Warner Jeffords EPA Letter Re: Coal Tar Pavement Sealants 09-13-06

8/7/2019 Warner Jeffords EPA Letter Re: Coal Tar Pavement Sealants 09-13-06

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.., JAMES M INHOFEJOHN W.WARNER,VIRG!NIACHRISTOPHER S. BOND, MISSOURIGEORGE V VOINOVICH, OHIOMICHAEL D. CRAPO,IDAHOLINCOLN CHAFEE, RHODE ISLANDJOHN CORNYN, TEXASLISA MURKOWSKI, ALASKACRAIG THOMAS, WYOMINGWAYNE ALLARD, COLORADO

ANDREW WHEELER, MAJORITY STAFF DIRECTORKEN CONNOlLY,MIN ORITY STAFF DIRECTOR

September6, 2006

The HonorableStephenL. JohnsonAdministratorU.S. EnvironmentalProtectionAgencyAriel Rios Building1200PennsylvaniaAvenue,NWWashington,DC 20460Dear AdministratorJohnson:

Weare writing to you regarding the results of recent collaborative studies conducted bythe City of Austin, Texas, and the United StatesGeological Survey (USGS) that have identifiedcoal-tar based sealcoat-the black, shiny surface often applied to asphalt pavement -as asignificant and previously unrecognized source of extremely elevated concentrations ofpolycyclic aromatic hydrocarbons (PARs) in streams.PARs are suspectedhuman carcinogensand are toxic to aquatic life. We believe that the findings of these studies have majorimplications for the City of Austin and the rest of the country becausethese sealantsare usednationwide.

The studies show that runoff from parking lots sealed with coal tar-based sealanthadPAH concentrations 65 times higher than concentrations in runoff from unsealedparking lots. Inthe greater Austin area, an estimated 660,000 gallons of coal-tar sealant are applied annually.PAHs are increasing in Town Lake sediments, which receives drainage from many of Austin'surban creeks. (The attached articles contain specific information about the levels of PAHsdetected in selected Austin streams.) Biological studies conducted by the City indicate that thesesealantsare toxic to aquatic life at levels found in local waterways and are degrading the healthof Austin's creeks, as indicated by a loss of speciesand decreasednumbers of organisms. As aresult of these findings, the City banned the use of coal-tar sealants in November 2005.According to studies conducted by the USGS of38 reservoirs and lakes sampled in 18

metropolitan areas acrossthe nation from 1996 -2001, PARs in lakes and rivers are increasing.The biggest increasesare in areaswith watershedsaffected by urban sprawl. For example, PARsincreased ten-fold in Lake in the Hills (suburban Chicago, Illinois) as the watershed rapidlydeveloped. This infonnation raises important local and national policy questions about the use ofsealantsand methods to prevent contaminated runoff from reaching urban water bodies.In 1992, the EPA excluded coke product residues, including coal tar, from classificationsas hazardouswastes if they are recycled. As a result, under the Resource Conservation Recovery

PRINTEDON RECYClEDPAPER

, OKLAHOMA. CHAIRMANJAMESM JEFFORDS. VERMONTMAX BAUCUS. ,'JiONTANAHARRY REID. NEVADABOB GRAHAM. FLORIDAJOSEPH I. LIEBERMAN. CONNECTICUTBARBARA BOXER. CALIFORNIARON WYDEN. OREGONTHOMAS R. CARPER. DELAWAREHILLARY RODHAM CUNTON. New YORK COMMITTEE ON ENVIRONMENT AND PUBLIC "VORKS

WASHINGTON, DC 20510-6175


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Act (RCRA), these coal-tar sealantsare consideredproducts that contain recycled coal tar and aretherefore not regulated. In the July 26, 1991 notice of proposed rulemaking (56 FR 35758) thatdiscussedthis recycling exemption for coke product residues that are blended with coal tarproduct that is sold, EPA stated: "For these reasons,the Agency believes that reinsertion of theseresiduals into coke ovens and mixing of these residuals with coal tar to be sold as a product arerecycling practices that do not increase the levels of hazardous constituents in the final coke by-product, and therefore do not pose any significantly increased risk to human health and theenvironment." In light of the studies conducted by the USGS and the City of Austin that showthat coal-tar based sealantscontribute to PAH contamination in urban and suburban water bodies,we request that the EPA revisit this rulemaking and determine whether coke product residuesblended with coal tar and sold as a product should be regulated under RCRA.

Additi~nally, we would like your responsesto the following questions:1. What action is the EP A taking to investigate the application of coal-tar based sealanttoasphalt as a major source ofF AH contamination in water bodies across the country?

Please specify the EPA's current strategy for controlling PAHs in urban environments.How will identification of this new source ofF AH contamination influence futurestrategies?How is the EPA working with its Regional Offices, the States, stonnwater liaisons at thefederal and local levels, and trade associationsto advise communities about this research,its potential implications for aquatic wildlife, and the existence of safer sealantalternatives?

3.

We urge the EPA to perfonn a national study and report its findings on how coal-tarbased sealantsincrease PAHs in water bodies, and the effects of these PAHs on human healthand the environment. We appreciate your immediate responseto this matter.

Sincerely,

~ ~ 2.s~~~~~~::~~"'-JohnWarnerAttachments:(1) The Coal Tar Facts,www.citvofaustin.orl!(2) Van Metre, P.C.; Mahler, B.J.; Bashara,T.J.; Wilson, J.T.; Johns,D.A. Parking Lot Sealcoat:An UnrecognizedSourceof Urban Polycyclic Aromatic Hydrocarbons.Environ. Sci. Techno/.2005, 39, 5560.(3) Parking-LotSealcoat:A Major SourceofPAHs in Urban and SuburbanEnvironments,U.S.GeologicalSurvey,CongressionalBriefing, December2,2005.


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What are the alternatives?Asphalt based sealants are a comparable alternative offeringa level of protection similar to coal tar sealants with lowerI~vels of PAHs. Sealant products* that do not contain coaltar include:RETAIL:

What are coal tar sealants?Coal tar sealants are surface finishes for parking lots,driveways and airports. They contain varying concentrationsof coal tar depending on product and formulation.What's the problem?Coaltar sealants contain extremely high levels of PAHs(PolycyclicAromatic Hydrocarbons). PAHsare a group ofchemicals formed during the incomplete burning of coal,gasoline, wood, garbage or other organic substances,suchastobacco and charbroiled meat. Becausethe sealantswear off the asphalt surface,recommendations call forreapplying them every two to three years. An estimated660,000 gallons are applied annually in the Austin area. Asthe sealantswear off pavement surfaces,stormwater washesthe particles into local waterways. PAHsare increasing inTown lake sediments, where many of Austin's urban creeksdrain to. City staff has documented that coal tar sealantsaretoxic to aquatic life at levels found in local waterways andare degrading the health of Austin'screeks.

Henry PM2000 Premium Driveway sealer/FillerHenry Elastomeric Emulsion Crack Filler

COMMERClAUWHOLESALE:PaveshieldJennite Asphalt Emulsion Pavement SealerGilsonite Asphalt Driveway Sealer

For updates see:www.cit-/ofaustin.org/watershed/coaltar_altproducts.h*There may be other sealant products available that do not contain coaltar so please read labels carefully. Listing of a specific product trade namedoes not constitute an endorsement of its use.PAHTrends in Town Lake Sediment (Core) Samples

1960-2000 PAH Concentration in Asphalt Basedand CoalTar Based Sealants(Note: Percentagesare on a Jog scale)

Toxicity of CoalTar Sealants in Sediments to Aquatic Organisms(Hya/feJaazteca) at three treatment levels (low, med, high)100

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Of~{j..~~\)..,f",;::;;,~/j} ;~..~~,Oll_1t_D~1?"science ii,r a changing world

Prepared ill cooperation with the City of Austin, Texas

Sealcoatis usedcommerciallyand by homeownersacrossthe Nation.It commonlyis appliedto parking lotsassociatedwith commercialbusinesses(including strip malls and shoppingcenters);apartmentand condominiumcomplexes;churches,schools,and busi-nessparks;andresidentialdriveways.The City of Austin, Texas,estimatesthatabout600,000gallons of sealcoatareapplied everyyear in the greaterAustinarea.

Collaborativestudies bythe City of Austin and United StatesGeologicalSurvey(USGS)haveidentified coal-tarbasedsealcoat-the black,shinyemulsionpaintedor sprayedon asphalt pave-mentsuch as parking lots-as a majorand previouslyunrecognizedsourceof polycyclicaromatichydrocarbon(PAH)contaminationin someAustin area streamsediments.PAHsare suspectedhumancarcinogensand are toxic to aquaticlife. The studiesshowthat runoff from coal-tarbasedsealcoatedparking lots has concentrationsof PAHsthat are about65 times higherthan concen-trations in particleswashed off parking lots that have not beensealcoated.Biologicalstudies,conductedbythe City of Austin in the field and in the laboratory,indicatethat localizedPAHlevelsin sedimentscontaminatedwith abradedsealcoatare toxic to aquaticlife and are degrad-ing aquatic communities,as indicatedby loss of speciesand decreasednumbersof organisms.Identificationof this sourcemayhelp to improvefuture strategiesfor controllingPAHsin urbanwater bodiesacrossthe Nationwhere parking lot sealcoatis used.

National usenumbersare not avail-able; however,use-patternssuggestthatasphalt-basedsealcoatis more commonlyusedon the WestCoastand coal-tarbasedsealcoatis morecommonlyusedinthe Midwest,the South,and on the EastCoast.What are PAHs, coal tar, andsealcoat:?Polycyclic aromatichydrocarbons(orPARs)are a groupof organiccontam-inants that form from the incompletecombustionof hydrocarbons,suchascoaland gasoline.PARs are an environmentalconcernbecausethey aretoxic to aquaticlife and becauseseveralare suspectedhumancarcinogens.Coal tar is a byproductof the cokingof coal, and can contain50 percentormore PARs by weight.Sealcoatis a blackliquid that issprayedor paintedon asphaltpave-mentin an effort to protectand beautifythe asphalt.Most sealcoatproductsarecoal-taror asphaltbased.Many coal-tarsealcoatproductscontainas muchas30 percentcoal tar by weight. Productanalysesby the City of Austin indicatedthat coal-tar sealantproductshadmedianconcentrationsof total PARs about70times higherthan asphalt-basedsealants.

Runofffrom coal-tar based sealcoatedparking lots has concentrations of PAHsthat areabout 65 times higherthan concentrations in particles washed off parking lots that have notbeen sealcoated.


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How does sealcoat getfrom parking lots into theenvironment?Vehicletires abradeparking lot sealcoatinto smallpieces.Thesesmallparticlesare washedoff parking lots by precip-itation into stormsewersand streams.Sealcoat"wear and tear" is visible in hightraffic areaswithin a few months afterapplication.Sealcoatmanufacturersrec-ommendreapplicationevery2 to 3 years.

ments.PARstendto attachto sediments;the ProbableEffect Concentration(PEC)-a widely usedsediment-qualityguidelinethat is the concentrationof acontaminantin bed sedimentexpectedto adverselyaffectbenthic(or bottom-dwelling) biota-is 22.8milligrams perkilogram (mg/kg) for totalPAR. Stud-ies by USGSand City of Austin didnot evaluatehuman-healthrisk fromexposureto sealcoat.Human-healthriskfrom environmentalcontaminantsis oftenevaluatedin termsof exposurepathways.For example,peoplecould potentiallybe exposedto PAHs in sealcoatthroughskin contactwith abradedparticlesfromparking lots, inhalationof wind-blownparticles,and inhalationof fumes thatvolatilize from sealedparkinglots. PARsin streamsand lakesrarelyposea human-healthrisk via drinking waterbecauseof their tendencyto attachto sedimentratherthandissolvein water.In addition,becausePARsdo not readilybioaccu-mulate within the food chain,possiblehuman-healthrisksassociatedwith con-sumptionof fish arelow.

What are environmentaland human-health concernsassociated with PAHs?

Concentrationsof total PAHsin particulatein runoff from sealed parking lots greatlyexceeded concentrationsfrom unsealedparking lots. The bar on each graph is themean concentration.PAHs are toxic to mammals(includ-

ing humans),birds, fish, amphibians,invertebrates,andplants.Possibleeffectsof PAHs on aquaticinvertebratesincludeinhibited reproduction,delayedemer-gence,sedimentavoidance,and mortal-ity, andpossibleadverseeffects on fishinclude fin erosion,liver abnormalities,cataracts,andimmune systemimpair-

What concentrations of PAHsare in runoff from sealed andunsealed parking lots?

How did USGS study parking-lot runoff?USGSresearcherssampledrunoff at 13 parking lotsrepresentinga rangeof different sealantr,ypesinAustin. Theyalso took scraping-samplesof parkinglot surfacesto comparesourcematerialsto wash-offparticulates.Sourcematerialsand wash-off particu-lateswere analyzedfor a suite of PAHs,majorele-ments,and traceelements.USGS researcherssprayedwater on four differenttypesof parking-lot surfacesin Austin: lots sealedwith coal-tarbasedsealcoat(top photo),lots sealedwith asphalt-basedsealcoat,unsealedasphaltlots, and unsealedconcretelots. Therunoff wascollectedbehind spill berms,pumpedintocontainers(middle photo)and filtered throughTeflonfilters to collectthe particulatesfor analysis(bot-tom photo). The particulates,the filtered water,andsamplesof sealcoatscrapedfrom the parking-lotsur-faceswere analyzedfor PAHs at the USGSNationalWaterQualir,yLaboratory.Concentrationsand yields(the amountof PAHscoming off eachlot) were usedto determinelevelsof contaminationin runoff fromeachtype of lot and the importanceof sealedlots asasourceof PAHsto urbanstreams.

Concentrationsof PAHswere muchhigher in runoff from parking lots sealewith coal-tarbasedsealcoatthan fromall othertypesof parking-lotsurfaces.Specifically,the averageconcentrationin runoff from coal-tarsealedlots was3,500mg/kg, about65 times higher thathe averageconcentrationin particleswashedoff parking lots that were notsealcoated(54 mg/kg). The averageconcentrationin particleswashedoffparking lots sealedwith asphalt-basedsealcoatwas 620 mg/kg, about6 timesless thancoal-tarbasedsealcoat,but stil10 times higherthan the concentrationfrom unsealedparking lots.Concentrationsof PAHs in particlewashedoff eachof the differentsurfacetypes-including the unsealedparkinglots-exceeded the PEC of 22.8 mg/kg.This is not surprisingbecauserunoff froparking lots is likely to containPAHsfrom manysources,including leakingmotor oil, tire particles,vehicle exhausand atmosphericdeposition.However,the largedifferencesbetweenconcentrations associatedwith sealedand unsealparking lots indicate that abradedsealcis a majorand previouslyunrecognizedcontributorto PAH contaminationinurbanand suburbanwaterbodies.


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2000 500 1,000 1,500 2,000Changein total PAHs,in microgramsper gramorganiccarbon(upstreamto downstream)

2,500

Field assessmentsin selected Austin streamsshowed loss of species (taxa)and decreasesin the number of aquatic organismsdownstreamof coal-tar sealed parking lots that can be, in large part, explained by increasesin total PAHs.

How do F-AHsfrom sealcoatimpact t~le quality and biologyof streamls?

cantbiological degradationin responsetosealcoatadditions.Finally,field assess-mentsin selectedAustin streamsshowedloss of speciesand decreasesin thenumberof aquaticorganismsdownstreamfrom inflows of runoff from sealedpark-ing lots. The impactscoincidedwithincreasesin concentrationsof PARs instreamsedimentsbelowsealedparkinglots. Overall,City of Austin scientistshavereportedPAR contaminationat lev-els predictedto be toxic to benthicinver-tebratesin over 13 percentof sampledAustin creeks.

their currentloadsif all of the parkinglots wereunsealed.Studiesby City of Austin biologistsshowedthat sealcoatparticlesenteringstreamscould be adverselyaffectingaquaticcommunities.Specifically,toxic-ity testingof organismsin the laboratoryshowedlargeincreasesin mortality assealcoatamounts/concentrationswereincreased,and thatcoal tar sealantsinsedimentsweretoxic to aquaticlife atPAHconcentrationsobservedin Austinwaterways.Controlledexperimentsthatusedaquariumswith diversenaturalbiological communitiesshowedsignifi-

How did City of Austin scientists conduct biological studies?City of Austin biologistsconductedlaboratoryandfield studiesto evaluatetheeffectsof sealcoatedparking lots on aquaticcommunitiesin areastreams.Thesestudiesincludedtoxicity testing in controlled laboratoryexperimentsthatexposedorganismsto sedimentsspikedwith coal-tarand asphalt-basedsealcoat(left photo);controlledexperimentsthatusedaquariumswith diversenaturalbiological commu-nities to which sealcoatwasadded(middle photo); and field assessmentsof aquaticcommunitiesin streamsupstreamand downstreamfrom inflows of runoff fromsealedparking lots (ri~t photo).

Studiesby USGSscientistsdemonstratedpossibleconnectionsbetweenPARs inparticleswashedfrom sealedparkinglots and PARs in suspendedsedimentinfour streamsin Austin and Fort Worth,Texas.Findingsshowedthat PARs insuspendedsedimentsin the streamswerechemicallysimilar to thosein runofffrom parking lots sealedwith coal-tarbasedsealcoat.Analysis of the total massof PARsexpectedto washoff sealedparking lots and the total massof PARsmeasuredin suspendedsedimentsin thefour streamsafterrainstormsindicatedthatrunoff from sealedparking lots couldaccountfor the majority of PAR loadstothe streams.Apart from the sealcoatingitself,unsealedand sealedparking lots receivePARs from the sameurbansources-tire particles,leaking motor oil, vehicleexhaust,and atmosphericdeposition-yet the averageyield of PARs fromsealedparking lots was50 times greaterthan that from unsealedlots. What wouldbe the effect on PAR loading to thestreamsif parking lots were not sealed?Estimatesfrom the USGS studyindicatethat total loadsof PARs coming fromparking lots in the studiedwatershedswould be reducedto aboutone-tenthof

50

100

150


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How do these findings apply tourban liakes and reservoirs?

thoughtto be dominatedby numerousnonpointsources,suchasleaking motoroil, tire wear,vehicularexhaustandatmosphericdeposition.Suchsourcesaredifficult to quantify or controlbecauseoftheir diffuse, nonpointnature.In contrast,sealedparking lots contributeto urbanstormwaterrunoff (seephoto below),and the useof sealcoatis voluntaryandcontrollable.Possiblealternativestocoal-tarbasedsealcoatingof parkinglotsincludethe useof concreteand unsealedasphaltpavementandthe useof asphalt-basedsealantsthat contain1.owerlevelsof PAHs.

links to related publications,data and mapsCity of Austin Coal Tar SealantInformation-http..//www.ci.austin.tx.us/watershedbs_coaltar:htmUSGS frequently asked questions-http..//water;usgs.gov/nawqa/asphalsealers.htmlBasic information on the toxicity ofPARs to biological organisms,U.S. Environmental Protection Agenc(USEPA)-http..//www.epa.gov/R5Super/ecologhtmlltoxprofiles.htm#pahsGeneral information on PAHexposure, Agencyfor Toxic Substanceand DiseaseRegistry (ATSDR)-http..//www.atsdr;cdc.gov/toxprofilesphs69.html

PARs in lakesand reservoirsacrossthe Nationare increasing,as indicatedby USGSstudiesof 38 reservoirsandlakessampledin 18 metropolitanareasacrossthe country from 1996to 2001.Sedimentcores(vertical tubesof mud)were collectedfrom reservoirandlakebottoms(seephoto below); analysisofthesecoresprovidesa reconstructionofhistorical waterquality over time, muchlike usingtree rings to reconstructhistori-cal climate.Runoff carriessoil, debris,and attachedcontaminantsto lakesandreservoirs,which settleto the bottom; asthe sedimentbuilds up, changesin waterquality are recordedin the successivesedimentlayers.USGSfindings showthatconcen-trationsof total PARs in the majority oflakesandreservoirsin urbanand sub-urbanareasacrossthe Nation increasedsignificantly from 1970to 2001.The.increases were greatestin lakes withrapidly urban-izing water-sheds(urbansprawl); forexample,overj the last 10., yearsPARs

increasedten-fold in Lakein the Hills(suburbanChicago,illinois) as the watershedrap-idly developed.Furtherstudyis neededto assessdirect links betweenthe use ofsealcoatand PAH trendsin theselakes.

References"Mahler,B.J., Van Metre,P.C.,Bashara,T.J.,Wilson, J.T.,and Johns,D.A.,2005.Parkinglot sealcoat:An unrec-ognizedsourceof urbanPARs:Envi-ronmentalScienceand Technology,vol. 39, no. 15,p. 5560-5566.

Currently,coal-tarbasedsealcoatis not federallyregulated.In 1992,theU.S. EnvironmentalProtectionAgency(USEPA)excludedcoke productresidues,including coal tar, from classificationashazardouswastesif they arerecycled.Underthe ResourceConservationandRecoveryAct, coal-tarbasedpave-ment sealantsare productsthat containrecycledcoal tar and,therefore,are notregulated.Furtherstudiesare neededtoevaluatepotentialimpactson the aquaticenvironmentin otherpartsof the country.

Van Metre,P.C.and Mahler,B.J., 2005.Trendsin hydrophobicorganiccon-taminantsin urbanandreferencelakesedimentsacrossthe United States,1970-2001:EnvironmentalScienceand Technology,vol. 39, no. 15,p.5567-5574.

City of Austin. 2005.PAHs in Austin,Texas.(http://www.ci.austin.tx.us/watershedldownloads/coaltar_draft-pah_study.pdf)What are the implications of

these studies?The study of parking-lotsurfacesby theUSGSand the City of Austin showthatabradedsealcoatcould be a major sourceof PAHsto urbanand suburbanwaterbodiesin watershedswheresealcoatisused.Suchfindings mayhaveimpli-cationsthat extendbeyondTexasassealcoatis usednationwide.Identificationof this major newsourcemay influencefuture strategiesfor controlling PAHs inurbanenvironments.In the past,sourcesof PAHs in urbanwatershedswere

Contacts for additionalinformationPeter Van Metre and Barbara MahlerU.S. GeologicalSurvey8027ExchangeDriveAustin, Texas78754-4733(512) 927-3506or [email protected](512)927-3566or [email protected] ScogginsCity of Austin,WatershedProtectionand DevelopmentReviewDepartment505 BartonSpringsRoad,11thFloor..Austin, Texas78704(512) [email protected]


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Environ. $ci. Techno/.2005, 39, 5560-5566

BARBARA J. MAHLER, ..tPETER C. VAN METRE,tTHOMAS J. BASHARA,*JENN[FER T. WILSON,tANDDAVID A. JOHNS*United States Geological Survey,8027 Exchange Drive,Austin, Texas 78754, and City ofAustin Watershed ProtectionDepartment, P.O. Box 1088, Austin, Texas 78767

Polycyclic aromatic hydrocarbons (PAHs)are a ubiquitouscontaminantin urban environments. Although numeroussources of PAHsto u..rbanrunoff have been identified, theirrelative importance remains uncertain. We show that apreviously unidentified source of urban PAHs,parking lotsealcoat,maydominateloadingof PAHsto urbanwater bodiesin the United States. Particles in runoff from parking lotswith coal-tar emulsion sealcoathad mean concentrationsofPAHs of 3500 mgjkg, 65 times higher than the meanconcentration from unsealed asphalt and cement lots.Diagnostic ratios of individual PAHs indicating sources aresimilar for particles from coal-tar emulsion sealed lotsand suspended sediment from four urban streams.Contaminantyields projected to the watershed scale forthe four associated watersheds indicate that runoff fromsealed parking lots could accountfor the majority of streamPAH loads.

underlying asphalt pavement and enhance appearance.Thtwo primary sealcoat materials on the market are refinecoal-tar-pitch-based emulsion and asphalt-basedemulsionAlthough similar in appearance (glossyblack), coal tar anasphalthave different molecular structures stemming fromtheir origins: coal tar is a byproduct of the production ocoke from coal,whereas asphaltis derived from the refiningof crude petroleum. Coal tar, a known human carcinogenis 50% or more PARs by weight (2); the predominanconstituents of asphalt are bitumens, complex mixtures ohydrocarbons that include asphaltenes,saturates,aromaticand resins (9). Coal-tar-emulsion- and asphalt-emulsionbased sealcoatstypically contain 20-35% of the emulsionParking lot sealants are used extensively in the UnitedStates and Canada. Although national use figures are noavailable, the Blue Book ofBuilding and Construction (10a directory for the construction industry, lists over 330pavement sealantcompaniesin 28 U.S.states.One companadvertisesthe application of 1.7billion liters to dateworldwid(11),and another reportshaving sealedover33 million squarmeters (12). The City of Austin, population 650000 (200census),estimates that about 2.5 million liters of sealcoatiused annually in this city (13).Sealcoatabrades from the parking lot surface relativelrapidly, and reapplicationis recommended everytwo to threyears (14). In 2003, the City of Austin identified abradeparking lot sealcoatas a possible source of high concentrations of PARsin streambed sediment (15). Here we presenevidence suggesting that parking lot sealcoat could indeebe the dominant source of PARs to watersheds withresidential and commercial development.

IntroductionConcentrationsof polycyclic aromatic hydrocarbons(PAHs)-a group of widely recognized aquatic contaminants (1)comprising numerouscarcinogens(2)-have beenincreasingin recent decadesin many urban lakes,particularly in areasundergoing rapid urban growth (3). PARs adversely affectmammals (including humans), birds, fish, amphibians,invenebrates, and plants; in the aquatic environment, theeffectsofPAHs on invenebrates include inhibited reproduc-tion, delayedemergence,sediment avoidance,and monality,and the effects on fish include fin erosion,liver abnormalities,cataracts,and immune system impairments (4). Numeroussources of PARs to urban runoff have been identified,including automobile exhaust,lubricating oils, gasoline,tireparticles, erosion of street material, and atmospheric depo-sition (5-8), but uncenainty remains as to their relativeimponance. Investigations of urban sources of PARs havethus far overlooked a potentially major source: parking lotsealants,also called "sealcoat". Our objective in this studywasto evaluatethe contribution ofPAHs from sealedparkinglots to urban streams.In the United States and Canada, sealcoatis applied tomany parking lots and drivewaysin an effon to protect the

.Corresponding author phone: (512) 927-3566;fax: (512)927.3590;e-mail: [email protected] United StatesGeological Survey.* City of Austin Watershed Protection Department.5560. ENVIRONMENTAL SCIENCE & TECHNOLOGY I VOL 39. NO. 15. 2005

ExperimentalSectionSample Collection. We compared concentrations and yieldof particulate PAHs in simulated runoff from parking lotsealed with coal-tar-based sealcoat, from lots sealed withasphalt-based sealcoat, and from unsealed asphalt ancementlots. Thirteen urban parking lots,representinga rangof sealanttypes that are currently in use in Austin, TX, wersampled (Table 1). In addition, four test plots, each abou120 m2,were sampled. Three of the test plots were sealejust prior to testing, and one was left unsealed (asphasurface).The test plots are at the Robert Mueller MunicipaAirport, Austin, TX, which has been closed since 1999.A fudescription of the sampling is given in ref 16. In brief, 50 mareas of each parking lot and the test plots were sprinklewith 2 mm of distilled water (100 L over a 50 m2 area) tsimulate a light rain, and concentrations of PAHs weranalyzed in particles filtered from the runoff. The studfocused on the particulate fraction, as PAHs in urban runofparticularly those of higher molecular weight, are mostassociatedwith particulates (7,17); for selectedsamples (teplots and sevenparking lots), the dissolved phase also waanalyzed.The testing followed a minimum of 5 days with nrainfall. The parking lots were sampled once, and the teplots were sampled three times over a 6 week period. Watwas sprayed from a plastic hand-held sprayer at a rate oabout 7 L/minfrom a height of abouto.75 to 1 m. Spill bermwere used at the down-slope end of the delineated area tgather water, which was then pumped into high-densipolyethylene (HDPE) containers (Figure SI, SupportinInformation). Recovery of water and observations abolossesof water to wetting and leakageunder the berms wenoted. The water was returned to the laboratory, poureinto a 50 L chum to keep the sample well mixed, and fIlterethrough 0.45 !tm pore size PTFE filters. The filters wer

10.1021/esO501565 CCC: $30.25 @ 2005 American Chemical SociePublished on Web 06/22/200


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date of sealantapplicationAug 5-6, 2003Aug 5-6, 2003Aug 5-6, 2003Aug 5-6, 2003

samplingdate8/21/20038/21/20038/21/20038/21/20039/9/20039/9/20039/9/20039/9/20039/26/20039/26/20039/26/20039/26/20039/7/20039/7/20039/28/20039/7/20039/28/20039/28/20039/30/20039/30/20039/30/20039/8/20039/30/20039/8/20039/8/2003

TABU:1. SamplingSite Characteristicssite name surface type

CTTP1 coal-tar emulsion sealantCTTP2 coal-tar emulsion sealantASTP asphalt emulsion sealantUNSASTP unsealed asphalt pavementCTTP1 coal-tar emulsion sealantCTTP2 coal-tar emulsion sealantASTP asphalt emulsion sealantUNSASTP unsealed asphalt pavementCTTP1 coal-tar emulsion sealantCTTP2 coal-tar emulsion sealantASTP asphalt emulsion sealantUNSASTP unsealed asphalt pavementASPL1 asphalt emulsion sealantASPL2 asphalt emulsion sealantASPL3 asphalt emulsion sealantCT PL1 coal-tar emulsion sealantCT PL2 coal-tar emulsion sealantCT PL3 coal-tar emulsion sealantCTPL4 coal-tar emulsion sealantCT PL5 coal-tar emulsion sealantCT PL6 coal-tar emulsion sealantUNSASPL 1 unsealed asphalt pavementUNSASPL2 unsealed asphalt pavementUNSCONpL 1 unsealed concrete pavementUNSCONpL2 unsealed concrete pavement

June 2003June 2003July 2003March 2003July 2003July 2003July 2003July 1999Nov 2000

study componenttest plottest plottest plottest plottest plottest plottest plottest plottest plottest plottest plottest plotparking lotparking lotparking lotparking lotparking lotparking lotparking lotparking lotparking lotparking lotparking lotparking lotparking lot

particles was associatedwith the water volume lost to surfacewetting and that water leaking past the bemls had the sameSSCand contaminant levelsasrecoveredwater. For unsealedasphalt lots, the loss to wetting was estimated as36 L for amaximum potential recovery of 64 L. Thus, to estimate thetotal yield of sediment from each lot, SSCwas multiplied bythe assumedmaximum recovery (82L for sealedand cementlots and 64 L for unsealed asphalt lots) to account forrecovered water and leakage past the bemls.Yields ofPAHwere estimated by multiplying the total yield of sedimenttimes particle concentrations.Chemical Analysis. Sampleswere prepared by extractingabout 0.5 g dry weight of sample using pressurized solventextraction at 120 and 200 C with a mixture of water andisopropyl alcohol. The samples were extracted at eachtemperature at a pressureof 13800kPa.Surrogatecompoundswere addedto the sample prior to extraction to verify methodrecoveries. The extract was cleaned up using polystyrenedivinylbenzeneand Florisil solid-phase extraction cartridges.The extract was concentrated, solvent exchanged to ethylacetate,and diluted to 10mL. An internal standard mixturewas added to an aliquot of the extract, and the extract wasanalyzed by full-scan gas chromatography/mass spectrom-etry (GC/MS). Difficult sample matrices were diluted beforethe full-scan analysis,and diluted surrogateswere estimatedin the samples.Compound identifications were based on comparison ofpeak retention times and mass spectra to those of authenticstandard compounds for the target compounds. Responsefactors were calculated for each compound from a set ofcalibration standards.Quantitation was carried out followingthe methods of Olson et al. (19).For PAHsin the particulatephase,the estimated method reporting limit (MRL) is 5 !.tglkg for a 25 g sample. Aslessthan 25 g was extracted,the MRLwasraised accordingly,on a sample-by-samplebasis.In somecases,MRLswereraisedbecauseof backgroundinterferences.Dissolved-phase samples were analyzed following themethod described by Fishman and Friedman (20), with the

massagedinside locking bags to remove retained particles,as described in ref 18, and the recovered particulates weresubmitted as chilled slurries in clean glassvials to the U.S.GeologicalSurveyNational Water Quality Laboratory (NWQL)for analysis. In some casesthe filtrate also was shipped, inchilled and clean amber glass bottles, to the NWQL foranalysis of dissolvedPAR.One or more samplesof unfilteredwater were collected from the churn for measurement ofsuspendedsediment concentration (SSC), usedto determinethe mass of sediment recovered during each test. Althoughthe 2 mm of simulated rain was not enough to wash off allof the mobile sediment, the recovered water was visiblyclearertoward the end of eachapplication. In samplesfromthe five sitesin which SSCwas measured in the fIrst 50L andfinal 50 L of water, SSCdecreasedby a mean of 65% (rangeof 39-84%). We therefore assumed that the testsrecoveredmost of the sediment that would be mobilized from theparking lot surfacesby a rain event,regardlessof magnitude.Large,intense storms,however,likelywould generatea higheryield of sediment.The test plot and parking lot scrapings were obtained byscraping a small area (lessthan 0.25 mZ) with a metal paintscraper.The particulates removedwere brushed onto a pieceof new cardstockand then into a cleaned glassjar. The paintscraper was cleaned between sites, and a new brush wasused at each site. Scrapings were examined by light andelectron microscopy (Figure S2, Supporting Information),and submitted to the NWQL for PAR analysis.Computation of Yields. Losses of water to wetting andlosses of water and sediment leaking under the berms wereestimated. Recoveryof water ranged ftom 19to 85 L with amedian of 58 L The lowestrecoverieswere from flat, unsealedasphalt lots, and the highestrecoverieswere from sealedlotsand cement lots with gentle slopes.On the basis of recoveriesand field observations, it was concluded that about 18 L ofwater was retained on the surface of sealed lots and cementlots and that the remainder of the water loss was a result ofleakage past the berms. It was assumed that no yield of

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--c;~"OJgcnJ:~0T-OE::JU)

.difference that continuous liquid-liquid extraction wassubstituted for use of the separatory funnel. In brief, 1 Lsamplesfortified with surrogate compounds were extractedby continuous liquid-liquid extraction for 6 h under acidicand then basic conditions. Internal standards were addedand sample extracts concentrated to 1 mL. Sampleswereanalyzed by GC/MS in electron impact mode. Sampleidentifications were made by matching retention times andmass spectra with those of standard compounds. Quanti-tation involved use of internal standards and calibrationcurvesgeneratedby standardcompounds of known amounts.Quality control (QC) consisted of environmental andinternal laboratory samples. Two duplicate enVironmentalsamples for particulate analysis of PAR were collected. Forone of the sets of duplicates, 2:PARdiffered by 8%; for thesecond (which had ~AR > 4000 mg/kg), 2:PARdiffered by54%. In the equipment blank analyzed for dissolved PAR,three parent PARs were detected at concentrations abouthalf that of the environmental sample with the lowestconcentrations, and less than 1% that of the environmentalsample with the highest concentrations.Laboratory QC samples for particulate PAR analysesconsisted of analysis of spiked samples,blanks, and samplesof certified reference material (CRM).The median recoveryfor the six spiked samples was 76%. For the six laboratoryblanks, an analyte was detected in 85 of 336 possible cases.The detected concentrations ranged from 0.1% to 3.5% ofthat in the enVironmental sample with the lowest concen-tration for that analyte. For the two analyses of CRM, therecoveries were within the NWQL-established acceptablerange for 83% of the cases.Three commercially available asphalt-based emulsionsealcoatproducts and six coal-tar-based emulsion sealcoatproducts were analyzed at DHL Analytical, Round Rock,TX,using EPAmethod SW8270 (21). In each case,the productsamplewas taken directly from the container. Concentrationsof 16 parent PARswere detemiined. The sealantsanalyzedwere not necessarily the same as those applied to the testplots or on the parking lots in use,although there was someoverlap (product ASpAwas used on test plot A5TP;productCTpFwas used on test plot CTTP2)(Table 2).ResultsConcentrations and yields of total particulate PAH and totaldissolved PAH in the runoff and total PAH in the scrapingswere computed and compared between parking lot surfacetypes (Table2). The total particulate PAH (LPAll) concentra-tion was computed for each sample as the sum of naph-thalene, 2-methylnaphthalene, acenaphthylene, acena-phthene, fluorene, phenanthrene, anthracene,fluoranthene,pyrene, benz[a]anthracene, chrysene,benzo[a]pyrene,anddibenz [ah]anthracene,which are the sameas those used forthe consensus-basedsediment quality guidelines of Mac-Donald et al. (22). For unsealed parking lots (asphaltpavement and concrete combined), the mean~AH was 54mg/kg (rangeof7.2-75 mg/kg),more than twice theprobableeffect concentration sediment quality guideline of 22.8mgl~g (22) (Table 2), and in the range of those found by othersin urban and roadway runoff (e.g.refs 23-25). However, themean ~PAH concentration from the asphalt-sealedparkinglots was more than 10 times higher (mean of 620 mg/kg,range of 250-830 mg/kg) than that from unsealed parkinglots, and the mean ~AH concentration from the coal-tar-sealedparking lots was 65 times higher (mean of 3500 mglkg, range of 520-9000 mg/kg) (Table 2; complete concen-tration data are given in ref 16). ~AH concentrations inrunoff from coal-tar-sealedlotswere significantly higherthanin runoff from other surface types (Kruskal-Wallis test ofcomparisons, hypothesis of no difference between groupsrejected for p < 0.05). PAH concentrations from coal-tar-

CT AS USFIGURE1. Sumof 10PAHs(fluoranthene,pyrene,benz[a]anthracene,benzo[a]pyrene,benzo[e]pyrene,indeno[12,3-cdJpyrene.chrysene.benzo[b]fluoranthene,benzo[k]fluoranthene,and benzo[ghl]perylene)in particles in runoff from simulated rainfall on coal-tar emulsionsealcoat (CT),asphalt emulsion sealcoat (AS),and Illnsealedcementand asphalt (US) parking lots (0) and test plots 18). Parking lotswere sampled once, and test plots \\rere sampled three times.Concentrations for other PAH sources reported in the literaturealso are indicated. These 10 PAHs werle summedfor this graph tofacilitate comparison between experimental and reported con-centrations.sealed lots also were much higher. in most cases by ordersof magnitude, than PAH concentrations in other urbansources such as tire particles, motor oil, and weatheredasphalt (Figure 1; note that this figure uses a differentsummation of PAll). ~AH concentrations in runoff fromthe sealed test plots were generally lower than those fromthe sealed parking lots, but the difference was not statisticallysignificant, and concentrations from unsealed surfaces, withthe exception of one outlier, were similar for test plots andparking lots.Concentrations of ~AH in the scrapings ranged from9500 to 83000 mg/kg forcoal-tar-emulsion-sealed surfaces(including test plots) and from 110to 2000mg/kgfor asphalt-emulsion-sealed surfaces (Table 2). Scrapings of two unsealedasphalt parking lots had ~AH concentrations of7.1 and 20mg/kg. Scrapings were observed under light and electronmicroscropy (Figure S2, Supporting Information).Concentrations of total dissolved PAH (~AHdiss, com-puted as the sum of the same PAHs as in ~AH excluding2-methylnaphthalene; nondetections treated as zeros) forthe test plots were about an order of magnitude greater insamples from the coal-tar-sealed test plots than concentra-tions in samples from the asphalt-sealed test plot, which inturn were about an order of magnitude greater than thosefrom the unsealed test plot (Table 2). Nine of the 16 PAHsanalyzed for were detected (complete data are in ref 16).Higher weight PAHs-benzo[b]fluoranthene, benzo[k]-fluoranthene, benzo [a] pyrene, indenopyrene, benzo[ghzl-perylene, benz[a]anthracene, and dibenz[ah]anthracene-were not detected at laboratory reporting levels ranging from1.7 to 3.4flg/L. Four PAHs (acenaphthylene, acenaphthene,chrysene, and fluorene) were detected only in runoff fromthe coal-tar-sealed test plots; anthracene was detected inrunoff from all the sealed test plots but not from the unsealedsite. A similar suite of PAHs were detected at those parkinglots for which the fIltrate was analyzed (Table 2; completedata are in ref 16).Concentrations of ~AH in the commercially availablesealant nroducts and surface scrapings exceeded those of

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1,000,000-0;~'" 100,000.. 10,0001,000

100101

TABLE2. Concentrationsof PAHin WashoffSamples,:Scrapings,and UnappliedSealcoat Produc~wash off samples scrapings productI:PAH. I:PAHdi...mg/kg Jlg/l

Test Plots211700 14530460

I;PAH.mgikg ~PAH(dry),mg/kg .CTTP1,8/12/03CTTP1,8/21/03CTTP1,9/9/03CTTP1,9/26/03 83000 CTpACTpBCTpCCTpDCTpE

CTpF

34000113000202000860004900061000

c.21C~c0":I:~~6.9

CT TP2,CT TP2,CT TP2,CT TP2,

117.3 1100012004000140 ASpAASpSASpC66001300300

FIGURE 2. Comparison of I;PAH concentrations in (:ommerciallvavailable sealcoat products, scrapings from parking lots, andparticles in wash oft from parking lots for coal tar (0) and asphalt(e) based sealants.

3.8ASTP, 8/12/03ASTP, 8/21/03ASTP,9/9/03ASTP, 9/26/03UNSASTP, 8/12/03UNSASTP, 8/21/03U NSASTP, 9/9/03UNSASTP, 9/26/03 0.17

Parking LotsCTPL1 2000 NA 25000CT PL2 9000 5.4 15000CTPL3 2000 7.1 11000CTPL4 1300 12 9500CT PL5 520 2.3 9900CTPL6 5900 16 17000ASPL1 250 NA 340ASPL2 830 NA 2000ASPL3 770 5.1 420UNSCONpL 1 75 NA NAUNSCONpL2 69 NA NAUNSASPL1 64 NA 7.1UNSASPL2 7.2 0.24 20

'Sums are as defined in the text. NA = not analyzed, CT = coal-tar-based emulsion, AS = asphalt-based emulsion, UNSAS= unsealedasphalt pavement, and UNSCON = unsealed concrete pavement.

1.31.2 110964028 0.640.160.344102514

concentrations for the different surface types suggestthatabraded sealant products are a potentially important (andheretofore unrecognized)contributor to PAH contaminationin urban and suburban water bodies.Comparison of Medium, Aging, and Vehicle Use onConcentrations and Yields. For both coal-tar- and asphalt-emulsion-basedsealants,the ~AH concentration decreasedfrom the unapplied sealantproducts to the scrapingsto thewashoff samples. as did the difference in concentrationbetweenthe coal-tar-basedand asphmt-basedsealantsamples(Figure2). The difference in the median ~AH concentrationbetween the coal-tar-based and asphalt-basedsealantswas70-fold for the products analyzed and decreasedto 40-foldfor the scrapings and to a factor of about 8 for the washoffsamples.Although the chemicalchangesbetweentheproductpre- and postapplication were not the focus of this study.the decreasein ~AH concentrations from the scrapings tothe washoff particulates and the magnitude of the differencebetween the coal-tar-sealedlots and the asphalt-sealedlotscan be attributed to dilution of abraded particles with lesscontaminated street dust and the greater abrasion of theasphalt-sealedcompared to the coal-tar-sealed surfaces.Asimple mass balance. assuming dilution of the coal tarscrapings (median ~AH concentration of 13000mg/kg) bystreet dust (median ~AH concentration of 50 mg/kg) at aproportion of 1 part abraded particles to 7 parts street dust,results in the concentration found in the washoff. If theproportion of abraded particles is increased for the asphaltlots on the basis of the increasedyields measured for asphalt-sealedlots (assuming that the greatermedian particle yieldof 320 mg/m2 from asphalt-sealed lots versus 200 mg/m2from coal-tar-sealed lots results from increased abrasion),the concentration found in the washofffrom asphalt-sealedlots is well approximated.The effect of aging of sealantson concentration over theshort term (7 weeks)was evident at the testplots (Figure 3a).Overall, the concentration of ~AH and ~AHdiss in thewashoff from eachtest plot decreasedover the 7 week periodfollowing application. In one instance (CTTP2.second sam-piing ofwashotl) kPAH exceededthat previously sampled.but in all cases the concentration at the end of the periodwas less than that at the beginning. The PAH assemblagechanged over the same period as well, as represented by acomparison of higher molecular weight (MW) to lower MWPAHs. In the particulate samples the ratio of higher MWPAHs (represented by benzo[a]pyrene + chrysene) to thelower MW PAHs (represented by fluorene + phenanthrene;these two PAHswere chosenas they were detected in mostof the samples)increased at all of the sealed test sites.As thelower MW PAHs are more volatile and soluble than the higherMW PAHs, volatilization and leaching of the lower MW PAHs

the particulates in the washoff. Concentrations of 1:PAHincommercially available coal-tar-based sealcoat productsranged from 3.4 to 20 wt %, compared to 0.03 to 0.66 wt %for asphalt-based~sealcoatproducts analyzed (fable 2;complete data in Table SI, Supporting Information).Yields of 1:PAH(mass of LPAH per unit area of parkinglot) computed for the simulated rainfall followed patternssimilar to those of concentrations. Complete data for yieldscan be found in TableS2 in the Supporting Information. Aswith the concentrations,there was a wide range in the yieldsfor a given surface type, in most casesmore than an orderof magnitude. The mean yield from coal-tar-sealed lotsexceededthat from asphalt-sealedlots by more than a factorof 2, although this difference was not statistically significant(Kruskal-Wallis test of comparison, p < 0..05).However,themean yield from sealed lots (asphaltand coal tar combined)exceededthat from unsealed lots by a factor of 50, and thedifference was statistically significant.DiscussionRunoff from parking lots typically is contaminated with PAHsfrom leaking motor oil, tire particles, vehicle exhaust,andatmospheric fallout, and it is not surprising that the meanconcentration of LPAH in particles washed off each of thedifferent surfacetypesexceededthe probable effect sedimentquality guideline. Howexer, the large differences between

VOL. 39, NO. 15, 2005 I ENVIRONMENTAL SCIENCE & TECHNOLOGY. 5563

8/12/038/21/039/9/039/26/03


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~

~

x

2,500Ii~..2.0 ~I ry-'.00 500 1.000 1.500 2.000

Days since product appliedRGURE3. 1:PAHconcentrations (closed symbols) and PAH ratiosof higher and lower molecular weight PAHs (open symbols) (a) inscrapings and particles washed off coal-tar-sealed test plots(D. 0) and an asphalt-sealed plot (6) and (b) as they relate to theage of coal-tar sealant in samples from parking lots in use.

0.0,,'.\.v x

from the newlyapplied sealantmight be responsiblefor someof the decreasein concentration. For the parking lots, onlycoal-tar-sealedlots representeda range of ages,and for theselots there was no relationship between concentration orhigher MW to lower MW PAH ratio and age of the sealant(Figure 3b). This might be because the parking lots wereeachsampled only once; the very wide range in PAHcontentbetween products, even those of a similar kind, may maskthe effect of aging when time-series data are not available.Although the data are limited, they suggest that lots witholder sealant tend to have a higher ratio of higher MW tolower MW PAHs, and that that ratio may reach a plateauafter a period of time.Comparison of the yields from the parking lots to thosefrom the test plots, which receive no vehicle traffic, dem-onstrates the importance of abrasion of sealcoatby vehicleson 1:PAHyield: the mean kPAH yield was 20 and 160timesgreater for the coal-tar-sealed and asphalt-sealed parkinglots, respectively,than for the analogoustestplots. This doesnot appear to be attributable to use patterns, although trafficcounts were not made: the coal-tar-sealed lots are a mix oflotsin constantuse throughout the day (e.g.,shopping center)and those with all-day parking (e.g., office), which areassumed to receive less use than those in constant use; allof the asphalt-sealedlots are all-day parking.Environmental Implications. Given the extremely el-evated concentrations of PAHs in particles washed fromsealed parking lots, how important is this contribution tothe total mass of PAHs in urban streams?To answer thisquestion,we compared the PAHassemblagesand estimatedPAHloads associatedwith particulates in parking lot runoffto thoseassociatedwith suspendedsedimentcollectedduringstorm flow in four streams: Williamson Creek (Austin, TX)(18) and influent streams to Echo Lake, Fosdic Lake, andLake Como (Fort Worth, TX) (26).These four streams are inhighly urbanized watersheds (land use for the Austinwatershed is about 65% urban, and for the three Fort Worth

1.1.51.41.

: 1.0I, n A

5564. ENVIRONMENTAL SCIENCE & TECHNOLOGY I VOL 39. NO. 15. 2005

" ri ~::t"'~:, .: ..6,'.,0.6' '-'-. ...I1.0 1.2 1.4 1.6 1.8 2.0Fluoranthene:pyrene

.1.8, -I

1.8N...1.4 ~~~'1.2 ...,..-; :I:.~" ,',.+. ,1.0 "\., .~"":'~;.:~:~~)..,. .'.', +. .0.8 ','" ' 4" ,0.6 ",'0.4 0.6 0.8 1.0 12 14 1.6 1.8

Benzo[s ]pyrene: benzo[e]pyrene1.6 ,1.~1.21.0

0.8l, 0.6 r "'""",:O.~1.0 1.2 1.4 16 1.8 2.0

Fluoranthene:pyreneSamples and ellipse approximate distribution of:

0 Coal-tar sealed parking lots,.,~: Asphalt sealed parking Jots'..'(~) Unsealed asphalt and cement parking lots


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.200Lake Como Inflow "0IV.Q:I:c{Q.H"0Q)"'iUE:wII)W

1,00010 ! e~~f~::iJ SOD60011,000 400200

0

Fosdic Lake Inflow

10.110,000 Williamson Creek I

10010ln

StOml eventsFIGURE 5. Comparison of estimated event loads of I;PAH fromsealed parking lots and measured instream storm-event loads forfour urban watersheds. The interquartile range of estimated loadsis s~lown in gray shading, on the basis of 25th and 75th percentileyields computed for sealed parking lots; the mean estimated loadis indicated by a dashed line. Measured instream loads for four toeight individual events are shown as bars.discriminant function analysis. In discriminant functionanalysis, each significant independent variable adds todiscrimination between multiple groups. The three ratios(tluoranthene:pyrene, indeno[l ,2,3-cd]pyrene:benzo [ghll-peryiene, and benzo[a]pyrene:benzo[e]pyrene)were enteredinto the analysis as the independent variables, with thedifferent types of samples (coal-tar-emulsion-sealed lots,asphalt-emulsion-sealed lots, unsealed lots, and urbanstormtlow stream sediments) defining four groups of de-pendent variables. All three variables were shown to con-tribute significantly to discrimination between the groups (p< 0.001).The distances between the centroids of the groupswere determined by computing the squared Mahalanobisdistance, which is a measure of the distance between twopoints in the space defmed by two or more correlatedvariables.The centroid of the group defined by the suspendedsediment from urban streamsis closestto the centroid of thecoal-tar-based sealant group, next closest to that of theunsealed lot group, and farthest from that of the asphalt-based sealantgroup (squaredMahalanobis distances of 5.7,13.0, and 25.0, respectively). Thus, on the basis of the threeratios diagnostic of coal-tar sources,the PAHassemblageofthe suspendedsediment from the urban streamsmost closelyresemblesthat of the coal-tar-basedsealantgroup,supportingthe hypothesis that coal-tar-based sealantsare an importantsource of PAHs in urban streams.

Moving to a mass-balance approach at the watershedscale for each of the four urban watersheds,we comparedmeasured storm-event stream loads of LPAH to thoseestimated to be contributed by sealed parking lots. Digitalland-use maps that included parking lots were provided bythe Cities of Austin and Fort Worth and were updated usingrecent aerial photography and site inspections. Sealedand

o~ o~ o~ 0"-,~~ ,~~ ,~~ 0,,0~O *-0 *-0 O~00 v~ v~ ~0 .c, '"*-0 ",ao ~O" .$-~v~ "V 0 ~"

FIGURE6. Comparison of event loads ~If1:PAH fDr four urbanwatersheds estimated for parking lots in their current (2004)state(sealed by gray bars and unsealed by white bars) ;~ndprojectedloads if all existing parking lots were unse,aled(black bars). Loadswere estimatedon the basis of the yields from the runo:ffexperimentsand the area of parking lots in each watershed.unsealed lots were identified by site inspection. We computedthe hypothetical storm-event load generated by sealedparking lots in each watershed by multiplying the mean yieldfor sealed parking lots (coal-tar and asphalt emulsion sealcoatcombined) determined from the runoff experiments by thesealed parking lot area of each watershed. We assumed thatthe 2 rom of water applied for the field tests mobilized allavailable particles, and that all runoff from parking lotsentered storm sewers and was delivered to the stream.Although there is substantial variation in event loads for eachstream (18, 26), for all four watersheds the estimated kP AHloads contributed by sealed parking lots are similar inmagnitude to measured stream loads, even though sealedparking lots cover only 1-2% of each watershed (Figure 5).These results might explain why an investigation carried outin Marquette, MI, found that runoff from commercial parkinglots contributed 64% of the PAH load to the urban watershedstudied (33).What would be the effect on PAH loading to thesewatersheds if parking lots were not sealed? For each of thefour watersheds, we compared the kPAH load contributedby parking lots (computed on the basis of the aerial extentof unsealed and sealed parking lots) to that obtained byapplying the average yield for unsealed lots to all parkinglots (Figure 6). We estimate that the kPAH load from parkinglots in these watersheds would be reduced to 5-11 % of thecurrent loading if all lots were unsealed.With the exception of the sealcoat itself, unsealed parkinglots receive PAHs from the same urban sources as do sealedparking lots-e.g., tire particles, leaking motor oil, vehicleexhaust, atmospheric fallout-yet the average yield of PAHsfrom sealed parking lots is 50 times greater than that fromunsealed lots. PAH assemblages and estimated loads furthersuggest that sealed parking lots could be dominating PAHloading in watersheds with commercial and residential landuse. The implications of these results extend beyond Texasto the rest of the United States and Canada, where parkinglot sealcoat is used extensively, and to other countries wheresealcoat is being introduced. Previously identified urbansources of PAHs, such as automobile exhaust and atmo-spheric deposition, have been difficult to control or evenquantify because of their nonpoint nature. In contrast, sealedparking lots are point sources, and use of the sealant isvoluntary and controllable.AcknowledgmentsWe thank Robert Eganhouse, E. Terrence Slonecker, and threeanonymous reviewers for critical reading of the manuscript.

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(20) Fishman, M. J.; Friedman, L C. Methods for determination ofinorganic substances in water and fluvial sediments; U.S.Geological Survey Open-File Repon 93-125; U.S. GeologicalSurvey: Denver, CO, 1993.(21) Method 8270D: Semivolatile organic compounds by gaschromatography/mass spectrometry (COMS); U.S. Environ-mental Protection Agency: Washington, DC; http://www.epa.gov/ epaoswer/hazwaste/test/8_series.htm(accessedMarch2005).(22) MacDonald, D. D.; Ingersoll, C. G.; Berger,T. A. Developmentand evaluation of consensus-based quality guidelines forfreshwaterecosystems.Arch. Environ. Contam. Toxicol. 2000,39,20.(23) Brenner, R C.; Magar, V. S.; Ickes,J. A.; Abboutt, J. E.; Stout,S.A.; Crecelius,E. A.; Bingler, L S. Characterizationand FATEofPAH-contaminated sediments at the Wyckoff/Eagle HarborSuperfund Site. Environ. Sci. TechnoL2002, 36, 2605.(24) Krein, A.; Schorer, M. Road runoff pollution by polycyclicaromatic hydrocarbons and its contribution to river sediments.WaterRes.2000, 34, 4110.(25) Durand, C.; Ruban, V.; Ambles, A.; Oudot, J. Characterizationof the organic matter of sludge: determination of lipids,hydrocarbons and PAHsfrom road retention/infiltration pondsin France. Environ. PoUut. 2004, 132,375.(26) Van Metre, P. C.; Wilson, J. T.; Harwell, G. R; Gary, M. 0.;Heitmuller, F. T.; Mahler, B. J. Occu"ence, trends,and sourcesin particle-associatedcontaminants in selectedstreamsand lakesin Fort Worth, Texas;U.S. Geological SurveyWater ResourcesInvestigationsRepon 03-4169;U.S.GeologicalSurvey: Denver,CO, 2003.(27) Yunker,M. B.; Macdonald,R. W.; Vingarzan,R.; Mitchell, R H.;Goyette,D.; Sylvestre,S. PAHsin the FraserRiverbasin: a criticalappraisal of PAH ratios as indicators of PAH source andcomposition. Org. Geochem.2002, 33, 489.(28) Eganhouse, R P.; Gossett, R. W. Historical deposition andbiogeochemical fate of polycyclic aromatic hydrocarbons insediments near a major submarine wastewater outfall inSouthern California. In Organic Substancesand SedimentsinWater;Baker,RA., Ed; LewisPublishers: BocaRaton,FL,1991;p 191.(29) Heit, M. The relationship of a coal fired power plant to thelevels of polycyclic aromatic hydrocarbons (PAH) in thesediment of Cayuga Lake. WaterAir Soil Pollut. 1985, 24, 41.(30) Canton, L; Grimalt, J. O. Gas chromatographic-massspectro-metric characterization of polycyclic aromatic hydrocarbonmixtures in polluted coastal sediments.]. Chromatogr. 1992,607, 279.(31) Marvin, C. H.; McCarry, B. E.; Villella, J.; Allan, L M.; Bryant,D. W. Chemicaland biological profiles of sedimentsas indicatorsof sources of genotoxic contamination in Hamilton Harbour.Part I: Analysis of polycyclic aromatic hydrocarbons and thia-

arene compounds. Chemosphere2000,41,979.(32) Lake, J. L; Norwood, C.; Dimock, C.; Bowen, R. Origins ofpolycyclic aromatic hydrocarbons in estuarine sediments.Geochim.Cosmochim.Acta 1979,43,1847.(33) Steuer, J.; Selbig, W.; Hornewer, N.; Prey, J. Sources of con-tamination in an urban basin in Marquette,Michigan and ananalysis of concentrations, loads,and data quality; U.S. Geo-logical SurveyWater ResourcesInvestigations Repon 97-4242;U.S. Geological Survey: Denver, CO, 1997.(34) Takada,H.; Onda, T.; Harada, M.; Ogura, N. Distribution andsources of polycyclic aromatic hydrocarbons (PAHs)in streetdust from the Tokyo Metropolitan area. Sci.TotalEnviron. 1991,107,45.(35) Yang,S.Y.N.;Connell,D. W.;Hawker,D. W.; Kayal,S.I.Polycyclicaromatic hydrocarbons in air, soil and vegetation in the vicinityof an urban roadway. Sci. Total Environ. 1991, 102,229.

..This research was carried out asa cooperative project betweenthe U.S. Geological Survey and the City of Austin.SupportingInformationAvailableTwo figures and three tables. This material is available freeof charge via the Internet at http://pubs.acs.org.LiteratureCited

(1) u.s. Environmental Protection Agency. The incidence andseverity ofsedimentcontamination in surfacewater ofthe UnitedStates;EPA823-R-97-006;Washington, DC.(2) Report on Carcinogens,lOth ed.; National Toxicology Program,Public Health Service,U.S. Department of Health and HumanServices: Washington, DC, 2002.(3) Van Metre, P. C.; Mahler, B. J.; Furlong, E. T. Urban sprawlleaves its PAHsignature. Environ. Sci. Technol.2000, 34,4064.(4) U.S.Environmental ProtectionAgency.Information on the ToxicEffects of Various Chemicals and Groups of Chemicals,2003.http://www.epa.gov/R5Super/ecology/htrnl/toxprofiles.htrn#(accessedJanuary 2005).(5) Jiries,A. Vehicular contamination of dust in Ammam, Jordan.Environmentalist 2003, 23, 205.(6) Takada, H.; Onda, T.; Ogura, N. Determination of polycyclicaromatic hydrocarbons in urban street dusts and their sourcematerialsby capillarygaschromatography.Environ.Sa. Technol.1990,24; 1179.(7) Hoffman, E. J.; Mills, G. L; latimer, J. S.; Quinn, J. G. Urbanrunoffas a sourceofpolycyclic aromatic hydrocarbonsto coastalwaters. Environ. Sa. Technol. 1984, 18, 580.(8) Rogge,W. F.; Hildemann, L. M.; Mazurek, M. A.; Cass,G. R.Sources of fine organic aerosol: Road dust, tire debris, andorganometallic brake lining dust: roads as sourcesand sinks.Environ. Sa. Technol. 1993, 27, 1892.(9) Irwin, R. J.;VanMouwerik,M.; Stevens,L; Seese,M. D.; Basham,W. Environmental Contaminants Enclyclopedia;National ParkService,Water ResourcesDivision: Washington, DC, 1997.(10) Contractors Register, Inc. The Blue Book of Building andConstruction; JeffersonValley, NY, 2005.(11) SealMaster Pavement Products and Equipment. http://www.sealmaster.net/ (accessedJune 2005).(12) New England Sealcoating Sealcoating and Striping. http://www.newenglandsealcoating.com/sealcoating.htrn(accessedJune 2005).(13) City of Austin Report to Council on Coal Tar. http://www.cLaustin.tx.us/watershed/bs_coaltar.htrn(accessedJanu-ary 2005).(14) Dubey,G. Sellingsealcoating.Pavement1999,MarchI April, 42.(15) Haurwitz, R. Parking Lot Contaminant Theory Explored. InAustin American-Statesman;Austin, Texas, Cox Communica-tions: Atlanta,GA, 2003; p A6.06) Mahler, B. J.; Van Metre, P. c; Wilson, J. T. Concentrations ofpolycyclic aromatic hydrocarbons (PARs)and major and traceelements in simulated rainfall runoff from parking lots,Austin, Texas,2003;U.S. Geological SurveyOpen-File Report2004-1208;U.S. Geological Survey: Denver, CO, 2004; http://water. usgs.govIpubsl of/2004/1208/pdfl ofr2004-1208.pdf(ac-cessedJanuary 2005).07) Eganhouse,R. P.; Kaplan, I. W. Extractable organic matter inurban storrnwater runoff. 1. Transport dynamics and massemission rates. Environ. Sa. Technol. 1981, 15,310.08) Mahler, B. J.; Van Metre, P. C. A simplified approach formonitoring of hydrophobic organic contaminants associatedwith suspendedsediment- methodologyand applications.Arch.Environ. Contam. Toxicol. 2003, 44, 288.09) Olson, M. C.; Iverson, J. L; Furlong. E. T.; Schroeder,M. P.Methods ofanalysisby the U.S.GeologicalSurveyNational WaterQuality Laborato~Determination of polycyclic aromatichydrocarboncompounds in sediment by gas chromatographyImass spectrometry;U.S. Geological Survey Water ResourcesInvestigations Report03-4318;U.S.GeologicalSurvey: Denver,CO, 2004.

Receivedfor review January 24, 2005. Revised manuscriptreceivedApril 29, 2005.AcceptedMay 2, 2005:E50501565

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