Australia’s Moreton Bay

as Coral ‘Lifeboat’

Science (Aug. 13, 2010) — An international team of scientists has been exploring Moreton Bay, close to Brisbane, as a possible ‘lifeboat’ to save corals from the Great Barrier Reef at risk of extermination under climate change.

In a new research paper they say that corals have been able to survive and flourish in the Bay, which lies well to the south of the main GBR coral zones, during about half of the past 7000 years.

Corals only cover about 1 per cent of the Moreton Bay area currently, and have clearly been adversely affected by clearing of the surrounding catchments and human activities on land and sea, says lead author Matt Lybolt of the ARC Centre of Excellence for Coral Reef Studies and The University of Queensland.

“The demise of tropical coral reefs around the world is due mainly to overfishing, pollution and climate change. There is also plenty of historical evidence that coral reefs can move from one environment to another as the climate and other conditions change,” Matt explains.

“In view of this, various places — including Moreton Bay — are being investigated as possible refuges in which coral systems can be preserved should they begin to die out in their natural settings. Indeed, some people have even talked of relocating and re-seeding corals in other locations that better suit their climatic needs.”

The team’s study of Moreton Bay reveals that it is not exactly ideal coral habitat, being cold in winter, lacking sufficient direct sunlight, subject to turbid freshwater inflows and — more recently — to a range of human impacts.

“Even before European settlers came on the scene the Bay underwent phases in which corals grew prolifically — and phases in which they died away almost completely. We understand what causes corals to die back, but we are less clear about what causes them to recover,” Matt says.

“Broadly, the corals seemed to do well at times when the climate, sea levels and other factors were most benign and stable — and to decline when El Nino and other disturbances made themselves felt.”

The Moreton Bay corals have been in an expansionary phase during the last 400 years, initially dominated by the branching Acropora corals but, since the Bay’s catchment was cleared and settled, these have died back leaving mainly slow-growing types of coral.

“Under climate change we expect winters to be warmer and sea levels to rise — and both of these factors will tend to favour the expansion of corals in Moreton Bay,” Matt says.

“However this expansion of corals may not occur unless we make a major effort to improve water quality in the Bay, by not allowing effluent, polluted runoff or sediment to enter it, and also by regrowing mangrove forests and seagrass beds within the Bay. ”

The team concludes that Moreton Bay’s potential as a good ‘lifeboat’ for corals is limited by four major factors:

• It is highly sensitive to what the 2 million residents of its catchment do that affects it
• It presently has very few branching corals left
• The area on which corals can grow is limited, both naturally and by human activity
• Finally, the historical record suggests the Bay is only a good coral refuge about half of the time.

Matt says that there is nevertheless scope for changes in the management of the Bay and its surrounding catchments that can improve its suitability as a coral environment. “The reefs of today don’t look anything like they did in the past, so it’s really a question of ‘What sort of coral reef do you want?’,” he says.

However there needs to be a clearer scientific understanding of the drivers that have caused corals to boom and bust within the Bay over the past seven millennia before we can be sure it is worthwhile attempting to make Moreton Bay a ‘lifeboat’ for the GBR, he cautions.

Matt noted that there are very few suitable coral habitats south of the southern end of the GBR to which corals can migrate, should the northern parts of the reef become untenable for corals due to the impact of global warming.

Their paper “Instability in a marginal coral reef: the shift from natural variability to a human-dominated seascape” by Matt Lybolt, David Neil, Jian-xin Zhao, Yue-xing Feng, Ke-Fu Yu and John Pandolfi appears in the latest issue of the journal Frontiers in Ecology and Environment.

Sourced & published by Henry Sapiecha

Mimicking Insects to Avoid Sinking

Using Surface Tension

July 1, 2006 — A new robot made of ultralight carbon-fiber can stand or slowly walk on water. The principle it uses is borrowed from insects — surface tension tends to prevent the water’s surface from breaking, and the robot’s legs from sinking in.

PITTSBURGH — Nature inspires many things, from fashion to perfume to furniture. Now, technology gets a little inspiration.

After watching tiny bugs like these walk on water, Carnegie Mellon University mechanical engineer Metin Sitti wanted one of his own.

“We tried to make a robot to simulate the insect,” he tells DBIS. He tried and succeeded. This new tiny, lightweight, spindly legged creature is a robot that can propel itself across water in all directions. It can turn even sharp corners like the insect does, so it’s very agile.

The robot’s body is made of a super-light carbon fiber material. Its steel legs are coated with non-stick Teflon to repel water. A tiny battery gives it power.

“Right now we move by five centimeters per second, and the real insect can go up to one meter per second. So we are like around 20-times less speed,” Sitti says.

It might be slower, but just like insects, the robot doesn’t float. It stands on top of water thanks to the physics of surface tension. The surface is so strong that the robot’s feet only dent the water without breaking the surface while supporting the weight of the robot without sinking.

“When they put their legs on the surface of the water surface, they repel each other,” Sitti says. “And that repulsion can lift the body because it’s so light bodyweight.”

In the near future, Sitti says his creation could carry sensors to detect toxins in water supplies. “We can make many of them, like tens or hundreds of them, and cover a wide range and give you constant, continuous, water quality report,” he says.

Researchers have already received interest in the robot as an educational toy, to educate students and the public about water surface effects, and to provide entertainment.

LONDON (UPI) — A new ocean is being born in Africa that will eventually split the continent in two, British researchers say.

Scientists at Britain’s Royal Society say a 40-mile crack in the Earth opened in Ethiopia in 2005 and has been growing ever since, the BBC reported Friday.

The crack will eventually became the sea bed of a new ocean that will divide Africa in two, though the process will require about 10 million years, scientists say.

Used to understanding planetary changes on timescales involving millions of years, scientists say the crack in the remote Afar region of Ethiopia is dramatic in the speed at which it is growing.

The 40-mile crack opened to a width of 22 feet in just 10 days, they say.

Ultimately, they say, the horn of Africa will split from the continent, and the crack, in a region below sea level, will fill with salt water.

“It will pull apart, sink down deeper and deeper and eventually … parts of southern Ethiopia, Somalia will drift off, create a new island, and we’ll have a smaller Africa and a very big island that floats out into the Indian Ocean,” said Dr. James Hammond, a seismologist from the University of Bristol.

Copyright 2010 by United Press International

Sourced & published by Henry Sapiecha

New Study Helps Explain

Decompression Sickness

Science(June 28, 2010) — As you go about your day-to-day activities, tiny bubbles of nitrogen come and go inside your tissues. This is not a problem unless you happen to experience large changes in ambient pressure, such as those encountered by scuba divers and astronauts. During large, fast pressure drops, these bubbles can grow and lead to decompression sickness, popularly known as “the bends.”

A study in the Journal of Chemical Physics, which is published by the American Institute of Physics (AIP), may provide a physical basis for the existence of these bubbles, and could be useful in understanding decompression sickness.

A physiological model that accounts for these bubbles is needed both to protect against and to treat decompression sickness. There is a problem though. “These bubbles should not exist,” says author Saul Goldman of the University of Guelph in Ontario, Canada.

Because they are believed to be composed mostly of nitrogen, while the surrounding atmosphere consists of both nitrogen and oxygen, the pressure of the bubbles should be less than that of the surrounding atmosphere. But if this were so, they would collapse.

“We need to account for their apparent continuous existence in tissues in spite of this putative pressure imbalance,” says Goldman.

If, as is widely believed, decompression sickness is the result of the growth of pre-existing gas bubbles in tissues, those bubbles must be sufficiently stable to have non-negligible half-lives. The proposed explanation involves modeling body tissues as soft elastic materials that have some degree of rigidity. Previous models have focused on bubble formation in simple liquids, which differ from elastic materials in having no rigidity.

Using the soft-elastic tissue model, Goldman finds pockets of reduced pressure in which nitrogen bubbles can form and have enough stability to account for a continuous presence of tiny bubbles that can expand when the ambient pressure drops. Tribonucleation, the phenomenon of formation of new gas bubbles when submerged surfaces separate rapidly, provides the physical mechanism for formation of new gas bubbles in solution. The rapid separation of adhering surfaces results in momentary negative pressures at the plane of separation. Therefore, while these tiny bubbles in elastic media are metastable, and do not last indefinitely, they are replaced periodically. According to this picture, tribonucleation is the source, and finite half-lives the sink, for the continuous generation and loss small gas bubbles in tissues.

Sourced & published by Henry Sapiecha

WASHINGTON (UPI) — U.S. researchers say they’ve determined undersea forces produced by strong hurricanes are powerful enough to rupture underwater oil pipelines.

The scientists at the U.S. Naval Research Laboratory said the pipelines could crack or rupture unless they are buried or their supporting foundations are built to withstand hurricane-induced currents.

“Major oil leaks from damaged pipelines could have irreversible impacts on the ocean environment,” the researchers said, noting a hurricane’s winds can raise waves 66 feet or more above the ocean surface.

Based on unique measurements taken during a powerful hurricane, the researchers said their study is the first to show hurricanes propel underwater currents with enough force to dig up the seabed, potentially creating underwater mudslides and damaging pipes or other equipment resting on the bottom.

They said they’re not sure what strengths of forces underwater oil pipelines are built to withstand. However, “Hurricane stress is quite large, so the oil industry better pay attention,” said Hemantha Wijesekera, who led the study.

The findings are to appear in the June10 issue of the journal Geophysical Research Letters.

Sourced and published  by Henry Sapiecha

Why Icicles Are Long And Thin

Mathematical Physics Explains

How Icicles Grow

When droplets of melted snow drip down an icicle, they release small amounts of heat as they freeze. Heated air travels upwards and helps slow down the growth of the icicle’s top, while the tip is growing rapidly. Knowledge of the mathematical equations that govern icicle growth — the same that apply to stalactites — could help in the prevention of icicle formation on power lines.

Icicles can be dangerous and deadly, yet they can create some of the most amazing winter scenes. And for scientists, those winter scenes are playgrounds for discovery.

It’s on those playgrounds that experts in physics and mathematics are building their theories on what it takes to create an icicle.

We all know icicles form when melting snow begins dripping down a surface. But what scientists didn’t know is how their shape is formed. What makes each icicle different?

University of Arizona Physicist Martin Short turned to mathematics to find out.

“Icicles have a certain mathematical shape, and this mathematical shape is universal among icicles,” Short tells DBIS.

So what is the math behind an icicle?

“Here I’ve drawn the profile of an icicle. Here is the height, and here’s the radius … Here’s the profile here, and I’ve written the formula here. The height is proportional to the radius to the four-thirds,” he says.

What does the formula have to do with an icicle’s shape? “It kind of looks like a carrot,” says Short. “It starts out flat and then sort of up as you go.”

As water drips onto an icicle and freezes, it releases heat. The warm air rises up the sides of the icicle. Short says that warm air layer acts like a blanket that’s an insulator, and so the blanket is very thin near the tip and thick at the top. That allows the top to grow very slowly and the tip to grow rapidly — creating a long, thin icicle.

It’s the same equation scientists use to study stalactites in caves, but instead of water, stalactites are formed by the buildup of calcium left after the water evaporates.

“If we know the mechanisms by which stalactites form, well, we could better preserve our natural caves that we have here, and try to stop them from eroding,” Short says.

And now that scientists know how icicles are made, it could lead to breakthroughs to prevent them from forming on power lines and trees.

Renewable Energy:

Inexpensive Metal Catalyst

Can Effectively Generate

Hydrogen from Water

Science (May 1, 2010) — Hydrogen would command a key role in future renewable energy technologies, experts agree, if a relatively cheap, efficient and carbon-neutral means of producing it can be developed. An important step towards this elusive goal has been taken by a team of researchers with the U.S. Department of Energy’s (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California, Berkeley. The team has discovered an inexpensive metal catalyst that can effectively generate hydrogen gas from water.

“Our new proton reduction catalyst is based on a molybdenum-oxo metal complex that is about 70 times cheaper than platinum, today’s most widely used metal catalyst for splitting the water molecule,” said Hemamala Karunadasa, one of the co-discoverers of this complex. “In addition, our catalyst does not require organic additives, and can operate in neutral water, even if it is dirty, and can operate in sea water, the most abundant source of hydrogen on earth and a natural electrolyte. These qualities make our catalyst ideal for renewable energy and sustainable chemistry.”

Karunadasa holds joint appointments with Berkeley Lab’s Chemical Sciences Division and UC Berkeley’s Chemistry Department. She is the lead author of a paper describing this work that appears in the April 29, 2010 issue of the journal Nature, titled “A molecular molybdenum-oxo catalyst for generating hydrogen from water.” Co-authors of this paper were Christopher Chang and Jeffrey Long, who also hold joint appointments with Berkeley Lab and UC Berkeley. Chang, in addition, is also an investigator with the Howard Hughes Medical Institute (HHMI).

Hydrogen gas, whether combusted or used in fuel cells to generate electricity, emits only water vapor as an exhaust product, which is why this nation would already be rolling towards a hydrogen economy if only there were hydrogen wells to tap. However, hydrogen gas does not occur naturally and has to be produced. Most of the hydrogen gas in the United States today comes from natural gas, a fossil fuel. While inexpensive, this technique adds huge volumes of carbon emissions to the atmosphere. Hydrogen can also be produced through the electrolysis of water — using electricity to split molecules of water into molecules of hydrogen and oxygen. This is an environmentally clean and sustainable method of production — especially if the electricity is generated via a renewable technology such as solar or wind — but requires a water-splitting catalyst.

Nature has developed extremely efficient water-splitting enzymes — called hydrogenases — for use by plants during photosynthesis, however, these enzymes are highly unstable and easily deactivated when removed from their native environment. Human activities demand a stable metal catalyst that can operate under non-biological settings.

Metal catalysts are commercially available, but they are low valence precious metals whose high costs make their widespread use prohibitive. For example, platinum, the best of them, costs some $2,000 an ounce.

“The basic scientific challenge has been to create earth-abundant molecular systems that produce hydrogen from water with high catalytic activity and stability,” Chang says. “We believe our discovery of a molecular molybdenum-oxo catalyst for generating hydrogen from water without the use of additional acids or organic co-solvents establishes a new chemical paradigm for creating reduction catalysts that are highly active and robust in aqueous media.”

The molybdenum-oxo complex that Karunadasa, Chang and Long discovered is a high valence metal with the chemical name of (PY5Me2)Mo-oxo. In their studies, the research team found that this complex catalyzes the generation of hydrogen from neutral buffered water or even sea water with a turnover frequency of 2.4 moles of hydrogen per mole of catalyst per second.

Long says, “This metal-oxo complex represents a distinct molecular motif for reduction catalysis that has high activity and stability in water. We are now focused on modifying the PY5Me ligand portion of the complex and investigating other metal complexes based on similar ligand platforms to further facilitate electrical charge-driven as well as light-driven catalytic processes. Our particular emphasis is on chemistry relevant to sustainable energy cycles.”

This research was supported in part by the DOE Office of Science through Berkeley Lab’s Helios Solar Energy Research Center, and in part by a grant from the National science Foundation.

Sourced and published by Henry Sapiecha 2nd May 2010