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Dangerous waters - {9£,‘ H r K ‘ Outhouse in Ufiaka...

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Unformatted text preview: ....{9£_,‘. H r K ‘ \ Outhouse in Ufiaka, the capital of BangIadesh, I J provides the only kind of ”plumbing" forthe - surrounding slum. According to the World Bank, _. one-third of Dhaka’s 12 million residents Iack 'j. _ .i'. . sanitation facih‘ties, and almost one-third stih' lack safe drinking water. DANGEROUS WATERS Twenty percent of the people on Earth lack access to clean water. And even that dismal number is likely to grow. by Sharon P. Nappier. Robert 8. Lawrence, Kellogg J. Schweb so many freshwater and marine systems. After depleting the top predators and the largest species. fishermen turn their nets on successively smaller organisms. he upshot ofall those assaults is that freshwater organ- isms rank among the world's most threatened species. Data on global trends are sparse. but what biologists do know paints a bleak picture ofstrikiug declines across taxa. Freshwater dragonflies. damselflies. mussels. fishes. amphibians, reptiles, birds. and mammals—all are suf- fering. To prevent a wave oi'irreversible extinctions and ecosystem collapses, people need to take better care of fragile freshwater habitats. Fortunately, there is much people can do. We can re- move obsolete dams and design new ones that take into account natural patterns of river How. We can reduce the need for massive water extractions by changing the way we grow our food and our cities; more efficient irrigation techniques and increased capture oi'rainwater. even in wet areas, would help. Conservation may be the best "new" source of water. particularly as climate change begins to shift water supplies globally. We can start to reduce our polluting ways by avoiding harmful chemicals in the first place. In the end. keeping more water in freshwater habitats and maintaining its quality must be a top global priority. The future of the Mekong lies in the balance. Today. it remains one of the world's least—degraded large rivers. The olissrratlonal-ifstal Is unponifié Ipd." —Doug P9sooiih.o hor ol Grlzily Years $39.95 hardcover. The-Dinosauria ...5 DAVID B WEISHAMPEL PETER ooD'soN. ANDilALSZKA . osmOLsrtA, E ons ‘ 459‘o'ond. Edition,- wln'Poperbaelr -"_Th_'9 ottlmoto rotorénoe on tllnosaurs.... Irst: tor- tho sorlot'u student at 1:. "-ll mummy-T“ -_1+-—n C 2 < to 221 tn _l -< O ‘n n > I" 'n 0 30 Z 3, 'o 2') to to in At .hTfi'okstdttas or _ www. Depress. 9du 1.333;. E '" “‘ ' _._ -mhold, startled, 9nd pondering; Nomanrho- ._ __ . reads this can more our collective Mtg-1m on ---Paul Hawksn. author of Blessed Unmt 39-1. 95 hardcover but the primacy ol‘economic growth threatens to tip the balance towards decline across the entire river system. Still, there are hopeful signs. Several translaoundary initiatives are in the works among the six nations that share the Me- kong. which should help balance the needs ofpeople and wildlife. Then there's the Mekong River Connnission. Formed in the 1950s. the commission has moved away from its original focus on dams and irrigation projects to- ward tnore holistic management that takes environmental health into consideration. But the MRC is only as strong as the resolve ofthe governments it represents: China and Myanmar are not members. which may undermine its effectiveness in protecting the basin. Internationally. the Ramsar Convention on Wetlands. with 155 signatory nations, guides conservation ()i-l,(175 globally important wetland ecosystems. As with the Me- kong River Commission. however, Ramsar’s strength rests on the decisions of its signatories: it has no enforcement mechanism. It should come as no surprise, then. that—as with conservation choices in general—-most decision mak- ers have consistently chosen short4term economic gain over the long-term health of aquatic systems. Current societies value few things more than gold. But though one can survive, even live well, without gold. the same is not true for water. Ultimately. the true value of gold is reduced to this: it can buy You fresh. clean water—if there‘s any for sale. Cl flAmerican Chestnut The titer. Death. and Rebirth of a Perfect Tr99 SUSAN FREINKEL “In promos strong and quietly _ _"i_'_ul 'as the American chestnut itself. Freinkei profiles the silent catastrophe of a near-extinction and the impas- sioned struggle to bring a species back wont, new foooll undo, new ordination lrom tho brink... .A perfect book.” —Mary Roach, author of stiff and Speak $29.95 hammer 52?.50 hardcovor ADniAN LISTER AND__ I Foreword by- JoanM. It dazzling: liturgy _, _ most. morals: " . . soltlor'r Incorporates recent genetic theories. and more. On Deep History Earth under Fire r l and the Brain How Global Wag Is Changing the World GARY BRAASCH Afterward or am McKibberl "Earth Under Firs is that rare book. a and: o‘tiljisolil-lflltflllworkthotndodsto h -' trig “A new paradigm for the study of history that will be regarded as revolutionary but which Is also well lustlflsd.... J_o. oth9r. hook into grates the stud! of ‘:.}.- DANIEI. LORD SMAIL uni afim’om or. biologi- ItfitiFrT—liitrfifi‘oo such on ' ' nthitlous._9§gi§_.1 —stid Sloan'Wllson. _ author of Darwin's Cathedral . $21.55hardcmr An estimated 1,000 new synthetic compounds are introduced every year— some of them inevitably seep into drinking-water sources. taught in Australia. Water shortages in northern China. The desertification ofwestern Africa. Almost daily, such headlines roll offthe presses and issue from the airwaves. Undoubtedly, diminished access to Freshwater is a dire threat to people around the world. But consider the condition ofthe water when it finally trickles down people's throats. Infectious pathogens and harmful chemicals—from parasites to poisons—contaminate the world’s freshwater and contribute to the deaths of mil- lions of people worldwide every year. Understanding the effects ofthose contaminants holds the key to protecting our drinking water. And figuring out how we are exposed to harmful agents is the first order of business in choosing proper water-treatment techniques. The burden ofthose agents weighs heavily on commu— nities around the world. Nearly 2 million people—most ofthem children under five—die every year from diar— rheal diseases. That statistic is not surprising when you realize just how much dirty water flows. or in many cases lies stagnant. across the continents. Nearly 20 percent of the 6.6 billion people in the world lack ac- cess to a supply of clean water, and 40 percent lack safe sanitation facilities. No new headlines there: as far back as 1981 the United Nations recognized the need for improved water supplies and sponsored a water-themed decade through 1990. in hopes of rallying international aid. Yet the percentage of people who have sufficient access to clean water supplies has remained fairly static. Arguably. the battle is uphill. As quickly as innovative filters and water-transport systems enter the market. new contaminants and diseases arise. populations grow, and competing demands for water increase. Certain micro— organisms cau be elusive, causing severe illness at doses as low as One infectious organism per drink of water. And those disease-causing organisms don't stand still while we figure out how to combat them: dirty water can lead to increased virulence. as in the case of antibiotic—resistant bacteria. Battling, let alone eliminating. those ever— changing organisms, along with the plethora ofsynthetic contaminants. seems only to be getting more difficult. One thing will never change: people need water for survival. Circulating inside. outside. and across our cells, water constitutes as much as 70 percen t of on r body weight. Although we may survive four weeks without food. our bodies last. at best. only a few days without water. Fur— thermore, we use water for the most basic daily activities: drinking. cooking. bathing. washing. and sanitation. For at least the past six thousand years. civilizations have understood the need to engineer water treatment teclmiques. Greek and Sa nskrit texts discuss approaches to water sanitation that include boiling. straining, exposing to sunlight, and charcoal filtering. The ancient Egyptians employed coagulants—chemicals that are frequently used even today to remove suspended particles in drinking water—and other methods of purification. The earliest large-scale water treatment plants, such as the one built in 1804 to serve the city ofl’aisley. Scotland, used slow—sand filtration. By the 18505 London was sending all ofits city water through sand filters and saw a dramatic reduction in cholera cases. he discovery of chlorine as a microbicide in the early 1900s was a turning point in drinking—water engineering. That, in turn. led to a major advance in public health. Chlorination was initiated in the United States around 1910, and during the next several decades change was evident: the previously high mortality rate from typhoid fever—twenty-five deaths per 100,000— plummeted to almost zero. Although chlorine readily inactivates viruses and bacteria. its killing power flags when faced with hardy protozoan oocysts (developing cells). such as those of Crypmsperiditmi parvnm—an agent of diarrheal disease. Another. and perhaps even nastier. drawback is that chlorine and organic matter may create carcinogenic by-produc ts when they mix in the treatment plant. Nevertheless. chlorine is still one of the cheapest and most effective disinfectants in use today. No panacea for water disinfection exists, however. To ensure that the water supply is clean enough to drink. most modern drinking-water plants amass an arsenal of treatment options. A multibarrier approach might include physical processes such as coagulation and flocculation (creating clumps of particles). sedimentation, and filtra- tion. in conjunction with disinfectants such as chlorine, chlorine dioxide, chloramines. or ozone. Such systems for cleansing community water are public investments that pay dividends. Clean water improves general health and reduces health—care costs. thereby en— abling greater productivity among community members and redirection of public funds to other pressing needs. Unfortunately. rural and low-income localities cannot afford the infrastructure required for large. centralized drinking-water facilities. _ On a global scale, of course, an ideal filter is natural vegetation. Protecting entire watersheds could vastly im— November 200.7 naturist ulsroiu’ 47 Water-associated pathogens that threaten human health include. from left to right. Norovirus. the Non-rail: virus; Legionella. the bacterium responsible for Legionnaires’ disease, a kind ofpneumonia; Plasmodlum. the protozoan that causes malaria (pictured here inside a red blood cell): Cryptosporidium, a protozoan that causes severe diarrhea and resists treatment with chlorine; Vibrio cholerae, the cholera bacterium: and Giardia lamblia. another protozoan that causes diarrhea. prove water quality worldwide; benefits could come from actions as simple as maintaining hillside growth to prevent soil erosion and flooding. But because many watersheds span several states or even countries. most management plans are politically complex. A comprehensive watershed- management plan must incorporate multiple stakeholders‘ needs and conflicting interests. ater scarcity goes hand in hand with disease. As renewable freshwater becomes a dearer Commodity worldwide, waterborne disease agents and other contaminants become harder to control. When deal— ing with diarrheal diseases, for instance, the quantity of available water often matters more than the quality. both to fend off the disease and to foil its spread. Then there’s trachoma. a condition that can cause blindness; today it affects 6 million people and is associated with poor personal hygiene. often resulting from a dearth ofwater. Every person, every day. needs at least thirteen gallons of water for drinking, cooking, bathing, and sanitation. in I990 tnore than a billion ofthe world’s people used less than that. By contrast, average per—capita water usage in the U.S. now exceeds 150 gallons a day. That discrepancy illustrates how the level ofpersonal use correlates not only with the economic development ofa region. but also with the degree of urbanization and with the overall public health in the region. All that water filling swimming pools and soaking gardens might seem extraordinarily wasteful. but only 8 percent of the planet’s freshwater supply goes toward personal. household. and municipal water use. Agriculture accounts for 70 percont, and industry for 22 percent. of current freshwater use. It takes more than fifty gallons of water to produce a single cup ofmilk. That's modest as virtual water content goes: consider a quarter-pound hamburger (470 gallons) or a cotton T—shirt (520 gal— 48} NATURAL ms'l'okr NovemberEGO? Ions). Then consider how many cotton T-shirts are tucked away in your closets. It’s no surprise that demand is exceeding suppiy. aily water needs are exceedingly hard to meet in areas where rapid urbanization is taking place. Antiquated water—supply systems are simply not equipped to provide enough water and sanitation to people living in progressively crowded shantytowns or on the urban fringe. About half the world’s people are now city dwellers. This new urban majority puts great stress on infrastructure. increasing the likelihood that illegal connections will be inserted into existing water systems and that. as a result. the piped drinking water will become contaminated. Countries undergoing urban population booms often face acute microbial hazards. In countries where per— capita income is low. roughly 200 children under the age of live die every hour from a water—associated microbial in lection. Many ofthe infections derive from the inges- tion of water contaminated with human or animal feces that carry pathogenic bacteria. viruses. protozoa. or hel- niinthes. That's the classic. but not the only. pathway for waterborne disease spread. Exposure to contaminated water extends beyond the drinking fountain. Many diseases. once introduced into a population. can spread via person-to-person contact. in aerosol droplets. or through food preparation. rather than direct consumption ofcontaminated water. For ex— ample. rnalaria-carrying mosquitoes use stagnant water as a breeding ground: Giardia can be acquired during a swim in a local lake: clothing or beddingtnay carry scabies mites; noroviruses can be transmitted by eating oysters [see piwmmirrqqmpirs on there two pages]. Emerging infectious diseases (the ones whose incidence in humans has increased in the past two decades or threat- ens to increase soon) have recently caused some public— health scares. Noroviruses—headlined for causing cruise ship infections—are already on the rise. Crlyimsporr'rlfimr panamr sickened some 400,000 residents of Milwaukee. Wisconsin in 1993, when the local water-treatment pro— cess was changed in what had seemed to be a minor way. 5. tell 0157zH7 is another ofthe more common emerging infectious pathogens in the U.S.joining the hefty ranks of dangerous bacteria, many of which are becoming re— sistant to multiple standard antibiotics. ut pathogenic micro- organisms are not the sole cause of water— associated illnesses. Chemi— cals, too, pose serious risks. About a thousand new syn— thetic Compounds are intro- duced every year, joining the ranks of tens of thou— sands more that are already in widespread use—diox- ins, PCBs, and halogenated hydrocarbons included. Many inevitably seep into the water system and ac- , ‘ cumulate in the Food chain. In the United States, for instance, some 700 chemi- cals have been detected in drinking water sources, and more than a hundred of those chemicals are considered highly toxic. Advanced technologies enable investigators to detect harmful chemicals in the water supply, even in low con- centrations—a critical step, since their effects on human health are often unknown. Several emerging chemicals Drawing copied from the wall of an Egyptian pharaoh's tomb— dated to about 1450 tic—depicts an early method of water purification. One person, shown on right, pours water into the purifier, while another, shown on left. appears to USE suction power to draw the water through a series of filters. of utmost concern are fuel additives, such as methyl tertiary-butyl ether, or MTBE; by—products ofdisinfec- tion: antibiotics, hormones, and psychoactive drugs; the antibacterial soap ingredients triclocarban and triclosan; and persistent organic pollutants, such as perfluorinared chemicals and phthalates. Most people have a sufficiently robust immune system to handle exposure to a certain amount of water pollut~ ants. But some—infants, the elderly, people living with cancer or AIDS—are i1nniunocompromised. Elderly adults often sicken on exposure to only a small Fraction of the infectious dose that others requirefivan issue For the US. as it baby boomer population ages. ust as an aging population poses a concern For public health, so too does an aging infrastructure pose a concern For water delivery. U.S. water infrastruc— ture is outdated and deficient. In the next few decades, measures must be taken to reinforce or restore our water delivery pipes and systems. equipping them for both natural disasters and terrorist threats. Once again the United _ . . - Nations has declaredawater ‘ '.' _‘_i ‘_, decade: 2005 through 2015 I I ' I will be the Water For Life Decade. Among the UN's Millennium Development Goals outlined for the decade are reducing the number of people worldwide who lack . '_ - adequate waterand sanitation j; by half. Additional efforts - will concentrate on curbing the unsustainable exploita- tion of water. As with the UN's approach to increasing literacy, facilitating income generation, and curbing - II population growth, the fo- cus will be on empowering women as a means ofachiev- ing its goals. Certainly the goals are challenging. Achieving them will require coopera— tion among many stakehold- ers who are committed to expanding investments in water and wastewater infra- structure. New management strategies must embody conservation and efficiency for people everywhere, lest we find ourselves changing too slowly to quench the world‘s thirst. El November 200? NATL'RAI insrniw 49 ...
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