Chemical Formula: Ca(MoO4) Locality: Peacock Mine, Cuprum, Seven Devils District, Adams Co., Idaho, USA Name Origin: Named after the American geologist, John Westly Powell (1834-1902).Powellite is a calcium molybdate mineral with formula Ca(MoO4). Powellite crystallizes with tetragonal – dipyramidal crystal structure as transparent adamantine blue, greenish brown, yellow to grey typically anhedral forms. It exhibits distinct cleavage and has a brittle to conchoidal fracture. It has a Mohs hardness of 3.5 to 4 and a specific gravity is 4.25. It forms a solid solution series with scheelite (calcium tungstate, CaWO4). It has refractive index values of nω=1.974 and nε=1.984.Powellite was first described by William Harlow Melville in 1891 for an occurrence in the Peacock Mine, Adams County, Idaho and named for American explorer and geologist, John Wesley Powell (1834–1902).
It occurs in hydrothermal ore deposits of molybdenum within the near surface oxidized zones. It also appears as a rare mineral phase in pegmatite, tactite and basalt. Minerals found in association with powellite include molybdenite, ferrimolybdite, stilbite, laumontite and apophyllite.
History
Authors: MELVILLE Discovery date : 1891 Town of Origin : PEACOCK CLAIM, SEVEN DEVILS DIST., ADAMS CO., UTAH Country of Origin: USA
Optical properties
Optical and misc. Properties: Transparent – fluorescent Refractive Index: from 1,96 to 1,97
Physical properties
Hardness : from 3,50 to 4,00 Density : 4,23 Color : yellow; greenish yellow; greenish; brown; grayish; white; blue; blackish blue; grey; greenish blue Luster : sub-adamantine; greasy; nacreous Streak: pale yellow; greenish; grey white Break: irregular Cleavage: yes
A team of scientists has discovered that a giant ‘burp’ of carbon dioxide (CO2) from the North Pacific Ocean helped trigger the end of last ice age, around 17,000 years ago.
A recent study, led by Dr James Rae of the University of St Andrews, found that changes in ocean circulation in the North Pacific caused a massive ‘burp’ of CO2 to be released from the deep ocean into the atmosphere, helping to warm the planet sufficiently to trigger the end of the ice age.
Previously, scientists have suggested that the Antarctic Ocean and North Atlantic were the only places likely to release deglacial CO2, due to their deep water formation. However, a change in rainfall over the North Pacific region, caused by the East Asian monsoon and the Westerly storm track, made the ocean surface saltier and less buoyant, allowing it to form deep water. This allowed CO2 stored in the deep Pacific to be released to the atmosphere, where it helped warm the planet and melt back the ice sheets that covered much of the Northern Hemisphere.
Dr James Rae, of the University’s Department of Earth and Environmental Sciences, explained:
“Our study shows that North Pacific deep water penetrated all the way into the deep ocean, allowing it to release deep ocean CO2. We tested this idea further with a climate model, which showed that deep water formation in the North Pacific causes ocean CO2 release, large enough to drive the atmospheric CO2 rise recorded at the start of the deglaciation.
The results of our study came as a big surprise, as we were expecting to see a signature of CO2 release from the ocean around Antarctica, which has been the leading hypothesis for deglacial CO2 rise. Instead we found a signal we can only explain with CO2 release from the North Pacific.”
The team of scientists from the University of St Andrews, University of Bristol and University of Kiel, Germany, made a series of chemical measurements on minuscule fossil shells to trace ocean CO2 storage and circulation patterns up to two miles beneath the ocean’s surface.
Dr Gavin Foster, of the University of Southampton, added; “This study is only really possible thanks to new developments in geochemistry, that allow us to reconstruct the pH of the ocean in the past for the first time, giving an accurate measurement of how ocean CO2 is stored and released”.
The new findings will help scientists understand how the earth’s climate can operate, and the different ways in which the ocean and atmosphere can exchange CO2.
Dr Rae concluded:
“Although the CO2 rise caused by this process was dramatic in geological terms, it happened very slowly compared to modern man-made CO2 rise. Humans have driven CO2 rise in the atmosphere as large as the CO2 rise that helped end the last ice age, but the man-made CO2 rise has happened 100 times faster. This will have a huge effect on the climate system, and one that we are only just starting to see.”
More information:
Rae, J. W. B., M. Sarnthein, G. L. Foster, A. Ridgwell, P. M. Grootes, and T. Elliott (2014), “Deep water formation in the North Pacific and deglacial CO2 rise,” Paleoceanography, 29, DOI: 10.1002/2013PA002570.
Note : The above story is based on materials provided by University of St Andrews
Iron is an essential element in all living creatures, and its availability in seawater can have a profound effect on phytoplankton growth and, consequently, the earth’s carbon cycle. In the journal Nature, Seth John and Tim Conway have just published an assessment of the various sources of dissolved iron in the north Atlantic Ocean.
Iron is present in tiny concentrations in seawater. On the order of a few billionths of a gram in a liter.
“I did a calculation once on a ton of ocean water,” says Seth John, an assistant professor in the department of marine science at the University of South Carolina. “The amount of iron in that ton of water would weigh about as much as a single eyelash.”
Given that there is so little iron in seawater, one might conclude that its presence there is inconsequential.
Hardly. Iron is one of the essential elements of life. Found in enzymes like myoglobin and hemoglobin and cytochrome P450, iron is an essential cog in the biomachinery of every living cell. And its scarcity in the ocean, the earth’s wellspring of life, only magnifies its importance.
“The key reason that everybody cares about iron is because it limits the growth of phytoplankton, such as algae, in maybe a fifth of the ocean,” says John, a researcher in the School of Earth, Ocean and Environment in South Carolina’s College of Arts and Sciences.
In those iron-poor places, there’s plenty of everything else that phytoplankton, the base of the food web, need to grow—sunlight, carbon, fixed nitrogen, water. Just a small change in the amount of iron that finds its way there can have a dramatic impact on the growth of photosynthetic organisms and their concomitant uptake of carbon dioxide.
When algae and other phytoplankton grow, they take carbon dioxide out of the atmosphere, converting it into proteins and other carbon-based molecules that constitute living cells. And it takes very little iron to keep this process going—in a typical cell, for every atom of iron, there are about a million atoms of carbon, says John. A little iron goes a long way in allowing phytoplankton to grow and pull carbon dioxide out of the air.
Knowing how iron moves into the oceans is thus crucial for scientists to fully understand the details of the carbon cycle on earth.
John and his colleagues have spent the past several years working to fill in those details. They’ve been collecting ocean samples and developing their analytical techniques for quantifying different natural isotopes of iron in seawater, which is one means of tracking the origins of the dissolved metal.
Iron finds its way into seawater from a variety of sources. The ratio of the stable natural isotopes iron-56 and iron-54 from these sources can differ from the ratio in the earth’s crust because a number of chemical processes change the ratio by favoring the release of one of the two isotopes. The processes controlling release of iron from distinct sources vary, and so different sources can have characteristic iron-56/iron-54 ratios. Tiny variations in this ratio in seawater samples thus provide insight into the origin of the iron found there.
For example, one source is sediments from the ocean’s floor, from which iron is typically released into the ocean under very low-oxygen (anoxic) conditions, and release of ‘light’ iron-54 is favored. Another source is dust from the atmosphere, from which Fe is typically released into the ocean with processes favoring ‘heavy’ iron-56. Using this information, the researchers were able to establish, for the first time, where dissolved iron in seawater had originated.
John and postdoctoral associate Tim Conway have developed a high-throughput means of purifying seawater samples and determining the iron-56/iron-54 ratio, a method capable of handling the nearly 600 samples they collected in a high-resolution transect of the north Atlantic Ocean on a GEOTRACES cruise.
From those samples, they were able to show in a paper published in the journal Nature that the largest source of iron in the north Atlantic, somewhere between 70 and 90 percent, comes from dust that blows in from the Sahara desert.
The results are helping define a very poorly understood but essential component of the carbon cycle.
“It could help us understand past climate change, like glacial-interglacial cycles,” says John. “There would have been huge changes in dust fluxes to the ocean in glacial times, and so understanding how much iron comes from dust in the modern day helps us figure out whether that was an important driver of glacial-interglacial cycles.”
The breakdown of the sources might surprise many, according to John and Conway.
“I think that a lot of people thought that there would be a lot of dust in the north Atlantic, and so while it’s very satisfying to have proved that, it’s perhaps more surprising that there’s 20 percent that comes from other sources,” says John. “I think before we published this paper, you would have found many, many people who would have guessed that that was zero percent or very close to zero percent.”
“That’s one interesting thing that the iron isotopes really show on the east margin,” says Conway. “Off the coast of Africa you have really high iron, and in the past most people attributed that just to dust. We can show from the iron isotopes that there’s actually iron coming from sediments.
“People have always argued whether it was dust or sediments. This is one of the first studies to really show clearly that sediments are important as well.”
Chemical Formula: KNa2B3Si12O30 Locality: From Mont Saint-Hilaire, Quebec, Canada. Name Origin: Named for the Poudrette family, operators of the quarry where type material was discovered.
Poudretteite is an extremely rare mineral and gemstone that was first discovered as minute crystals in Mont St. Hilaire, Quebec, Canada, during the 1960s. The mineral was named for the Poudrette family because they operated a quarry in the Mont St. Hilaire area where poudretteite was originally found.
History
Discovery date : 1987 Town of Origin : MONT SAINT-HILAIRE, ROUVILLE CO., QUEBEC Country of Origin: CANADA
Physical properties
Hardness : 5,00 Density : 2,51 Color : colorless; pale pink Luster : vitreous Streak: white Break : conchoidal; splintery Cleavage : NO
When the 1893 World’s Fair opened in Chicago, fairgoers aboard the world’s first Ferris wheel soared high enough to compare two cities: the White City—gleaming whitewashed architecture built for the massive fair—and its dark twin, the blackened, soot-stained buildings of the Loop just a few miles to the north.
Chicago, like many industrialized cities in the 19th century, lay under a thick layer of soot of its own making. Dirt from trains and factories soiled linen shirts and blew into homes past tightly shut windows. Across the Atlantic in London, residents lit lamps at midday to wade through pea-soup fogs, yellow with sulfur, that lingered over the city for days.
Nineteenth-century meteorologist Luke Howard called London “the volcano of a hundred thousand mouths,” referring to the city’s factories and engines that constantly exhaled soot, which is mostly made up of tiny particles of black carbon. Black carbon is released when things burn: coal and other fuels, bush fires, and the combustion that powers diesel engines and generators.
In the 20th century, scientists began to learn exactly how bad soot is for human health—it accelerates heart failure and burrows into lung tissue, aggravating asthma and respiratory conditions. More recently, scientists have started to realize that carbon particulates play a second unwelcome role: the second largest contributor to climate change.
Environmental regulations have helped to clear the skies over many cities. Yet the U.S., along with other countries around the world, still releases particles of carbon from trucks and generators, and we still don’t really understand what happens to it once it leaves the exhaust pipe.
But there is one bright spot in the study of soot. Unlike carbon dioxide, which will remain for hundreds of years, it can cycle out of the atmosphere within weeks. Whatever harm carbon particulates do to the atmosphere is temporary, at least theoretically. That is, if we could only stop.
“Changing habits is perhaps the most difficult challenge of all,” said Argonne scientist Rao Kotamarthi.
Carbon dioxide has long been established as the most notorious contributor to climate change. But aerosolized carbon particles floating around in the atmosphere also influence climate, although their combined effect is substantially more complex. For example, aerosols can scatter incoming solar radiation away from Earth—fling it back into space—which cools the Earth. Or they can absorb solar radiation, which contributes to global warming.
Though they by and large tend to absorb heat, carbon particles are big enough to serve as nuclei for cloud formation. And clouds reflect more sunlight, which cools the Earth. However, there’s some evidence that clouds formed around black carbon don’t last as long; the dark nucleus absorbs heat and evaporates the cloud.
Researchers try to understand this massive puzzle by building extremely detailed virtual models of the atmosphere. At Argonne, climate scientists like Yan Feng pack all the data they can get their hands on into an elaborate working picture of the atmosphere and how it behaves.
To make sure that the model’s analyses line up with the real world, scientists go through a process called “ground-truthing.” “We compare our model’s results to measurements taken at actual sites and see how they compare,” Feng said.
Once they know the model is reliable, Feng and her colleagues can run models forward in time to see what might happen in 10, 25, 100 years, depending on whether we cut aerosol emissions or let them run wild.
“It’s an extremely complex puzzle, but we can address it by looking carefully at problems one by one,” said Rao Kotamarthi, who manages a climate modeling program at Argonne.
Carbon aerosols are in some ways more difficult to model than carbon dioxide. Whereas carbon dioxide spreads fairly evenly around the world, black carbon tends to affect weather more locally. Carbon particulates often linger in the same region where they are emitted because the particles are too heavy to mix into the atmosphere but not as easily washed out in raindrops as other aerosols. A lot of carbon aerosol modeling, therefore, relies heavily on meteorology: charting the local ebb and flow of wind and water and temperature to map how the particles travel. “For example, large-scale meteorology, like a big cold front, can wipe out some of the carbon’s effects—but not all,” Feng said.
In the past few years, Feng has turned her attention to a second type of carbon in the atmosphere, called brown carbon. These are organic particles with different chemical compositions; they can be tar balls or fats. Long, smoldering fires give off brown carbon; hot fires release black.
There’s a lot more brown carbon in the atmosphere by mass, but it can’t trap as much heat by mass as black carbon—”Think of wearing a black shirt in the sun,” Kotamarthi said—so it’s largely been overlooked.
Only recently have researchers at Argonne and elsewhere begun to explore brown carbon’s effects and habits more closely. “We have a little idea of how black carbon behaves,” Feng said. “But brown carbon was only identified as a potentially significant factor in the past several years.”
Feng, along with Kotamarthi and Professor V. Ramanathan at the Scripps Institution of Oceanography, recently published the first global model study to estimate how much heat brown carbon traps in the atmosphere. “Our model shows how carbon is distributed across the atmosphere,” she said. “We can use that to predict how much solar radiation is being trapped in the atmosphere, and from that we can estimate how much the global temperature may rise.” Feng thinks that brown carbon could turn out to be a significant factor in how aerosols affect Earth’s climate.
There are still a lot of uncertainties in the model, though. “Getting more data is the biggest problem,” Kotamarthi said.
That’s where Argonne environmental scientist David Streets comes in. Streets specializes in collecting data on emissions; he modeled Beijing’s air quality before it hosted the 2008 Summer Olympics. In 2005, along with Professor Tami Bond of the University of Illinois, he published the gold standard figures for soot sources now used by modelers around the world.
“We tell them what’s being emitted into the air,” Streets said. “They use meteorology to get where it winds up and how it affects weather and climate.”
To ensure the accuracy of his data, Streets works with collaborators all over the world, including rapidly industrializing countries like China and India.
Climate modelers also keep an eye on a number of different global economic indicators, because the health of the world’s economies significantly affects emissions. In 2008, scientists saw the economic crash written out in the sky. Aerosols dropped noticeably. The skies cleared over Greece in 2010 as the debt crisis squeezed its citizens below.
This is a central reason why aerosol emissions control is so hard. Carbon, like carbon dioxide, tends to ride piggyback on economic development. In particular, developing countries—where the electricity sometimes goes out because the power infrastructure hasn’t quite kept up with demand—tend to rely heavily on diesel generators. They produce a lot of black carbon.
And aerosols are a major human health problem in developing countries. The World Health Organization puts smoke from solid fuels as the 10th major mortality risk factor globally; it estimates that smoke contributes to approximately two million deaths annually, particularly affecting women and children. Urban air pollution ranks among the top 10 risk factors in middle and developed countries too.
We’ve succeeded in reducing emissions from factories and other sources in developed countries like the U.S. and Europe; in many places, black carbon emission levels are lower than they’ve been in decades, if not centuries. In Chicago, cleaners scrubbed a century’s worth of soot off several buildings in the Loop to discover stone and brick underneath in shades of delicate pastels that probably hadn’t been seen since the last tourists left the World’s Fair more than 100 years ago.
“Purely from a technical standpoint, we could do this,” Streets said. “We have the technology.”
Note : The above story is based on materials provided by Argonne National Laboratory
Soot, a.k.a. black carbon, is finding its way to snow-covered peaks and glaciers around the world. Primarily the result of particulate emissions from burning fossil fuels, such as coal-fired power plants and diesel engines, soot has an impact on the regional and global climate. In the Arctic, soot increases ice and snow melt, causing a series of events that are heating up the climate.
No one but a Grinch enjoys black snow—it has no redeeming qualities. Yet scientists at Pacific Northwest National Laboratory trained their sights on soot to understand its undesirable effects on the Arctic environment. Using global climate model simulations, they evaluated soot’s effects in Northern China and the Arctic against measurements over the region. PNNL and a University of Michigan collaborator found key model parameters that correctly spot soot buildup and melt-away in a complex seasonal and latitudinal dependence swing. Their study will help the climate modeling community better understand soot’s great influence on regional and global climate.
Soot, a.k.a. black carbon, may have a greater impact on the fast-retreating Arctic snow pack and glaciers than any other human-caused climate-warming agent. Soot is black, and black draws and holds heat from the sun. Soot from combustion of fossil fuels, such as diesel and coal, as well as forest fires and other organic burning, travels through the atmosphere and falls on snow and glacier ice pack. Like a dark blanket, it heats up the snow and ice and also reduces the amount of the sun’s rays normally reflected back into space from bright, white snow. It’s a one-two punch for the world’s store of ice and snow. This study helps researchers understand how black carbon’s impacts are registered and reproduced in climate models, providing valuable information in predicting the future of the Arctic climate.
The research team led by Dr. Yun Qian at PNNL evaluated the simulated black carbon on snow against measurements collected from multiple field campaigns over the Arctic and Northern China. They conducted a series of sensitivity experiments using the newly improved Community Atmosphere Model version 5 (CAM5) to examine the impact of several key parameters. They looked at the impact of snow aging, and the melt-water scavenging efficiency parameters on black carbon’s concentration and radiative forcing in the model. They also compared the uncertainty (the range of possible answers), resulting from the black carbon deposition, with the uncertainty related to how snow-aging and melt-water scavenging is treated for black carbon in the model.
The sensitivity simulations in CAM5 indicated that the melt-water scavenging efficiency parameter plays an important role in regulating black carbon concentrations in the Arctic through the post-depositional enrichment, which not only drastically changes the amplitude but also shifts the seasonal cycle of the black carbon in snow concentration and its radiative forcing in the Arctic. They found that the improvements of black carbon transport and deposition in CAM5 have a stronger influence on black carbon in snow than perturbations of the two snow model parameters over Northern China.
Scientists are planning research that will explore the limitations of simulating black carbon in snow that were highlighted in this study, including in situ observations and laboratory studies with a focus on snow aging and melt-water scavenging of black carbon.
More information:
Qian Y, H Wang, R Zhang, M Flanner, and PJ Rasch. 2014. “A Sensitivity Study on Modeling the Black Carbon in Snow and its Radiative Forcing over the Arctic and Northern China.” Environmental Research Letters 9:064001. DOI: 10.1088/1748-9326/9/6/064001
Note : The above story is based on materials provided by Pacific Northwest National Laboratory
Polybasite with Chalcopyrite Chispas Mine (Pedrazzini mine), Arizpe, Mun. de Arizpe, Sonora, Mexico Miniature, 5.5 x 4.3 x 3.2 cm “Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”
Chemical Formula: [(Ag,Cu)6(Sb,As)2S7][Ag9CuS4] Name Origin: From the Greek, poly, “many” and basis, “a base” in allusion to the basic character of the compound.
Polybasite is a sulfosalt mineral of silver, copper, antimony and arsenic. Its chemical formula is [(Ag,Cu)6(Sb,As)2S7][Ag9CuS4].It forms black monoclinic crystals (thin, tabular, with six corners) which can show dark red internal reflections. It has a Mohs hardness of 2.5 to 3. It is found worldwide and is an ore of silver. The name comes from the number of base metals in the mineral.
History
Discovery date : 1829 Town of Origin : GUARISAMEY, DURANGO Country of Origin : MEXIQUE
Optical properties
Optical and misc. Properties: Translucide – Opaque Reflective Power: 30,2-31,7% (580) Refractive Index: from 2,72 to 2,73 Axial angle 2V : 22°
Physical properties
Hardness : from 2,00 to 3,00 Density: 6,10 Color : iron black; steel black; black grey Luster: metallic; adamantine; unpolished Streak : reddish black; dark red; black Break : irregular Cleavage : yes
Researchers found that Titan’s ice shell, which overlies a very salty ocean, varies in thickness around the moon, suggesting the crust is in the process of becoming rigid. Credit: NASA/JPL -Caltech/SSI/Univ. of Arizona/G. Mitri/University of Nantes
Scientists analyzing data from NASA’s Cassini mission have firm evidence the ocean inside Saturn’s largest moon, Titan, might be as salty as Earth’s Dead Sea.
The new results come from a study of gravity and topography data collected during Cassini’s repeated flybys of Titan during the past 10 years. Using the Cassini data, researchers presented a model structure for Titan, resulting in an improved understanding of the structure of the moon’s outer ice shell. The findings are published in this week’s edition of the journal Icarus.
“Titan continues to prove itself as an endlessly fascinating world, and with our long-lived Cassini spacecraft, we’re unlocking new mysteries as fast as we solve old ones,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, who was not involved in the study.
Additional findings support previous indications the moon’s icy shell is rigid and in the process of freezing solid. Researchers found that a relatively high density was required for Titan’s ocean in order to explain the gravity data. This indicates the ocean is probably an extremely salty brine of water mixed with dissolved salts likely composed of sulfur, sodium and potassium. The density indicated for this brine would give the ocean a salt content roughly equal to the saltiest bodies of water on Earth.
“This is an extremely salty ocean by Earth standards,” said the paper’s lead author, Giuseppe Mitri of the University of Nantes in France. “Knowing this may change the way we view this ocean as a possible abode for present-day life, but conditions might have been very different there in the past.”
Cassini data also indicate the thickness of Titan’s ice crust varies slightly from place to place. The researchers said this can best be explained if the moon’s outer shell is stiff, as would be the case if the ocean were slowly crystalizing and turning to ice. Otherwise, the moon’s shape would tend to even itself out over time, like warm candle wax. This freezing process would have important implications for the habitability of Titan’s ocean, as it would limit the ability of materials to exchange between the surface and the ocean.
A further consequence of a rigid ice shell, according to the study, is any outgassing of methane into Titan’s atmosphere must happen at scattered “hot spots” — like the hot spot on Earth that gave rise to the Hawaiian Island chain. Titan’s methane does not appear to result from convection or plate tectonics recycling its ice shell.
How methane gets into the moon’s atmosphere has long been of great interest to researchers, as molecules of this gas are broken apart by sunlight on short geological timescales. Titan’s present atmosphere contains about five percent methane. This means some process, thought to be geological in nature, must be replenishing the gas. The study indicates that whatever process is responsible, the restoration of Titan’s methane is localized and intermittent.
“Our work suggests looking for signs of methane outgassing will be difficult with Cassini, and may require a future mission that can find localized methane sources,” said Jonathan Lunine, a scientist on the Cassini mission at Cornell University, Ithaca, New York, and one of the paper’s co-authors. “As on Mars, this is a challenging task.”
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the mission for NASA’s Science Mission Directorate in Washington.
Note : The above story is based on materials provided by NASA/Jet Propulsion Laboratory.
The Madeira River is a major waterway in South America, approximately 3,250 km (2,020 mi) long. The Madeira is one of the biggest tributaries of the Amazon. A map from Emanuel Bowen in 1747, held by the David Rumsey Map Collection, refers to the Madeira by the pre-colonial, indigenous name Cuyari:
“The River of Cuyari, called by the Portuguese Madeira or the Wood River, is formed by two great rivers, which join near its mouth. It was by this River, that the Nation of Topinambes passed into the River Amazon.”
Climate
The mean inter-annual precipitations on the great basins vary from 750 to 3,000 millimetres (30 to 118 in), the entire upper Madeira basin receiving 1,705 millimetres (67.1 in). The greatest extremes of rainfall are between 490 to 7,000 millimetres (19 to 276 in). At its head, the Madeira on its own is still one of the largest rivers of the world, with a mean inter-annual discharge of 18,000 cubic metres per second (640,000 cu ft/s), i.e. 536 cubic kilometres (129 cu mi)/yr, approximately half the discharge of the Congo River. The mean inter-annual contribution of the Bolivian Andes is 4,170 cubic metres per second (147,000 cu ft/s), i.e. 132 cubic kilometres (32 cu mi)yr, representing 25% of the discharge of the entire upper Madeira basin. On the further course towards the Amazon, the mean discharge of the Madeira increases up to 31,200 cubic metres per second (1,100,000 cu ft/s).
Course
Between Guajará-Mirim and the falls of Teotônio, the Madeira receives the drainage of the north-eastern slopes of the Andes from Santa Cruz de la Sierra to Cuzco, the whole of the south-western slope of Brazilian Mato Grosso and the northern slope of the Chiquitos sierras. In total, the catchment area is 850,000 km2, almost equal in area to France and Spain combined. The waters flow into the Madeira from many large rivers, the principal of which, (from east to west), are the Guaporé or Itenez, the Baures and Blanco, the Itonama or San Miguel, the Mamoré, Beni, and Mayutata or Madre de Dios, all of which are reinforced by numerous secondary but powerful affluents. The climate of the upper catchment area varies from humid in the western edge with the origin of the river’s main stem by volume (Río Madre de Dios, Río Beni) to semi arid in the southernmost part with the andine headwaters of the main stem by length (Río Caine, Río Rocha, Río Grande, Mamoré).
All of the upper branches of the river Madeira find their way to the falls across the open, almost level Mojos and Beni plains, 90,000 km2 (35,000 sq mi) of which are yearly flooded to an average depth of about 3 feet (0.91 m) for a period of from three to four months.
The falls of Teotônio and of San Antonio exceed the more famous Boyoma Falls in Africa by volume and total drop. From these rapids, the Madeira flows northward forming the border between Bolivia and Brazil for approximately 100 km (62 mi). Below the confluence of the Rio Abunã, the Madeira meanders north-eastward through the Rondônia and Amazonas states of north west Brazil to its junction with the Amazon. At its mouth is Ilha Tupinambaranas, an extensive marshy region formed by the Madeira’s distributaries.
Note : The above story is based on materials provided by Wikipedia
Chemical Formula: PbO2 Locality: Leadhills, Lanark, Scotland Name Origin: Named after the German metallurgist, K. F. Plattner (1800-1858).Plattnerite is an oxide mineral and is the beta crystalline form of lead dioxide (β-PbO2), scrutinyite being the other, alpha form. It was first reported in 1845 and named after German mineralogist Karl Friedrich Plattner. Plattnerite forms bundles of dark needle-like crystals on various minerals; the crystals are hard and brittle and have tetragonal symmetry.
Occurrence
Plattnerite is found in numerous arid locations in North America (US and Mexico), most of Europe, Asia (Iran and Russia), Africa (Namibia) and Southern and Western Australia. It occurs in weathered hydrothermal base-metal deposits as hay-like bundles of dark prismatic crystals with a length of a few millimeters; the bundles grow on, or sometimes within various minerals, including cerussite, smithsonite, hemimorphite, leadhillite, hydrozincite, rosasite, aurichalcite, murdochite, limonite, pyromorphite, wulfenite, calcite and quartz.
History
Discovery date : 1845 Town of Origin : LEADHILLS, LANARKSHIRE Country of Origin : ECOSSE
Optical properties
Optical and misc. Properties : Fragile, cassant – Opaque – Translucide – Macles possibles – Reflective Power : ~13%
Physical properties
Hardness : 5,50 Density : 9,42 Color : black; brownish black; black grey Luster : bright metallic; adamantine; unpolished Streak : brown Break : conchoidal Cleavage : NO
This is an atom probe tomography, or APT, analysis result showing the sub-nanoscale elemental distribution within a single aerosol particle. Credit: Arun Devaraj, EMSL
Dust storms, volcanic eruptions and hurricanes are tangible events that send particles of sand, soot and salt into the atmosphere. These particles can alter the climate cycles that heat and cool the Earth. Less obvious sources of aerosols affect these cycles, too; the sea salt sprayed off breaking waves or volatile organic compounds emitted from trees. But nearly untraceable chemical transformations also lead to the birth of new atmospheric particles. Accounting for these newborn particles and their role in cloud formation is key to improving climate models. Scientists recently gathered at EMSL to discuss ways to more accurately chronicle the clandestine lives of these aerosols in the lab and the field.
The precise processes that govern how new particles are created out of vapor, then grow and nucleate clouds – enticing other organic molecules into chemical reactions – largely remains a mystery. Increasingly sophisticated instruments provide scientists with new details about these transformations; they also point out big gaps between theoretical models and field findings.
“We discovered nucleation is an important source of atmospheric particles more than 20 years ago. And ever since we’ve been trying to figure out the chemical and physical processes that lead to their creation,” says Peter McMurry, a professor at the University of Minnesota. “The goal is to achieve closure between the rates observed in the atmosphere and those predicted by models. This will lead to more credible climate models. Right now we can’t do that.”
In the Beginning
Part of the problem is catching the particles in the act of doing whatever it is they do. Researchers spend weeks in the field stalking new particle formation events. With little lead time the particles are born. Within a few hours they grow to sizes large enough to serve as cloud condensation nuclei, sending a brief bloom of data across suites of specialized sampling instruments. “It’s a challenge,” says McMurry. “Some of the species that lead to particle formation are found in almost unimaginably low concentrations. Sometimes it’s like trying to pick out one person in a thousand or a million Earths.”
From Field to Lab: An Inside Job
For the last 15 years Alexander Laskin, an atmospheric aerosol chemist at EMSL, and collaborators have been using the unique analytical chemistry capabilities of EMSL on particle samples collected from test facilities, laboratory studies and far-flung field sites. A variety of off-line chemical imaging techniques have been advanced at EMSL – including mass spectrometry, spectroscopy, microscopy and microanalysis methods – to probe the composition and properties of these particles. But there’s no single technique in existence that gives us all the information we need to know. says Laskin”
The ability to run multi-modal analyses on the same sample is a particular strength at EMSL. But even interrogating particles with multiple techniques can’t answer some of the pressing questions. So EMSL researchers are devising new strategies in collaboration with scientists across the country.
Laskin and his colleagues want to understand the physical and chemical properties of aerosols that nucleate ice clouds. Although ice nucleation has been studied for more than two decades, much about the process remains unknown.
“In the traditional view of ice nucleation events, there are very few particles in the atmosphere with the right properties to become ice nuclei,” says Laskin. “But now there’s growing evidence that’s not always case,” he says. “Particles with mediocre ice nucleation propensity – but present at high number concentrations – can play an equivalently important role. So the big question is how to delineate the two scenarios: Under which conditions would different nucleation particles prevail?”
It would be easier to figure out if they could visualize nucleation events, says Bingbing Wang, a postdoctoral researcher at EMSL. To see which individual particles nucleate ice first, he started a project coupling ice nucleation experiments with scanning electron microscopy, complemented with particle spectro-microscopy. Then he can probe the composition of the instigating particles. “From that knowledge we can achieve better understanding of heterogeneous ice nucleation. Then with further data analysis we can provide better parameterizations for cloud and climate models,” says B. Wang.
The study involves a group of Pacific Northwest National Laboratory experts in collaboration with Daniel Knopf of Stony Brook University and Mary Gilles at Lawrence Berkeley National Laboratory.
An Outside Approach
Another way to analyze these perplexing particles is to look at them one by one. To accomplish this, transmission electron microscopy, or TEM, is the technique of choice for Peter Buseck, a professor at Arizona State University who attended the recent user meeting at EMSL. “We want to know the intimate details about these aerosol particles,” he says. “TEM has been used on a larger scale, but now the technique is needed on a nanometer scale because there’s a whole range of particle sizes in the atmosphere.”
Although Buseck already has the TEM capabilities he needs, EMSL could devise novel ways to combine electron microscopy with instruments such as the helium ion microscope in EMSL’s Quiet Wing. No one’s doing that now with aerosols, says Buseck.
Probing the Surface
It’s not just the particles that need to be accounted for.
“An intrinsic scientific problem is how reactions occur and the particle surface is key for those. From mass spectrometry you can find out what kind of molecules are in aerosols, but you don’t know how they are arranged on the particle surface,” says Hongfei Wang, a chief scientist at EMSL.
To get at the structure of the surface, in 2011 H. Wang and his colleagues developed a unique high-resolution sum frequency generation, or HR-SFG, spectrometer to discern surface particle reactions with a resolution 10 times better than any other instruments out there. That kind of resolution was critical for Sergey Nizkorodov who studies aerosol photochemistry in his laboratory at the University of California at Irvine and then sends samples to H. Wang for high-resolution studies at the surface.
“We want to be able to detect minor species that might be important for controlling reactions,” says H. Wang. “We’ve improved resolution, but the sensitivity of the signal needs to be improved for field measurements. It’s possible – but will take at least several years. It will be a real milestone to do this.”
Another pioneer in applying SFG spectroscopy to aerosol particles is Franz Geiger of Northwestern University. After meeting H. Wang at an American Chemical Society conference two years ago, he started using the high-resolution instrument to study alpha-pinene, one of the main components of secondary organic aerosol particles. EMSL’s HR-SFG gave Geiger a significant improvement in his analytics, getting resolution from standard values of about 10 wave numbers down to 0.6 wave numbers.
To bridge the gap between particle analysis in the lab and the field, Geiger is working with Northwestern colleague Regan Thomson, Victor Batista of Yale University and Scot Martin at Harvard University on an EMSL user project and with matching funds from Northwestern (and he hopes, the National Science Foundation).
Geiger is focused on the organic emissions of trees, namely pinene, that react with ozone at the ground level. The resulting cascades of reactions create aerosols that can interact with water vapor and ultimately make clouds. The questions he wants to answer are: Will future, possibly warmer, climates lead to faster emission rates of pinene over the Northern hemisphere? And if more organic particles form, potentially leading to more clouds, would this cause a negative feedback mechanism to cool our planet?
The answers to how these particles form will be found on their surfaces, thinks Geiger. But it’s hard to analyze what’s never been identified before. So the collaborators are creating synthetic compounds they surmise could be created when pinene reacts with ozone and are also surface reactive. By analyzing the chemical signatures of these lab-made components they’ll build a reference library to help identify the unknown surface components they discover on these particles.
“There’s no silver bullet,” says Geiger. “But more current tools will give us a more complete understanding.”
Helping Solve Problems
Aerosol research may also get a boost with instruments that haven’t traditionally been used for studies in this field. In the past, the tiny sample sizes and filter collection methods for aerosol particles have hampered efforts to use analytic techniques such as nuclear magnetic resonance, or NMR, spectroscopy. But at the recent EMSL user meeting, NMR lead scientist Karl Mueller told researchers they’re building smaller and better tools to aid aerosol research.
“NMR is phenomenal for determining chemical structure,” says Nancy Washton, the capability lead for EMSL’s NMR group. “But it’s considered an insensitive technique because it requires such a large sample size – I want a vial full of stuff, about 20 milligrams.”
Now Mueller and Washton are working with a team of scientists to make very small volume NMR detectors. “We’re combining our abilities as ‘spin jocks’ with miniaturization and microfabrication capabilities to work with picoliter amounts more suitable for aerosol studies. Success here would be a real breakthrough,” says Mueller.
Washton anticipates they’ll be able to run aerosol samples within the year. The possibilities have already enticed collaborators to send samples and she thinks NMR will be very useful for scientists who are synthetically producing atmospheric molecules.
Another technique that might prove useful is atom probe tomography, or APT. EMSL Scientist Arun Devaraj thinks APT could provide a way to visualize the three-dimensional element distribution within a single aerosol particle at sub-nanometer spatial resolution.
“Even if a potential user doesn’t quite know what capabilities they need, the staff at EMSL can discuss their needs and provide guidance,” says Alex Guenther, the lead scientist for atmospheric aerosol science at EMSL. The staff will make extraordinary efforts to understand what scientists need for their research and how the laboratory’s capabilities can be applied to answer their scientific questions, he says.
Although new tools are nice, Nicole Riemer, a computer modeler at Illinois University, thinks researchers may squeeze more information out of the tools already on hand. “As modelers, we are using different tools from the researchers in the lab who measure these things,” says Riemer. “But we’re trying to solve the same problems.”
The aerosols are really, really small. So it’s difficult to develop equations that reflect the complexity of those minuscule – but critical – interactions without bogging down the ability to scale up to global proportions. Riemer believes careful, repeated experiments under varied conditions, using the equipment already in EMSL laboratories, can provide key details needed to derive more accurate aerosol predictions. For example, our models are based on particles with spherical shapes, says Riemer. Yet Laskin’s work shows particle morphology changes. “Is that important?” she says. “If it is, we need to know how it changes over time so we can incorporate it into our equations.”
Gathering Better Field Samples
But even the best available laboratory instruments don’t really capture the conditions in the atmosphere. So, Guenther invited scientists to brainstorm better ways to get samples from the field. Among the more immediately feasible possibilities discussed were ways to build a better Orbitrap.
“I was excited to hear discussions about making a smaller high-resolution mass spectrometer to carry around in a truck or plane,” says Nizkorodov. “If there’s a way to get those measurements in real time, that would be a big step forward.”
With that kind of innovation, Franz Geiger may one day realize a decades-old research dream: to analyze aerosol particle surfaces without plucking them out of the air. “People once said we couldn’t study aerosols from ships or planes and now we do that all the time,” he says. “It’s not impossible.”
Note : The above story is based on materials provided by Environmental Molecular Sciences Laboratory
The Euphrates is the longest and one of the most historically important rivers of Western Asia. Together with the Tigris, it is one of the two defining rivers of Mesopotamia. Originating in eastern Turkey, the Euphrates flows through Syria and Iraq to join the Tigris in the Shatt al-Arab, which empties into the Persian Gulf.
Etymology
The Ancient Greek form Euphrátēs (Ancient Greek: Εὐφράτης) was borrowed from Old Persian Ufrātu, itself from Elamite ú-ip-ra-tu-iš. In Akkadian the river was similarly called Purattu, which has been perpetuated in Semitic languages (cf. Syriac P(ə)rāṯ, Arabic al-Furrāt) and in other nearby languages of the time (cf. Hurrian Puranti, Sabarian Uruttu). The Elamite, Akkadian, and possibly Sumerian forms are from an unrecorded substrate language.
The earliest references to the Euphrates come from cuneiform texts found in Shuruppak and pre-Sargonic Nippur in southern Iraq and date to the mid-3rd millennium BCE. In these texts, written in Sumerian, the Euphrates is called Buranuna (logographic: UD.KIB.NUN). The name could also be written KIB.NUN.(NA) or dKIB.NUN, with the prefix “d” indicating that the river was a divinity. In Sumerian, the name of the city of Sippar in modern-day Iraq was also a written UD.KIB.NUN, indicating a historically strong relationship between the city and the river.
Course
The Euphrates is the longest river of Western Asia. It emerges from the confluence of the Kara Su or Western Euphrates (450 kilometres (280 mi)) and the Murat Su or Eastern Euphrates (650 kilometres (400 mi)) 10 kilometres (6.2 mi) upstream from the town of Keban in southeastern Turkey.Daoudy and Frenken put the length of the Euphrates from the source of the Murat River to the confluence with the Tigris at 3,000 kilometres (1,900 mi), of which 1,230 kilometres (760 mi) falls in Turkey, 710 kilometres (440 mi) in Syria and 1,060 kilometres (660 mi) in Iraq. The same figures are given by Isaev and Mikhailova. The length of the Shatt al-Arab, which connects the Euphrates and the Tigris with the Persian Gulf, is given by various sources as 145–195 kilometres (90–121 mi).
Both the Kara Su and the Murat Su rise northwest from Lake Van at elevations of 3,290 metres (10,790 ft) and 3,520 metres (11,550 ft) amsl, respectively. At the location of the Keban Dam, the two rivers, now combined into the Euphrates, have dropped to an elevation of 693 metres (2,274 ft) amsl. From Keban to the Syrian–Turkish border, the river drops another 368 metres (1,207 ft) over a distance of less than 600 kilometres (370 mi). Once the Euphrates enters the Upper Mesopotamian plains, its grade drops significantly; within Syria the river falls 163 metres (535 ft) while over the last stretch between Hīt and the Shatt al-Arab the river drops only 55 metres (180 ft).
Discharge of the Euphrates
The Euphrates receives most of its water in the form of rainfall and melting snow, resulting in peak volumes during the months April through May. Discharge in these two months accounts for 36 percent of the total annual discharge of the Euphrates, or even 60–70 percent according to one source, while low runoff occurs in summer and autumn. The average natural annual flow of the Euphrates has been determined from early- and mid-twentieth century records as 20.9 cubic kilometres (5.0 cu mi) at Keban, 36.6 cubic kilometres (8.8 cu mi) at Hīt and 21.5 cubic kilometres (5.2 cu mi) at Hindiya. However, these averages mask the high inter-annual variability in discharge; at Birecik, just above the Syro–Turkish border, annual discharges have been measured that ranged from a low volume of 15.3 cubic kilometres (3.7 cu mi) in 1961 to a high 42.7 cubic kilometres (10.2 cu mi) in 1963.
The discharge regime of the Euphrates has changed dramatically since the construction of the first dams in the 1970s. Data on Euphrates discharge collected after 1990 show the impact of the construction of the numerous dams in the Euphrates and of the increased withdrawal of water for irrigation. Average discharge at Hīt after 1990 has dropped to 356 cubic metres (12,600 cu ft) per second (11.2 cubic kilometres (2.7 cu mi) per year). The seasonal variability has equally changed. The pre-1990 peak volume recorded at Hīt was 7,510 cubic metres (265,000 cu ft) per second, while after 1990 it is only 2,514 cubic metres (88,800 cu ft) per second. The minimum volume at Hīt remained relatively unchanged, rising from 55 cubic metres (1,900 cu ft) per second before 1990 to 58 cubic metres (2,000 cu ft) per second afterward.
Tributaries
In Syria, three rivers add their water to the Euphrates; the Sajur, the Balikh and the Khabur. These rivers rise in the foothills of the Taurus Mountains along the Syro–Turkish border and add comparatively little water to the Euphrates. The Sajur is the smallest of these tributaries; emerging from two streams near Gaziantep and draining the plain around Manbij before emptying into the reservoir of the Tishrin Dam. The Balikh receives most of its water from a karstic spring near ‘Ayn al-‘Arus and flows due south until it reaches the Euphrates at the city of Ar-Raqqah. In terms of length, drainage basin and discharge, the Khabur is the largest of these three. Its main karstic springs are located around Ra’s al-‘Ayn, from where the Khabur flows southeast past Al-Hasakah, where the river turns south and drains into the Euphrates near Busayrah. Once the Euphrates enters Iraq, there are no more natural tributaries to the Euphrates, although canals connecting the Euphrates basin with the Tigris basin exist.
Watershed
The drainage basins of the Kara Su and the Murat River cover an area of 22,000 square kilometres (8,500 sq mi) and 40,000 square kilometres (15,000 sq mi), respectively. The estimates that have been made for the area of the Euphrates drainage basin vary widely; from a low 233,000 square kilometres (90,000 sq mi) to a high 766,000 square kilometres (296,000 sq mi). Recent estimates put the basin area at 388,000 square kilometres (150,000 sq mi), 444,000 square kilometres (171,000 sq mi) and 579,314 square kilometres (223,674 sq mi). The greater part of the Euphrates basin is located in Turkey, Syria and Iraq. According to both Daoudy and Frenken, Turkey’s share is 28 percent, Syria’s is 17 percent and that of Iraq is 40 percent. Isaev and Mikhailova estimate the percentages of the drainage basin lying within Turkey, Syria and Iraq at 33, 20 and 47 percent respectively. Some sources estimate that approximately 15 percent of the drainage basin is located within Saudi Arabia, while a small part falls inside the borders of Kuwait. Finally, some sources also include Jordan in the drainage basin of the Euphrates; a small part of the eastern desert (220 square kilometres (85 sq mi)) drains toward the east rather than to the west.
Note : The above story is based on materials provided by Wikipedia
CU-Boulder Associate Professor Jaerlyn Eberle, left, and research colleagues collect ancient sharks teeth on Banks Island in the Arctic Circle. Oxygen isotopes in the teeth indicated sharks living in the Eocene Arctic Ocean roughly 50 million years ago were tolerant of brackish water, unlike their shark relatives living today. Credit: Courtesy Jaelyn Eberle, University of Colorado
Sharks were a tolerant bunch some 50 million years ago, cruising an Arctic Ocean that contained about the same percentage of freshwater as Louisiana’s Lake Ponchatrain does today, says a new study involving the University of Colorado Boulder and the University of Chicago.
The study indicates the Eocene Arctic sand tiger shark, a member of the lamniform group of sharks that includes today’s great white, thresher and mako sharks, was thriving in the brackish water of the western Arctic Ocean back then. In contrast, modern sand tiger sharks living today in the Atlantic Ocean are very intolerant of low salinity, requiring three times the saltiness of the Eocene sharks in order to survive.
“This study shows the Arctic Ocean was very brackish and had reduced salinity back then,” said University of Chicago postdoctoral researcher Sora Kim, first author on the study. “The ancient sand tiger sharks that lived in the Arctic during the Eocene were very different than sand tiger sharks living in the Atlantic Ocean today.”
The findings have implications for how today’s sharks might fare in a warming Arctic region, which is heating up at about twice the rate of the rest of the planet due to increasing greenhouse gases, said CU-Boulder geological sciences Associate Professor Jaelyn Eberle, a study co-author. The potential consequences of warming in the Arctic include changes in freshwater runoff and atmospheric water vapor and decreases in salinity that can affect marine biology and seawater circulation dynamics.
“As more freshwater flows into the Arctic Ocean due to global warming, I think we are going to see it become more brackish,” said Eberle, also curator of fossil vertebrates at the University of Colorado Museum of Natural History. “Maybe the fossil record can shed some light on how the groups of sharks that are with us today may fare in a warming world.”
A paper on the subject was published online June 30 in the journal Geology. Other co-authors include David Bell from the University of Wyoming, Dewayne Fox from Delaware State University and Aspen Padilla, a CU-Boulder graduate who worked with Eberle as a master’s candidate. The study was funded in part by the National Science Foundation.
The new findings on Arctic Ocean salinity conditions in the Eocene were calculated in part by comparing ratios of oxygen isotopes locked in ancient shark teeth found in sediments on Banks Island in the Arctic Circle and incorporating the data into a salinity model. The team also compared its information to prior studies of sediment cores extracted from an oceanic region in the central Arctic Ocean called the Lomonosov Ridge — a steep hump of continental crust that rises more than 1,000 feet from the ocean floor — to estimate past environmental conditions in the Arctic Ocean.
“Oxygen isotopes in ancient bones and teeth reflect the water animals are living in or drinking,” said Kim, a former postdoctoral researcher at the University of Wyoming. “Because sharks are aquatic, the oxygen from the ocean is constantly being exchanged with oxygen in their body water, and that’s what is incorporated into their teeth. When I analyzed their isotopic composition, the numbers seemed weird at first because they indicated an essentially freshwater environment.”
The team analyzed 30 fossil sand tiger shark teeth exhumed from Banks Island and 19 modern sand tiger shark teeth from specimens caught in Delaware Bay bordered by Delaware and New Jersey. The paleo-salinity estimate for the modern sand tiger sharks is consistent with the continental shelf salinity present from Delaware south to Florida and from the coastline to roughly six miles offshore, known hunting grounds for modern sand tiger sharks, which have formidable teeth and can reach a length of nearly 10 feet.
The Eocene Epoch, which ran from about 56 to 34 million years ago, was marked by wild temperature fluctuations, including intense greenhouse periods when lush rainforests abounded in the Arctic. Previous studies by Eberle and colleagues showed the fauna there included ancestors of tapirs, hippo-like creatures, crocodiles and giant tortoises. Despite the six months of darkness each year, the terrestrial Arctic climate included warm humid summers and mild winters with temperatures ranging from just above freezing to about 70 degrees Fahrenheit.
“We now know a fair amount about the terrestrial animals and plants that were living in the Eocene Arctic greenhouse period,” said Eberle. “To finally get some data on the Eocene marine environment using these shark teeth will help us to begin filling in the gaps.”
Eberle said the Eocene Arctic Ocean was largely isolated from the global oceans. “Increased freshwater runoff from the land due to an intensified hydrologic cycle and a humid Arctic would have turned it more brackish pretty quickly,” she said.
The salinity gradient across the Eocene Arctic Ocean that provided habitat for the ancient sand tiger sharks also was found to be much larger than the salinity gradient tolerated by modern sand tiger sharks living in the Atlantic Ocean, said Eberle. “The Eocene lamniform group of sharks had a much broader environmental window than lamniform sharks do today.”
Eberle and Kim said the early-middle Eocene greenhouse period from 53 to 38 million years ago is used as a deep-time analog by climate scientists for what could happen on Earth if CO2 and other greenhouse gases in Earth’s atmosphere continue to rise, and what a “runaway” greenhouse effect potentially could look like.
“Through an analysis of fossil sand tiger shark teeth from the western Arctic Ocean, this study offers new evidence for a less salty Arctic Ocean during an ancient ‘greenhouse period,’ ” says Yusheng “Chris” Liu, program director in the NSF’s Division of Earth Sciences, which co-funded the research with NSF’s Division of Polar Programs. “The results also confirm that the Arctic Ocean was isolated during that long-ago time.”
Note : The above story is based on materials provided by University of Colorado at Boulder.
New research has revealed the causes and warning signs of rare tsunami earthquakes, which may lead to improved detection measures
New research has revealed the causes and warning signs of rare tsunami earthquakes, which may lead to improved detection measures.
Tsunami earthquakes happen at relatively shallow depths in the ocean and are small in terms of their magnitude. However, they create very large tsunamis, with some earthquakes that only measure 5.6 on the Richter scale generating waves that reach up to ten metres when they hit the shore.
A global network of seismometers enables researchers to detect even the smallest earthquakes. However, the challenge has been to determine which small magnitude events are likely to cause large tsunamis.
In 1992, a magnitude 7.2 tsunami earthquake occurred off the coast of Nicaragua in Central America causing the deaths of 170 people. Six hundred and thirty seven people died and 164 people were reported missing following a tsunami earthquake off the coast of Java, Indonesia, in 2006, which measured 7.2 on the Richter scale.
The new study, published in the journal Earth and Planetary Science Letters, reveals that tsunami earthquakes may be caused by extinct undersea volcanoes causing a “sticking point” between two sections of the Earth’s crust called tectonic plates, where one plate slides under another.
The researchers from Imperial College London and GNS Science in New Zealand used geophysical data collected for oil and gas exploration and historical accounts from eye witnesses relating to two tsunami earthquakes, which happened off the coast of New Zealand’s north island in 1947. Tsunami earthquakes were only identified by geologists around 35 years ago, so detailed studies of these events are rare.
The team located two extinct volcanoes off the coast of Poverty Bay and Tolaga Bay that have been squashed and sunk beneath the crust off the coast of New Zealand, in a process called subduction.
The researchers suggest that the volcanoes provided a “sticking point” between a part of the Earth’s crust called the Pacific plate, which was trying to slide underneath the New Zealand plate. This caused a build-up of energy, which was released in 1947, causing the plates to “unstick” and the Pacific plate to move and the volcanoes to become subsumed under New Zealand. This release of the energy from both plates was unusually slow and close to the seabed, causing large movements of the sea floor, which led to the formation of very large tsunami waves.
All these factors combined, say the researchers, are factors that contribute to tsunami earthquakes. The researchers say that the 1947 New Zealand tsunami earthquakes provide valuable insights into what geological factors cause these events. They believe the information they’ve gathered on these events could be used to locate similar zones around the world that could be at risk from tsunami earthquakes. Eyewitnesses from these tsunami earthquakes also describe the type of ground movement that occurred and this provides valuable clues about possible early warning signals for communities.
Dr Rebecca Bell, from the Department of Earth Science and Engineering at Imperial College London, says: “Tsunami earthquakes don’t create massive tremors like more conventional earthquakes such as the one that hit Japan in 2011, so residents and authorities in the past haven’t had the same warning signals to evacuate. These types of earthquakes were only identified a few decades ago, so little information has been collected on them. Thanks to oil exploration data and eyewitness accounts from two tsunami earthquakes that happened in New Zealand more than 70 years ago, we are beginning to understand for first time the factors that cause these events. This could ultimately save lives.”
By studying the data and reports, the researchers have built up a picture of what happened in New Zealand in 1947 when the tsunami earthquakes hit. In the March earthquake, eyewitnesses around Poverty Bay on the east coast of the country, close to the town of Gisborne, said that they didn’t feel violent tremors, which are characteristic of typical earthquakes. Instead, they felt the ground rolling, which lasted for minutes, and brought on a sense of sea sickness. Approximately 30 minutes later the bay was inundated by a ten metre high tsunami that was generated by a 5.9 magnitude offshore earthquake. In May, an earthquake measuring 5.6 on the Richter scale happened off the coast of Tolaga Bay, causing an approximate six metre high tsunami to hit the coast. No lives were lost in the New Zealand earthquakes as the areas were sparsely populated in 1947. However, more recent tsunami earthquakes elsewhere have devastated coastal communities.
The researchers are already working with colleagues in New Zealand to develop a better warning system for residents. In particular, new signage is being installed along coastal regions to alert people to the early warning signs that indicate a possible tsunami earthquake. In the future, the team hope to conduct new cutting-edge geophysical surveys over the sites of other sinking volcanoes to better understand their characteristics and the role they play in generating this unusual type of earthquake.
Note : The above story is based on materials provided by Imperial College London
Locality: Kolwezi District, Katanga Copper Crescent, Katanga (Shaba), Democratic Republic of Congo (Zaïre) Dimensions: 5.9 cm x 3.2 cm x 2.6 cm”Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”
Chemical Formula: Cu8(Si8O22)(OH)4·H2O Locality: Tantara and Kambowe, Zaire. Name Origin: Named after J. Planche who brought it from Africa.
Plancheite is a hydrated copper silicate mineral with the formula Cu8(Si8O22)(OH)4·H2O. It is closely related to shattuckite in structure and appearance, and the two minerals are often confused.
Structure
Plancheite is a chain silicate (inosilicate), with double chains of silica tetrahedra parallel to the c crystal axis. It occurs as sprays of acicular or fibrous radial clusters, with fibers extended parallel to the chains, i.e. along the c crystal axis; it can also form tiny tabular or platy crystals. It is a member of the orthorhombic crystal class m m m (2/m 2/m 2/m), which is the most symmetrical class in the orthorhombic system.
History
Discovery date : 1908 Town of Origin : MINDOULI Country of Origin : ZAIRE ex-CONGO
Optical properties
Optical and misc. Properties: Translucide Refractive Index: from 1,69 to 1,74 Axial angle 2V: 88,5°
Physical properties
Hardness : 6,00 Density : from 3,65 to 3,80 Color: pale blue; dark blue; green blue; greenish blue Luster: adamantine; silky; unpolished; bright; satin-like Streak : pale blue Cleavage : NO
PNNL scientists developed an approach that allows climate models at different scales to share parameterizations and other information.
A new climate modeling approach that combines a detailed regional model with a more wide-ranging global model was developed by a team of researchers at Pacific Northwest National Laboratory, in collaboration with the University of Wyoming. This approach, described in a recent article in the journal Geoscientific Model Development, improves the way models represent atmospheric particles, clouds, and particle-cloud interactions and how they vary at regional and local scales. The approach minimizes inconsistencies in how process information is parameterized—that is, translated into simplifications that well represent process complexity.
“Our approach facilitates comparisons and produces results that agree more closely with real-world observations than previous approaches,” said Dr. Po-Lun Ma, PNNL atmospheric scientist and lead author of the paper.
Understanding the past and predicting future climate trends takes lots of computational power. Global climate models break up the planet in chunks of 100 kilometers and then average climate processes over that large grid space. Because of this large scale, scientists have struggled to accurately capture regional and local variations and extreme weather events in these models. Instead, researchers often use regional-scale climate models to characterize real-world weather events, but different representations of physical, chemical, and other processes between global and regional climate models produce inconsistent information about the atmosphere. In this study, scientists used the new modeling approach to consistently share the climate’s physical process complexities at all scales-global, regional, and local.
The PNNL research team transferred a set of Community Atmosphere Model version 5.1 (CAM5) physical parameters into the regional model Weather Research and Forecasting with Chemistry (WRF-Chem). The resulting approach allowed both the high-resolution regional model and the lower-resolution global model to share information, using the same equations and computer codes for the physical and chemical representation of clouds and aerosols and consistent estimates of emissions of gases and aerosol particles. Sharing information between the models helped the researchers understand the impact of model resolution on the simulation using a consistent framework and allowed them to avoid problems typically encountered when connecting models.
The team applied the approach at multiple horizontal resolutions over an area encompassing the northern Pacific Ocean, northeast Asia, and northwest North America for April 2008. This timeframe took advantage of the data collected by a series of field campaigns managed by the U.S. Department of Energy’s (DOE’s) Atmospheric Radiation Measurement (ARM) Climate Research Facility. The researchers then evaluated the model results against those field campaign measurements, data from satellites, and ground-based observations. The modules they created through this approach are now a part of WRF-Chem 3.5, which is available online for use by other researchers.
Scientists will use data from other field campaigns to determine which set of physical and chemical representations in the models produce results more consistent with observations and why. They will focus on simulations that explore how the scale of the model affects clouds and atmospheric particles in different climate regimes.
More information:
Ma PL, PJ Rasch, JD Fast, RC Easter, WI Gustafson Jr, X Liu, SJ Ghan, and B Singh. 2014. “Assessing the CAM5 Physics Suite in the WRF-Chem Model: Implementation, Resolution Sensitivity, and a First Evaluation for a Regional Case Study.” Geoscientific Model Development 7:755-778. DOI: 10.5194/gmd-7-755-2014
Note : The above story is based on materials provided by Pacific Northwest National Laboratory
Shatt al-Arab is a river in Southwest Asia of some 200 km (120 mi) in length, formed by the confluence of the Euphrates and the Tigris in the town of al-Qurnah in the Basra Governorate of southern Iraq. The southern end of the river constitutes the border between Iraq and Iran down to the mouth of the river as it discharges into the Persian Gulf. It varies in width from about 232 metres (761 ft) at Basra to 800 metres (2,600 ft) at its mouth. It is thought that the waterway formed relatively recently in geologic time, with the Tigris and Euphrates originally emptying into the Persian Gulf via a channel further to the west.
The Karun river, a tributary which joins the waterway from the Iranian side, deposits large amounts of silt into the river; this necessitates continuous dredging to keep it navigable.
The area is judged to hold the largest date palm forest in the world. In the mid-1970s, the region included 17 to 18 million date palms, an estimated one-fifth of the world’s 90 million palm trees. But by 2002, war, salt, and pests had wiped out more than 14 million of the palms, including around 9 million in Iraq and 5 million in Iran. Many of the remaining 3 to 4 million trees are in poor condition.
In Middle Persian literature and the Shahnama (written between c. 977 and 1010 AD), the name اروند Arvand is used for the Tigris, the confluent of the Shatt al-Arab. Iranians also used this name specifically to designate the Shatt al-Arab during the later Pahlavi period, and continue to do so after the Iranian Revolution of 1979.
Territorial disputes
Conflicting territorial claims and disputes over navigation rights between Iran and Iraq were among the main factors for the Iran–Iraq War that lasted from 1980 to 1988, when the pre-1980 status quo was restored. The Iranian cities of Abadan and Khorramshahr and the Iraqi city and major port of Basra are situated along this river.
Control of the waterway and its use as a border was a source of contention between Iran and the predecessor of the Iraqi state since a peace treaty signed in 1639 between the Persian and the Ottoman empires, which divided the territory according to tribal customs and loyalties, without attempting a rigorous land survey. The tribes on both sides of the lower waterway, however, are Marsh Arabs, and the Ottoman Empire claimed to represent them. Tensions between the opposing empires that extended across a wide range of religious, cultural and political conflicts, led to the outbreak of hostilities in the 19th century and eventually yielded the Second Treaty of Erzurum between the two parties, in 1847, after protracted negotiations, which included British and Russian delegates. Even afterwards, backtracking and disagreements continued, until British Foreign Secretary, Lord Palmerston, was moved to comment in 1851 that “the boundary line between Turkey and Persia can never be finally settled except by an arbitrary decision on the part of Great Britain and Russia”. A protocol between the Ottomans and the Persians was signed in Istanbul in 1913, which declared that the Ottoman-Persian frontier run along the thalweg, but World War I canceled all plans.
During the Mandate of Iraq (1920–32), the British advisors in Iraq were able to keep the waterway binational under the thalweg principle that worked in Europe: the dividing line was a line drawn between the deepest points along the stream bed. In 1937, Iran and Iraq signed a treaty that settled the dispute over control of the Shatt al-Arab. The 1937 treaty recognized the Iranian-Iraqi border as along the low-water mark on the eastern side of the Shatt al-Arab except at Abadan and Khorramshahr where the frontier ran along the thalweg (the deep water line) which gave Iraq control of almost the entire waterway; provided that all ships using the Shatt al-Arab fly the Iraqi flag and have an Iraqi pilot, and required Iran to pay tolls to Iraq whenever its ships used the Shatt al-Arab. By the late 1960s, the build-up of Iranian power under Shah Mohammad Reza Pahlavi, who had gone on a gargantuan military spending spree, led Iran to take a more assertive stance in the Near East. In April 1969, Iran abrogated the 1937 treaty over the Shatt al-Arab, and as such, Iran ceased paying tolls to Iraq when its ships used the Shatt al-Arab. The Shah justified his move by arguing that almost all river borders all over the world ran along the thalweg, and by claiming that because most of the ships that used the Shatt al-Arab were Iranian, the 1937 treaty was unfair to Iran. Iraq threatened war over the Iranian move, but when on 24 April 1969 an Iranian tanker escorted by Iranian warships sailed down the Shatt al-Arab, Iraq being the militarily weaker state did nothing. The Iranian abrogation of the 1937 treaty marked the beginning of a period of acute Iraqi-Iranian tension that was to last until the Algiers Accords of 1975.
All United Nations attempts to intervene as mediators were rebuffed. Under Saddam Hussein, Baathist Iraq claimed the entire waterway up to the Iranian shore as its territory. In response, Iran in the early 1970s became the main patron of Iraqi Kurdish groups fighting for independence from Iraq. In March 1975, Iraq signed the Algiers Accord in which it recognized a series of straight lines closely approximating the thalweg (deepest channel) of the waterway, as the official border, in exchange for which Iran ended its support of the Iraqi Kurds. In 1980, Hussein released a statement claiming to abrogate the treaty that he signed, and Iraq invaded Iran. (International law, however, holds that in all cases no bilateral or multilateral treaty can be abrogated by one party only.) The main thrust of the military movement on the ground was across the waterway which was the stage for most of the military battles between the two armies. The waterway was Iraq’s only outlet to the Persian Gulf, and thus, its shipping lanes were greatly affected by continuous Iranian attacks. When the Al-Faw peninsula was captured by the Iranians in 1986, Iraq’s shipping activities virtually came to a halt and had to be diverted to other Arab ports, such as Kuwait and even Aqaba, Jordan. At the end of the Iran–Iraq War both sides agreed to once again treat the Algiers Accord as binding.
Recent conflicts
In the 2003 invasion of Iraq, the waterway was a key military target for the Coalition Forces. Since it is the only outlet to the Persian Gulf, its capture was important in delivering humanitarian aid to the rest of the country, and also to stop the flow of operations trying to break the naval blockade against Iraq. The British Royal Marines staged an amphibious assault to capture the key oil installations and shipping docks located at Umm Qasr on the al-Faw peninsula at the onset of the conflict.
Following the end of the war, the UK was given responsibility, subsequently mandated by United Nations Security Council Resolution 1723, to patrol the waterway and the area of the Persian Gulf surrounding the river mouth. They were tasked until 2007 to make sure that ships in the area were not being used to transport munitions into Iraq. British forces also trained Iraqi naval units to take over the responsibility of guarding their waterways after the Coalition Forces left Iraq in December of 2011.
On two separate occasions, Iranian forces operating on the Shatt al-Arab have captured British Royal Navy sailors who they claim have trespassed into their territory.
In June 2004, several British servicemen were held for two days after purportedly straying into the Iranian side of the waterway. After being initially threatened with prosecution, they were released after high-level conversations between British Foreign Secretary Jack Straw and Iranian Foreign Minister Kamal Kharrazi. The initial hardline approach was put down to power struggles within the Iranian government. The British marines’ weapons and boats were confiscated.
In 2007, a seizure of fifteen more British personnel became a major diplomatic crisis between the two nations. It was resolved after thirteen days when the Iranians unexpectedly released the captives under an “amnesty.”
Note : The above story is based on materials provided by Wikipedia
