Predicting Bacteria Concentrations On The Nation's Beaches Walter Frick, Ph.D., Marirosa Molina, Ph.D OfficeofResearcharidDevelopnnent, NationalExposure ResearchLaboratory, EcosystemsResearch Division,Athens, Georgia Year of Thirty /ears of Progress Through Pa Environmentallssue Withthepossibleexceptionofthosewhovaluesolitudeaboveallelse,noonewants beachesclosedasaresultofhighbacterialwaterconcentrations. Although microbioiogyisconstantlymakingnewbreakthroughsinmicrobialdetectionand identification,beach closuredecisionsstillfrequ en tlyre lyon ti m e- i n te n si vet est sfor indicatorbacteriawhichdonotdifferentiatebetweensewageplumesfromdistant sourcesreachingabeachandthevisitofflocksofseagullstothebeachthe previousday.Currentprocedurealiowsonl yf oraft er-th e-f actre acti on st oh i g h bacterialcounts,costingmunicipalitiesuntolddollarsinlostrevenuesand remediation actions. Approach ERDscientistsaredevelopingmodelsthatwillintimebeabletoaccuratelytrackthe movementofwaterandsourcesontothenation'sbeaches.Models,liketheERD Visual Plumesmodel,wi!lbemodifiedtotrackbothpointsources(likesewage treatmentplants)andnon-pointsources(likebirdsonbeaches).Anotheraspectof thisresearchseekstodevelopandimprovebacterialsubmodelsthatwillbespecific toactualpathogens,ratherthanindicators.Toadvance,pathogensmustbe positivelyidentifiedandmodeled.MicrobialSourceTracking(MST)isatechniquefor quantifyingpathogens.ERDResearchersaredevelopingafastandreproducible a Ite m at i ve D N A-b as ed MSTmeth od ol ogyt oi tern ize comp I ex sou rc em ixt u res. Thisworkenvisionsamodel,workingtitle"Visual Beach",thatwillusereal-timedata andadvancedbiologicalinputs,forexample,MicrobialSourceTracking(MST),GIS d at a( ba th ym et ry), fore castd at a, pa rt i cu I arlyw eath erdata, a n d, i n coast al area s, astron om i calti d efa ctors. Impact Microbiaicontaminationleadstobeachclosureandposesthreatstohumanhealth. Thepurposeofthisworkistohelpprotectaquaticecologicalsystemsand recreationairesources.lfsuccessful,themodelwillhelpdeviseeffectivesource controlstrategiesandheipdifferentiatebetweendangerousepisodes, requiring closure,andbenignonesnotrequiringdrasticmeasures.ltwouldenablehealth official stodiscriminatebetweendangerousandbenignexposurelevelsandhelp treatmentplantoperatorsdevelopstrategiestopreventmostbeachclosuresdueto importantpointsources. NationalScope Anexampleofanationalproblem, Huntington Beach,Californiawasclosedn 1999 duet oelevatedbacterialcounts.VisualPlumeshasbeensuccessfullytestedon this problem July-August1999BeachClosureMaplocatestheclosedbeach(greenstripe)and themajorOrangeCounty4-milelongsewageoutfalldischargingat60mdepth. Insetsshowbeachsceneandtreatmentplant. IndianaDunesNationalSeashore Values, Resources, and Problems IndianaDunesNationalSeashore ThemodeldescribedherewillbetestedonWestBeach(lndianaDunesNationalSeashore,LakeMichigan)datathissummer. ¦ - . M ~ I o " .. 3 E •" , ~ ¦ " " — j, t— H s • -—- : • ¦ . • Modeling AVisualPlumessimulation. Areleaseofsewageformingaplume(redoutline) trackedfor36hours(plumeelementismovedin2-hrincrements)andforminga plumethatencroachesHuntington Beachinwinter2001 ,arareevent. Notspaghetti,amonth-longVisualPlumessimulation. June-July2000 simulationsshowaeasreachedbysimilarlycontaminatedplumesduringthat period. Note,thesourcedidnotimpactthebeachduringthattime.lnsetdiagram showshowsolarintensity(akillerofwaterbornebacteriafactoredintoVisual PI umes)decreasesrapidlywithdepth. Hydrodynam icsandPCR Thebeachbacteriamodelingspanstwomaindisciplines,hydrodynamicsand microbiology. Sh ownhereisalaborat oryplumeimageprodu cedthrou ghlaser- i n d u ce df I u oresc en cei ma gi n g. Bot h su rf ac ef eatu re san df al s ec ol ore ross- se cti on al featuresareshown. Towingchannelplume,laser-inducedfluorescenceimagery PlansfortheLakeMichiganModel Thenextgenerationofbeachbacteriamodels willincludedensecurrentinformationbasedonfinite-elementhydrodynamical model st h at'wi i I m a kef ore ca sts pos si bl e. Th i sex am p I e sh ows ac u rre n tf i eld (light greenarrows) andanembeddedplumerepresentingacombinedseweroverflow. PolymeraseChainReaction(PCR) PCRisamethodbywhichverylowconcentrationsofDNAareamplifiedtoimprove detection oft argetorganisms. However,con ventionalPCRmethodscannotbe usedtodetermineba cterialnumbers.Recently,research ershavedevelopedan alternativePCRmethodcommonlyknownasreal-timePCR,wherethenumberof amplicons(amplifiedDNAproducts)fromeachreactioncyclearemeasured. Productaccumuiationisquantifiedduringtheexponentialphaseoftheamplifi cation process.Theprocedurecanbeusedwith16S-rDNAprimersspecifictoagroupor speciesoffecalindicatorbacteria.Thisapplicationwillallowaccuratemonitoring an dquantificati on ofspecificfecalindicatorbacteriain recreation al waters an dm ay reducedetectiontimeto3hours.Theschematicdiagramshowsprinciplesofthe applicationofpolymerasechainreactiontechnology. Schem aticofthepoIymerasechainreaction(PCR) Conclusion TheVisual Beachmodelingapproachattemptstoprovideaholisticconceptualand numericalmodelofbacteriatransportandfate.ltattemptstorealisticallymodelthe mostimportanttransportandfatemechanisms.ltanswersquestionslike:Wheredid thewatercomefrom?Whatweretheconcentrationsofbacteriainitially?Towhat stressorswerethebacteriaexposedduringtheirtransitfromsourcetoreceptor regions?Andsoon.Thebasicphilosophyisthatincreasinglybettermodelswillhelp betterunderstandandmodelbacteriatransportandfateandultimatelyhelpreduce beach dosures. Acknow! edgement :Th e o Partnering to -ProtectHuman Escherichiacoli, fecalindicatorbaeterium talwetland ------- |