Aquaculture production of seafood will probably remain the most rapidly increasing food production system worldwide through 2025, according to an assessment published in the January 2009 issue of BioScience.  The assessment, by James S. Diana of the University of Michigan at Ann Arbor, notes that despite well-publicized concerns about some harmful effects of aquaculture, the technique may, when practiced well, be no more damaging to biodiversity than other food production systems.  Moreover, it may be the only way to supply growing demand for seafood as the human population increases.

Diana notes that total production from capture fisheries has remained approximately constant for the past 20 years and may decline.  Aquaculture, in contrast, has increased by 8.8 percent per year since 1985 and now accounts for about one-third of all aquatic harvest by weight.  Finfish, mollusks, and crustaceans dominate aquaculture production; seafood exports generate more money for developing countries than meat, coffee, tea, bananas, and rice combined.

Among the most potentially harmful effects of aquaculture, according to Diana, are the escape of farmed species that then become invasive, pollution of local waters by effluent, especially from freshwater systems, and land-use change associated with shrimp aquaculture in particular.  Increased demand for fish products for use in feed and transmission of disease from captive to wild stocks are also hazards.

Nonetheless, when carefully implemented, aquaculture can reduce pressure on overexploited wild stocks, enhance depleted stocks, and boost natural production of fishes as well as species diversity, according to Diana.  Some harmful effects have diminished as management techniques have improved, and aquaculture has the potential to provide much-needed employment in developing countries.  Diana points to the need for thorough life-cycle analyses to compare aquaculture with other food production systems.  Such analyses are, however, only now being undertaken, and more comprehensive information is needed to guide the growth of this technique in sustainable ways.

Wind, water, and waves erode billions of tons of soil from the earth’s surface.  As a result, many rivers are plagued with excessive amounts of suspended sediment.  According to the U.S. Environmental Protection Agency, such eroded sediment is the largest nonpoint source pollution in the environment.

While the mechanism responsible for soil erosion may seem obvious –wind, water and wave forces breaking apart particles – in fact, the precise conditions or criterion that sets a particle free from its mates has not been identified.  For 72 years, scientists and engineers have been working with a time-averaged force criterion, originally proposed by A. Shields, an American engineer, to describe threshold conditions for sediment to become mobile.

Now, a team of Virginia Tech College of Engineering faculty members and graduate students have demonstrated that sustained spikes in turbulence are responsible for dislodging particles, whether on land or in the water.  They report their research results in the October 31 issue of Science in the article, “The Role of Impulse on the Initiation of Particle Movement Under Turbulent Flow Conditions.”*

Scientists and engineers have long suspected that turbulence, an ubiquitous feature of natural fluid flow phenomena, was part of the equation.  Anyone who has flown has experienced turbulence.  So a guess that turbulence is the culprit was still not sufficiently informative.

“There has been a need to develop a method that accounts for the role of turbulence on soil erosion in a quantitative way,” said civil and environmental engineering Professor Panos Diplas, lead author on the research.”If you measured the velocity of the air flowing across a fixed place in the middle of Virginia Tech’s drill field, you would see that velocity fluctuates wildly,” Diplas said.

“Wildly and randomly,” said mechanical engineering Associate Professor Clint Dancey, co-author.

“When a weather report includes a high wind warning, it will go something like, ‘30 mph gusting to 70.’  Yet the present system for determining erosion potential in a flow only measures a single, time-averaged value.  “It does not account for the spikes or their duration,” said Diplas.

Diplas, Dancey, and their students began to do experiments to determine the influence of the spikes.  What they discovered is that not all spikes are created equal.

Using a metal ball slightly nested among Teflon balls, they introduced electromagnetic pulses of known magnitude and of different millisecond durations.  The magnetic field simulated the drag of water in a river.  “I had an ‘aha moment’ when I saw the video of that controlled experiment,” said Dancey.

“We saw that, in addition to their amplitude, it was the duration of the ‘gusts’ that caused the metal ball to be dislodged or eroded from its resting pocket” said Diplas.

Using electromagnetic pulses, the team was able to establish a range of combinations of magnitude and duration that result in particle dislodgement.  They call this product of magnitude and duration ‘impulse’.

Next, the team moved their investigation to a two-foot-wide, 65-foot-long flume with actual water in the Baker Environmental Hydraulics Laboratory (www.hydraulicslab.cee.vt.edu) at Virginia Tech.  The flume is used to simulated phenomena encountered in natural streams.  A half-inch diameter ball was slightly nested on a bed of immobile ‘pebbles’.  Laser Doppler velocimetry (LDV) measured the instantaneous flow velocity of the water, which was allowed to move with the typical random turbulence of channel flows.  Laser beams shining through the flume from outside recorded when the mobile grain moved.  Thus the conditions of drag that caused erosion were captured.  The results agreed with the findings of the electromagnetic study, the Science article reports.

“It is fundamental physics with broad applications to water or air flows,” said Dancey.  “The goal is to produce criteria that are more broadly applicable and have more predictive power.”

And not only for the thresholds that result in soil erosion, but for the movement of contaminants.  “A lot of particles have chemicals attached to them.  At what point does pollution occur?”  Said Diplas.  “That is, if pollutants are resting in a river bed, and there is a flood, at some point the turbulence is going to move the pollutants downstream.  We need to know when this will happen!”

Another force capable of mobilizing particles is lift, the force that moves a buried particle out of its bed?.  “We have employed a theoretical approach to explain what is happening when lift is the prevailing force experienced by a soil particle.  The results in this case agree with those obtained from the electromagnet experiments when drag was the dominant force.  Impulse, not just force, represents the more general criterion for identifying the critical conditions for particle dislodgement.”  Dancey said.

“We anticipate that this same mechanism will be responsible for particle dislodgement under the more general condition when both drag and lift forces contribute to particle movement,” added Diplas.

New research by the University of East Anglia (UEA) has demonstrated for the first time that human activity is responsible for significant warming in both polar regions.

The findings by a team of scientists led by UEA’s Climatic Research Unit will be published online by the Nature Geoscience this week.

Previous studies have observed rises in both Arctic and Antarctic temperatures over recent decades but have not formally attributed the changes to human influence due to poor observation data and large natural variability.  Moreover, the International Panel on Climate Change (IPCC) had concluded that Antarctica was the only continent where human-induced temperature changes had yet to be detected.

Now, a newly updated data-set of land surface temperatures and simulations from four new climate models show that temperature rises in both polar regions are not consistent with natural climate variability alone and are directly attributable to human influence.

The results demonstrate that human activity has already caused significant warming, with impacts on polar biology, indigenous communities, ice-sheet mass balance and global sea level.

“This is an important work indeed,” said Dr Alexey Karpechko of UEA’s Climatic Research Unit.

“Arctic warming has previously been emphasized in several publications, although not formally attributed to human activity.  However in Antarctica, such detection was so far precluded by insufficient data available.  Moreover circulation changes caused by stratospheric ozone depletion opposed warming over most of Antarctica and made the detection even more difficult.

“Since the ozone layer is expected to recover in the future we may expect amplifying Antarctic warming in the coming years.”

Ants prefer salty snacks to sugary ones, at least in inland areas that tend to be salt-poor, according to a new study published this week in the journal Proceedings of the National Academy of Sciences.Ecologists from the University of California, Berkeley, the University of Arkansas at Little Rock (UALR) and the University of Oklahoma tested the salt versus sugar preferences of ants from North, Central and South America, using ant populations at varying distances from the ocean. While ocean spray and storms can spread salt tens of miles from the coast, areas farther inland are often deprived of salt, and the researchers suspected they might find different taste choices between coastal and inland ants.

In fact, they found that ants living more than 60 miles inland often preferred a 1 percent salt solution over a sugar solution 10 times more concentrated. This was true primarily for plant-eating ants, however. Carnivorous ants, such as fire ants, apparently get enough salt from their prey. For similar reasons, grazing animals such as bison and deer seek out salt licks to complement their salt-poor vegetarian diet, while carnivores like mountain lions and wolves get all the salt they need from bloody meat.

“Attractiveness to salt increases with distance from the ocean,” said co-author Robert Dudley, UC Berkeley professor of integrative biology. “It’s really fascinating that we see a pattern on this grand, continental scale.”

“Ants will always go for the sugar because they need sugar to provide the basic energy for life and for their activity,” said co-author Steve Yanoviak, an assistant professor of biology at UALR. “But when you see ants spending increasing amounts of time or employing increasingly large numbers of individuals foraging for salt, it suggests that salt is a resource that is limiting to them. Their ability to be competitive and maintain themselves in different environments could be limited by a resource like salt.”

What holds true for ants may well be true of all insects and even microbes, the researchers argue, pointing to a role for salt, or sodium chloride, in the ecosystem that has not been recognized before.

“One implication of this study is that even basic ecosystem processes, like the whole carbon cycle, may be influenced by the availability of sodium,” said ant ecologist and lead author Michael E. Kaspari of the University of Oklahoma in Norman. “If you want to have a nice lawn or grow vegetables, you add the big-three nutrients: nitrogen, phosphorous and potassium. Salt is almost like fertilizer for animals.”

Kaspari plans to test whether spraying salt on the litter of the forest floor cranks up ecosystem activity and decomposition, releasing more carbon dioxide, in the same way salty Gatorade improves the performance of sports teams.

Dudley, Yanoviak and Kaspari instigated the study after spending several “intolerable” days doing research on insects in the treetops of Peru, near the headwaters of the Amazon River and far from the Pacific Ocean - an area that contrasts starkly with the relatively pest-free treetop conditions in Panama, where no place is more than 25 kilometers from the ocean. The three researchers were tossing ants from the tree canopy to study the insects’ ability to glide.

“We were working up in the trees in the Western Amazon on hot, still days, and tiny sweat bees were swarming all around and flying up our noses, something I hadn’t noticed in Panama,” he said. “Why were there so many?”

Because ants are easier to study than bees, Kaspari designed a “cafeteria experiment” that offered ants a choice between salt and sugar. The researchers tested not only Peruvian and Panamanian ants, but also ants from Costa Rica, Arkansas, Oklahoma, Arizona and Florida. In all, they conducted experiments at 17 sites, ranging from rainforest trails in the Amazon to Kaspari’s front yard.

“What makes this experiment so elegant is Mike’s simple design: fill up vials with sugar or salt and drop them along the trail in the forest,” Yanoviak said. “What we didn’t realize was how tiring it is to bend over and pick up more than a hundred vials.”

By merely counting the ant species attracted to cotton balls soaked in salt or sucrose (table sugar) solutions, they discovered that herbivorous or omnivorous species more than 10-100 kilometers (6-60 miles) from the ocean preferred salt over sugar, and the farther inland, the greater the preference for salt. Ants living mostly on green vegetation had a greater preference for salt than did those living among the decaying leaves of the forest floor, while carnivorous ants had little preference for salt over sugar.

Activity at sugar baits was highest between 10 and 100 kilometers from the shore, suggesting that this near-coastal belt may be a sweet spot for animals with “just enough salt to meet requirements, but not enough to be toxic or inhibit the plants they feed on,” Kaspari said.

Animals’ need for salt stems from the high sodium concentrations needed to maintain the body’s nerve and muscle activity and water balance, Dudley said. Animal blood and fluids, including those of humans, are 100 to 1,000 times saltier than the average salt concentration - 1 milligram of sodium per kilogram of weight - in terrestrial plants.

Meat eaters get adequate salt in the diet, but animals that rely primarily on plants for food must seek out environmental sources: human settlements have historically been near supplies of salt; grazing animals require natural or human-supplied salt licks; gorillas look for salt in decaying logs; butterflies cluster around evaporating pools of urine to obtain salt; and some crickets are known to cannibalize their brethren for salt.

Similarly, carnivorous ants appear to get sufficient salt from their diet of termites, mites and other forest-floor creatures. Those in the genus Formica, however, which feed on pollen, nectar and plant exudates, show increased attraction to salt with increasing distance from the ocean. In Oklahoma, Kaspari found that carpenter ants preferred sodium chloride over sugar; in Peru and Panama, the gliding ants in the genus Cephalotes showed increasing preference for salt the farther inland they lived.

“One of the most effective ways to attract ants is to put out a Pecan Sandy™, a shortbread cookie. It turns out this is effective not only because they’re packed with fat, protein, carbohydrates and sugar, but because they’re one of the saltiest cookies out there,” Kaspari said.

Dudley noted that the salt content of a specific environment depends on soil, rainfall and other conditions in addition to distance from the ocean, but the new findings show the importance of micronutrients in determining the distribution of animals.

“Here, we’ve established that salt puts limits on an ecosystem, and show that micronutrients can be just as important as macronutrients in some cases,” he said.

The researchers are continuing their study of salt limitations, including experiments to determine whether it is the sodium or the chloride in salt that is essential to the well-being of ants, and possibly to that of other animals.

The teeth and bones of mammals, the protective shells of mollusks, and the needle-sharp spines of sea urchins and other marine creatures are made-from-scratch wonders of nature.Used to crush food, for structural support and for defense, the materials of which shells, teeth and bones are composed are the strongest and most durable in the animal world, and scientists and engineers have long sought to mimic them.

Now, harnessing the process of biomineralization may be closer to reality as an international team of scientists has detailed a key and previously hidden mechanism to transform amorphous calcium carbonate into calcite, the stuff of seashells. The new insight promises to inform the development of new, superhard materials, microelectronics and micromechanical devices.

In a report today (Oct. 27) in the Proceedings of the National Academy of Sciences (PNAS), a group led by University of Wisconsin-Madison physicist Pupa Gilbert describes how the lowly sea urchin transforms calcium carbonate — the same material that forms “lime” deposits in pipes and boilers — into the crystals that make up the flint-hard shells and spines of marine animals. The mechanism, the authors write, could “well represent a common strategy in biomineralization….”

“If we can harness these mechanisms, it will be fantastically important for technology,” argues Gilbert, a UW-Madison professor of physics. “This is nature’s bottom-up nanofabrication. Maybe one day we will be able to use it to build microelectronic or micromechanical devices.”

Gilbert, who worked with colleagues from Israel’s Weizmann Institute of Science, the University of California at Berkeley and the Lawrence Berkeley National Laboratory, used a novel microscope that employs the soft-X-rays produced by synchrotron radiation to observe how the sea urchin builds its spicules, the sharp crystalline “bones” that constitute the animal’s endoskeleton at the larval stage.

Similar to teeth and bones, the sea urchin spicule is a biomineral, a composite of organic material and mineral components that the animal synthesizes from scratch, using the most readily available elements in sea water: calcium, oxygen and carbon. The fully formed spicule is composed of a single crystal with an unusual morphology. It has no facets and within 48 hours of fertilization assumes a shape that looks very much like the Mercedes-Benz logo.

These crystal shapes, as those of tooth enamel, eggshells or snails, are very different from the familiar faceted crystals grown through non-biological processes in nature. “To achieve such unusual — and presumably more functional — morphologies, the organisms deposit a disordered amorphous mineral phase first, and then let it slowly transform into a crystal, in which the atoms are neatly aligned into a lattice with a specific and regular orientation, while maintaining the unusual morphology,” Gilbert notes.

The question the Wisconsin physicist and her colleagues sought to answer was how this amorphous-to-crystalline transition occurs. The sea urchin larval spicule is a model system for biominerals, and the first one in which the amorphous calcium carbonate precursor was discovered in 1997 by the same Israeli group co-authoring the current PNAS paper. A similar amorphous-to-crystalline transition has since been observed in adult sea urchin spines, in mollusk shells, in zebra fish bones and in tooth enamel. The resulting biominerals are extraordinarily hard and fracture resistant, compared to the minerals of which they are made.

“The amorphous minerals are deposited and they are completely disordered,” Gilbert explains. “So the question we addressed is ‘how does crystallinity propagate through the amorphous mineral?’”

To answer it, Gilbert and her colleagues observed spicule development in 2- to 3-day-old sea urchin larvae. The sea urchin spicule is formed inside a clump of specialized cells and begins as the animal lays down a single crystal of calcite in the form of a rhombohedral seed, from which the rest of the spicule is formed. Starting from the crystalline center, three arms extend at 120 degrees from each other, as in the hood ornament of a Mercedes-Benz. The three radii are initially amorphous calcium carbonate, but slowly convert to calcite.

“We tried to find evidence of a massive crystal growth, with a well defined growth front, propagating from the central crystal through the amorphous material, but we never observed anything like that,” Gilbert says. “What we found, instead, is that 40-100 nanometer amorphous calcium carbonate particles aggregate into the final morphology. One starts converting to crystalline calcite, then another immediately adjacent converts as well, and another, and so on in a three-dimensional domino effect. The pattern of crystallinity, however, is far from straight. It resembles a random walk, or a fractal, like lightning in the sky or water percolating through a porous medium,” explains Gilbert.

The new work, according to Gilbert, brings science a key step closer to a thorough understanding of how biominerals form and transform. Knowing the step-by-step process may permit researchers to develop new crystal structures that can be used in applications ranging from new microelectronic devices to medical applications.

Even though the U. S. Environmental Protection Agency (EPA) has given final approval for use of a new pesticide, regulators in California and other states are taking a closer look at the substance’s potential adverse health effects before allowing the chemical to be used, according to an article scheduled for the Oct. 27 issue of Chemical & Engineering News, ACS’ weekly newsmagazine.

In the article, C&EN Associate Editor Britt E. Erickson notes that EPA first considered approving the pesticide, methyl iodide, in 2006 as a replacement for methyl bromide —which is now being phased out because of environmental concerns that it may damage the ozone layer. Although methyl iodide appears unlikely to have that effect, it is toxic to nerve cells and may carry a risk of thyroid damage, cancer, and other adverse health effects.

At least one environmental group and some scientists opposed EPA’s approval of the pesticide, alleging that EPA had been secretive during the review process, failing to fully consider the chemical’s health effects, and they pointed to an apparent conflict of interest involving the pesticide’s manufacturer. States like California and Florida had their own concerns about the pesticide’s safety and decided to do their own risk assessments before allowing use of methyl iodide. Florida finished its assessment and approved the use of methyl iodide last July, but not before requiring additional safety measures beyond those required by EPA. California’s assessment is still ongoing, the article notes.

VIB researchers at Ghent University have discovered the substance that governs the formation of root offshoots in plants, and how it works. Root offshoots are vitally important for plants – and for farmers. Plants draw the necessary nutrients from the soil through their roots. Because they do this best with a well-branched root system, plants must form offshoots of their roots at the right moment. The VIB researchers describe how this process is controlled in the prominent professional journal Science. A key player in this process is a protein called ACR4. Depending on the signals that it receives from its environment, this protein triggers the formation of a root offshoot. Now that we know the control mechanism, we can begin to stimulate plant roots to form more, or fewer, offshoots. This can lead to a more ecological agriculture and to the production of better crops at the same time. An efficient network

It is difficult to overstate the importance of plants in our lives − they are responsible for our oxygen and for food, clothing, energy, and countless other things. And in turn, the importance of a plant’s roots is unquestionable: they provide the plant with necessary nutrients and moisture. The more the roots are subdivided, in breadth and depth, the better they can do their work. So, a well-coordinated, controlled formation of root offshoots is crucial to a plant. But, until now, how a plant determines when and where an offshoot should be formed was unknown.

Asymmetric cell division

The presence of stem cells is very important in the development of plants and animals. Stem cells are cells that can transform themselves into various types of cells. In animals, tissues and organs are formed before birth; but in fully-grown plants, stem cells continue to play a major role in the formation of new organs or tissues, such as root offshoots.

These stem cells are found inside the root, and several of them will induce the formation of an offshoot. These ‘root-founder’ cells undergo an asymmetric cell division. In contrast to the usual cell division, which gives rise to two identical cells, asymmetric cell division produces two different cells: a stem cell that is identical to the original cell, and a cell that is ready to become a specialized cell – in this case, a secondary root cell.

The decisive signal

With the aid of the mouse-ear cress (Arabidopsis thaliana), a frequently used model plant, Ive De Smet and Valya Vassileva in Tom Beeckman’s group have been studying how a plant determines which cells will trigger offshoots. To do this, the VIB researchers in Ghent have employed a special technology that makes it possible to make synchronous offshoots develop at different moments. This allowed them to isolate the cells that induce the formation of offshoots. They found out which genes are active in these cells and compared them with the genes that are crucial to normal cell division. In this way, the researchers identified a specific set of genes that control asymmetric cell division and send the signal for the formation of offshoots.

ACR4: control over asymmetric division

The researchers then examined one of these genes more closely. The ACR4 gene contains the DNA code for a receptor, a protein that is often located on the exterior of a cell to pick up signals from the outside and transmit them to the controlling mechanisms within the cell. When the researchers disrupted the function of ACR4 in plant cells, the precisely orchestrated asymmetric cell division was also disturbed. From this finding, De Smet and Vassileva inferred that ACR4 plays a key role in the creation of offshoots. Because the protein has a receptor function, triggering the formation of offshoots depends on its reaction to signals from the environment.

Desired or undesired

With this research, the scientists have discovered a fundamental mechanism − fundamental for the plant, and very important for plant-breeders as well. This new knowledge enables us to promote, or retard, the formation of offshoots − both activities are useful in a large number of applications.

Promoting an extensive root system helps plants absorb nutrients more readily, and thus they need less fertilizer. Such plants can also grow more easily in dry or infertile soils. Furthermore, plants with a well-developed root system are more firmly anchored in the soil and can be used to counteract erosion.

On the other hand, slowing down secondary root formation can be advantageous in tuberous plants, like potatoes or sugar beets. This enables these food crops to invest all their energy in the production of nutrients. Fewer root offshoots also makes it easier for farmers to harvest these crops.

Plant research with medical possibilities?

This plant research sheds light on the control of asymmetric cell division − and this kind of cell division is similar to the cell division of stem cells in animals, too. So, these results can also provide greater insight into how animal stem cells specialize.

For example, irregular cell division plays a role in the development of various types of cancer, and similar control mechanisms might underlie this process as well. This is clearly an important area for future research.

‘Global change, environment and natural resources management, sustainable development, poverty reduction, and environment and human health, are some of the major scientific research challenges currently being tackled by ICSU.  But these issues cannot be solved without understanding the impact of people on these issues and the impact of these issues on people—that is, social science,’ said Anne Whyte, a member of ICSU’s Committee on Scientific Planning and Review (CSPR) and a former Director General for Environment and Natural Resources of the International Development Research Centre (IDRC) in Canada.  The report, ‘Enhancing Involvement of Social Sciences in ICSU’, identifies social sciences as being essential for the implementation of the ICSU Strategic Plan 2006-2011.  Recommendations in the report include: that ICSU continue to encourage the participation of social sciences on its committees, task forces and collaborative research initiatives; stimulate more social sciences unions to join ICSU; and to work with the International Social Sciences Council (ISSC) as a key partner in strengthening international social science of relevance for implementing ICSU’s Strategic Plan.  Whyte said, ‘ICSU’s mission is to strengthen international science for the benefit of society.  To do this, the natural and social sciences must be fully involved; working together to provide knowledge to solve global challenges.’ Heide Hackmann, Secretary-General of the International Social Sciences Council (ISSC) agreed, ‘High quality social scientific knowledge is becoming necessary knowledge for policymakers, business and community leaders, and natural scientists alike.  In this environment the ISSC has taken on the challenge of becoming the major global social scientific player alongside, and in collaboration with, ICSU in addressing key global challenges’.  But it’s not all smooth sailing.  There are barriers that must be overcome: natural and social scientists speak different languages; many institutions are not equipped to deal with interdisciplinary research; and there is resistance among some scientists from both sides of the table.  ‘The key to success is that natural and social scientists must work together on research agenda setting.  One field cannot merely provide services for the other—they both must be involved in setting research goals.  And you need to choose the right people,’ said Roberta Balstad of the Center for Research on Environmental Decisions, at Columbia University in New York, and a member of CSPR.  Over the years, ICSU has actively involved the social sciences, particularly through its global environmental change programmes.  The Earth System Science Partnership (ESSP) successfully integrates natural and social sciences in order to investigate how changes in the Earth System affect global and regional sustainability.  And new ICSU programmes, such as ‘Integrated Research on Disaster Risk’ and ‘Ecosystem Change and Human Well-being’, have involved both the natural and social sciences from the earliest planning stages.  ‘Indeed, it could be argued that ICSU is at a point in its history where it is increasingly dependent on social science to fulfil its mission.  Thus, better integration of the social sciences into ICSU is no longer an option, it is a necessity,’ said Balstad.

Children are exposed to a wide range of environmental threats that can affect their health and development early in life, throughout their youth and into adulthood. Writing in a forthcoming issue of the International Journal of Environmental Health scientists from the World Health Organization and Boston University suggest that it is time for both industrialized and developing countries to assess the environmental burden of childhood diseases with the aim of improving children’s environments.

Maria Neira, Fiona Gore, Marie-Noël Bruné, and Jenny Pronczuk de Garbino of the Department of Public Health and Environment, at the World Health Organization, in Geneva, Switzerland, working with Tom Hudson of Boston University, highlight a recent WHO report that estimated that almost one in four illnesses has an environmental cause. Such high levels of disease kill more than ten million children each year and are, the team says, unacceptable.

They point out that environmental hazards are multiplying and becoming more visible because of environmental change, rapid population growth, overcrowding, and the speedy industrialization uncontrolled pollution of many regions. Those environmental factors that have the greatest disease burden lead to diarrheal diseases, lower respiratory infections and malaria, as well as malnutrition, poisonings, and perinatal conditions.

Work must now be done, they stress, to distinguish the main environmental threats affecting children’s health so that nations can identify the various factors and address them through remediation and education through better-informed policy-making decisions. Factors such as polluted indoor and outdoor air, contaminated water and lack of adequate sanitation, chemical and other toxic hazards, disease vectors, ultraviolet radiation and degraded ecosystems are all important environmental risk factors affecting children around the world.

It is crucial to recognize that children are more vulnerable than adults to environmental risks because they are generally constantly growing and more active and so breathe more air, consume more food and drink more water weight for weight than adults. The child’s developing central nervous, immune, reproductive, and digestive systems, are also more susceptible to irreversible damage from toxins and pollutants.

They also point out that two other important factors affect the environmental risks experienced by children differently from adults. First, children play and crawl on the ground where they are exposed to dust and chemicals that accumulate on floors and soils. Secondly, they have far less control over their environment than adults have and are usually less aware of risks and unable to make choices to protect their health.

The team hopes that taking action to address all such issues will ultimately reduce the burden of disease affecting children globally and so contribute towards the Millennium Development Goals (MDGs).

Environmental gains derived from the use of nanomaterials may be offset in part by the process used to manufacture them, according to research published in a special issue of the Journal of Industrial Ecology.Hatice Şengül and colleagues at the University of Illinois at Chicago assert that strict material purity requirements, lower tolerances for defects and lower yields of manufacturing processes may lead to greater environmental burdens than those associated with conventional manufacturing. In a separate study of carbon nanofiber production, Vikas Khanna and colleagues at Ohio State University found, for example, that the life-cycle environmental impacts may be as much as 100 times greater per unit of weight than those of traditional materials, potentially offsetting some of the environmental benefits of the small size of nanomaterials.

Materials engineered at dimensions of 1 to 100 nanometers¬ (1 to100 billionths of a meter) ¬exhibit novel physical, chemical and biological characteristics, opening possibilities for stunning innovations in medicine, manufacturing and a host of other sectors of the economy. Because small quantities of nanomaterials can accomplish the tasks of much larger amounts of conventional materials, the expectation has been that nanomaterials will lower energy and resource use and the pollution that accompanies them. The possibility of constructing miniature devices atom-by-atom has also given rise to expectations that precision in nanomanufacturing will lead to less waste and cleaner processes.

“Research in this issue reveals the potential of environmental impacts from nanomanufacturing to offset the benefits of using lighter nanomaterials,” says Gus Speth, dean of the Yale School of Forestry & Environmental Studies. “To date, most attention has focused on the possible toxic effects of exposure to nanoparticles¬ and appropriately so. But considerations of pollution and energy use arising from the production technologies used to make nanomaterials need attention as well.”

Other topics explored in the special issue include:

• Approaches for identifying and reducing the life cycle hazards of nanomaterials
• Quantified life cycle energy requirements and environmental impacts from nanomaterials
• Tradeoffs between nanomanufacturing costs and occupational exposure to nanoparticles
• Efficiency of techniques for nanomaterials synthesis
• Improvement of the sustainability of bio-based products through nanotechnology
• Industrial frameworks for responsible nanotechnology
• Industrial and public perception about the risks and benefits of nanomaterials
• Governance and regulation of nanotechnology

Industrial ecology is a field that examines the opportunities for sustainable production and consumption, emphasizing the importance of a systems view of environmental threats and remedies. “Through the use of tools such as life cycle assessment, green chemistry and pollution prevention, industrial ecology takes a broad and deliberate view of environmental challenges,” states Reid Lifset, editor-in-chief of the Journal of Industrial Ecology. “This special issue shows the power of this approach.”

The practice of no-till has increased considerably during the past 20 yr. The absence of tillage coupled with the accumulation of crop residues at the soil surface modifies several soil properties but also influence nitrogen dynamics. Soils under no-till usually host a more abundant and diverse biota and are less prone to erosion, water loss, and structural breakdown than tilled soils. Their organic matter content is also often increased. In addition, no-till is proposed as a measure to mitigate the increase in atmospheric carbon dioxide concentration. To assess the net effect of no-till on greenhouse gas emissions, other gases also have to be examined.

The authors concluded that their investigation indicates “that no-till can result in incremental nitrous oxide emissions that can more than offset the soil carbon dioxide sink during the first 5 yr after adoption of this soil conservation practice in a heavy clay soil…. Consequently, the potential of no-till for decreasing net greenhouse gas emissions may be limited in fine-textured soils that are prone to high water content and reduced aeration”.

Differences in the response of nitrous oxide emissions when converting to a no-till practice between the clay and loam soils were striking. While emissions were similar in both tillage treatments in the well-aerated loam, they more than doubled under no-till in the clay soil. Differences in emissions between tillage practices in the clay soil were observed in spring and summer but were greater and more consistent in the fall after plowing operations. The influence of plowing on nitrous oxide flux in the heavy clay soil was likely the result of increased soil porosity that maintained soil aeration and water content at levels restricting denitrification and nitrous oxide production. Accordingly, denitrification rates are usually increased in denser and wetter no-till soils and the anticipated benefits of the adoption of soil conservation practices on net soil-surface greenhouse gas emissions could be offset by increases in nitrous oxide emissions.

Predicting the impacts of no-till on nitrous oxide emissions is required for a full assessment of the influence of this practice on net greenhouse gas emissions. Researchers at Agriculture and Agri-Food Canada are pursuing their investigations to understand the factors that control the mechanisms leading to nitrous oxide emissions under contrasting soil tillage practices.  Specifically, they now focus their efforts on the role of soil aeration with the hypothesis that the “adoption of no-till only increases nitrous oxide emissions in poorly aerated soils”. Field studies and mathematical modeling of the impact of no-till on soil nitrous oxide emission has yielded contrasting results and an explanation of the high intersite variability of the influence of no-till on soil nitrous oxide emissions is still lacking. 

Each year hundreds of thousands of people are killed and millions injured, displaced or have their livelihoods destroyed by natural disasters.  There has been a dramatic increase in the frequency of disasters—when communities are overwhelmed and need outside assistance—from around 30 per year in the 1950s to more than 470 per year since the beginning of this century.  ‘Integrated Research on Disaster Risk (IRDR) will provide an enhanced capacity around the world to address hazards and make better decisions to reduce their impacts’, said Gordon McBean, Canadian climatologist and Chair of the ICSU Planning Group for Hazards.  ‘In 10 years, as a result of this programme, we would like to see a reduction in loss of life, fewer people adversely impacted, and wiser investments and choices made by governments, the private sector and civil society’.  Invariably, it is the poorest countries that are least well equipped to cope with disasters and which suffer the most.  ‘Disaster events in a region like Africa can have an enormous impact on economic activities and livelihoods.  Mozambique is especially vulnerable to disasters, particularly those triggered by weather and climate.  IRDR will provide knowledge that will support better decision making processes within the country, paving the way for improved disaster risk management,’ said Filipe Domingos Freires Lucio, a member of the ICSU Planning Group and a former Director-General of the National Institute of Meteorology of Mozambique, now at the World Meteorological Organization.  ‘With the predicted impacts of climate change, countries like Mozambique have no alternative but to integrate disaster risk reduction in development planning and climate change adaptation.’ The new programme, which builds on existing research activities, will address the impacts of disasters on all scales, from local to global.  It will combine experience and expertise from around the world, and provide an unprecedented opportunity for the natural and social sciences to work together as never before.  McBean said, ‘A truly global, interdisciplinary approach is essential if we are to provide the knowledge that can avoid unnecessary losses and save thousands, or even millions of lives’.  IRDR will focus on all hazards related to geophysical, oceanographic, climate and weather trigger events—and even space weather and impact by near-Earth objects.  The programme will also take account of the effects of human activities in creating hazards—or making them worse.

When reef fish get a mouthful of sand, coral reefs can drown.

That’s the latest startling evidence to emerge from research into the likely fate of reefs under climate change and rising sea levels, at the ARC Centre of Excellence for Coral Reef Studies (CoECRS).

“We’ve known for a while that having a lot of sediment in the water is bad for corals and can smother them.  What we didn’t realize is how permanent this state of affairs can become, to the point where it may prevent the corals ever re-establishing,” says Professor David Bellwood of CoECRS and James Cook University.

The killer blow for a degraded coral reef is a thick mat of sand and weeds that shrouds the rocky surfaces on which the corals would normally grow, preventing them from re-establishing.  This gritty algal ‘turf’ has shown itself to be remarkably hardy and, once in place, makes it almost impossible for the corals to return.

If sea levels rise, then the smothered reef ‘drowns’ and never recovers, Prof, Bellwood says.  “We know this from geological history, at the time of previous sea level rises.  The reason we are doing the work is to see whether or not coral reefs will be able to keep up with rising sea levels under climate change.”

But Prof.  Bellwood and colleague Dr Chris Fulton from the Australian National University have also uncovered a remarkable link in the chain which explains why the algal turf can win in its ‘turf war’ with the corals.

When the water is thick with sediment and it settles on the seaweeds, herbivorous reef fish turn up their noses at the gritty food, much as humans disdain a sandwich that has been dropped on a sandy beach.

“Remarkably we found that when there is little sediment around and plenty of fish, the fish ‘mowed’ the weeds very fast, eating two thirds of their length in about 4 hours.  This action by fish in keeping the algal turf down gives the corals a chance to re-establish” said Dr Fulton.

“But if there is a lot of sediment in the water, the fish go off their feed, the weeds grow, more sand settles – and the murky shroud that smothers the reef becomes more stable, often permanent.  Then, when sea levels rise, the reef drowns.”

Prof.  Bellwood says that in many cases the sediment is generated naturally by the reef itself, particles are swept into its back lagoon and then stirred up by wind, tide and wave to settle on the turf-covered flats.  “In those cases it is almost like the reef defecating onto itself,” he adds.

In other cases the sediment is released from the land, often as a result of human activity such as farming, grazing, land clearing or construction.

In either case, if there is enough sediment in the water to settle on the seaweed, it turns the weed-eating fish off their meal.  “We’re not entirely sure why this is it may be that the sediment acts as an antacid and gives the fish indigestion by preventing their stomach acids digesting their food.  Or it may simply be that fish, like people, don’t appreciate a mouthful of sand and mud.”

There is not a lot that humans can do to disrupt the natural processes that cause reefs to smother under stable algal turfs, then drown as sea levels rise, Prof.  Bellwood says.

However, he adds, there is plenty we can do to reduce our own impact on the process by checking the flow of erosion off the land onto coral reefs, and by ensuring that populations of weed-eating fish are maintained at levels high enough to control the weeds and give the corals an even chance of making a comeback.

In one of the first comparisons of its kind, researchers have demonstrated that wetlands in tropical areas are able to absorb and hold onto about 80 percent more carbon than can wetlands in temperate zones.

The scientists extracted soil cores from wetlands in Costa Rica and in Ohio and analyzed the contents of the sediment from the past 40 years.  Based on their analysis, they estimated that the tropical wetland accumulated a little over 1 ton of carbon per acre per year, and the temperate wetland accumulated .6 tons of carbon per acre per year.  William Mitsch

The temperate Ohio wetland in the study covers almost 140 acres, meaning it sequesters 80 tons of carbon per year.  The tropical wetland covers nearly 290 acres and stores 300 tons of carbon each year.

“Finding out how much carbon has accumulated over a specific time period gives us an indication of the average rate of carbon sequestration, telling us how valuable each wetland is as a carbon sink,” said William Mitsch, senior author of the study and an environment and natural resources professor at Ohio State University.  “We already know wetlands are outstanding coastal protection systems, and yet wetlands continue to be destroyed around the planet.  Showing that wetlands are gigantic carbon sequestration machines might end up being the most convincing reason yet to preserve them.”

Mitsch, also director of the Wilma H. Schiermeier Olentangy River Wetland Research Park at Ohio State, conducted the study with graduate student Blanca Bernal, who presented a poster on this research Wednesday (10/8) at the Geological Society of America joint meeting in Houston.

Often called the “kidneys” of the environment, wetlands act as buffer zones between land and waterways.  In addition to absorbing carbon and holding onto it for years, wetlands filter out chemicals in water that runs off from farm fields, roads, parking lots and other surfaces.

But wetlands are also a natural source of methane, and bacteria present during the decay of organic material cause wetlands to release this greenhouse gas into the atmosphere.

“A big issue in wetland science is how carbon sequestration balances against the release of greenhouse gases,” Mitsch said.  “Methane is a more effective greenhouse gas than is carbon dioxide in terms of how much radiation it absorbs, but it also oxidizes in the atmosphere.  Carbon dioxide does not degrade – it is an end product.  If you take that into account, I think wetlands are very effective systems for sequestering carbon.”

Mitsch and Bernal collected soil cores from Old Woman Creek, a freshwater wetland near Lake Erie in northern Ohio, and from a similar flow-through wetland located at EARTH University in northeastern Costa Rica.  Old Woman Creek had accumulated between 16 and 18 centimeters (about 7 inches) of sediment since 1964, while the Costa Rican wetland accumulated between 30 and 38 centimeters (12 to 15 inches) of sediment during the same time period.

To determine the age of the sediments, the researchers used radiometric dating with cesium-137.  Above-ground nuclear testing in the mid-20th century left behind the cesium-137 compound as a marker in sediments throughout the world.  Based on how deep cesium-137 was detected in the soil cores, the researchers were able to date sediment from each wetland that has built up since 1964, the year the concentration of the compound reached its peak.

The tropical wetland sediment was more densely packed with carbon.  Its average carbon density was 110 grams of carbon per kilogram of soil (almost 1.8 ounces for every pound of soil), while the Ohio wetland’s average carbon density was less than half that, 53 grams of carbon per kilogram of soil (.86 ounces per pound).

Mitsch and Bernal plan to conduct additional comparisons of carbon sequestration in wetlands from different climates to look for patterns that might inform policymakers who are exploring carbon storage options across the world as a strategy to offset greenhouse gas emissions.

Earlier this summer, the U.S. Supreme Court agreed to review a series of lower court rulings that restrict the Navy’s use of sonar in submarine detection training exercises off the coast of Southern California.  The court is due to hear the case after its term begins again this month.

For many years, professor Chris Parsons has been tracking the patterns of mass whale strandings around the world.  In his most recent paper, “Navy Sonar and Cetaceans: Just how much does the gun need to smoke before we act?”  Parsons and his co-authors bring together all of the major whale and dolphin strandings in the past eight years and discuss the different kinds of species that have been affected worldwide.  They also strongly argue for stricter environmental policies related to this issue.

“We are increasingly finding if there is a beaked whale mass stranding, there is a military exercise in the area,” says Parsons.  “Sonar is killing more whales than we know about.”

Parsons is a national delegate for the International Whaling Commission’s scientific and conservation committees, and on the board of directors of the marine section of the Society for Conservation Biology.  He has been involved in whale and dolphin research for more than a decade and has conducted projects in South Africa, India, China and the Caribbean as well as the United Kingdom.

Though Parsons believes that there is a good chance the U.S. Supreme Court will rule in favor of the Navy, he thinks there is a chance for a win-win situation on both sides.

“If the Navy uses proper mitigation efforts, it can still perform its exercises and affect less of the whale population,” he says.  However, he argues they need to avoid sensitive areas completely, and have trained, experienced whale experts as lookouts when performing these exercises—”not just someone who has watched a 45-minute DVD, which is sadly the only training most naval lookouts get with respect to finding and detecting whales.”

Even with all these efforts, however, Parsons worries that sonar is affecting many more whales than we even know about.  “Eventually the Navy may have to reconsider the use of certain types of sonar.  Without strict mitigation, they could be wiping out entire populations of whales, and seriously depleting others.”