water Different?

    Water isn’t always sloshing around in giant oceans. Both in nature and in man-made devices, water is often confined to unimaginably tiny spaces, like reverse micelles, carbon nanotubes, proton exchange membranes, and xerogels (which are highly porous glassy solids).

    Both experiment and calculation seem to indicate that water confined by solid walls to tiny regions of space, whose size is comparable to that of a few hundred molecules, begins to exhibit quantum mechanical effects, including delocalization and quantum coherence. These properties are strikingly different from those of bulk water, and could influence everything from biological cells to geological structures. It could be also be of considerable practical significance, for example in designing more efficient desalinization systems.

    Current results remain somewhat ambiguous, however, and more work in this area remains to be done in order to determine the nature of water under confinement.

    See the full article here .

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    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

  • richardmitnick 12:51 pm on December 19, 2015 Permalink | Reply
    Tags: , , Water   

    From Eos: “The Coming Blue Revolution” 

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    17 December 2015
    Kate Wheeling

    The dry lakebed visible at Australia’s Lake Hume is a stark reminder that water scarcity is one of modern societies’ most pressing challenges. Credit: Tim J Keegan, CC BY-SA 2.0

    Human civilizations have always sprouted up around bodies of water. We’ve created increasingly efficient infrastructures to harness and store the precious resource, reaching a scale so enormous that human activities now have a substantial impact on the global water cycle. Kumar provides a framework to integrate cross-disciplinary approaches to water scarcity in order to reveal innovative, holistic solutions.

    The water cycle is intimately linked with Earth’s carbon, nutrient, and energy cycles—all of which have been greatly impacted by human activities. The complexity of these interconnected systems ensures that any perturbation—for example, a forest fire, a catastrophic flood, or an extended drought—will have unpredictable consequences as it propagates through each cycle. Because these emergent responses are nearly impossible to plan for or protect against, they pose a great threat to humans

    “We are being called upon to address problems that are complex and messy because no clear pathways of solutions may exists, and often multiple solutions may present equally (un)satisfying outcomes,” the author writes. His integrated framework of the water cycle and humanity’s place in it, which he calls “hydrocomplexity,” aims to identify the best practices for addressing emergent threats against water security that come from climate change, increasing reliance on limited resources, and intensive land management and development.

    The author argues that in order to model how perturbations will propagate through the water, carbon, and nutrient cycles and generate various emergent responses, scientists need a comprehensive understanding of the processes at play in each of the interconnected cycles.

    He also suggests that hydrologic patterns will likely be revealed through the integration of models with a rapidly growing body of diverse observational records by computational systems that crunch large volumes of data.

    Finally, understanding how information flows through institutional networks and triggers human action will also provide insights toward developing effective solutions to water scarcity that people will actually adopt.

    Already, much of the world is dealing with an extreme and chronic shortage of freshwater; essentially, humans are using the resource faster than it can be replenished by the normal hydrologic cycle. The underlying idea of the author’s framework is that understanding our role in the complex water cycle is the first step toward managing inevitable water security challenges of the future. (Water Resources Research, doi:10.1002/2015WR017342, 2015)

    Citation: Wheeling, K. (2015), The coming blue revolution, Eos, 96, doi:10.1029/2015EO041535. Published on 17 December 2015.

    See the full article here .

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    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

  • richardmitnick 10:10 pm on November 12, 2015 Permalink | Reply
    Tags: , , , Water   

    From U Hawaii: “UH Researchers Shed New Light on the Origins of Earth’s Water” 

    U Hawaii

    University of Hawaii

    12 November 2015
    Dr. Lydia Hallis
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    Scanning electron microscope image of a Baffin Island picrite (type of basaltic rock). The mineral olivine, shown as abundant mid-gray color cracked grains (A), hosts glassy melt inclusions (B) containing tiny amounts of water sourced from Earth’s deep mantle. Image by Lydia J. Hallis.

    Water covers more than two-thirds of Earth’s surface, but its exact origins are still something of a mystery. Scientists have long been uncertain whether water was present at the formation of the planet, or if it arrived later, perhaps carried by comets and meteorites.

    Now researchers from the University of Hawaii at Manoa, using advanced ion-microprobe instrumentation, have found that rocks from Baffin Island in Canada contain evidence that Earth’s water was a part of our planet from the beginning. Their research is published in the 13 November issue of the journal Science.

    The research team was led by cosmochemist Dr. Lydia Hallis, then a postdoctoral fellow at the UH NASA Astrobiology Institute (UHNAI) and now Marie Curie Research Fellow at the University of Glasgow, Scotland.

    The ion microprobe allowed researchers to focus on minute pockets of glass inside these scientifically important rocks, and to detect the tiny amounts of water within. The ratio of hydrogen to deuterium in the water provided them with valuable new clues as to its origins.

    Hydrogen has an atomic mass of one, while deuterium, an isotope of hydrogen also known as “heavy hydrogen,” has an atomic mass of two. Scientists have discovered that water from different types of planetary bodies in our solar system have distinct hydrogen to deuterium ratios.

    Dr. Hallis explained, “The Baffin Island rocks were collected back in 1985, and scientists have had a lot of time to analyze them in the intervening years. As a result of their efforts, we know that they contain a component from Earth’s deep mantle.

    “On their way to the surface, these rocks were never affected by sedimentary input from crustal rocks, and previous research shows their source region has remained untouched since Earth’s formation. Essentially, they are some of the most primitive rocks we’ve ever found on Earth’s surface, and so the water they contain gives us an invaluable insight into Earth’s early history and where its water came from.

    “We found that the water had very little deuterium, which strongly suggests that it was not carried to Earth after it had formed and cooled. Instead, water molecules were likely carried on the dust that existed in a disk around our Sun before the planets formed. Over time this water-rich dust was slowly drawn together to form our planet.

    “Even though a good deal of water would have been lost at the surface through evaporation in the heat of the formation process, enough survived to form the world’s water.

    “It’s an exciting discovery, and one which we simply didn’t have the technology to make just a few years ago. We’re looking forward to further research in this area in the future.”

    The paper is entitled Evidence for primordial water in Earth’s deep mantle. UH co-authors are Dr. Gary Huss, Dr. Kazuhide Nagashima, Prof. G. Jeffrey Taylor, Prof. Mike Mottl, and Dr. Karen Meech.

    The research was funded by the University of Hawaii NASA Astrobiology Institute under Cooperative Agreement No. NNA09-DA77A.

    See the full article here .

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    System Overview

    The University of Hawai‘i System includes 10 campuses and dozens of educational, training and research centers across the Hawaiian Islands. As the public system of higher education in Hawai‘i, UH offers opportunities as unique and diverse as our Island home.

    The 10 UH campuses and educational centers on six Hawaiian Islands provide unique opportunities for both learning and recreation.

    UH is the State’s leading engine for economic growth and diversification, stimulating the local economy with jobs, research and skilled workers.

  • richardmitnick 7:16 am on October 7, 2015 Permalink | Reply
    Tags: , , Pilbara in Australia, Water   

    From CSIRO: “New Pilbara water study to guide sustainable development” 

    CSIRO bloc

    Commonwealth Scientific and Industrial Research Organisation

    7 October 2015

    A new study has delivered an unprecedented account of water resources in Western Australia’s Pilbara region, providing an in-depth understanding of local water systems and the potential impacts of climate change on water availability.

    Water discharging from fractured rock into a gorge in the Hamersley Range.

    The Pilbara Water Resource Assessment project, a $3.5 million partnership between CSIRO, BHP Billiton and the Government of Western Australian, will allow water managers and local industry to plan for future water use in an area rich in resources and environmental assets.

    “Knowing how the water systems operate right across the region, such as how groundwater is affected by rainfall and storm events, helps with the planning and management of local water use,” said CSIRO’s Dr Don McFarlane, the project leader.

    “By helping to put a lot of smaller local water resource investigations into a broader context, this study provides a strong framework for water managers and local industries well into the future.”

    BHP Billiton said its contribution to the project reflected the Company’s commitment to responsible and sustainable water use at its Pilbara-based iron ore operations.

    “The study provided an opportunity to discuss our regional water resource key considerations and highlight the areas requiring further investigation,” said Blair Douglas, BHP Billiton Iron Ore’s Water Practice Lead.

    “The collaboration between industry and scientists in both the state and federal governments has delivered a comprehensive outcome. The fundamental science delivered by the study can be applied by industry to achieve practical and sustainable water management solutions.”

    The study revealed some of the mechanisms responsible for filling the Pilbara’s groundwater stores. It found that between 8 and 30 millimetres of rainfall is required before runoff starts in most catchments, which leaks through streambeds to provide the main source of aquifer replenishment. Water from these shallow alluvial aquifers then recharges deeper paleochannels or dolomite aquifers, which can store large quantities of water in inland areas.

    It also examined how ecosystems dependent on the region’s groundwater sources have changed as a result of wet and dry periods, finding they expand during wet periods and contract during dry periods but have remained relatively stable in number over the past 23 years.

    The Assessment was funded by a $0.5 million contribution from BHP Billiton and $1.5 million each from CSIRO and the Government of Western Australia through the Royalties for Regions program. The research project was led by CSIRO and overseen by officers from the Department of Water, BHP Billiton, the Pilbara Development Commission and the Water Corporation.

    View the final assessment reports at Pilbara Water Resource Assessment.

    The pipeline that takes water to the West Pilbara Water Supply Scheme.

    Ashburton River near the North West Coastal Highway

    The four reporting regions for the Pilbara Water Resource Assessment.

    See the full article here .

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    CSIRO campus

    CSIRO, the Commonwealth Scientific and Industrial Research Organisation, is Australia’s national science agency and one of the largest and most diverse research agencies in the world.

  • richardmitnick 9:20 am on September 4, 2015 Permalink | Reply
    Tags: , , Water   

    From Rice: “Rice researchers demo solar water-splitting technology” 

    Rice U bloc

    Rice University

    September 4, 2015
    Jade Boyd

    Rice University researchers have demonstrated an efficient new way to capture the energy from sunlight and convert it into clean, renewable energy by splitting water molecules.

    The technology, which is described online in the American Chemical Society journal Nano Letters, relies on a configuration of light-activated gold nanoparticles that harvest sunlight and transfer solar energy to highly excited electrons, which scientists sometimes refer to as “hot electrons.”

    Isabell Thomann

    “Hot electrons have the potential to drive very useful chemical reactions, but they decay very rapidly, and people have struggled to harness their energy,” said lead researcher Isabell Thomann, assistant professor of electrical and computer engineering and of chemistry and materials science and nanoengineering at Rice. “For example, most of the energy losses in today’s best photovoltaic solar panels are the result of hot electrons that cool within a few trillionths of a second and release their energy as wasted heat.”

    Capturing these high-energy electrons before they cool could allow solar-energy providers to significantly increase their solar-to-electric power-conversion efficiencies and meet a national goal of reducing the cost of solar electricity.

    In the light-activated nanoparticles studied by Thomann and colleagues at Rice’s Laboratory for Nanophotonics (LANP), light is captured and converted into plasmons, waves of electrons that flow like a fluid across the metal surface of the nanoparticles. Plasmons are high-energy states that are short-lived, but researchers at Rice and elsewhere have found ways to capture plasmonic energy and convert it into useful heat or light. Plasmonic nanoparticles also offer one of the most promising means of harnessing the power of hot electrons, and LANP researchers have made progress toward that goal in several recent studies.

    Rice University researchers have demonstrated an efficient new way to capture the energy from sunlight and convert it into clean, renewable energy by splitting water molecules

    Thomann and her team, graduate students Hossein Robatjazi, Shah Mohammad Bahauddin and Chloe Doiron, created a system that uses the energy from hot electrons to split molecules of water into oxygen and hydrogen. That’s important because oxygen and hydrogen are the feedstocks for fuel cells, electrochemical devices that produce electricity cleanly and efficiently.

    To use the hot electrons, Thomann’s team first had to find a way to separate them from their corresponding “electron holes,” the low-energy states that the hot electrons vacated when they received their plasmonic jolt of energy. One reason hot electrons are so short-lived is that they have a strong tendency to release their newfound energy and revert to their low-energy state. The only way to avoid this is to engineer a system where the hot electrons and electron holes are rapidly separated from one another. The standard way for electrical engineers to do this is to drive the hot electrons over an energy barrier that acts like a one-way valve. Thomann said this approach has inherent inefficiencies, but it is attractive to engineers because it uses well-understood technology called Schottky barriers, a tried-and-true component of electrical engineering.

    “Because of the inherent inefficiencies, we wanted to find a new approach to the problem,” Thomann said. “We took an unconventional approach: Rather than driving off the hot electrons, we designed a system to carry away the electron holes. In effect, our setup acts like a sieve or a membrane. The holes can pass through, but the hot electrons cannot, so they are left available on the surface of the plasmonic nanoparticles.”

    Rice University researchers (clockwise from left) Chloe Doiron, Hossein Robatjazi, Shah Mohammad Bahauddin and Isabell Thomann.

    The setup features three layers of materials. The bottom layer is a thin sheet of shiny aluminum. This layer is covered with a thin coating of transparent nickel-oxide, and scattered atop this is a collection of plasmonic gold nanoparticles — puck-shaped disks about 10 to 30 nanometers in diameter.

    When sunlight hits the discs, either directly or as a reflection from the aluminum, the discs convert the light energy into hot electrons. The aluminum attracts the resulting electron holes and the nickel oxide allows these to pass while also acting as an impervious barrier to the hot electrons, which stay on gold. By laying the sheet of material flat and covering it with water, the researchers allowed the gold nanoparticles to act as catalysts for water splitting. In the current round of experiments, the researchers measured the photocurrent available for water splitting rather than directly measuring the evolved hydrogen and oxygen gases produced by splitting, but Thomann said the results warrant further study.

    “Utilizing hot electron solar water-splitting technologies we measured photocurrent efficiencies that were on par with considerably more complicated structures that also use more expensive components,” Thomann said. “We are confident that we can optimize our system to significantly improve upon the results we have already seen.”

    Robatjazi is a graduate student in electrical and computer engineering, Bahauddin is a graduate student in physics and astronomy and Doiron is a graduate student in applied physics. The research was supported by the Welch Foundation and a National Science Foundation CAREER Award.

    See the full article here.

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    Rice U campus

    In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

    This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

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