TUESDAY, OCTOBER 5, 2010


KLMNO SCIENCE NEWS THEGREENLANTERN Some ideas about water are all wet


BY NINA SHEN RASTOGI The local environmental club


keeps urging me to stop “wast- ing water” — to take shorter showers, for instance, and to water my lawn less often. But howis it possible towastewater when it’s constantly being recy- cled through evaporation and rain? It’s true: Thanks to the hydro-


logic cycle, we drink and bathe in the same H2


RUBBERBALL/ALAMY Listening to one side of a conversation can be unsettling.


Hearing half a dialogue can be more distracting than hearing both sides Have you noticed, while sitting on theMetro or waiting in


an office, that it’s hard to ignore a cellphone conversation going on near you? You’re hearing only half the conversation, but, according to a group of researchers, that’s preciselywhy it may be hard for you to concentrate on your own tasks. Unpredictable noises — or silences — tend to distract, and


the one-sided conversations of overheard cellphone chats — what the researchers termed “halfalogues” — fall well into that category. To test the effect, researchers from Cornell University


selected 24 undergraduates and gave them two tasks. First, they were told to use a computer mouse to track a


moving dot on a computer screen; then they were instructed to push a button every time they sawfour specific letters flash on the screen. They completed these attention-requiring tasks while the researchers randomly played a recording of a two-person dialogue, a one-person monologue or a halfalogue. Research- ers controlled the volume and told the participants to ignore the sounds and just concentrate on the assignment. At other times, no recording was played and the tasks were done in silence. The researchers found that performance was lowest — as


determined by missed responses, incorrect hits and other mistakes—when the halfalogues were being played. Inthe moving-dot test, the students reacted six times faster


during the dialogue than during the halfalogue. On average, students did 10 percent worse on the letter- response test when they heard the halfalogue than when they worked in silence or when they heard dialogues or mono- logues. To ensure that these differences were caused by the halfalogue’s unpredictable and incomplete nature — and not the acoustic characteristics of speech — researchers filtered the one-sided conversation so that it soundedmuffled, as if the voice were being heard underwater. That had no significant effect on participants’ accuracy. “This leads us to believe it has to do with the information content being unpredictable,” said Lauren Emberson, lead author of the study. The results were published in the September issue of Psychological Science. —Leslie Tamura


SCIENCE SCAN O that rained on the


dinosaurs. And, theoretically at least, the Earth has more than enough for all of us: According to Brian Richter, co-director of the Nature Conservancy’s Global Freshwater Program, human ac- tivities — agriculture, manufac- turing, bathing, drinking and so on — consume only about 10 percent of the planet’s available freshwater supply. Water shortages are really a problem of distribution. We may have enough freshwater on Earth to meet the global population’s current needs, but we can’t al- ways make it available where it’s needed, when it’s needed and in the quality in which it’s needed. You can think of a community’s


water supply as a bank balance: If the community takes out more than can be returned in a timely fashion, it may reach a point at which it doesn’t have enough water to grow crops, wash clothes or flush toilets. Communities withdraw water


from local surfacewaters (such as rivers, lakes and reservoirs), groundwater aquifers or both. Those sources eventually get replenished by precipitation, but that can be a very long, slow process; with groundwater, for example, it can take hundreds or even thousands of years. Storing the water is a challenge as well: According to a 2003 report from the Government Accountability Office, the holding capacity of the United States’ reservoirs may be declining due to aging dams and increased sedimentation. Con- structing new dams not only is expensive; it can also damage aquatic ecosystems. When considering a region’s


water balance, remember that not all water uses are created equal. When the Lantern was growing up in California in the late ’80s, the brochures she brought home from school listed all kinds of no-no’s: — running the tap while brushing your teeth,


MICHAEL SLOAN FOR THE WASHINGTON POST


watering your lawn at high noon, not letting the yellow mellow before you flush the toilet. But depending on where your com- munity sends its wastewater, some of those uses may be more damaging than others. Let’s say your jurisdiction


takes water from a nearby river and then returns its treated wastewater to the same source. In that case, the water that goes down your sink, toilet and tub stays in the local system; it quick- ly gets recycled, becoming avail- able for reuse in the same com- munity. On the other hand, water


sprayed on a lawn will ultimately evaporate or transpire: It’s essen- tially lost to thecommunityandis categorized as consumptive use of water. (That category includes most water consumed by hu- mans, animals and plants, and water that is incorporated into products.) That watermay return from the atmosphere as rain, but if you live in an area that doesn’t get a lot of precipitation, then you can’t exactly count on receiving a timely, balance-restoring deposit. So when it comes to conserving


Energy costs further distort


The Green Lantern is a weekly environmental column from Slate. Read previous columns at www.slate.com/greenlantern.


water, your first priority should be cutting down on excess con- sumptive use, such as lawn care or car washing. If you live in a city that pumps


most of its water out of the ground, however, the distinction between consumptive and non- consumptive uses may be moot. Though some utilities make an effort to pump treated wastewa- ter back into the source aquifer, most discharge it into a stream or river that eventually flows out to the ocean — which means that water that spirals down your drain doesn’t get returned to the city’s account. So in those places, epic showers are just as sinful as profligate lawn spraying.


LETTERS WHERE TO WRITE: health-science@washpost.com or The Washington Post, Health and Science, 1150 15th Street NW, Washington D.C. 20071


An unwanted comeback


Whooping cough is staging a comeback in California, but it’s no stranger to Virginia and this region, either [“Whooping cough makes a comeback,” Sept. 28]. While the author reports there were about 150 cases this year in Virginia and 89 inMaryland, last year there were 208 cases of whooping cough reported in Vir- ginia alone.This was up 5 percent from 2008. Whooping cough—which can


SCIENCE CHANNEL


Kari Byron hosts a Science Channel after-school show. ENTERTAINMENT


Tests on the tube


“HEAD RUSH,” SCIENCE CHANNEL Middle-school students who insist on plopping onto the


couch and watching television after school could do far worse than an episode of “Head Rush.” The 60-minute, commercial- free show is dominated by segments from the popular “MythBusters” series, interspersed with three-to-five-minute science experiments and quizzes, hosted by Kari Byron. Example: What will happen when Byron microwaves steel wool? Will it: a) burn, b) explode, or c) short-circuit the microwave? It’s good that Byron reminds viewers not to try this at home both before and after the experiment, because when the steel wool sparks and smokes (“a” is the correct answer), the inner curious child — and probably a middle- school student or two— really wants to find some steel wool. “HeadRush” airs weekdays at 4 p.m. and Saturday at 7 a.m. on the Science Channel.


CONSERVATION He’s quite a Guy


GUY HARVEY MAGAZINE, FALL 2010 To folks who have never heard of marine-life artist and


conservationist Guy Harvey, his eponymous quarterly maga- zine, which is in its first year, is a bit like stepping into an alternate universe that revolves around thismysterious man. Readers can learn about the Guy Harvey Ultimate Shark Challenge, a catch-and-release competition; the T-shirts that Harvey designed to raise money for oil-spill cleanup; and his chain of “island casual” restaurants.He is mentioned 18 times on Page 17, which purports to be an editorial, not advertising, page.Non-Harvey features include a gorgeous photo portfolio of whales feeding on sardines and a disturbing article about shark fin soup.


—Rachel Saslow


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GHI If you don’t get it, you don’t get it. S087 1x4


cause pneumonia, brain damage, seizures and mental retardation — was especially prevalent in Fairfax County (27 cases). More startling, the vaccination rate for Virginia’s children dropped from 86 percent to 73 percent from 2005 to 2008, ranking the com- monwealth 40th in the nation. Childhood diseases, which


had all but been eradicated by vaccines, are threatening today’s generations because too many people forgo lifesaving vaccines. This is particularly true among minority populations. Like California, minority pop-


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ulations in this area are under- served in health care, including childhood immunizations. The immunization rate is one of six key areas in whichHispanics and other minorities experience seri- ous disparities in health out- comes. The Centers for Disease Control and Prevention reports pneumococcal vaccination cover-


age forHispanics was 36 percent, compared with 60 percent for non-Hispanic whites, and flu vac- cination coverage for Hispanics was 49.6 percent, compared with 68.6 percent for non-Hispanic whites. The National Hispanic Medi-


cal Association along with na- tional minority health initiatives


are working to close the gap in immunization rates with the goal of achieving and maintaining childhood immunization rates at 90 percent.


Elena Rios President & CEO, National


Hispanic Medical Association Washington


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Stroke – Are You at Risk?


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the image ofwater as a renewable resource. For every gallon of tap water you use, your utilitycompa- ny has to extract it, clean it,pump it to your house,pumpit back out, reclean it and eventually dis- charge it. National numbers haven’t yet


been compiled, but supplying a Northern Californian with pota- ble tap water and then treating thatwater requires about 0.4kilo- watt-hours of electricity per day. (The Lantern based this back-of- the-envelope calculation on a 2006 report from California esti- mating the life-cycle energy costs ofwateranda 1999study suggest- ing that an individual uses about 70 gallons of water indoors daily.) That’salmost asmuchenergy as it takes to run a 60-watt light bulb for seven hours, but it doesn’t include heating the water, which takes even more energy than the treatment processes combined. So, to conserve energy along with your water, keep it cool.


Is there an environmental quandary that’s been keeping you up at night? Send it to ask.the.lantern@gmail.com.


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