Greening the clean room

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<ul><li><p>New research from severalEuropean teams suggests thatthe same catalytic convertersthat reduce harmful atmosphericpollution from automobiles may becreating a new environmentalproblem by widely broadcastingsmall amounts of the platinumgroup metals (PGM)platinum,palladium, and rhodiuminto theenvironment.</p><p>A study by a French and Italianteam led by Carlo Barbante at theUniversity of Venice found increas-ing concentrations of PGM inGreenland snow and ice. The re-searchers attribute the trend toemissions from catalytic converters(Environ. Sci. Technol. 2001, 35 (5),835839). A second study hints thatpalladium is much more mobile inthe environment than previouslybelieved. English researchers, led byenvironmental chemist Kym Jarvisof Kingston University, report thatmore than one-third of the palladi-um in road dust is soluble in simu-lated rain (Environ. Sci. Technol.2001, 35 (6), 10311036).</p><p>The United States, Canada, andJapan introduced cars with catalyt-ic converters in 1976. Europe fol-lowed in the late 1980s. Theplatinum and palladium in thesedevices catalyze oxidation reac-tions that convert carbon monox-ide and hydrocarbons into lessnoxious emissions. Rhodium cat-alyzes reduction reactions that</p><p>convert NOx into lessharmful gases.</p><p>Scientists have beenconcerned for a numberof years that the ever-increasing use of auto-mobile catalytic con-verters might lead towidespread dispersionof PGM into the envi-ronment, althoughBarbante calculates that emissionsare currently low, about 0.51.4tons of platinum per year world-wide.</p><p>The recent studies, together withan impending European Commis-sion report, show that PGMs in theenvironment need attention now,according to environmental chem-ist Gregory Morrison at ChalmersUniversity of Technology in Gte-borg, Sweden. Levels now are verylow, but the issue is what happensas there are more cars and moreconverters. Thats why we need topay attention to PGMs so that wecan avoid a problem in the future,he says.</p><p>Barbante and colleagues collect-ed snow and ice from centralGreenland and took samples fromthe Greenland Ice Core Project,which provides material datingback more than 7700 years. Theyfound PGM concentrations in sam-ples from 1995 that are 40120times higher than values in the an-cient ice, which has values of 0.01</p><p>pg/g for platinum and palladiumand 7 104 pg/g for rhodium. Thescientists attribute the increases tocatalytic converter emissions be-cause the time trends in Greenlandsnow are similar to the PGM de-mand curves, says Barbante. Theincreases are more likely to comefrom refining and smelting opera-tions in Siberia, whose output alsomatches the time trends and ele-ment ratios, says Rob Searles, di-rector of the Association forEmissions Control by Catalyst, atrade group based in Brussels.Searles also notes that studies haveshown that PGM particles, whichare relatively heavy, typically donttravel far from car exhaust pipesbut fall out at the edges of road-ways.</p><p>A number of studies have indeedshown increased PGM at the edgesof major roadways, but it has beenassumed the metals would be inert,says Jarvis. Her research shows thatmore than one-third of the palladi-um in road dust is soluble in simu-lated rain, while only about 1% ofplatinum and rhodium are soluble.This suggests that some, if not all,of the palladium in road dust is in aform such as a chloride or oxidespecies, whereas platinum andrhodium are probably there aszero-valent metals, she says.</p><p>The Jarvis study is important be-cause it provides an explanation forhow palladium is getting into theenvironment, says Morrison.</p><p>EnvironmentalNews</p><p>Catalyzing pollution</p><p>W earinsidethehoneycombedstructureofacatalyticconvertercanreleasemetalstotheenvironment.</p><p>SBA</p><p>STIENRA</p><p>UCH</p><p>SBA</p><p>STIENRA</p><p>UCH</p><p>Researchersareusingalaserablationsystem (left)andaninductivelycoupledplasmamassspectrometer(right)tostudyplatinum groupmetalsassociatedwithcatalyticconverters.</p><p>138 A ENVIRONMENTAL SCIENCE &amp; TECHNOLOGY / APRIL 1, 2001</p></li><li><p>Together with Sbastien Rauch,Morrison has found that palladiumaccumulates in the freshwater crus-tacean Asellus aquaticus. They havealso found that the concentrationof palladium has been increasingover time in the feathers of Swedishraptors.</p><p>Although this new research sug-gests that PGMs in the environmentmay merit more scrutiny, the immi-</p><p>nent European Commission studyfinds that exposure to PGMs fromautomotive catalysts does not posea human health risk. Ambient airlevels of platinum, which rangefrom 1 to 100 pg/m3, are several or-ders of magnitude below safe levels(calculated to be between 15 and150 ng/m3). Levels of the otherPGM metals in air are also very low.REBECCA RENNER</p><p>Wetlands go dry?In a landmark 54 split decision onJanuary 9, the U.S. Supreme Courtstruck down federal regulation ofisolated ponds and wetlands. Thecourt ruled that Congress did notintend the Clean Water Act (CWA)to apply to isolated waters such asprairie potholes and vernal pools.The decision could leave morethan 20% of the nations wetlands,including cypress domes in theEverglades, vulnerable to drainageand filling, according to theNational Wildlife Federation, anenvironmental group.</p><p>The action was triggered 10years ago when the U.S. ArmyCorps of Engineers denied a permitto the Solid Waste Agency ofNorthern Cook County (SWANCC),a consortium of 23 Illinois cities, tofill an abandoned strip mine withgarbage. SWANCC sued the Corps,asserting that it had no right toregulate isolated wetlands be-cause the CWA only covers wa-ters that could be used fornavigation or are connected tonavigable waters. The SupremeCourt agreed, adding that federalregulation of isolated wetlandswould infringe on states rights.</p><p>EC action planThe Sixth Environmental ActionProgram (EAP), proposed by theEuropean Commission (EC) in lateJanuary, outlines Europes courseof action on the environment overthe next 5 to 10 years. The newEAP is expected to receive a read-ing in the European parliament thismonth and then move on to theEnvironmental Council of Ministers.</p><p>Under the program, the EC willwork harder on implementing ex-</p><p>Levels of polybrominated diphenylethers (PBDEs) in Lake Michigansalmon are among the highest everreported for fish in open waters,providing further evidence that thisclass of compounds is a ubiquitousenvironmental threat (Environ. Sci.Technol. 2001, 35 (6), 10721077).PBDEs are used as flame retardantsin polyurethane foam, textiles, andplastic electric and electronic com-ponents, with penta-, octa-, anddeca-BDE as the most commonlyused commercial preparations.</p><p>PBDEs have only recently re-ceived attention as environmentalpollutants, after they were detectedin diverse environments rangingfrom the deep sea to human bloodserum and breast milk (Environ Sci.Technol. 2000, 34 (9), 223A226A).U.S. data on the prevalence ofPBDEs in the environment are stillscarce compared to data that have</p><p>been collected in Europe. JonManchester of the University ofWisconsins Water ChemistryProgram has added to the U.S. data-base by using archived fish extractoriginally prepared for PCB analysis.Other researchers could do thesame, he suggests, contributing [tothe] database [on PBDEs in the U.S.]very quickly.</p><p>Environmental PBDE contamina-tion has raised significant concernin Europe, leading the EuropeanCommission to propose a ban onpenta-BDE this past January. Theproposal followed the advice givenby the European Union (EU) in anextensive risk assessment on pen-ta-BDE that was published lastAugust (, whichitself was prompted by the presenceof penta-BDE in human breast milkand uncertainties regarding itshealth effects on infants. PBDEs are</p><p>Government Watch</p><p>Lake Michigan heavily contaminated with PBDEs</p><p>PBDEconcentrationsinsalmonfrom LakeM ichiganareamongthehighestintheworldforfishinopenwaters,researchersfrom theUniversityofW isconsinrevealed.</p><p>WISCO</p><p>NSINSE</p><p>AGR</p><p>ANT</p><p>APRIL 1, 2001 / ENVIRONMENTAL SCIENCE &amp; TECHNOLOGY 139 A</p><p>Continued on Page 141A</p></li><li><p>also targeted to be phased outunder the recent and disputed EUproposals to restrict hazardous sub-stances in electric and electronicequipment. The EU bromine indus-try is fighting to prevent bans onocta- and deca-BDE. Risk assess-ments on these two substances areimminent.</p><p>Although deca-BDE accountsfor 82% of the global BDE produc-tion, it is the smaller congenerstetra-BDE and penta-BDEthatare most commonly found in hu-mans and the environment.However, this is no reason to bemore relaxed about deca- andocta-BDE, suggests ke Bergman,professor for EnvironmentalChemistry at Stockholm Universityand one of the most experiencedresearchers on brominated flameretardants. He stresses that thecommercial mixture sold as octa-BDE, in fact, mainly consists ofhexa- and hepta-BDE, and he is es-pecially worried about deca-BDEshigh reactivity, which makes it</p><p>prone to act as a human carcino-gen. He also suspects the lack ofreliable data on deca-BDE in theenvironment is partly due to diffi-culties with its analysis.</p><p>A comparison between PBDEand PCB levels in the Lake Michigansalmon used in the University ofWisconsin study show a high corre-lation, suggesting that PBDEs havealso been around for at least one ortwo decades. Manchester thereforeintends to investigate historicalPBDE input into Lake Michigan byanalyzing sediment, river, and airsamples, and also to conduct amore detailed food chain analysis.Personally, I feel uncomfortablewith any anthropogenic compoundbuilding up in people and the envi-ronment, Manchester states.Bergman is equally worried aboutPBDEs due to what he perceives asa general lack of knowledge onbrominated compounds. In myopinion, also octa- and deca-BDEdont belong on the market.ANKE SCHAEFER</p><p>140 A ENVIRONMENTAL SCIENCE &amp; TECHNOLOGY / APRIL 1, 2001</p><p>EnvironmentalNews</p><p>Although semiconductors are pro-duced in carefully controlled cleanrooms, the process of making themcan be a fairly dirty business, envi-ronmentally speaking. A newmethod that relies heavily on CO2can simultaneously improve the per-formance of key parts of the pho-tolithography process for creatingsilicon-based chips while reducingthe amount of waste and toxicity as-sociated with them. In time, it couldrender clean rooms obsolete for thesemiconductor industry.</p><p>Traditionally, applying, develop-ing, and removing the thin polymerfilms that serve as masks, orpatterns, for the circuits that willeventually be etched onto semicon-ductors requires the use of solventsand large quantities of water. Thespin-coating and removal processesdevised by Joseph DeSimone, a pro-fessor of chemistry and chemicalengineering at both the Universityof North CarolinaChapel Hill andNorth Carolina State University, aregreen because they use nontoxicchemicals, mainly CO2, and need nowater, he says.</p><p>Although the semiconductor in-dustry is trying hard to reduce itsenvironmental impact, DeSimonebelieves the major appeal of thenew processes is their ability to cir-cumvent problems that have be-come apparent as the industrymoves toward smaller channels onlarger wafers. Traditional solventsand water simply cannot consis-tently scour out channels that meetthe tight specifications for the nextgeneration of chips, says RobertAllen, manager of the LithographyMaterials Research Department atIBMs Almaden Research Center inSan Jose, CA.</p><p>With a 400-nm film, the capillaryforce of water can crush the narrowportions of these layers if their res-olution is below 100 nm, explainsAllen. This problem is known aspattern collapse, and Allen, in addi-tion to a number of U.S. andJapanese researchers, is also tryingto tackle this problem by using CO2.</p><p>Greening theclean room</p><p>As part of its ongoing strategy tointroduce clean technologies andreduce greenhouse gas emissionsin developing nations, the GlobalEnvironment Facility (GEF) hasgiven a green light to the use offuel cell buses in a demonstrationproject in five nations.</p><p>Between 2002 and 2003, GEFplans to pay the incremental costsfor the operation of 4050 fuel cellbuses in Sao Paulo, Brazil; MexicoCity, Mexico; New Delhi, India;Cairo, Egypt; and Beijing andShanghai, China, pending ap-proval for the project from eachcountry. Brazil is slated to be thefirst to use the fuel cell buses. TheGEF, a multilateral trust fund,which works through the UnitedNations Development Programme(UNDP), the U.N.s EnvironmentProgramme, and the World Bank,will contribute $60 million of the$130 million projected cost.</p><p>Remaining costs will be pickedup by the five countries, with a</p><p>small amount contributed by pri-vate industry.</p><p>Although the initial cost offuel cell buses is substantial, the33-member GEF is taking intoconsideration the eventual com-mercialization of the technology,which is projected to occur be-tween 2007 and 2010, to drivedown the price to a level that iscompetitive with conventionaldiesel engines. According toRichard Hosier, UNDP-GEFs prin-cipal technical adviser on climatechange, each country will need itsown manufacturing infrastructureto increase production. Once thishappens, he says, the costs perbus will fall. This leaves two majorareas of riskone, if the actualperformance of the fuel cells andthe hydrogen supply falls short ofexpectation, and two, if the de-mand for these buses does notgrow rapidly enough to pushdown the suppliers cost curve.PATRICIA E. DEMPSEY</p><p>Fuel cell buses in developing countries</p></li><li><p>APRIL 1, 2001 / ENVIRONMENTAL SCIENCE &amp; TECHNOLOGY 141 A</p><p>isting environmental laws, integrat-ing environmental policy moredeeply and effectively into otherpolicy areas from agriculture toeconomics, and involving bothbusiness and consumers in thedecision-making process. Thesewere listed as weaknesses in anassessment of the preceding EAP,which covered 1992 to 1999.</p><p>The new program singles outfour areas for particular empha-sisclimate change, nature andbiodiversity, environment andhealth, and natural resources andwaste. But environmentalists andindustry representatives, while ex-pressing cautious support of theprogram, point out that only the cli-mate change and waste policieshave any targets listed at all.</p><p>U.K. trades with itselfThis month, the United Kingdom(U.K.) is poised to become the firstcountry actively trading CO2 emis-sions, according to the U.K.sDepartment of the Environment,Transport and the Regions. Thecountry has no trading partners,but it is undertaking the programin hopes it will kick start inter-national trading, says MichaelMeacher, environment minister forthe department.</p><p>Although quick to praise theemissions trading program forleading the world, some observersare concerned that it will conflictwith other U.K. policies aimed atgreenhouse gas reductions, theClimate Change Levy, and theRenewables Obligation. We havemoved from energy efficiency toemissions trading, but [the situa-tion is] complicated by the fact thatthe generators (utilities) are not in-cluded and seem unlikely to comein the first round, explains CharlesCrosthwaite Eyre, director ofCarbon Risk Management for AonLimited, a firm that is insuring theprice of carbon credits for emis-sions trading.</p><p>Government WatchBecause CO2 al...</p></li></ul>


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