“When I started out, I just asked the question, how did lakes stay clean for thousands of years? And the answers came to me, there was the spring and fall turnover, and in the tropical climates periodic typhoons and hurricanes and monsoons that turn the lakes over, and that puts oxygen down on the bottom. So I duplicated that and accelerated it,” Laing told America.gov.

Manipulating constituents of the water, aerating sediment with oxygen and introducing bacteria, he found, effectively restored dead waters. “I had  a number of friends with lakes or ponds; we tried it on them and it was very successful. And we went on from there.” Laing founded CLEAN-FLO in 1970.

His innovation drew resistance. “He was the first one in and he took all the arrows from the industry,” says Brian Kling, who took over CLEAN-FLO with Laing’s blessing on the founder’s retirement in 2005. “There are still consultants out there that say aeration doesn’t work and that what you’ve got to do is spend $2 million to dredge your lake.”

But results demonstrate the CLEAN-FLO process -- continuous laminar flow inversion oxygenation system (CLFIOS) -- does work: Since 1970, more than 2,000 lakes, rivers, ponds, reservoirs and wastewater projects in the United States and internationally have been transformed by it.

One satisfied customer installed the system in a 190 million liter manure lagoon at a biofuels plant in Mead, Nebraska, in 2007. Manure from 30,000 cattle produced methane gas in anaerobic digesters, but that clogged the lagoon. Within two months after installation of the CLEAN-FLO system, markedly increased oxygen levels were recorded.

Oxygen is infused in the organic sediment on the bottom, says Kling, with “compressed air from the shoreline going through a self-sinking air line to diffusers that we manufacture that sit on the bottom.” The diffusers “maximize oxygen transfer.” Once the sediment is aerated, bacteria ingest the decaying organic matter and clean up the water to restore a healthy ecosystem.

A CLEAN-FLO diffuser works to aerate a lake and restore it to a healthy balance. (Courtesy CLEAN-FLO)

Initially, gases like carbon dioxide, methane and hydrogen sulfide are released when sediment is stirred up. “It’s a relatively quick release. You are basically exhausting what’s down there,” Kling says. “By running the system, you are preventing a buildup of those gases long term. Are we harming anything by releasing? It’s a one-time release.”

Community lakes frequently become polluted with fecal bacteria and weeds -- in worst cases, in the American Southwest, infestations of Naegleria fowleri (called the brain-eating amoeba because it attacks the human central nervous system) occur. Such problems can be eliminated by the CLEAN-FLO process.

Collins Lake in Scotia, New York, was closed for swimming because of bacteria and poor water quality. In 2006, “a significant drop in bacteria levels was observed” one week after an inversion and oxygenation system was installed, according to a letter from park supervisor Jim Marx. By August, the beach reopened. The project will be featured in an upcoming film for the Sustainable Planet film festival, Kling says.

Nutrients from sewage and fertilizer runoffs create conditions that choke lakes, rivers and streams with algae and make it impossible for fish, animals or people to use the water. “Most people aren’t willing to cut the use of fertilizers. The stream qualities coming into lakes and ponds are getting worse and worse every year with the runoff and other pollutants.” Kling said.

The CLEAN-FLO system runs continuously to counter these kinds of runoff. Even in clean water, “eventually, over time, that organic load is going to build up again at the bottom,” he said.

Kling said the system is more cost-effective than conventional dredging and chemical treatment, which can cost 10 times to 15 times more. “In dredging, you are removing that material … but you are not going to stop it from coming back in. Whereas with CLEAN-FLO, once we reverse the anaerobic cycle and go aerobic and we get a lot of that stuff out of there, we are going to be able to better keep up the water body.”

Kling previously was a consultant doing watershed and fish  studies, “doing some dredging type applications, doing some chemical treatments” to control algae and weed growth. In his experience with conventional chemicals, Kling said, he found “you had to use higher and higher doses of chemicals and in some cases you just couldn’t control the growth anymore.” That’s when he looked for an alternative and found Bob Laing and CLEAN-FLO. Kling’s company became a CLEAN-FLO dealer before Kling became CLEAN-FLO’s president.

Demand for the process has doubled each year since. “What we do is improve the water quality for all applications,” Kling said. Fish are healthier, odor disappears as bacteria and weeds are eliminated, people can safely swim and enjoy clear, blue water.

Global warming and shrinking water resources could bring such technologies into wider use as water becomes more precious. “There’s no question that the quality of water degrading across the country and across the world is definitely bringing us more business,” says Kling.

 “Power Plants” features flora from around the world: field crops, palms, trees and flowering annuals. The 0.4-hectare (one-acre) exhibit aims to educate visitors about the raw materials of biomass.

“We have 21 plants on display here that are currently being used to produce ethanol and biodiesel or have the potential to do so. They range all the way from … traditional crops like corn and barley and soybeans and things that are tropical and subtropical, sugar cane and jatropha and cuphea, and even some unusual plants such as algae,” Arboretum Director Thomas S. Elias said.

Different regions of the world have different organic renewable energy resources, he said.

“This garden will give people a hands-on opportunity to see the plants,” Elias said.

“Is soy the answer? Is corn the answer? We are addressing a very relevant issue by having all the examples here so people can come and see and learn about them and help understand the issues.”

Garden director Scott Aker said of a unique patch of soybeans, “These are interesting because the trunks or stems of them can actually be used as cellulose for paperboard or for ethanol” and the soybeans for food. “These will get 6 feet [1.8 meters] tall, and they yield a lot of soybeans,” a “very good plant for no-till” farming, he said.

Under a big tent nearby, representatives from 27 American universities engaged in renewable energy research explained their projects.

WIDE RANGE OF PROMISING RESEARCH PROJECTS

Steve Taylor, director of the Auburn University Center for Bioenergy and Bioproducts, stood beside a portable biomass gasification unit engine, explaining the process as it chugged away. “We put woodchips in one end and electricity comes out the other end,” he said, holding up a jar of “very clean” synthetic diesel fuel made from biomass sources like wood or switchgrass.

The unit, the size of a large trailer, can be hauled easily to crop-residue accumulation sites.

Cuphea oil could be the new jet fuel, having similar carbon chains that allow use at extreme temperatures. (Keith Weller USDA/ARS)

“They are typically residues that you cannot afford to haul very far. Transportation is not cost effective. Onsite you can use it to generate your own power or other fuels,” instead of merely incinerating it, Taylor said. “It’s onsite power from onsite residue.” One goal is to reduce the cost of such power units.

Robb Walt, president of Community Power Corporation, a partner in Auburn’s research, added, “Theoretically you could absolutely provide power for a house” with household waste, but the current focus is to “provide farms with an opportunity to be energy independent.”

Among high-potential plants are algae. K.C. Das from the University of Georgia explained why algae are good candidates for energy generation. “It is a plant, even though it doesn’t have roots or leaves. It does the same thing, photosynthesis … and it’s the fastest-growing plant in the world.”

Its productivity outpaces other plants, and it has lipids -- “oils that may be extracted to make biodiesel, which is why it’s attractive,” Das said. It’s a nonfood oil, so demand for it would not affect food supplies.

Algae need a lot of water to propagate -- 1 ton needs 1 million gallons -- but they can grow in fresh or saline environments. Experiments growing algae in closed containers yield promising results, he said.

Algae’s lipid, carbohydrate and protein content make them potential sources for bioplastics, biofuels, food and feed. Several universities are pursuing algae research.

The University of Maine, located in America’s lushly forested northeast, turns forest waste into energy under its Forest Bioproducts Research Initiative (FBRI). The university recently received a $30 million grant from the U.S. Department of Energy (DOE) to build a small-scale commercial biorefinery.

FBRI Director Stephen Shaler said forest bioproducts include not only fuel and electricity, but chemicals and plastics. “Advances in science, coupled with better understanding of the ecosystem, the biology of tree growth and the chemistry of breaking down wood,” make refining more efficient, he said.

Innovative greenhouses that utilize all available space with multistory growing platforms and fuel pellets and nonpetroleum plastics from biomass and farm waste are other technologies in development.

Ernie Shea, from exhibit co-sponsor 25x25, said farmers are crucial in the sustainable energy effort, and will strengthen national security and rural economies. Doing it right, he said, means setting a clear goal and “producing energy in a sustainable way … that improves soil, water and air quality, in a way that doesn’t compromise food production. We feel that we can produce food, feed, fuel and fiber simultaneously to meet society’s needs, and do it in a way that is affordable.”

The National Arboretum, established in 1927, is administered by the U.S. Department of Agriculture’s Agricultural Research Service.

Learn more about nature’s power plants on the U.S. National Arboretum’s Web site.

See also “Advances in Technology Position Biofuels for Clean Future.”

Afforestation is the planting of a forest on cleared or unforested land.

Agricultural waste is waste from farming and livestock operations, including animal manure and harvest residues. Such wastes are sources of pollutions but also potential energy sources.

Air pollution is the contamination of the atmosphere by substances, including emissions from manufacturing plants, construction, power plants and vehicles, detrimental to health and the environment.

Air quality standards are regulatory limits set by the U.S. government for the maximum safe levels of pollutants or contaminants in the atmosphere.

The Arctic Council, established in Ottawa in 1996, is a high-level forum created to protect the Arctic environment and promote the economic, social and cultural well-being of northern peoples. Its members include Canada, Denmark, Finland, Iceland, Norway, the Russian Federation, Sweden and the United States.

Atmosphere includes all the layers of gases that surround Earth, protect it from solar radiation and help create conditions conducive to life. Nitrogen, oxygen, carbon dioxide and water vapor are among the gases in the atmosphere.

The Bali Strategic Plan for Technology Support and Capacity Building, adopted in Bali, Indonesia, on December 4, 2004, seeks to support environment-related technology and build capacity for effective environmental management in developing countries and in countries whose economies are in transition.

The Berlin Mandate is a “decision of the parties” reached at the first session of the Conference of the Parties to the United Nations Framework Convention on Climate Change (COP-1) to begin a process to strengthen the commitments of industrialized countries to reduce greenhouse gas emissions beyond the year 2000 through the adoption of a protocol or other legal instrument.

Biodegradable refers to the ability of a substance to be broken down over time by sun, wind, water and microorganisms. Most products derived from plants and animals -- like paper, fabric and food -- biodegrade.

Biodiversity refers to the variety of living organisms, from single-celled to complex life forms, in the ecosystems where they naturally occur.

Biofuel is any liquid, solid or gas fuel refined in whole or in part from sustainable biological materials, usually plants. Some biofuels, like ethanol, are refined from food plants such as corn, but technologies are being developed to use nonfood plants and crop residue from food plants.

Biomass is organic material from plants or animals that can be used to produce biofuels. Examples include switchgrass, miscanthus, corn, sugarcane and oil palm.

Bioremediation is the use of living organisms such as bacteria to remove pollutants from water or land.

Biosphere encompasses all areas of the Earth -- land, air and water -- that support life.

Biota refers to all living plants and animals in a defined area.

Carbon sequestration is a method that reduces greenhouse gas emissions by capturing carbon dioxide where it is generated and storing it underground for decades, perhaps centuries.

Chlorofluorocarbons (CFCs) are a class of chemicals -- once commonly used as coolants, fire retardants and aerosol propellants -- that depleted the protective ozone layer in the Earth’s upper atmosphere. Most uses of CFCs were banned under a 1987 international agreement known as the Montreal Protocol.

Compact fluorescent lamps (CFLs) are light bulbs that use far less energy and last up to 10 times longer than standard incandescent light bulbs.

CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) is a 1973 international agreement that restricts trade in wild animals, plants and any products derived from them to ensure such trade does not threaten their survival.

Clear cutting is the felling of large forest tracts for agriculture or development, a practice that destroys habitat, kills flora and fauna and leads to erosion, flooding and sedimentation of streams and lakes.

Climate change, also called “global warming,” is the gradual, long-term alteration of weather patterns on a planetary scale. Scientists believe human activities are affecting climate change and accelerating the speed at which it is occurring.

Conservation is the preservation and renewal of natural resources through good management for use by future generations.

Ecology is the study of ecosystems to examine how all living organisms relate to each other and the environment.

Ecosystem refers to the interaction of plants and animals with each other and their physical environment. Ecosystems may be as small as organisms living under a rock or involve large geographic areas.

Emission standards are regulatory limits set by the U.S. government on the pollutants that can be released into the atmosphere from sources like motor vehicles or manufacturing plants.

Endangered species is a variety of animal or plant in danger of extinction.

Endangered Species Act is a 1973 U.S. federal law that protects endangered species (likely to become extinct in the foreseeable future) and threatened species (likely to become endangered in the foreseeable future) by safeguarding habitats as well as the plants and animals themselves.

Erosion is the loss of soil and wearing away of rock, particularly by wind and water. Erosion can be exacerbated by agricultural practices, residential and commercial land clearing and road construction.

Fossil fuels, which include coal, oil and natural gas, are nonrenewable energy sources derived from hydrocarbons formed from fossilized remains of plants and animals by the pressure and action of the Earth over millions of years.

Geothermal energy is energy derived from the natural heat and water resources within the earth, such as volcanoes and hot springs.

Global warming, a term often used interchangeably with climate change (see entry above), refers to the gradual changes in global weather patterns observed by researchers that suggest mean temperatures are rising planetwide.

Greenhouse effect describes a rise in temperatures on Earth due to the accumulation of certain gases in the atmosphere, such as water vapor, carbon dioxide, nitrous oxide and methane, which trap the sun’s energy and prevent the escape of heat into space.

Greenhouse gases, which include water vapor, carbon dioxide, nitrous oxide, ozone and methane, are released in large quantities by some human activities and are believed to contribute to global warming.

Greenhouse gas intensity is a measure of gas emissions per pound of production.

Groundwater is a potential source of drinking water found beneath the Earth’s surface and accessed by drilling wells or tapping underground springs. Pesticides, sewage, industrial waste and agricultural runoff can contaminate groundwater.

Hydrocarbon is an organic chemical compound comprising hydrogen and carbon atoms.

The Kyoto Protocol is an amendment to the U.N. Framework Convention on Climate Change (UNFCCC). Countries that ratified this protocol committed to reducing their emissions of carbon dioxide and five other greenhouse gases, or engage in emissions trading if they maintained or increased emissions of these gases, which have been linked to global warming.

The Lacey Act Amendments of 1981 is a U.S. law that prohibits the import, export, transport, purchase or sale of fish, wildlife and plants taken or possessed in violation of federal, state or tribal law. Interstate or foreign commerce in fish and wildlife taken or possessed in violation of other nations’ laws also is illegal.

The Montreal Protocol on Substances that Deplete the Ozone Layer, a 1987 international agreement to which the United States is a party, called for phasing out production and consumption of compounds that deplete ozone in the stratosphere -- chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform. This was accomplished in 2000 for most of the listed substances and in 2004 for methyl chloroform.

Ozone is a chemical compound comprising three oxygen atoms. At ground level, ozone is an air pollutant that irritates the respiratory system. In the stratosphere, ozone is a protective layer that shields the planet from harmful ultraviolet radiation.

A pesticide is a manufactured or naturally occurring substance applied to open areas, crops, storage facilities and residences to kill or repel organisms that destroy crops or spread disease. Some pesticides can be toxic to nonpest species and can persist in soil and water.

Pollution is a contamination of air, land or water with substances that compromise the ecosystem; threaten human, animal or plant health; or adversely affect use of natural resources.

Rain forest is a tropical or subtropical forest with a vast leaf canopy that requires an average annual rainfall of approximately 2,000 millimeters. Rain forests absorb large quantities of carbon dioxide and shelter a large percentage of the world’s plant and animal species.

Recycling is the practice of collecting reusable waste materials for reprocessing into new products. Glass, metal, paper and plastics can be recycled, as can salvaged construction materials.

Renewable energy refers to sources of fuel and power that are sustainable resources such as geothermal, biomass, wind and sun.

Smog is a cloud of air pollutants -- dust, smoke, factory emissions and vehicle exhausts -- usually centered on urban areas. Smog can trigger or exacerbate respiratory ailments. Typical chemical components of smog include ozone, sulfur dioxide, nitrogen dioxide and carbon monoxide.

Surface water refers to open expanses of water such as rivers, lakes, reservoirs, ponds, streams, seas, estuaries, wetlands, springs and wells.

Sustainable agriculture connotes farming methods that conserve the environment by minimizing damage to soil, water sources, species habitat and other natural resources. Examples include no-till farming, crop rotation, and prevention of runoff or leaching of fertilizers and pesticides.

Wetlands are water-saturated or frequently flooded areas like swamps, marshes, deltas and coastal zones that support flora and fauna especially adapted to a watery environment. Wetlands also purify water and absorb excess rainfall.

Wildlife refuge is a tract of land or seashore legally set aside to protect wildlife and plants.

The world is spending $300 billion every year to subsidize fossil fuels that pollute the air, wreck the climate ... and run the world's economy.

So what if we, as taxpayers, stopped spending $300 billion on coal, oil and natural gas, and started spending it instead on wind, sun and water?

That's the question at the heart of a new report from the United Nations Environment Program, which concludes that eliminating fuel subsidies would not only reduce greenhouse gas emissions, but might just inspire new economic growth. (Further, it concludes that fossil fuels subsidies sold as a way to help the poor keep the lights on actually do more to help the rich.)

“In the final analysis many fossil fuel subsidies are introduced for political reasons but are simply propping up and perpetuating inefficiencies in the global economy – they are thus part of the market failure that is climate change,” UNEP Executive Director Achim Steiner said.

Isn't it remarkable how subversive the U.N. can be?

The world spends about 0.7% of GDP on fossil fuel subsidies. The cost of curtailing carbon emissions to meet scientific goals by 2050 has been estimated at 1% of GDP. (The cost of not curtailing carbon emissions, measured in weather calamities, mass migrations and the like, could be 5-10% of GDP.)

The problem, of course, is that most nations are not willing to give up fossil fuels, their subsidies, or their profits. We focus on ourselves, and the addiction to oil we all admit to. But think about Russia, fat on oil wealth, and willing to thumb its nose at the international community. Can we reasonably expect that Russia will join in the latest United Nations talks, ongoing this week in Ghana, and agree to slash its carbon emissions?

Russian fossil fuel subsidies, at $40 billion annually, are the largest on the planet, according to the U.N. report. Others that top the list: Iran, China, Saudi Arabia, India, Indonesia, Ukraine and Egypt.

Wiping out oil subsidies, unfortunately, is akin to telling countries -- many of them unwilling to listen to international opinion in the first place -- not to act in their own national interest.

Still, the U.N. report is telling: The cost of transforming an economy to run on renewable fuels always seems daunting, so ingrained are our dependencies on fossil fuels. But if you consider how much is spent to make those fossil fuels affordable in the first place, the price tag doesn't look so daunting.

Tempe Town Lake, on the northern edge of Arizona State University (ASU), is just one of a multitude of lakes, small ponds, canals and dams combining flood control, water delivery, recreational opportunities and aesthetics, and altering perception of water availability and economics in the area.

What are the consequences of such human-made tinkering with land cover and hydrology on surrounding native ecosystems and biodiversity? This question forms the backdrop for a case study proffered by an ASU research team and published in the journal BioScience, which found that one of the most profound impacts of urbanization is the "reconfiguration of surface hydrology."

Lead author John Roach, now with Simbiotic Software in Missoula, Mont., ASU professors Nancy Grimm and J. Ramon Arrowsmith and other former graduate students mapped water resources and connectivity and tracked land-use change in the Indian Bend Watershed (IBW). The researchers, associated with the Central Arizona-Phoenix Long Term Ecological Research project (CAP-LTER) and the Integrative Graduate Education and Research Training (IGERT) in Urban Ecology funded by the National Science Foundation, found that construction of artificial lakes and canal systems along with extensive groundwater pumping have had "unintended impacts on nutrient cycling."

"As Phoenix grew from a small settlement to the large urban center it is today, it built an extensive canal network to bring water from the Salt, Verde, and Colorado rivers to agricultural fields and city taps," says Roach. "While these canals enabled farmers to grow crops in the desert, they also cut across stream channels, disrupting the flow of water and sediments from tributary networks to the main channel. In pristine streams, sandbars and other patches created where these sediments collect are often ideal places for nutrient cycling. By starving streams of their historic supply of this material, canals accidentally alter the way nutrients are cycled in stream ecosystems."

Humans have altered water systems in the Phoenix area as far back as 300 B.C. The Hohokam people constructed an extensive series of canals for irrigation in the region (until 1450 AD). A new group of settlers arrived in the 1860s and immediately began building "ditches" or simple irrigation canals. Construction continued through the 1900's as dams were built to harness the Salt and Verde rivers and the canal system was expanded to bring more land under cultivation. As the area became more urban, flood control became more important, necessitating construction of the Indian Bend Wash greenbelt, one of the first non-structural flood management structures in the United States. These activities altered surface water availability, dramatically increasing the timing and spatial distribution of stream flow.

"Prior to these alterations, channel systems like those of Indian Bend Wash were ephemeral, storm precipitation-driven systems with only a limited connection to the groundwater (via loss from the channel bed)," notes Ramon Arrowsmith, professor with School of Earth and Space Exploration in ASU's College of Liberal Arts and Sciences. "Now, the surface and subsurface hydrologic network is short circuited with water entering the channel from well and canal sources, and water leaving by important evaporation, seepage, and canal redirection."

The authors emphasize how modern urban water systems shatter any limitations imposed by the topographic contours of a region. The Central Arizona Project cuts a blue swatch across the Sonoran Desert and subdivides watersheds, to deliver a reported 1.7 × 109 m3 per year (or 1.5 million acre-feet) of surface water to the area. In addition, the pumping of ground water has dropped the water table 90 meters and connected surface and subsurface flows, "not only increasing the spatial and temporal availability of water, but having the unintended effect of increasing the flux of NO3 through urban waterways by returning nitrogen leached from historic fertilizer applications to surface flows."

One concern is the potential impact on riparian species, the "integrity of native ecosystems and the continued delivery of goods and services from these ecosystems."

Streams in deserts are often overlooked in their importance because of their ephemeral nature; however, streams in general have been shown to be critical to the removal of excess nitrogen from agricultural fields and waste water run-off from urban areas. Denitrification, a bacterially-mediated process, converts nitrate to nitrogen gas, which then is released harmlessly to the atmosphere. High nitrogen loads from urban areas can overwhelm streams' capacity to remove nitrates and the resulting pollution of downstream rivers has been linked to the proliferation of coastal dead zones.

"We were surprised by how frequently the concentration of nitrate in surface waters was determined by the turning of a tap," Roach notes. "Because the groundwater below the greater Phoenix ecosystem contains a lot of nitrate, when groundwater wells are tuned on, the concentration of nitrate in the canals and streams receiving this water goes up. This nitrogen, in turn, can act as fertilizer, stimulating unwanted growth and producing changes in what the stream looks like that are independent of the decision to deliver more water to city lawns."

The present study underscores the importance of understanding the structure and function of natural streams and arid ecosystems and how they are impacted by human-altered systems, water distribution and design. The authors point out that the unintended consequences "must be carefully evaluated – especially in arid and semiarid cities – if managers are to have any hope of mitigating them."

Grimm, a professor in the School of Life Sciences and member of the Global Institute of Sustainability at ASU, sums their study up: "Our findings contribute to answering the more general question of how fundamental ecosystem services – those processes of ecosystems that provide a natural resource or regulate properties of the resource, for example – change when people make large alterations to streams during the course of urban development. Perhaps our case study will help define how to best design such ecosystems to meet the need to provide multiple services – in this case, protection from flooding, recreation, and regulation of nutrient concentrations reaching downstream systems."

نام مقاله: ENVIRONMENTAL SCIENCE: PHYSICAL PRINCIPLES AND APPLICATIONS

نویسندگان:

A. Speranza, Department of Mathematics and Computer Science, University of

V. Lucarini, Department of Mathematics and Computer Science, University of

J A M E S J . C O R B E T T , * , †

J A M E S J . W I N E B R A K E , ‡ E R I N H . G R E E N , ‡

P R A S A D K A S I B H A T L A , |

V E R O N I K A E Y R I N G , ⊥ A N D A X E L L A U E R ⊥

In the world of alternative fuels, there may be nothing greener than pond scum.

Algae are tiny biological factories that use photosynthesis to transform carbon dioxide and sunlight into energy so efficiently that they can double their weight several times a day.

As part of the photosynthesis process algae produce oil and can generate 15 times more oil per acre than other plants used for biofuels, such as corn and switchgrass. Algae can grow in salt water, freshwater or even contaminated water, at sea or in ponds, and on land not suitable for food production.

On top of those advantages, algae — at least in theory — should grow even better when fed extra carbon dioxide (the main greenhouse gas) and organic material like sewage. If so, algae could produce biofuel while cleaning up other problems.