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US river flows altered by land and water management

2010-11-09T10:28:00.000+05:30

Credit: USGSThe amount of water flowing in streams and rivers has been significantly altered in nearly 90 percent of waters that were assessed in a new nationwide USGS study. Flow alterations are a primary contributor to degraded river ecosystems and loss of native species.

"This USGS assessment provides the most geographically extensive analysis to date of stream flow alteration," said Bill Werkheiser, USGS Associate Director for Water. "Findings show the pervasiveness of stream flow alteration resulting from land and water management, the significant impact of altered stream flow on aquatic organisms, and the importance of considering this factor for sustaining and restoring the health of the Nation's streams and ecosystems."

Flows are altered by a variety of land- and water-management activities, including reservoirs, diversions, subsurface tile drains, groundwater withdrawals, wastewater inputs, and impervious surfaces, such as parking lots, sidewalks and roads.

"Altered river flows lead to the loss of native fish and invertebrate species whose survival and reproduction are tightly linked to specific flow conditions," said Daren Carlisle, USGS ecologist and lead scientist on this study. "These consequences can also affect water quality, recreational opportunities and the maintenance of sport fish populations."

For example, in streams with severely diminished flow, native trout, a popular sport fish that requires fast-flowing streams with gravel bottoms, are replaced by less desirable non-native species, such as carp. Overall, the USGS study indicated that streams with diminished flow contained aquatic communities that prefer slow moving currents more characteristic of lake or pond habitats.

"Management practices related to water demand continue to alter stream flows in many places," said Jeff Ostermiller, Water Quality Manager with the Utah Division of Water Quality. "Understanding the ecological effects of these flow alterations helps water managers develop effective strategies to ensure that water remains sufficiently clean and abundant to support fisheries and recreation opportunities, while simultaneously supporting economic development."

Annual and seasonal cycles of water flows — particularly the low and high flows — shape ecological processes in rivers and streams. An adequate minimum flow is important to maintain suitable water conditions and habitat for fish and other aquatic life. High flows are important because they replenish floodplains and flush out accumulated sediment that can degrade habitat.

"While this study provided the first, national assessment of flow alteration, focused studies within specific geographic regions will provide a better understanding of the ecological effects of altered stream flows, which can be more effectively applied to local water management challenges," said Carlisle.

The severity and type of stream flow alteration varies among regions, due to natural landscape features, land practices, degree of development, and water demand. Differences are especially large between arid and wet climates. In wet climates, watershed management is often focused on flood control, which can result in lower maximum flows and higher minimum flows. Extremely low flows are the greatest concern in arid climates, in large part due to groundwater withdrawals and high water use for irrigation.

The study identified over 1,000 unimpaired streams to use as reference points to create stream flow models. The models were applied to estimate expected flows for 2,888 additional streams where the USGS had flow monitoring gauges from 1980-2007. The estimated values for the 2,888 streams were compared to actual, measured flows to determine the degree to which streams have been altered.

Contaminants in groundwater used for public supply

2010-05-23T17:41:00.001+05:30

More than 20 per cent of untreated water samples from 932 public wells across the United States contained at least one contaminant at levels of potential health concern, according to a new study by the U.S. Geological Survey.

About 105 million people — or more than one-third of the nation’s population — receive their drinking water from one of the 140,000 public water systems across the United States that rely on groundwater pumped from public wells. The USGS study focused primarily on source (untreated) water collected from public wells before treatment or blending rather than the finished (treated) drinking water that water utilities deliver to their customers.

“By focusing primarily on source-water quality, and by testing for many contaminants that are not regulated in drinking water, this USGS study complements the extensive monitoring of public water systems that is routinely conducted for regulatory and compliance purposes by federal, state and local drinking-water programs,” said Matthew C. Larsen, USGS Associate Director for Water. “Findings assist water utility managers and regulators in making decisions about future monitoring needs and drinking-water issues.”

Findings showed that naturally occurring contaminants, such as radon and arsenic, accounted for about three-quarters of contaminant concentrations greater than human-health benchmarks in untreated source water. Naturally occurring contaminants are mostly derived from the natural geologic materials that make up the aquifers from which well water is withdrawn.

Man-made contaminants were also found in untreated water sampled from the public wells, including herbicides, insecticides, solvents, disinfection by-products, nitrate, and gasoline chemicals. Man-made contaminants accounted for about one-quarter of contaminant concentrations greater than human-health benchmarks, but were detected in 64 per cent of the samples, predominantly in samples from unconfined aquifers.

“Detections of contaminants do not necessarily indicate a concern for human health because USGS analytical methods can detect many contaminants at concentrations that are 100-fold to 1,000-fold lower than human-health benchmarks,” said lead scientist Patricia Toccalino. “Assessing contaminants in these small amounts helps to track emerging issues in our water resources and to identify contaminants that may warrant inclusion in future monitoring.”

Scientists tested water samples for 337 properties and chemical contaminants, including nutrients, radionuclides, trace elements, pesticides, solvents, gasoline hydrocarbons, disinfection by-products and manufacturing additives. This study did not assess pharmaceuticals or hormones.

Most (279) of the contaminants analysed in this study are not federally regulated in finished drinking water under the Safe Drinking Water Act.

The USGS also sampled paired source and finished (treated) water from a smaller subset of 94 public wells. Findings showed that many man-made organic contaminants detected in source water generally were detected in finished water at similar concentrations. Organic contaminants detected in both treated and source water typically were detected at concentrations well below human-health benchmarks, however.

Additionally, the study shows that contaminants found in public wells usually co-occurred with other contaminants as mixtures. Mixtures can be a concern because the total combined toxicity of contaminants in water may be greater than that of any single contaminant. Mixtures of contaminants with concentrations approaching benchmarks were found in 84 percent of wells, but mixtures of contaminants above health benchmarks were found less frequently, in 4 percent of wells.

This USGS study identifies which contaminant mixtures may be of most concern in groundwater used for public-water supply and can help human-health researchers to target and prioritize toxicity assessments of contaminant mixtures. The USGS report identifies the need for continued research because relatively little is known about the potential health effects of most mixtures of contaminants.

Wells included in this study are located in 41 states and withdraw water from parts of 30 regionally extensive aquifers, which constitute about one-half of the principal aquifers used for water supply in the United States.

Human-health benchmarks used in this study include U.S. Environmental Protection Agency Maximum Contaminant Levels for regulated contaminants and USGS Health-Based Screening Levels for unregulated contaminants, which are non-enforceable guidelines developed by the USGS in collaboration with the EPA and other water partners.
Treated drinking water from public wells is regulated under the Safe Drinking Water Act. Water utilities, however, are not required to treat water for unregulated contaminants. The EPA uses USGS information on the occurrence of unregulated contaminants to identify contaminants that may require drinking-water regulation in the future.

This study and additional information about public wells can be found on the Quality of Water from Public-Supply Wells in the United States website.

New study shows rising water temperatures in US streams and rivers

2010-04-06T19:42:00.000+05:30

New research by a team of ecologists and hydrologists shows that water temperatures are increasing in many streams and rivers throughout the United States. The research, published in the journal Frontiers in Ecology and the Environment, documents that 20 major U.S. streams and rivers – including such prominent rivers as the Colorado, Potomac, Delaware, and Hudson – have shown statistically significant long-term warming.

By analyzing historical records from 40 sites located throughout the United States, the team found that annual mean water temperatures increased by 0.02-0.14°F (0.009-0.077°C) per year. Long-term increases in stream water temperatures were typically correlated with increases in air temperatures, and rates of warming were most rapid in urbanized areas.

"Warming waters can impact the basic ecological processes taking place in our nation's rivers and streams," said Dr. Sujay Kaushal of the University of Maryland Center for Environmental Science (UMCES) and lead author of the study. "Long-term temperature increases can impact aquatic biodiversity, biological productivity, and the cycling of contaminants through the ecosystem."

"It's both surprising and remarkable that so many diverse river systems in North America behaved in concert with respect to warming," said Dr. David Secor of the UMCES Chesapeake Biological Laboratory whose work focused on Maryland's Patuxent River, where he has noted a 3°F increase since 1939.

The analysis indicates that 20 of the 40 streams studied showed statistically significant long term warming trends, while an additional 13 showed temperature increases that were not statistically significant. Two rivers showed significant temperature decreases. The longest record of increase was observed for the Hudson River at Poughkeepsie, New York. The most rapid rate of increase was recorded for the Delaware River near Chester, Pennsylvania.

"We are seeing the largest increases in the most highly urbanized areas which lead us to believe that the one-two punch of development and global warming could have a tremendous impact on stream and river ecosystem health," said Dr. Kaushal.

Given long-term global warming and "urban heat island effects" related to the abundance of buildings, roads, concrete, and asphalt, the authors point out that conserving riparian forests, reducing impervious surfaces, adopting "green" infrastructure practices, and reducing greenhouse gas emissions can help reduce increased water temperatures.

New approach to water desalination

2010-03-26T00:33:00.000+05:30

A single unit of the new desalination device, fabricated on a layer of silicone. In the Y-shaped channel (in red), seawater enters from the right, and fresh water leaves through the lower channel at left, while concentrated brine leaves through the upper channel.
Photo: Patrick Gillooly/MITCould lead to small, portable units for disaster sites or remote locations.

A new approach to desalination being developed by researchers at MIT and in Korea could lead to small, portable desalination units that could be powered by solar cells or batteries and could deliver enough fresh water to supply the needs of a family or small village. As an added bonus, the system would also remove many contaminants, viruses and bacteria at the same time.

The new approach, called ion concentration polarization, is described in a paper by Postdoctoral Associate Sung Jae Kim and Associate Professor Jongyoon Han, both in MIT’s Department of Electrical Engineering and Computer Science, and colleagues in Korea.

The system works at a microscopic scale, using fabrication methods developed for microfluidics devices – similar to the manufacture of microchips, but using materials such as silicone (synthetic rubber). Each individual device would only process minute amounts of water, but a large number of them – the researchers envision an array with 1,600 units fabricated on an 8-inch-diameter wafer – could produce about 15 liters of water per hour, enough to provide drinking water for several people. The whole unit could be self-contained and driven by gravity – salt water would be poured in at the top, and fresh water and concentrated brine collected from two outlets at the bottom.

That small size could actually be an advantage for some applications, Kim explains. For example, in an emergency situation like Haiti’s earthquake aftermath, the delivery infrastructure to get fresh water to the people who need it was largely lacking, so small, portable units that individuals could carry would have been especially useful.

Jongyoon Han, left, and Sung Jae Kim explain their new process for water desalination. In foreground is a microscope used to observe the prototype unit in action.
Photo: Patrick Gillooly/MITSo far, the researchers have successfully tested a single unit, using seawater they collected from a Massachusetts beach. The water was then deliberately contaminated with small plastic particles, protein and human blood. The unit removed more than 99 percent of the salt and other contaminants. “We clearly demonstrated that we can do it at the unit chip level,” says Kim.

While the amount of electricity required by this method is actually slightly more than for present large-scale methods such as reverse osmosis, there is no other method that can produce small-scale desalination with anywhere near this level of efficiency, the researchers say. If properly engineered, the proposed system would only use about as much power as a conventional lightbulb.

The basic principle that makes the system possible, called ion concentration polarization, is a ubiquitous phenomenon that occurs near ion-selective materials (such as Nafion, often used in fuel cells) or electrodes, and this team and other researchers have been applying the phenomenon for other applications such as biomolecule preconcentration. . This application to water purification has not been attempted before, however.

Why it matters: Potable water is often in high demand and short supply following a natural disaster like the Haiti earthquake or Hurricane Katrina. In both of those instances, the disaster zones were near the sea, but converting salty seawater to potable fresh water usually requires a large amount of dependable electrical power and large-scale desalination plants – neither of which were available in the disaster areas.

One of the leading desalination methods, called reverse osmosis, uses membranes that filter out the salt, but these require strong pumps to maintain the high pressure needed to push the water through the membrane, and are subject to fouling and blockage of the pores in the membrane by salt and contaminants. The new system separates salts and microbes from the water by electrostatically repelling them away from the ion-selective membrane in the system– so the flowing water never needs to pass through a membrane. That should eliminate the need for high pressure and the problems of fouling, the researchers say.

Next steps: Having proved the principle in a single-unit device, Kim and Han plan to produce a 100-unit device to demonstrate the scaling-up of the process, followed by a 10,000-unit system. They expect it will take about two years before the system will be ready to develop as a product. “After that,” says Kim, “we’ll know if it’s possible” for this to work as a robust, portable system, “and what problems might need to be worked on.”

Tree roots planted to decontaminate hundreds of wells

2010-03-23T20:23:00.006+05:30

A girl drinking purified water in Kalpitiya.
(Photo: UNDP/CWI/SGP)On the Kalpitiya Peninsula, located on Sri Lanka’s western coast, relatively large scale irrigated monoculture agriculture is practiced. The associated heavy use of fertilizers has led to the contamination of farm and domestic wells with nitrates, which poses the risk of methaemoglobinemia (blue baby syndrome) and other concerns.

Building on successful bioremediation of wells demonstrated by the Neo Synthesis Research Centre, which achieved significant improvement in water quality, UNDP’s Community Water Initiative extended the technology to 39 public and 13 private wells serving more than 10,000 people, including church, hospital and school wells. Furthermore, the wells at St. Anne’s Church in Talawila provide water to up to 1.5 million pilgrims and visitors who visit the ancient Christian shrine each year.

Bioremediation improves water quality through the removal of contaminants from water by plant roots and soil microorganisms. In the course of four years, water quality testing showed significant reductions in levels of nitrate, nitrites, and chloride. The improved land management techniques demonstrated around wells and in home gardens increased soil fertility, leading to increased harvests and better household nutrition. The project’s methodology has been applied in other regions, such as the tsunami-affected Kalmunai on the eastern coast of Sri Lanka, leading to the purifying of 1,000 wells.

Nanotechnology could help Arab region

2010-02-21T18:16:00.000+05:30

"Nanotechnology could aid the future of development of the Arab region," says Mohamed H.A. Hassan, executive director of TWAS, the academy of sciences for the developing world, and president of the African Academy of Sciences. Hassan made his remarks at a panel session, "Re-emergence of Science, Technology and Education as Priorities in the Arab World," taking place at the AAAS's annual meeting in San Diego.

"The Arab region, home to some 300 million people, faces a host of daunting development challenges," Hassan notes. "Three of the most fundamental involve ensuring adequate supplies of water, energy and food." Advances in nanotechnology, he says, "could help achieve progress by helping to address each of these challenges."

For example, he notes that nano-filters could enhance the efficiency of desalinisation plants, helping to ensure adequate supplies of water in the region. Similarly, nanotechnology could improve the capacity of solar panels. More abundant supplies of water and energy, Hassan adds, "would boost irrigation and help increase agricultural output."

But none of this is likely to take place, he cautions, "without a strong commitment to training the next generation of scientists." The Arab region has some inherent demographic advantages when seeking to address human resource issues related to scientific capacity building. "Sixty percent of the population is less than 25 years old," he says.

"Yet, the region has some glaring weaknesses as well," he says. "Arab countries spend just 0.3% of their gross domestic product (GDP) on science and technology, compared to 1% in a growing number of developing countries and 2% to 3% in many developed countries. Scientists in the region publish less than 1% of the world's peer-reviewed scientific articles.

Hassan points to some encouraging recent signs, however. "A growing number of countries have invested in high-profile projects designed to quickly build scientific capacity in critical areas of science and technology." He cites, for example, the opening of King Abdullah University of Science and Technology (KAUST) for post-graduate studies in Saudi Arabia and Qatar's Science and Technology Park (QSTP).

But much more will need to be done, he says. To boost science, he calls on each Arab country "to create at least one world-class university" and "build at least one world-class state-of-the-art science centre." Hassan also believes the national merit-based academies in the region should become more engaged in their societies and stronger advocates for science education and science-based development.

He readily acknowledges that "with so many immediate challenges facing the region, it's difficult for governments to engage in long-term strategies for development." But he says that "unless countries within the Arab region make a sustained effort to build scientific capacity, they will find themselves unable to overcome the 'knowledge-deficit' obstacles that have impeded economic development for far too long."

"Nanotechnology may not be the first thing that comes to mind in discussions dealing with strategies to address the Arab region's most pressing challenges," Hassan concludes. But such investments in science and technology could be a key to the region's future."

Decade-old dream comes true for Lake Chad

2010-02-12T00:19:00.000+05:30

World Wetlands Day is being celebrated with the full recognition of Africa’s Lake Chad as a wetland of international significance, fulfilling an agreement made a decade ago by the four nations that share it.

The declaration by the Cameroon Republic that its portion of Africa’s fourth largest lake is being declared a wetland of international importance under the 1971 Ramsar Convention on Wetlands follows similar declarations by Niger and Chad (both in 2001) and Nigeria (2008).

Cameroon’s announcement will also clear the way for Lake Chad to become the largest of the world’s few recognised trans-boundary international wetlands, where countries make a formal agreement for joint protection and management of shared aquatic ecosystems and their resources.

“Lake Chad’s inscription as only the 13th trans-boundary formally recognised wetland is highly significant as 11 of the areas so far declared are in Europe,” said Denis Landenbergue, WWF International’s wetlands conservation manager. “Lake Chad joins the Saloum Delta shared by Senegal and Gambia as only the second such site in Africa.”

Lake Chad is the remnant of a much vaster lake known as Mega-Chad which 22,000 years ago drained a greener Sahara and was three times the size of Lake Victoria, now Africa’s largest lake. It is now the focal point of life in a huge expanse of arid Sahelian Africa. Technically best described as an inland delta, the new internationally protected wetland covers 2.6 million hectares vital to countless birds as well as endangered otters, gazelles and elephants. The Lake is also home to hippopotamuses and Nile Crocodiles.

The Lake Chad basin is home to over 20 million people with the majority dependent on the lake and other wetlands for their fishing, hunting, farming and grazing. But the Lake Chad basin is recognised as highly challenged by climate change, desertification and unsustainable management of water resources and fisheries.

“Lake Chad is one of the largest and most important of the vital watering points for migratory birds from Europe and west Asia that each year cross the Sahara and it is also where many of them stop and stay for the winter” said Landenbergue.

In another World Wetlands Day highlight, Algeria moved to designate several of the wetlands vital to many of the same migrating birds on the northern side of the Sahara. Ceremonies this Sunday in Algeria will mark the designation of five new Wetlands of International Importance for the country.

In Cameroon, adding the completing piece to the Lake Chad world wetland is but the latest of a string of Ramsar declarations over recent years.

“From the Mangrove forests of the Ntem Estuary, curling through the crater lakes of the Cameroon Highlands and into Waza Logone flood plain and the Lake Chad basin, Cameroon’s wetlands constitute a haven for biological diversity,” said Natasha Quist, head of WWF’s Central African Regional Programme.

WWF, which partnered with the Lake Chad Basin Commission, the Ramsar Convention and the Global Environment Facility on projects in Lake Chad and with the governments on achieving the declaration, said the challenge now was to “turn the promise of protection for Lake Chad into a reality for the millions that depend on it.”

World Wetlands Day celebrates the signing of one of the Convention on Wetlands on 2 February 1971 in the Caspian Sea city of Ramsar, Iran. The Convention, known generally as the Ramsar Convention, followed rising concern over the fate of migratory birds and was the first international environment treaty.

Solar-powered irrigation systems improve diet and income in rural sub-Saharan Africa

2010-01-13T18:43:00.002+05:30

The crops on this small farm in rural Benin are watered by a solar-powered drip irrigation system. Photo: Marshall BurkeSun-powered pumps installed in remote villages in Benin provide a cost-effective way of delivering irrigation water, particularly during the long dry season.

Solar-powered drip irrigation systems significantly enhance household incomes and nutritional intake of villagers in arid sub-Saharan Africa, according to a new Stanford University study to be published in the Proceedings of the National Academy of Sciences (PNAS). The study found that solar-powered pumps installed in remote villages in the West African nation of Benin provide a cost-effective way of delivering much-needed irrigation water, particularly during the long dry season. The results are scheduled to be published the week of Jan. 4 in the online edition of PNAS.

"Our case study on women's farming groups in rural Benin revealed solar-powered drip irrigation – a clean, cost-competitive technology – significantly improved nutrition and food security as well as household incomes in one year," said lead author Jennifer Burney, a postdoctoral scholar with the Program on Food Security and the Environment at Stanford.

"Solar-powered drip irrigation systems break seasonal rainfall dependence, which typically limits farmers to a three- to six-month growing season, and support the production of diversified, high-value crops in rural Africa," Burney added.

She and her co-authors noted that much of sub-Saharan Africa's rural population is considered "food insecure," surviving on less than $1 per person per day. "And whereas most are engaged in agricultural production as their main livelihood, they still spend 50 to 80 percent of their income on food, and are often net consumers of food," they wrote.

Benin pilot project

In 2007, with support from Stanford's Woods Institute for the Environment, Burney and her colleagues partnered with the nonprofit Solar Electric Light Fund (SELF) on a pilot irrigation project in rural Benin. SELF financed and led the installation of three solar-powered drip irrigation systems in two villages in Benin's Kalalé district. Each system is used by a local women's agricultural group, which typically consists of 30 to 35 women who share the maintenance costs of the new irrigation technology.

"In Kalalé, 80 percent of the villagers live on less than $1.25 per day, which is representative of a number of poor, rural communities in Africa," said study co-author Rosamond Naylor, director of the Program on Food Security and the Environment and a professor of environmental Earth system science at Stanford.

In rural Benin, women and girls traditionally are responsible for hauling water by hand, often from very long distances. The solar-powered irrigation systems were designed to free them from hauling water to grow vegetable crops, particularly during the dry season.

To measure the impact of the solar-powered drip irrigation technology, the researchers monitored the agricultural groups using the new irrigation systems, as well as two "control" villages where women continued growing vegetables in traditional hand-watered gardens. Household surveys were conducted at the start of the project in November 2007 and again in November 2008.

Nutrition and income

The results were striking. "In just one year, we saw that photovoltaic drip irrigation systems had important implications for food and nutrition security, as well as household income," Burney said.

The three solar-powered irrigation systems supplied on average 1.9 metric tons of produce per month, including such high-valued crops as tomatoes, okra, peppers, eggplants and carrots. In villages irrigated with solar-powered systems, vegetable intake increased to three to five servings per day – the U.S. Department of Agriculture's Recommended Daily Allowance for vegetables – with most of the improvement taking place during the long dry season. In a world where 20 to 25 percent of global disease burden for children is due to malnutrition, such improvements could have a large impact over time, Burney said.

"Seventeen percent of project beneficiaries reported feeling less food insecure, demonstrating a remarkable effect on both year-round and seasonal food access," Naylor added.

As for household income, the authors found that women who used solar-powered irrigation became strong net producers of vegetables and earned extra income from sales, allowing them to significantly increase their purchases of high-protein food and other staples during the dry season.

Project benefits quickly spread to other community members, Burney said. For example, an elementary school curriculum was developed to help village children learn about the benefits of solar drip technology. "There was an overwhelming sense of pride in the new system by teachers, children and women participating in the farmer groups," she added.

Sustainability

Each solar-powered drip irrigation system is about 1.24 acres (0.5 hectare) in size, costs approximately $18,000 to install and requires about $5,750 a year to maintain, the authors said. Based on the projected earnings of the farmers, the system should pay for itself in about 2.3 years, they concluded. And despite higher up-front costs, the durable solar systems should be more economical in the long run than less expensive irrigation systems that use gasoline, diesel or kerosene pumps, with the added benefit of being emissions free, they added.

Focusing on novel irrigation technologies for farmers could be the needed tool for escaping poverty in sub-Saharan Africa, according to Burney. "The photovoltaic irrigation drip system could potentially become a 'game changer' for agricultural development over time," she added.

"Solar-powered irrigation provides a cleaner source of energy that is less susceptible to global price fluctuations," Naylor said. "Improved agricultural productivity in the developing world can play a critical role in global poverty alleviation, and productivity-enhancing technologies provide a sense of hope for persistently poor households."

Other co-authors of the PNAS study are Lennart Woltering and Dov Pasternak of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in Niger and Marshall Burke of the Department of Agricultural and Resource Economics at the University of California-Berkeley.

The research was supported by an Environmental Ventures Projects grant from the Woods Institute for the Environment at Stanford. The Program on Food Security and the Environment is jointly run by the Woods Institute and the Freeman Spogli Institute for International Studies at Stanford.

New solar pond distillation developed

2010-01-11T19:18:00.001+05:30

Francisco Suarez presented a portion of his solar pond research last month at the annual Fall AGU (American Geophysical Union) Conference in San Francisco. Photo by Mike Wolterbeek.Ecosystems of terminus lakes around the world could benefit from a new system being developed at the University of Nevada, Reno to desalinate water using a specialized low-cost solar pond and patented membrane distillation system powered by renewable energy.

“These lakes – hundreds worldwide – such as the Great Salt Lake, the Salton Sea, the Aral Sea and Walker Lake here in Nevada, see a decline in water levels and an increase in salinity from both human and natural processes,” Francisco Suarez, a doctoral student in hydrological sciences at the University, said. “The high levels of salinity are dangerous and unsustainable for aquatic life.”

He presented a portion of his solar pond research last month at the annual Fall AGU (American Geophysical Union) Conference in San Francisco that was attended by 16,000 geophysicists from around the world. A paper on his project will be published in the International Journal of Heat and Mass Transfer in early 2010.

Suarez is developing an artificial salt-gradient stratification process that traps solar heat at the bottom of the solar pond and uses the collected energy to power the membrane distillation system recently patented by the University. The system is designed to help sustain the ecosystems of these closed-basin regions where there is no outflow for the water and a high evaporation rate, leaving a high concentration of minerals and salts.

The hot brine in the lower storage zone of the pond, which can reach temperatures greater than 195 degrees Fahrenheit, may then be used directly for heating, thermal desalination, or for other low-temperature thermal applications.

“Our model results show that in a two-week period, the temperature in the bottom of the solar pond increased from 68 to 126 degrees Fahrenheit and, even though the insulating layer is being eroded by double-diffusive convection, the solar pond remained stable,” Suarez explained.

The process has been highly successful in the lab in a small-scale experiment using a 400-gallon tank, where dissolved solids and precise fiber-optic temperature sensing are being used to track the process as it desalinates the water. The next step for Suarez and the research group is to build a pilot-project, demonstration-scale, low-temperature desalination system in an open environment.

Suarez is working on this novel approach for sustainable production of freshwater with Civil and Environmental Engineering Department Professor and Chair Amy Childress and Professor Scott Tyler of the Department of Geological Sciences and Engineering. Childress and colleagues developed the patented membrane distillation system and Tyler developed the distributed temperature sensing system that uses a laser and fiber-optic cable to record temperatures in the solar pond.

“We’re working on funding and permissions to build a system at Walker Lake where dissolved solids have increased by a factor of five to an unhealthy level for aquatic life, and water levels have dropped 140 feet in the past 100 years,” Tyler said.

The cost to run the system is negligible because it uses the renewable energy of the sun, trapped as heat in the bottom, to power most of the system.

“This can operate 24 hours a day using the stored energy. Very little electricity would be used,” Suarez said. “For every surface acre of solar pond we can make three acre-feet of freshwater in about one year.

“The major advantages of this system are that renewable energy is used, the system is low maintenance and the stratification process that helps drive the process uses the salts from the lake itself.”

Hydrologist Tyler said the process could serve as one component of a salinity management program and, coupled with other remediation efforts, could desalinate Walker Lake enough to make it a safe aquatic habitat. The new technology he and his colleagues have developed could be applied to declining water systems anywhere, with preference to areas with good solar capabilities and adequate freshwater flows.

Suarez also presented his research at the International Symposium on Terminus Lakes held at the University of Nevada, Reno in October 2009, the 33rd International Association of Hydraulic Engineering & Research (IAHR) Biennial Congress in Vancouver in August 2009, the Chilean Congress of Hydraulic Engineering in October 2009 and the 24th Annual WateReuse Symposium in Seattle in September 2009.

Lost water of the Napa Valley vineyards

2009-12-16T17:34:00.000+05:30

Stanford researchers on how irrigation water slips away and how to stanch the flow

Getting the most out of every drop of water is a high priority for grape growers in the southern Napa Valley, where summers are hot and dry and vines have to be irrigated to make it through the growing season. But Stanford researchers have found that a significant portion of the water applied to the vines zips right by the plants, hardly even pausing.

"We found that about 10 per cent of the water that is applied is lost below the vine rooting zone and does not have contact with the soil and vine roots," said Eve Hinckley, who worked on the project for her PhD thesis in the department of geological and environmental sciences at Stanford. "This is a conservative estimate."

The problem lies in deep cracks that are a chronic feature in the clay-rich soils of the area due to the physical and chemical properties of these soils, they naturally swell when wet and shrink as they dry, producing cracks. Hinckley says that tendency is exacerbated by the weekly cycle of irrigating during the growing season, when vines are typically watered for 4 hours a week. Under a regular regimen of swelling and shrinking, the cracks become more pronounced and water speeds through them without interacting with the soil.

Hinckley is presenting her results at the fall meeting of the American Geophysical Union on Wednesday, Dec. 16.

She gathered her data by burying devices called lysimeters about 16 inches down in the soil – just below the root zone of the vines. That is also the depth to which many of the deep cracks penetrate in the vineyard where she did her study. The lysimeters captured water flowing through the soil, giving her data on the volume, chemical composition, and residence time of water in the soil.

The speedy passage of so much water through the cracks in the soil affects more than just the job of getting enough water to the vines. There are significant consequences on either end of that rapid flow. Upstream, it means that more water has to be stockpiled each winter than the vines are actually using.

All the water needed to sustain the vines through the summer has to be captured for each vineyard by the grower during the preceding winter. Most of that water is diverted from rivers and streams that are temporarily swollen – in a good year – by the winter rains. A lesser portion comes from rain falling directly into the reservoirs and runoff from adjacent slopes.

"You will often see a string of reservoirs coming off of a stream," Hinckley said. "The lowest one has the first water rights. When it's full, the grower closes it off and then the next grower up the slope is allowed to fill." In a winter with low rainfall, sometimes the higher reservoirs in the string never fill completely.

"Diversions are a pretty big deal up in the (river) system," Hinckley said. "And that is what has been a concern to the public, because it is siphoning water from the supply that would be going to groundwater recharge or to streams, where fish may be spawning." Chinook salmon and steelhead trout both spawn in the Napa River and its tributaries.

Hinckley said growers can take several approaches to reducing their water loss. Most vineyards have irrigation drip lines about a foot to 18 inches above the ground surface. Lowering those lines onto the ground – or even burying them – would reduce the speed and force with which irrigation water hits the ground, slowing its pace through the soil. But lowered or buried the lines are at risk of breakage during tilling operations and buried lines can get plugged.

Another possibility is slowing the rate at which water is delivered from the drip emitter, Hinckley said. "They could irrigate earlier in the day when evaporation rates are lower, and could irrigate for a bit longer, but still deliver less water to the vine and there would be more time for the water to soak into the soil."

Hinckley said some growers have systems that send small pipes down into the root zone of each vine, putting water directly where it is needed. "That is very labour intensive," she said, which makes it expensive to install. "But we are living in a world where water is a precious resource, so many growers are taking those measures."

Slower delivery could also help mitigate the problem of animal burrows, mainly ground squirrels, which are usually just below and parallel to the ground surface. Like the cracks, burrows offer water an easier path than slowly percolating through the soil and thus contribute to routing water away from the vines. Hinckley's lysimeters did not intercept water flowing through these burrows, which is one reason why she says the 10 per cent estimate of water loss is a minimum. She said she's been out in the vineyards during big rainstorms and seen the burrow's effect.

"It basically looks like an artesian well," she said. "Water is flowing up, just spurting out from the subsurface."

The winter storms also revealed another cause for concern.

To determine the residency time of irrigation water in the soil, Hinckley analysed the sulphur in the irrigation water she captured. Growers typically apply sulphur to their vines weekly throughout the growing season to combat mildew. The form of sulphur they use is chemically distinguishable from the sulphur found in the soil naturally, so by determining the quantity and type of sulphur in the water, she could tell whether the water had lingered in the soil long enough to react with it.

In addition to enabling her to calculate that at least 10 per cent of the irrigation water was zipping past the root zone without reacting, she discovered that during the winter rainstorms, all the sulphur applied to the vines during the previous growing season was getting washed below the rooting zone of the vines, and potentially out of the vineyard. That could have significant consequences for areas downstream, she said.

"The growers absolutely bathe the landscape in sulphur," Hinckley said. "They are broadcast spraying it across the whole vineyard."

"The next stage of work is to look at what the implications of that sulphur input are for aquatic systems down gradient of the vineyards," she said. "There, sulphur may interact with other elements, such as heavy metals, which could have ecological consequences."

NASA tech zooms in on water and land

2009-12-15T23:18:00.000+05:30

Photo:Dwight Barry/Peninsula CollegeIn a pilot project that could help better manage the planet's strained natural resources, space-age technologies are helping a Washington state community monitor its water availability. NASA satellites and sensors are providing the information needed to make more accurate river flow predictions on a daily basis.

"World leaders are struggling to protect natural resources for future generations," said Jeff Ward, a senior research scientist at the Department of Energy's Pacific Northwest National Laboratory, which is managed by Battelle. "These tools help us sustainably use natural resources while balancing environmental, cultural and economic concerns."

Ward manages a project on behalf of Battelle that is helping to better predict the flow of the Dungeness River, near Sequim, Wash., with data collected by NASA instruments. The project started by creating a new model that predicts river flows in the river's surrounding valley. It then expanded to help other communities in Kansas, Maine, Oregon and Washington state better manage their water and land resources with similar technologies.

The project – called the North Olympic Peninsula Solutions Network – is lead by the North Olympic Peninsula Resource Conservation & Development Council and supported by PNNL and others.

Lucien Cox of NASA will present the project's results Dec. 16 at the 2009 fall meeting of the American Geophysical Union in San Francisco.

The project will help regional natural resource managers assess the abundance – or lack thereof – of the Dungeness River. The river model was developed to show how NASA technologies like satellites, sensors and computational models could be used to improve short-term stream flow predictions. The river model relies on snowpack and temperature data collected from satellites, as well as real-time snowpack and water data collected by various agencies.

The new Dungeness River model's calculations can tell what kind of flow to expect – from a trickle to a deluge – on a daily and monthly basis. Before, resource managers primarily relied on either water levels physically measured at gauges or historical data to predict total expected water volume over two to six months. Neither method provided flow predictions as frequently as the new model.

Having more precise river flow predictions is especially important along the Dungeness River, where the towering Olympic Mountains create a drying rain shadow effect and steep slopes prevent above-ground water reservoirs. Sequim receives just 15 inches of rain annually. Water is so treasured that the agricultural city is home to a 114-year-old festival that celebrates a historic irrigation system.

"Improving the accuracy of stream flow predictions is important to a diverse group of water users, including irrigation-dependent farmers, planners making urban growth decisions and those concerned about salmon survival or water quality," said Clea Rome, North Olympic Peninsula RC&D coordinator. "Stream flow prediction tools can help us avoid a crisis by alerting us before droughts are in full effect, giving us enough notice to adjust water use."

But the practical use of NASA technologies isn't limited just to Sequim or river water. The North Olympic Peninsula Solutions Network is helping four other resource, conservation and development councils tackle their unique problems.

Another resource – soil – has the Solomon Valley RC&D in north central Kansas concerned about agricultural tilling and erosion. Striking a balance between agriculture and forestry is critical for the Threshold to Maine RC&D in southwest Maine. The Wy'East RC&D is looking to better manage water supply and demand in north central Oregon. And in Okanogan, Wash., the possibility of water shortages worries the North Central Washington RC&D.

"Space technologies can help us get the best science to the ground, to the decision makers here in the Okanogan Basin," said Samantha Bartling, North Central Washington RC&D coordinator. "We expect it'll help us more precisely predict water availability for a long time to come."

The four councils are working with North Olympic Peninsula Solutions Network leaders to determine how NASA technologies can best address their different challenges.

Bhopal children poisoned by toxic water supply

2009-12-01T22:51:00.000+05:30

Photo:WikimediaThousands of innocent people are being poisoned in Bhopal, India by the abandoned Union Carbide site leaching highly toxic chemicals into the water supply a report out today confirms.

The site of the World's worst ever industrial accident – the 1984 gas leak at Union Carbide India Ltd (UCIL), has never been cleaned up, and years of monsoon rains have washed its abandoned stockpiles of toxic chemicals in to the soil and groundwater aquifer that is still used by many as a source of drinking water.

Analysis carried out by accredited laboratories in Switzerland and the UK found at least sixteen contaminants at levels greatly exceeding World Health Organisation (WHO) safe guideline levels. Carbon Tetrachloride toxicity was recorded at more than 2400 times the WHO safe guidance level. This is a chemical that was banned in consumer products in the US as long ago as 1970.

Worse still, concentrations of some of the chemicals are still rising. One reading showed that Carbon Tetrachloride toxicity had risen by 270 per cent between May 2008 and June 2009.

Many of the chemicals found in the water supply are known, or suspected, carcinogens. They have potential neurotoxin properties and can cause damage to the body's organs. Many are especially harmful to children and foetuses.

The impact of people living in the area is shocking. It has been called Bhopal's 'second disaster', as a new generation, not even born at the time of the 1984 gas leak, have been exposed to decades of poisoning.

These toxic chemicals and heavy metals are in the soil, in the plants and animals, and even in the breast milk of nursing mothers. In the affected areas people are chronically sick; cancer rates are rising and children are born with terrible abnormalities. A preliminary study suggests as many as one child in twenty-five is born with a congenital defect.

The report concludes that the toxic chemicals in the water supply were those used at the UCIL plant in the production processes of the pesticide Sevin, and that there is no other possible source for the contamination. Dow Chemical, the American company who bought Union Carbide in 2001, has never been held to account for the cleanup.

Significantly, the report completely counteracts the recent statements made by Bhopal Gas Tragedy Relief and Rehabilitation Minister Babulal Gaur, when he said, "The plant is being opened to help people get rid of the apprehension and misconception that the chemical wastes lying in the factory are still harmful and are polluting the ground water of the nearby localities."

Jon Snow, broadcaster, and Patron of The Bhopal Medical Appeal, said of this year's Anniversary, "That's 25 years of evasion and denial from the parties responsible for this appalling crime. 25 years of struggle for justice on the part of the survivors."

Peter Finnigan, Executive Secretary at The Bhopal Medical Appeal, said,
"We hope that the combined authority of our tests, along with the findings of others taken over the last decade will dispel any notion of the site being 'safe' once and for all."

The Bhopal Medical Appeal Report was compiled using new, previously un-published test data, from accredited laboratories in Switzerland, and the United Kingdom, alongside the collated results of previous tests carried out by, Greenpeace; National Environmental Engineering Research Institute and SHRISTI.

Volatile gas could turn Rwandan lake into a freshwater time bomb

2009-11-17T23:57:00.000+05:30

Photo: Themalau/Wikimedia CommonsRIT professor organises workshop in Rwanda to grapple with the problem of Lake Kivu

A dangerous level of carbon dioxide and methane gas haunts Lake Kivu, the freshwater lake system bordering Rwanda and the Republic of Congo. Scientists can't say for sure if the volatile mixture at the bottom of the lake will remain still for another 1,000 years or someday explode without warning. In a region prone to volcanic and seismic activity, the fragility of Lake Kivu is a serious matter. Compounding the precarious situation is the presence of approximately 2 million people, many of them refugees, living along the north end of the lake.

An international group of researchers will meet Jan. 13-15 in Gisenyi, Rwanda, to grapple with the problem of Lake Kivu. A grant from the National Science Foundation won by Rochester Institute of Technology will fund the travel and lodging for 18 scientists from the United States to attend the three-day workshop. Anthony Vodacek, conference organiser and associate professor at RIT's Chester F. Carlson Centre for Imaging Science, is working closely with the Rwandan Ministry of Education to organise the meeting.

"Rwandan universities suffered greatly in the 1994 genocide and there are few Rwandan scientists performing significant work on the lake or within the rift system," Vodacek notes. "We will work with the government to identify interested researchers."

Vodacek is convening the workshop with Cindy Ebinger, an expert in East African Rift tectonics at the University of Rochester, and Robert Hecky, an expert in limnology – the study of lake systems – at University of Minnesota-Duluth. Core samples Hecky took in the 1970s initially brought the safety of Lake Kivu under question.

Addressing the lake as a whole system is a new concept for the workshop participants, who will bring their expertise in volcanology, tectonics and limnology to the problem. Vodacek's goal is to prioritise research activities and improve communication between the North American, European and African collaborators.

"Most scientists are fairly in agreement that the lake is pretty stable; it's not as if its going to come bursting out tomorrow," Vodacek says. "But in such a tectonically and volcanically active area, you can't tell what's going to happen."

One of the problems with Lake Kivu is that the 1,600-foot deep lake never breathes. The tropical climate helps stagnate the layers of the lake, which never mix or turn over. In contrast, fluctuating temperatures in colder climates help circulate lake water and prevent gas build up. Lake Kivu is different from both temperate and other tropical lakes because warm saline springs, arising from ground water percolating through the hot fractured lava and ash, further stabilise the lake. Scientists at the workshop will consider how these spring inputs may vary over time under changing climates and volcanic activity.

A number of catalysts could destabilise the gas resting at the bottom of Lake Kivu. It could be an earthquake, a volcanic explosion, a landslide or even the methane mining that has recently united Rwandan and Congolese interests.

Close calls occurred in 2008 when an earthquake occurred near the lake and in 2002 when a volcanic eruption destroyed parts of Goma in the Democratic Republic of Congo, only 11 miles north of Lake Kivu. Although scientists were alarmed, neither event sufficiently disturbed the gas.

Vodacek likens the contained pressure in the lake to a bottle of carbonated soda or champagne. "In the lake, you have the carbon dioxide on the bottom and 300 meters of water on top of that, which is the cap," he says. "That's the pressure that holds it. The gas is dissolved in water."

When the cap is removed, bubbles form and rise to the surface. More bubbles form and create a column that drags the water and the gas up to the surface in a chain reaction.

"The question is, and what's really unknown, is how explosive is that?" Vodacek says.

Through his own research Vodacek plans to simulate the circulation of Lake Kivu. Modelling the circulation patterns above the layers of carbon dioxide and methane will help determine the energy required to disrupt the gas and cause Lake Kivu to explode.

Western banks violate rights, law in Lao dam deal

2009-11-17T00:38:00.001+05:30

Theun Hinboun Dam Wall, Central Southern Laos. Photo: Laurence McGrath/WikimediaANZ, BNP Paribas and KBC Investment in Theun-Hinboun Dam Violates Equator Principles and Lao Law

The Theun-Hinboun Expansion Project - a dam and water diversion project now under construction in Central Laos - poses a threat to the livelihoods and food security of local communities living in the project area. The project also violates Lao law and the Equator Principles, according to Expanding Failure, a new report and video released today by International Rivers; BankTrack, FIVAS, Les Amis de la Terre; and Justice and International Mission Unit, Uniting Church in Australia.

The Theun-Hinboun Expansion Project involves a 65-meter high storage dam on the Nam Gnouang River and a doubling of capacity at the existing Theun-Hinboun hydropower plant, resulting in a doubling of the amount of water diverted into the Hai and Hinboun Rivers. The project is being financed by three international banks - ANZ of Australia, BNP Paribas of France and KBC of Belgium- that have adopted the Equator Principles, a set of social and environmental guidelines for private banks.

The report found that the project was in violation of Lao government resettlement law and the Equator Principles in numerous instances. The Theun-Hinboun Power Company is also failing to comply with its Concession Agreement and Resettlement Action Plan (RAP). These violations include: Compensation for loss of assets and livelihoods in the downstream villages as a result of the original Theun-Hinboun Project has not been paid [Violation of Lao resettlement law Article 6]; no provision of a range of resettlement options to the downstream villagers [Violation of Performance Standard 5], and no documentation on "good faith negotiations" with the affected indigenous communities [Violation of Performance Standard 7].

Ikuko Matsumoto, Lao Program Director for International Rivers and the report author says, "The violations documented in the report are unacceptable for a project that claims to be adhering to international standards, and that is being financed by three banks that have adopted the Equator Principles. The Theun-Hinboun Expansion project will undermine food security for up to 50,000 Laotians and the plans to restore livelihoods are woefully inadequate. The banks funding the project have promised that people's lives will be restored. They must take this responsibility seriously and put people before profits."

The project is displacing 4,186 indigenous people from the reservoir area and will affect another 51,441 people living downstream, on project construction lands, and in host villages. Already water levels along the Hai and Hinboun Rivers have dramatically changed as a result of the existing dam, which has caused erosion and flooding along the rivers leading to the loss of fertile agricultural land, fruit trees, riverbank gardens, livestock and boats in more than 55 villages.

The new project will result in additional flooding and displacement, making life unbearable for many people. As one of the villagers in Tha village told the researchers, "The project company did not appropriately compensate for the existing project and we are already poor. With the expansion project, the company will make us poorer!"

The report was sent for comments to the three Equator Banks and Statkraft, the Norwegian owner of the project, in advance of its public release. In their response, the three banks stated that they considered the project in compliance with the regulatory framework but refused to discuss the details of the project with civil society.

Sonja Willems, Campaign Officer for BankTrack says "Equator Principles Financial Institutions need to be publicly accountable and transparent in their implementation of the Equator Principles. We are calling on the banks financing this project to conduct a mission to the project site, engage with the company to ensure compliance with the Equator Principles and Lao law, and withhold disbursements to the company until the project is brought into compliance."

Genomics to provide more effective treatment options for mining wastewater

2009-11-16T15:34:00.000+05:30

Companies that are faced with the challenge of cleaning up toxic wastewater from mining operations will soon have more reliable bioremediation options.

New research from Genome BC will harness the potential of microbes naturally present in mine bioremediation to help improve strategies for cleaning up contaminated mine sites.

This method of bioremediation will provide a valuable alternative to some current mine effluent treatment methods that require large-scale employment of chemicals to treat water contaminated by metal leaching and acid rock drainage.

Dr. Sue Baldwin at The University of British Columbia is leading the USD1.5 million project entitled, "The Development of Genomic Tools for Monitoring and Improving Passive Mitigation of Mine Drainage."

"There are micro-organisms out there that can do all sorts of things, including the detoxification of water," says Baldwin. We are relying on the microbes that are already present in the environment to do this, and using genomics to determine how to create the conditions in which they will thrive."

Essentially, the micro-organisms digest the metal toxins in wastewater, sequestering them or reducing them to less toxic forms. One class of microbes in particular termed Sulfate-Reducing Bacteria (SRB), are known to be powerhouses in the cleanup of mine drainage.

But SRB do not work in isolation; they rely on members of a diverse microbial community to provide them with essential nutrients so they can thrive and carry out the detoxification.

This is where genomics come in. The researchers will study the microbial community as a whole, sequence the DNA to see how the organisms interact, and determine what sort of nutrients and conditions are necessary to ensure that they continue to do their jobs over time.

The researchers are gathering information from two test sites where they are setting up pilot treatment facilities. The sites are located at the Mt. Polley Mine, a copper and gold mine near Williams Lake, BC and at the Teck smelter near Castlegar, BC.

So what exactly would one of these natural treatments "facilities" look like?

"No different than the surrounding environment," says Baldwin. "The water would flow through a natural compost area which would serve to nourish the microbes, and this would be capped with grasses… it essentially looks like a series of grasses and water ponds."

These treatment facilities are universally applicable and can be set up in virtually any environment where there is sufficient space, and customised to include the natural microbial communities that are found there. "We have keen interest and active participation from the international mining community," says Baldwin.

MIT scientists pinpoint origin of dissolved arsenic in Bangladesh drinking water

2009-11-16T14:19:00.000+05:30

Rebecca Neumann of MIT hangs on bamboo scaffolding in a rice field near Bashailbhog village in Bangladesh as she connects the end of the tubing that will be used to suck up water from the rice field for analysis, including determining the arsenic content. The setup was used for an intensive sampling campaign that involved the collection and processing of surface water from seven locations, and subsurface water from 14 locations every day and night for six days.
Photo: Sarah Jane White, MITResearchers in MIT's Department of Civil and Environmental Engineering believe they have pinpointed a pathway by which arsenic may be contaminating the drinking water in Bangladesh, a phenomenon that has puzzled scientists, world health agencies and the Bangladeshi government for nearly 30 years. The research suggests that human alteration to the landscape, the construction of villages with ponds, and the adoption of irrigated agriculture are responsible for the current pattern of arsenic concentration underground.

The pervasive incidence of arsenic poisoning in Bangladesh and its link to drinking water were first identified in the scientific literature in the early 1980s, not long after the population began switching from surface water sources like rivers and ponds to groundwater from newly installed tube wells.

That national effort to decrease the incidence of bacterial illnesses caused by contaminated drinking water led almost immediately to severe and widespread arsenic poisoning, which manifests as sores on the skin and often leads to cancers of the skin, lung, liver, bladder and pancreas.

Since then, scientists have struggled to understand how the arsenic, which is naturally occurring in the underground sediment of the Ganges Delta, is being mobilised in the groundwater.

By 2002, a research team led by Charles Harvey, the Doherty Associate Professor of Civil and Environmental Engineering at MIT, had determined that microbial metabolism of organic carbon was mobilizing the arsenic off the soils and sediments, and that crop irrigation was almost certainly playing a role in the process. But the exact sources of the contaminated water have remained elusive, until now.

In a paper appearing online in Nature Geoscience Nov. 15, Harvey, former graduate students Rebecca Neumann and Khandakar Ashfaque and co-authors explain that ponds excavated for the purpose of providing soil to build up villages for flood protection are the source of the organic carbon that presently mobilizes the arsenic in their 6-square-mile test site. The carbon settles to the bottom of the ponds, then seeps underground where microbes metabolize it. This creates the chemical conditions that cause arsenic to dissolve off the sediments and soils and into the groundwater.

The researchers also found that in their test area, which is flooded by annual monsoons, the rice fields irrigated with arsenic-laden water actually serve to filter out much of the arsenic from the water system.

"Our research shows that water from the ponds carries degradable organic carbon into the shallow aquifer. Groundwater flow, drawn by irrigation pumping, transports that pond water to the depth where dissolved arsenic concentrations are greatest and where it is then pumped up into the irrigation and drinking wells," says Harvey. "The other interesting thing we found is that the rice fields are a sink of arsenic — more arsenic goes in with the irrigation water than comes out in the groundwater."

Scott Fendorf, a professor at Stanford University who studies arsenic content in soils and sediments along the Mekong River in Cambodia, says Harvey's previous research, published in 2002, "transformed the scientific community's outlook on the problem." The current work, he adds, has two big ramifications: "It shows that human modifications are impacting the arsenic content in the groundwater; and that while the rice cropping system appears to be buffering the arsenic, the ponds excavated to provide fill to build up the villages are having a negative impact on the release of arsenic."

Neumann, now a postdoctoral associate at Harvard University, took seven trips and spent nearly a year doing fieldwork in Bangladesh, studying the hydrologic behavior and chemical nature of rice fields and ponds, and performing tests on rice field and pond waters to determine if the organic carbon in these water bodies would stimulate arsenic mobilization. She and Ashfaque developed an understanding of the surface and underground water flow patterns over a seven-year period, using natural tracers and a 3-D model to track rice field and pond water as it traveled into and through the subsurface.

"When we compared the chemical signatures of the different water sources in our study area to the signatures of the aquifer water, we saw that water with high arsenic content originates from the human-built ponds, and water with lower arsenic content originates from the rice fields," says Neumann. "It's likely that these same processes are occurring at other sites, and it suggests that the problem could be alleviated by digging deeper drinking water wells below the influence of the ponds or by locating shallow drinking wells under rice fields." The researchers suggest that irrigation wells remain at the shallow level.

At 159 million people, Bangladesh is the seventh most populous country in the world, and it is growing quickly. That means that new tube wells and ponds are being dug every day to accommodate the growing population. Most of those wells are being drilled to less than 100 feet. At that depth, they draw water directly from the contaminated shallow aquifer.

Holly Michael, a professor at the University of Delaware and former PhD student in the Harvey Lab, also studies the physics of groundwater flow and transport of the dissolved arsenic in Bangladesh, but in the deeper aquifer.

"Charlie's team is looking at the impacts at and near the surface, and my team is looking at the potential impacts of human activities at depth," says Michael. "My team found that if only the drinking-water wells are put into the deep, low-arsenic parts of the aquifer — at depths greater than 450 feet — then it is likely that the supply of low-arsenic water will continue for a very long time over much of the arsenic-affected area. Because so much more water is pumped for irrigation, it is important that irrigation wells are not installed deeper, as this would likely cause high-arsenic groundwater to flow downward toward the wells."

Harvey estimates that the prevalence of arsenic poisoning in Bangladesh is approximately 2 million cases and that the incidence of death from arsenic-induced cancer will rise to approximately 3,000 cases per year if consumption of contaminated water continues. He and a team of environmental scientists and physicians are making plans for a multi-year study that would provide deep wells for two villages in Bangladesh whose inhabitants suffer from arsenic poisoning. There they would combine continual testing of the well water and hydrogeological modeling of the groundwater system with a study of how the clean water effects the villagers' health, placing special emphasis on the neurological development of children.

"There are all sorts of studies to show how arsenic hurts people. We're trying to turn it around and show how removal of the arsenic will help them," says Harvey.

Tiny bubbles clean oil from water

2009-11-16T02:22:00.001+05:30

New method targets oil sheen, other pollutants

Small amounts of oil leave a fluorescent sheen on polluted water. Oil sheen is hard to remove, even when the water is aerated with ozone or filtered through sand. Now, a University of Utah engineer has developed an inexpensive new method to remove oil sheen by repeatedly pressurising and depressurising ozone gas, creating microscopic bubbles that attack the oil so it can be removed by sand filters.

"We are not trying to treat the entire hydrocarbon [oil] content in the water – to turn it into carbon dioxide and water – but we are converting it into a form that can be retained by sand filtration, which is a conventional and economical process," says Andy Hong, a professor of civil and environmental engineering.

In laboratory experiments reported online this week in the journal Chemosphere, Hong demonstrated that "pressure-assisted ozonation and sand filtration" effectively removes oil droplets dispersed in water, indicating it could be used to prevent oil sheen from wastewater discharged into coastal waters.

What can be cleaned?

•So-called "produced water" from oil and gas drilling sites on land. Such oily water normally is re-injected underground. "If we have technology to clean it, it could be put into beneficial uses, such as irrigation, especially in arid regions where oil and gas tend to be produced," says Hong.

•Water from mining of tar sands and oil shale.

•Groundwater contaminated by MTBE, a gasoline additive that reduces harmful vehicle emissions but pollutes water due to leaking underground gasoline storage tanks.

•"Emerging contaminants," such as wastewater polluted with medications and personal care products.

•Soil contaminated with polychlorinated biphenyls (PCBs, from electrical transformers) or polycyclic aromatic hydrocarbons (PAHs, from fuel burning). Water and contaminated soil would be mixed into slurry, and then treated with the new method.

•Heavy metals in soil. Instead of ozone, air and metal-grabbing chelating agents would be pressurised with a slurry of the contaminated material.

•Refinery wastewater and oil spills at refineries or on waterways. The spill could be vacuumed, and then treated with the new method on-site or on a barge.

Hong conducted the study with two University of Utah doctoral students – Zhixiong Cha, who has earned his Ph.D., and Chia-Jung Cheng – and with Cheng-Fang Lin, an environmental engineering professor at National Taiwan University.

Zapping oily water with microbubbles from ozone under pressure

Hong says his method uses two existing technologies – ozone aeration and sand filtration – and adds a big change to the former. Instead of just bubbling ozone through polluted water, Hong uses repeated cycles of pressurisation of ozone and dirty water so the ozone saturates the water, followed by depressurisation so the ozone expands into numerous microbubbles in the polluted water, similar to the way a carbonated beverage foams and overflows if opened quickly.

The tiny bubbles provide much more surface area – compared with larger bubbles from normal ozone aeration – for the oxygen in ozone to react chemically with oil. Hong says pollutants tend to accumulate on the bubbles because they are not very water-soluble. The ozone in the bubble attacks certain pollutants because it is a strong oxidant.

The reactions convert most of the dispersed oil droplets – which float on water to cause sheen – into acids and chemicals known as aldehydes and ketones. Most of those substances, in turn, help the remaining oil droplets clump together so they can be removed by conventional sand filtration, he adds.

In his study, Hong showed the new method not only removes oil sheen, but also leaves the treated water so that any remaining acids, aldehydes and ketones are more vulnerable to being biodegraded by pollution-eating microbes.

"These are much more biodegradable than the parent compounds," he says.

Hong says the water is clean enough to be discharged after the ozonation and sand filtration, but that some pollution sources may want to use conventional methods to biodegrade remaining dissolved organic material.

Details of the experiments

Hong conducted his experiments using a tabletop chemical reactor that contained about a quart of oily water made by mixing deionised water with crude oil from the Rangely oil field in northwestern Colorado.

Ozone was produced by passing dry air through a high-voltage field, converting oxygen gas, which has two oxygen atoms, into ozone, which has three.

The ozone was pressurised to 10 times atmospheric pressure, about 150 pounds per square inch, which compares with inflation pressures of about 100 PSI for Hong's bicycle and 35 to 40 PSI for many automobile tires.

He found oily water was cleaned most effectively by pressurising and depressurising it with ozone gas 10 times, then filtering it through sand, then putting the water through 20 more pressurised ozone cycles, and then filtering it again through sand. That was at flow rates of 10 to 20 liters per minute [about 2.6 to 5.3 U.S. gallons per minute] in his laboratory apparatus.

Hong tested how well the ozonation worked by measuring chemical and biological oxygen demands of treated water samples. Both indirectly measure organic contents in the water. Hong also used mass spectrometry to identify what contaminants remained in the water.
He found that his most effective procedure removed 99 per cent of the turbidity from the "produced water" – leaving it almost as clear as drinking water – and removed 83 per cent of the oil, converting the rest to dissolved organic acids removable by biodegradation.

A tryout in China

With success in the laboratory, Hong now plans for larger-scale pilot tests.

"It is economical and it can be scaled up," he says.

One such test will be done in Wuxi, China, where a prototype desk-sized device capable of treating 200 liters [53 U.S. gallons] at a time will be tested at three to five polluted industrial sites that the government vacated for redevelopment, Hong says.

Meanwhile, the University of Utah Research Foundation has entered into options to license the technology to Miracotech, Inc., of Albany, Calif., and 7Rev, L.P., a Salt Lake City venture capital group, so the companies can bring the technology to market.

Hong says other methods of treating oil well "produced water" have met with varying degrees of success. They include centrifuges, membranes, regular ozonation and air bubbles to float off contaminants. But all have drawbacks, such as inability to handle dissolved oil or high levels of oil, or susceptibility to quickly getting fouled by the oil.

Neither ozonation nor sand filtration alone has been able to effectively treat oily "produced water." Hong says long-chain oil molecules don't react with ozone easily without his pressure treatment. And sand filters alone cannot remove oil.

How much water does the ocean have?

2009-11-12T16:51:00.000+05:30

Geodesy researchers observe the mass distribution of the oceans

The calculation of variations in the sea level is relatively simple. It is by far more complicated to then determine the change in the water mass. A team of geodesists and oceanographers from the University of Bonn, as well as from the GFZ German Research Centre for Geosciences and the Alfred-Wegener Institute for Polar and Marine Sciences, two centres of the Helmholtz Association, have now, for the first time succeeded in doing this. The researchers were able to observe short-term fluctuations in the spatial distribution of the ocean water masses. Their results are, amongst others, important for improved climate models.

In order to determine the ocean volume in a certain region, one only needs to know, in addition to the topography of the seabed, the height of the sea level. For this purpose, researchers have long been resorting to gauging stations and satellite altimetric procedures. The ocean mass depends, however, not only on the volume, but also on the temperature and on the salt content. Water expands when heated. Warm water, thus, weighs less than the same quantity of cold water.

For the calculation of the ocean mass it is, therefore, necessary to know the temperature and salt content profiles. However, this is not easy to quantify. "For our study we, therefore, combined different procedures so as to be able to judge changes in mass", explains Professor Dr. Juergen Kusche. The geodesist from Bonn is co-author of a scientific paper, which has just been published in the Journal of Geophysical Research.

On the one hand the researchers used data from the German-American satellite mission GRACE where the distance between two satellites (popularly known as Tom and Jerry as one chases the other in the same orbit ) are measured exactly to thousandths of millimetres. The larger the ocean mass at a certain point of the Earth, the stronger the gravitational strength. This influences the flight altitude of the satellites and thus the distance from each other. The gravitation and, hence, the mass distribution can be calculated from the change in distance between the two satellites.

The seabed bends under the weight of the water

In addition, the scientists put to use an effect which frequent book readers will have perceived. The ocean floor bends similarly to that of the shelves of an overfilled bookshelf. Thus, stationary GPS-gauging stations on land drop by up to one centimetre and move closer by a few millimetres. The heavier the water, the stronger is this movement.

"We combined these data with numerical models of the ocean" explains Kusche. "In this way we were able to prove, for the first time, that in particular in the higher latitudes, significant fluctuations of the water mass occur, and that this takes place within a time period of only one to two weeks".

So far one only knew that the mass of the world-wide ocean water varies seasonally by on average approximately three quadrillion kilogrammes (a quadrillion equals to 1 followed by 15 zeroes) - that implies a sea level variation of approx. seven to eight millimetres. This effect is brought about, among others, by variations in precipitation and evaporation as well as by the storage of water as snow. But, also, the melting of the glaciers and the ice masses in Greenland and in the Antarctic play a role.

By comparing the variation in volume and in mass the researchers want to determine changes in the amount of heat stored in the ocean. Therefore, in the near future, the long term changes are to be examined. The results will contribute to improved climatic models.

An urgent wish of the scientists is the realisation of a punctual follow-up mission for the satellite tandem GRACE. Otherwise the valuable information, particular in the registration of trends in the Earth system, obtained through GRACE, cannot be used to its full potential for Earth System and climate research.

New alternatives of renewable energy sources to produce water

2009-11-11T13:05:00.001+05:30

Solar desalination plant at Hameem. Photo: EADThe Environment Agency – Abu Dhabi (EAD) is studying new alternatives of renewable energy sources to produce water, in order to meet the rising demand for water and to enable water security in the future.

H.E Majid Al Mansouri, EAD's Secretary General, said that finding new renewable and environmental friendly energy resources to produce water is no longer an option but a necessity since the demand for freshwater resources is increasing. Al Mansouri added that EAD's efforts in this regard are in line with EAD's strategy to pursue the latest developments in the field of water production and to adopt the best economical and environmental methods and techniques.

He said, "H.H Sheikh Mohammed bin Zayed Al Nahyan, Crown Prince of Abu Dhabi and Honorary Chairman of EAD, wisely directed us to find environmentally friendly, low cost and highly efficient alternatives to produce water of adequate quality for domestic and industrial use."

Al Mansouri added that EAD had launched two pilot projects to produce desalinated water from brackish and saline groundwater using solar energy. So far, the preliminary results have indicated the success of the experiment and tangible results were achieved. He added that these results have encouraged the Agency to continue its efforts to develop more stations and reduce the cost of its capital cost to about 10 per cent in the future and increase efficiency at the same time.

Disposal of brine water from these desalination unites should be carefully considered. EAD is currently developing a mechanism for harvesting this brine rejected water to rehabilitate the existing natural vegetations. Evaporation ponds are especially suitable to dispose of reject brine from inland desalination plants in arid and semi-arid areas due to the abundance of solar energy whoever guidelines are needed for the design, construction, maintenance, and operation of evaporation ponds for reject brine disposal in an economical and environmentally-sensitive manner.

More efforts in the future will be done to increase the efficiency of the desalination recovery the more than 80 per cent and using to such brine water in the production of salt or animal fodder or fertilisers. This is expected to improve the economics of such systems in the future and reduce the environmental impact of disposing such brine water on the Arabian Gulf.

To raise awareness about the importance of making desalination and water reuse more sustainable and affordable, EAD recently participated in the International Desalination Association World Congress, which was held in Dubai under the theme "Desalination for a Better World." During the conference, Dr. Mohammed Dawoud, Manager of the Water Resources Department at EAD, delivered a presentation on the future use of renewable energy in the production of water, especially in areas where groundwater is very salty.

Dawoud said that "the use of renewable sources of energy in desalination is an essential part in the future of desalination in the region to reduce costs and increase efficiency, where technology to collect solar energy from solar cells and desalination plants based on reverse osmosis membrane technology".

He said that the real challenge is to increase the efficiency of solar energy collection system and reduce environmental impact, noting that EAD is currently developing a mechanism for safe disposal of water brine from these stations to increase the efficiency of the plant to more than 80 per cent and access to such high salinity water in the production of salt or animal feeds or fertilisers, which will improve the economics of such systems in the future and reduce the environmental impact of waste brine water in the Arabian Gulf or use it for injection into deep aquifers.

Widespread contamination of fish in U.S. lakes and reservoirs

2009-11-11T10:49:00.001+05:30

Salt Lake. Photo:Bobjgalindo/WikimediaA new EPA study shows concentrations of toxic chemicals in fish tissue from lakes and reservoirs in nearly all 50 U.S. states. For the first time, EPA is able to estimate the percentage of lakes and reservoirs nationwide that have fish containing potentially harmful levels of chemicals such as mercury and PCBs.

"These results reinforce Administrator Jackson's strong call for revitalised protection of our nation's waterways and long-overdue action to protect the American people," said Peter S. Silva, assistant administrator for EPA's Office of Water."EPA is aggressively tackling the issues the report highlights. Before the results were even finalised, the agency initiated efforts to further reduce toxic mercury pollution and strengthen enforcement of the Clean Water Act – all part of a renewed effort to protect the nation's health and environment."

The data showed mercury concentrations in game fish exceeding EPA's recommended levels at 49 per cent of lakes and reservoirs nationwide, and polychlorinated biphenyls (PCBs) in game fish at levels of potential concern at 17 per cent of lakes and reservoirs. These findings are based on a comprehensive national study using more data on levels of contamination in fish tissue than any previous study.

Burning fossil fuels, primarily coal, accounts for nearly half of mercury air emissions caused by human activity in the U.S., and those emissions are a significant contributor to mercury in water bodies. From 1990 through 2005, emissions of mercury into the air decreased by 58 per cent. EPA is committed to developing a new rule to substantially reduce mercury emissions from power plants, and the Obama Administration is actively supporting a new international agreement that will reduce mercury emissions worldwide.

The study also confirms the widespread occurrence of PCBs and dioxins in fish, illustrating the need for federal, state and local government to continue efforts to reduce the presence of these harmful chemicals in our lakes and reservoirs and ensure that fish advisory information is readily available.

It is important that women of child-bearing age and children continue to follow the advice of EPA and the Food and Drug Administration on fish consumption as it relates to mercury. This study is also a strong message to state and local governments to redouble their efforts in looking for opportunities to reduce mercury discharges, as well as developing fish advisories, especially to reach those in sensitive and vulnerable populations.

Results from the four-year National Study of Chemical Residues in Lake Fish Tissue show that mercury and PCBs are widely distributed in U.S. lakes and reservoirs. Mercury and PCBs were detected in all of the fish samples collected from the nationally representative sample of 500 lakes and reservoirs in the study. Because these findings apply to fish caught in lakes and reservoirs, it is particularly important for recreational and subsistence fishers to follow their state and local fish advisories.

EPA is conducting other statistically based national aquatic surveys that include assessment of fish contamination, such as the National Rivers and Streams Assessment and the National Coastal Assessment. Sampling for the National Rivers and Streams Assessment is underway, and results from this two-year study are expected to be available in 2011. Collection of fish samples for the National Coastal Assessment will begin in 2010.

Water evaporates from the climate change negotiating text

2009-11-06T00:36:00.001+05:30

The Stockholm International Water Institute joined governments, NGOs and United Nations agencies this week in calling on negotiators working to develop a climate change deal in Copenhagen later this year to recognise the critical role of water in climate change adaptation.

Participants in a special Water Day event on Tuesday called for recognition that water is the primary way that climate change will impact people, society and ecosystems, due to predicted changes in its quality and quantity.

The way that water is managed in and between countries will be a critical component for the success of any efforts to adapt to the impacts of climate change, according to the Stockholm International Water Institute. It will also be a vital consideration for many mitigation activities, including hydropower, agriculture and forestry projects.

However, negotiators meeting this week in Barcelona for the last round of UN climate talks before a big conference in Copenhagen next month are working on negotiating texts that have no reference to water and its management as tools for climate change adaptation.

“It is imperative that negotiators recognise the crucial importance of wetlands and freshwater as key factors in any climate adaptation plan,” said Denis Landenbergue, WWF International’s Manager of Wetlands Conservation. “To ignore the role of water is to cripple any climate change adaptation plans.”

Landenbergue said he encouraged negotiators to follow in the steps of their colleagues from the Conference of the Parties to the Ramsar Convention on Wetlands. Last year, they adopted a resolution promoting the conservation and proper management of wetlands and their natural resources – including water – as key requisites in national climate change mitigation and adaptation plans.

Previous negotiating texts discussed in Bonn and Barcelona contained clear references to proper land and water resource adaptation as key to stemming the effects of climate change. However, a streamlined text being discussed this week lacks any direct reference to water, even in sections about climate change impacts.

"Let me be very clear. There is no development without water,” said Pasquale Steduto, Chair, UN-Water and Service Chief, Food and Agriculture Organisation. “There is no food security without water. There is most likely also no energy security without water. Water is the primary medium through which climate change influences the Earth's ecosystems and therefore people's livelihoods and well-being. If water is not further recognised in adaptation strategies and plans, we are making a big mistake."

"Even with the best mitigation strategies, water related effects of climate change will come,” said Anders Berntell, Executive Director, SIWI. “The challenge for many nations is how to adapt. Climate Change is in effect Water Change, since it will be through water that the changes will be realised first and foremost."

Many developing countries already are beginning to experience the devastating impacts of climate change on the water cycle.

If precautions are not taken, this may lead to an increase in conflicts related to water availability and distribution. Extreme weather events leading to drought and floods, as recently witnessed in Kenya and the Philippines, are predicted to increase in frequency and intensity as a result of climate change, and are likely to become the norm' in coming decades.

Water-conserving irrigation strategies minimise overwatering, runoff

2009-11-05T20:44:00.000+05:30

Overhead irrigation system used to irrigate the three-gallon container-grown landscape shrubs in the experiment. Photo: Aaron WarsawContainer-grown woody ornamentals thrive with daily water use irrigation regimen

Conserving water and reducing the environmental impact of runoff are two of the most important issues confronting container nursery operations. Current regulations and laws in five states limit water consumption by container nurseries, and some states also limit nutrient concentrations in runoff. Excessive runoff from container plants often results from poor irrigation efficiency; in some cases as little as 13 per cent to 26 per cent of overhead irrigation is retained in the container.

When runoff is not properly managed, water, fertilisers, and other agricultural chemicals can end up in surrounding water resources, with the potential for environmental contamination. Facing predictions of increased water costs, lower water availability, and increasingly stringent legislation, nursery owners have a keen interest in implementing irrigation practices that conserve water and reduce runoff without adversely affecting crop quality.

Aaron L. Warsaw, R. Thomas Fernandez, Bert M. Cregg, and Jeffrey A. Andresen of Michigan State University published a research experiment in HortScience that investigated whether irrigation scheduling based on daily water use (DWU) – the combined loss of water from plant transpiration and substrate evaporation – could conserve water without negatively impacting plant growth. The researchers set out to determine the effect of scheduling irrigation according to DWU on water conservation and plant growth, determine DWU and water use efficiency (WUE) of several types of common container-grown woody ornamentals, and evaluate the effect of irrigation volume on substrate soluble salt levels.

Fernandez explained the significance of the experiment, remarking; "Applying irrigation based on plant demand or daily water use is a key concept in water conserving irrigation scheduling. However, scientific information regarding the water use of woody ornamentals is limited. Quantifying the DWU of a wide range of container-grown woody ornamentals will allow various species and cultivars to be categorised by water use so those with similar water uses can be grouped together, thus minimising overwatering and excess runoff."

Ten different woody ornamental plants were grown in containers in 2006 and 2007, and five in 2008. Overhead irrigation was applied in four treatments: a control irrigation rate, irrigation scheduled to replace 100 per cent DWU per application, irrigation alternating every other application with 100 per cent replacement of DWU and 75 per cent DWU, and irrigation scheduled on a three application cycle replacing 100 per cent DWU followed by two applications of 75 per cent DWU. Irrigation applications were separated by at least 24 hours during the experiment.

Daily water use was calculated by measuring the difference in volumetric moisture content 1 hour after irrigation and just prior to irrigation the following day. Species were classified as low, moderate, and high water users with six low, five moderate, and 13 high water users in the study.

According to the study, "scheduling irrigation according to plant DWU substantially reduced the amount of irrigation applied compared with a control for 23 of the 24 species of container-grown ornamentals evaluated in this experiment while producing larger or the same sized plants for all species."

The authors note that the best DWU treatment to use will depend on a number of factors. The ideal irrigation regimen should provide the most economical balance between crop returns and water management concerns; the cost of water, type of irrigation system, and programming capabilities of the system should all be considered when deciding which regimen to use.

"For example, a nursery in close proximity to a large urban area in a state where water use and runoff are highly regulated may elect to irrigate at a slight deficit using either the 100-75 or 100-75-75 irrigation schedules to minimise water extraction and runoff. However, using deficit or DWU irrigation techniques requires monitoring of soluble salts, which, although not found in our study, may build up under these regimes depending on climatic factors."

Rainwater is safe for household use

2009-11-04T12:41:00.000+05:30

Photo:Monash UniversityA world first study by Monash University researchers has found that rainwater is safe for household use.

The research was led by Associate Professor Karin Leder from the Department of Epidemiology and Preventive Medicine in conjunction with Water Quality Research Australia (previously the Cooperative Research Centre for Water Quality and Treatment).

"This is the first study of its kind. Until now, there has been no prospective randomised study to investigate the health effects of rainwater consumption, either in Australia or internationally," Associate Professor Leder said.

The study involved three hundred volunteer households in Adelaide that were given a filter to treat their rainwater. Only half of the filters were real while the rest were 'sham' filters that looked real but did not contain filters.

The householders did not know whether they had a real filter. Families recorded their health over a 12-month period, after which time the health outcomes of the two groups were compared.

"The results showed that rates of gastroenteritis between both groups were very similar. People who drank untreated rainwater displayed no measurable increase in illness compared to those that consumed the filtered rainwater," Associate Professor Leder said.

Adelaide was the location chosen for the study as it the city with the highest use of rainwater tanks in Australia.

Associate Professor Leder said some health authorities had doubts about drinking rainwater due to safety concerns, particularly in cities where good quality mains-water is available.

"This study confirms there is a low risk of illness. The results may not be applicable in all situations; nevertheless these findings about the low risk of illness from drinking rainwater certainly imply that it can be used for activities such as showering/bathing where inadvertent or accidental ingestion of small quantities may occur.

"Expanded use of rainwater for many household purposes can be considered and in current times of drought, we want to encourage people to use rainwater as a resource," she said.

The study was funded by the National Health and Medical Research Council and Water Quality Research Australia.

Robot fish could monitor water quality

2009-11-02T23:02:00.001+05:30

Michigan State University assistant professor of zoology Elena Litchman. Photo: G.L. Kohuth, Michigan State UniversityMichigan State University scientists developing biomimetic probes

Nature inspires technology for an engineer and an ecologist teamed up at Michigan State University. They're developing robots that use advanced materials to swim like fish to probe underwater environments.

"Fish are very efficient," explained Xiaobo Tan, an assistant professor of electrical and computer engineering. "They can perform very efficient locomotion and manoeuvring in the water."

Robotic fish – perhaps schools of them operating autonomously for months – could give researchers far more precise data on aquatic conditions, deepening our knowledge of critical water supplies and habitats.

Tan and Elena Litchman, an assistant professor of zoology based at MSU's Kellogg Biological Station on Gull Lake in Kalamazoo County, recently won funding from the National Science Foundation to integrate their research.

"The robotic fish will be providing a consistent level of data that hasn't been possible before," Litchman explained. "With these patrolling fish we will be able to obtain information at an unprecedentedly high spatial and temporal resolution. Such data are essential for researchers to have a more complete picture of what is happening under the surface as climate change and other outside forces disrupt the freshwater ecosystems. It will bring environmental monitoring to a whole new level."

The robotic fish will carry sensors recording such things as temperature, dissolved oxygen, pollutants and harmful algae. Tan also is developing electronics so the devices can navigate and communicate in their watery environment.

"This project will greatly advance bio-robotic technology," Tan said. "The project is very practical and we are designing the fish to be inexpensive so they can be used in various applications like sampling lakes, monitoring aquafarms and safeguarding water reservoirs."

The robotic fish might detect toxic algal blooms, for example.

"As air temperature increases, the lakes and reservoirs also heat up," Litchman said. "Increasing water temperature creates strong stratification within the various layers of the water and this may lead to increased growth of harmful algae. Some of these algal blooms create poor conditions for fish and exude toxins that also endanger people."

To mimic how fish swim and manoeuvre, Tan builds "fins" for robotic fish with electro-active polymers that use electricity to change shape. Similar to real muscle tissue, ion movements twist and bend the polymer when voltage is applied. The effect works in reverse, too – slender "feelers" could signal manoeuvring circuits in a sort of electro-active central nervous system. Infrared sensors also could be used for "eyes" to avoid obstacles.

The robots will communicate wirelessly with a docking station after surfacing at programmed intervals and could similarly be linked to other robotic fish for coordinated manoeuvres or signal relay. Global positioning system technology and inertial measurement units will allow precise navigation.

It's not big, but it's a keeper: A 9-inch prototype now swimming in Tan's laboratory tank is modelled on the yellow perch by John Thon, a member of the research team who teaches art at nearby Holt Junior High School. The device isn't strong enough to resist stiff currents, so for now must be confined to relatively still waters. Future versions will incorporate the ability to change buoyancy to assist locomotion and manoeuvre.

UN organisation targets land tenure for the first time

2009-10-29T23:00:00.002+05:30

Unravelling the land tenure issueLand ownership laws a key instrument in fighting hunger

UN Food and Agricultural Organisation (FAO) has begun widespread consultations over the first ever international guidelines on governance of tenure to land and other natural resources such as water supplies, fisheries and forests.

The consultations and negotiations, responding to requests from the international community and from governments, will take more than a year to complete.

They will involve governments, the private sector, poor farmers, indigenous groups, local authorities, academia and independent experts and will be led by a secretariat based at FAO headquarters.

“Secure access to land is seen as a key condition to improving food security of some of the world’s poorest people,” said Paul Munro-Faure, the Chief of the Land Tenure and Management Unit of FAO.

“FAO is taking the lead in this exercise because secure land access is the best safety-net for the poor, and because good governance of land is a necessary condition for secure land access and land tenure rights”.

Laws ignored

Although most FAO member nations have rules to protect farmers and forest dwellers, as well as domestic and foreign investors, from being thrown off their land or having their land seized arbitrarily, laws are often ignored or badly enforced.

“Competition for land and other natural resources is increasing due to population and economic growth, foreign direct investment for large scale food production, demands for biofuels and urban and industrial expansion,” said Alexander Müller, Assistant Director General of FAO’s Natural Resources Department.

“A shrinking natural resource base increases competition as land is abandoned because of degradation, climate change and violent conflicts,” he said. “Without responsible governance, growing demands for land threatens to foster social exclusion as the rich and powerful are able to acquire land and other natural resources at the expense of the poor and vulnerable.”

Weak governance is a cause of many tenure-related problems and hinders economic growth because of a reluctance to invest, from both large and small players.

"It also affects the sustainable use of natural resources, causing environmental degradation and condemning people to a life of hunger and in the worst scenarios can cause conflict and war,” he said.

Women vulnerable

Women, the disabled, illiterate and elderly are particularly vulnerable to having the land they farm arbitrarily seized as they often lack legal and social rights, or where those rights do exist are powerless to enforce them.

The work done by FAO and many other international partners has shown that there is a growing and widespread interest in an international instrument to improve governance of tenure of land and other natural resources.

The voluntary guidelines are intended to provide practical guidance to states, civil society and the private sector on responsible governance of tenure.

The guidelines will provide a framework and a point of reference that will allow government authorities, the private sector, civil society and citizens to judge whether their proposed actions and the actions of others constitute acceptable practices.

Germany, together with IFAD, Finland and GTZ are providing funding with UN agencies (UN-Habitat, UNDP), IPC, the International Land Coalition, the International Federation of Surveyors and many others closely supporting and collaborating with the initiative.

The guidelines will also steer a path for governments trying to cope with the growing trend of large-scale foreign investments for food and biofuels, as well as for investor countries with limited water and arable land.