U.S. Department of the InteriorU.S. Geological Survey

Fact Sheet 2009-3075 October 2009Printed on recycled paper

Key Findings

Acidrainhasacidifiedsoilsresultingintoxicaluminumin66percentof565assessedstreams.

Diatoms,anenvironmentallysensitivegroupofalgae,weremoderatelytoseverelyaffectedbyacidrainin80percentofassessedstreams.

Aquaticinsectsandrelatedorganismsreferredtoasmacroinvertebratesweremoderatelytoseverelyaffectedin52percentofassessedstreams.

Recoveryfromacidificationhasbeenminimalin11of12Adirondackstreamssampledpreviouslyintheearly1980s.

Thebase-cationsurplus,anewacidificationindexdevelopedforthisproject,indicatedthatnotmorethanone-thirdofmeasuredstreamaciditywasfromnaturalsources.

TraditionallylakeshavebeenthefocusofacidrainassessmentsintheAdirondackregionofNewYork.However,thereisagrowingrecognitionoftheimportanceofstreamsasenvironmentalindicators.Streams,likelakes,alsoprovideimportantaquatichabitat,butstreamsmorecloselyreflectacidraineffectsonsoilsandforestsandaremorepronetoacidificationthanlakes.Therefore,alarge-scaleassessmentofstreamswasundertakeninthedrainagebasinsoftheOswegatchieandBlackRivers;anareaof4,585km2inthewesternAdirondackregionwhereacidrainlevelstendtobehighestinNewYorkState.High flows such as seen in this Adirondack stream tend to have the most acidic stream water.

Acid Rain Effects on Adirondack Streams— Results from the 2003–05 Western Adirondack Stream Survey (the WASS Project)

Purpose of the Western Adirondack Stream Survey (WASS)AcidifiedsurfacewaterswerefirstdiscoveredintheAdirondackregion

ofNewYorkinthe1970s.ComprehensivemonitoringandassessmentofAdirondacklakes,ongoingsincetheearly1980s,hasidentifiedthisregionasoneofthemostaffectedbyacidicdepositioninNorthAmerica.However,assessmentsofstreamacidificationintheAdirondackregionhavebeenlimitedtoalargesurveyintheearly1980sandintermittentdatacollectiononafewstreamsthroughthe1980sand1990s.

Lakechemistryandstreamchemistryaregenerallysimilarwithinaregion,butlakechemistrycanbeanunreliableindicatorofstreamchemistrywhenassessingtheeffectsofacidicdeposition.Streamsaremorepronetoacidificationthanlakesbecausetheyreceivealargerfractionofwaterfromshallowsoilsthatareoftenineffectiveatneutralizingacidity.Lakesarealsoabletobuffertheacidityofstoredwaterbyin-lakeprocesses.

Streamacidificationismostprevalentduringperiodsofhighflow.Thetransientnatureofhighflow,whichcanlastfromafewhourstoafewweeks,resultsinepisodicacidificationthatisdifficulttomeasure.Thechemistryduringbaseflow(periodsbetweenstormsorrapidsnowmeltwhenchemicalconcentrationstendtoberelativelystable)iseasiertomeasure,butunderestimatestheextentoftheproblem.Forexample,inaCatskillMountainwatershed,thetotallengthofacidifiedstreamswasfoundtoincreasefrom16percentatbaseflowto82percentathighflow(Lawrence,2002).Harmfuleffectsonaquaticlifefromepisodicacidificationcanbesimilarorworsethanthosefromchronicacidification(McComickandLeino,1999;Passyandothers,2006).

ToassessthecurrentchemicalandbiologicalconditionsofstreamsintheregionoftheAdirondacksconsideredmostaffected,theWesternAdirondackStreamSurvey(WASS)wasconductedbytheU.S.GeologicalSurvey(USGS)incollaborationwiththeAdirondackLakesSurveyCorporation,theNewYorkStateDepartmentofEnvironmentalConservation,andtheUniversityofTexasatArlington,withfundingsupportfromtheNewYorkStateEnergyResearchandDevelopmentAuthority.ThisprojectisthefirstregionalassessmentofAdirondackstreamssincetheearly1980sandtheonlyassessmentconductedintheUnitedStatestocharacterizeepisodicacidificationonaregionallevel.

Project Objectives

• Developanimprovedmethodfordistinguishingbetweenthechemicaleffectsofacidicdepositionandtheeffectsofacidityfromnaturalsources.

• Determinethecurrentextentofeffectsofacidicdepositiononstreamchemistryandaquaticlifeinthisregion.

• Evaluatetheroleofsoilchemistryasacontrolofstreamchemistry.

• Determinetotheextentpossiblechangesinstreamchemistryoverthepasttwodecades.

Study ApproachThestudywasundertakeninthedrainagebasinsoftheOswegatchie

andBlackRivers,anareaof4,585squarekilometers(km2)inthewesternpartoftheAdirondackregionofNewYork.Atotalof200streamsrepresentingapopulationof565accessiblestreamswererandomlyselectedforsampling.Thepopulationofstreamshadminimalupstreaminfluencesfromlakesandponds.

Figure 1. Collection of a water sample from Buck Creek, Inlet, NY, during spring snowmelt. Ongoing monitoring of flow and water chemistry at this site provided valuable data on how variations in flow affected stream chemistry.

Fivesurveyswereconductedduringspringsnowmelt,summerlowflow,andfallhighflowtoaccountforvariationsinchemistrythatoccurredbothepisodicallyandseasonally.Allsamplesforeachsurveywerecollectedwithin3days(withafewexceptions)duringperiodswhenflowswereeitherelevatedorremainedlow.BuckCreek(drainagearea3.1km2),theonlystreaminthestudyregionmonitoredyear-roundforflowandchemistry,wasusedasanindexstreamtoplaceresultswithinthecontextofvariationsthroughoutthestudy(fig.1).

A New Chemical Index for Measuring AcidificationAssessmentsofacidicdepositioneffectsandrecoveryhave

reliedonANCGandpHastheprimarychemicalindicators.However,bothofthesemeasurementscanbesubstantiallyinfluencedbynaturallyproducedorganicacidity,whichisabundantinmanyAdirondackstreams.Tobetterdistinguishbetweenacidicdepositionandnaturalorganicacidity,anewchemicalindex,termedthebase-cationsurplus(BCS),wasdevelopedinthisproject.TheBCSisbasedonthemobilizationofinorganicaluminum(thetoxicform)withinthesoil,whichdoesnotoccurintheabsenceofacidrain.ABCSvaluelessthan0microequivalentsperliter(µeq/L)instreamwaterindicatesthatthesoilhasbecomesufficientlyacidifiedbyacidraintoenabletoxicformsofaluminumtomovefromthesoilintostreams(fig.2).MeasurementsoftheBCSinstreamsvariedseasonallyandwithchangesinflow.ResultsshowedthatstreamswithaBCSvaluebelow25µeq/LduringanyofthestreamsurveyswerelikelytohavenegativeBCSvaluesatsometimeoverthecourseofagivenyearandwerethereforedefinedaspronetoacidification.

Effects on the Chemistry of Stream and SoilsResultsshowedthat66percentofassessedstreams

werepronetoacidificationbyacidrain(BCSvalueslessthan25µeq/L).Ofthesestreams,approximatelyone-halfwerechronicallyacidifiedandone-halfwereepisodicallyacidified(acidifiedduringhighflows).Theprevalenceofacidifiedstreamsincreasedfromwesttoeastacrossthestudyregion(fig.3).Resultsalsoshowedthat718kilometers(km)oftotalstreamlengthwaspronetoacidificationwithinthestudyregion,althoughmorethan3,000kmofstreamsinthestudyregionwerenotassessedduetoinaccessibility.Naturalsourcesofaciditywerefoundtocontributeonly16to34percentoftheaciditymeasuredbytheBCS.

NeutralizationofacidityisdependentonrapidreactionsinthesoilthatbufferthepHofsoilwaterthroughthereleaseofbases(mostlycalcium)adsorbedtoparticlesurfaces(Lawrence,

ChemicalmeasurementsincludedpHandacid-neutralizingcapacitybyGrantitration(ANCG),themostcommonlyusedmeasuresofacidificationeffects.However,pHandANCG donotdistinguishbetweennaturalorganicacidity,whichiscommoninAdirondackwaters,andthatderivedfromacidicdeposition.Therefore,anewmeasure,termedthebase-cationsurplus(BCS),wasdevelopedtorelateacidicdepositioninputstothebufferingthresholdofsoilsbelowwhichtoxicaluminumismobilizedandenterssurfacewaters.Soilsamplesalsowerecollectedin11smallwatershedstoidentifylinksbetweensoilchemistryandstreamchemistry.

Diatoms,ahighlydiversegroupofalgaewithvariableenvironmentaltolerances,andmacroinvertebrates(insectsandotheraquaticlifesuchaswormsandcrustaceans)wereusedasbiologicalindicatorsinthisstudy.Diatomsampleswerecollectedineachofthe200surveystreamsduringthesurveysconductedinAugust2003,October2003,March2004,andAugust2004.Macroinvertebrateswerecollectedin36streamsthatrepresentedtherangeofacidification.

HistoricalmeasurementsofANCG,pH,andspecificconductancewereavailableintheearly1980sfor18Adirondackstreamsandlakeoutletswithinthestudyregion.Thehistoricalsamplingwasreplicatedinthisstudyduring2003–2005todetermineifwaterchemistrydifferedbetweenthetwoperiods.Becausestreamchemistryisstronglyinfluencedbyflow,datafromtheUSGSstreamgageontheIndependenceRiveratDonnattsburgwereusedtoaccountforflowvariationsduringbothsamplingperiods.

Figure 2. Concentrations of inorganic aluminum (the form toxic to aquatic life) plotted against values of the base-cation surplus to illustrate the threshold below which aluminum is mobilized in soils and transported into streams.

BASE-CATION SURPLUS,MICROEQUIVALENTS PER LITER

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Figure 4. A typical upper soil profile in Adirondack soil. The Oa horizon, comprised mostly of humus-like material, lies directly below the litter and decomposing leaves of the forest floor. The upper B horizon, comprised primarily of mineral matter formed from the breakdown of rocks lies directly below the gray, relatively inert E horizon.

Figure 3. Acidification categories of sites sampled in the March 2004 survey. Sites not acidified had base-cation surplus (BCS) values greater than 25 microequivalents per liter (µeq/L); sites prone to acidification had BCS values greater than 0 µeq/L but less than 25 µeq/L; acidified sites had BCS values less than 0 µeq/L.

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EXPLANATION

Not sampled in March 2004

75°30' 75°00' 74°30'

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Figure 5. The percent of streams in each of three categories of acid impact, derived from the mean diatom acidification index (ACI) values across the four diatom surveys. ACI represents the proportion of species in a diatom community with preference for acidic conditions. (NON, non-impacted; MOD, moderately impacted; HIGH, highly impacted).

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ACIDITY INDEX CATEGORIES

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2002).Ifinsufficientcalciumisavailable,toxicformsofaluminumareinsteadreleased.Soilsamplinginselectedwatershedsshowedacloserelationshipbetweentheavailabilityofbasesinthesoil,referredtoasthebasesaturation,andtheBCSinstreamwater.Throughthisrelationship,basesaturationintheupperBhorizonwasestimatedtobeinsufficienttopreventaluminummobilizationin90percentoftheassessedwatersheds.TheupperBhorizonhadbeengenerallyconsideredtheprimarysourceofcalciumforbufferingduringhighflows,butWASSresultsindicatedthattheorganicsoilhorizonclosetothesurface(Oahorizon)playsagreaterrolethantheupperBhorizon(fig.4)intheneutralizationofacidity.TheneutralizingcapacityoftheupperBhorizonhasbeenloweredbythedepletionofcalciumfromacidrain.

Effects on Aquatic lifeAssessmentofdiatomsshowedthatonlythemostacid-

tolerantspecieswerefoundbelowaBCSvalueof10µeq/L,whichapproachesthethresholdformobilizationofinorganicaluminum(BCS=0µeq/L).Thepercentageofstreamsinwhichdiatomcommunitiesweremoderatelyorseverelyimpactedbyacidicdepositionrangedfrom66to80percent(fig.5).Limitedvariationwasobservedinvaluesofthemeandiatomacidificationindex(ACI)amongthefoursurveysdespitetheconsiderablevariationinflow,season,andwaterchemistry.Whereasawatersamplereflectschemicalconcentrationsat

Figure 6. Collection of macroinvertebrates in an Adirondack stream by a scientist in the Stream Biomonitoring Unit of the New York State Department of Conservation.

themomentofcollection,thepresenceorabsenceofadiatomindividualreflectsenvironmentalconditions,includingwaterchemistry,overtheorganism’slifespan.ThesimilarityinACIvaluesfortheOctober2003andMarch2004surveysmostlikelyreflectsacidificationduringtheseveraldaysthatthesurveysoccurred.However,theACIvaluesfortheAugust2004survey,whichwassimilartotheOctober2003andMarch2004surveys,indicatesexposuretoacidificationatsometimepriortothesurvey.Thetimebetweentheexposureandthesurveywastooshortforrecoveryoftheacid-sensitivediatomspecies.Therefore,thediatomresultsreflectedvariationsinstreamchemistryoverapriorperiodofuptoseveralweeks,acharacteristicthatmakesdiatomshighlyvaluableintheassessmentofstreamacidificationwherewaterchemistrycanvarysubstantiallyoverafewhours.IntheAugust2003survey,33ofthe162samplestreamsweredryduetoextremelydryconditions.

Macroinvertebratesamplingof36streams(fig.6)withvaryingchemistrywasusedtocharacterizetherangeofacidificationimpactsonmacroinvertebratecommunitiesandtodefinecategoriesofbiologicalimpactbasedontherelationshipsamongBCS,aluminum,andanewAcidBiologicalAssessmentProfile(acidBAP)indexthatrelatesthemacroinvertebratecommunitytowaterchemistry.UsingtheMarch2005surveyresultsasthemedianchemicalcondition,52percentofthestreamshadmacroinvertebratecommunitiesthatweremoderatelytoseverelyaffectedbyacidrain.

Changes in Stream Chemistry Since the Early 1980sAcomparisonwithhistoricalstreamchemistrydata

showedstatisticallyhigherpHvaluesin2003–2005thanintheearly1980sin8ofthe12streamsand4ofthe6lakeoutlets,butlessthanone-halfofthesestreamsandoutletshadahigher

ANCGin2003–2005thanintheearly1980s.Theamountofchangewasrelativelysmall,andnearlyallthestreamsandoutletsexhibitedepisodicacidificationduringperiodsofhighstreamflowin2003–2005.

TheresultsindicatedthatrecoveryfromacidificationintheseAdirondackstreamsandoutletshasbeenminimal,withtheexceptionofBaldMountainBrookandFlyPondOutlet.However,eveninthesewaters,BCSvaluesduringthemostacidicsamplingconditionsin2003–2005approached0µeq/L;thethresholdformobilizationoftoxicaluminum.TheoverallincreaseinANCGforthe12streamswas13µeq/Lover23years.Thedegreeofchemicalrecoveryobservedinthishistoricalcomparisonprobablyresultedinlittleornobiologicalrecoveryinmostofthestreamsandoutlets.

ConclusionsTheWASS,thelargeststreamsurveyconductedin

theUnitedStatestocharacterizeepisodicacidification,hassubstantiallyexpandedourknowledgeofthecurrentconditionsofAdirondacksurfacewaters.Currenteffortstomodelchangesinsoilandwaterchemistryinresponsetochangesinatmosphericdepositionwillbenefitfromthedatacollectedinthisstudy,butadditionaldatawillbeneededtodocumenttheeffectsofenvironmentalchanges.Futuretrendsinatmosphericdepositionareuncertain,andupwardtrendsintemperatureandprecipitationinthestudyregion(Dello,2007)areexpectedtocontinue(Hayhoeandothers,2007).WASSresultswillbevaluableinthisregardbecausethestudycanberepeatedtoevaluatefuturechangesinstreamchemistryandbiotaunderbothbaseflowandepisodicconditions.

References Cited

Dello,K.,2007,TrendsinClimateinnorthernNewYorkandwesternVermont:Albany,NY.,StateUniversityofNewYork,UniversityatAlbany,M.S.thesis.

Hayhoe,K.,Wake,C.P.,Huntington,T.G.,Luo,L.,Schwartz,M.D.,Sheffield,J.,Wood,E.,Anderson,B.,Bradbury,J.,DeGaetano,A.,TroyT.J.,andWolfe,D.,2007,PastandfuturechangesinclimateandhydrologicalindicatorsintheUSNortheast:ClimateDynamics,v.28,p.238–407.

Lawrence,G.B.,2002,Persistentepisodicacidificationofstreamslinkedtoacidraineffectsonsoil:AtmosphericEnvironment,v.36,p.1589–1598.

McComick,J.H.,andLeino,R.L.,1999,Factorscontributingtofirst-yearrecruitmentfailureoffishesinacidifiedwaterswithsomeimplicationsforenvironmentalresearch:TransactionsoftheAmericanFisheriesSociety,v.128,p.265–277.

Passy,S.I.,Ciugulea,I.,andLawrence,G.B.,2006,DiatomdiversityinchronicallyversusepisodicallyacidifiedAdirondackstreams:InternationalReviewofHydrobiology,v.91,p.594–608.

AcknowledgmentsSupportfortheWesternAdirondackStreamSurveywasprovidedbytheNewYorkStateEnergyResearchand

DevelopmentAuthority(NYSERDA);theU.S.GeologicalSurvey(USGS);theNewYorkStateDepartmentofEnvironmentalConservation,DivisionofAirResourcesandDivisionofFish,WildlifeandMarineResources;andtheAdirondackLongTermMonitoringProgramconductedbytheAdirondackLakesSurveyCorporation.WatershedmonitoringdataatBuckCreekwasprovidedbytheAdirondackEffectsAssessmentProgramconductedbytheRensselaerPolytechnicInstituteincooperationwiththeUSGS.AdditionalsupportfortheBuckCreekWatershedStudywasprovidedbyNYSERDA.

Additional information on the Western Adirondack Stream Survey can be found in the following publications:Baldigo,B.P.,Lawrence,G.B.,Bode,R.W.,Simonin,H.A.,Roy,K.M.,andSmith,A.J.,2009,ImpactsofacidificationonmacroinvertebratecommunitiesinstreamsofthewesternAdirondackMountains,NewYork,USA:EcologicalIndicators, v.9,p.226–239.

Lawrence,G.B.,Roy,K.M.,Baldigo,B.P.,Simonin,H.A.,Capone,S.B.,Sutherland,J.S.,Nierswicki-Bauer,S.A.,andBoylen,C.W.,2008,ChronicandepisodicacidificationofAdirondackstreamsfromacidrainin2003–2005:JournalofEnvironmentalQuality,v.37,p.2264–2274.

Lawrence,G.B.,Roy,K.M.,Baldigo,B.P.,Simonin,H.A.,Passy,S.I.,Bode,R.W.,andCapone,S.B.,2008,Resultsfromthe2003–2005westernAdirondackstreamsurvey:NewYorkStateEnergyResearchandTechnologyAuthorityFinalReport08–22(November2008),variouslypaged,availableonlineathttp://www.nyserda.org/programs/Environment/EMEP/finalreports.asp.

Lawrence,G.B.,Sutherland,J.W.,Boylen,C.W.,Nierzwicki-Bauer,S.A.,Momen,B.,Roy,K.M.,Baldigo,B.P.,Simonin,H.A.,andCapone,S.B.,2007,Acidraineffectsonaluminummobilizationclarifiedbyinclusionofstrongorganicacids:EnvironmentalScienceandTechnology,v.41,p.93–98.

By Gregory B. Lawrence1, Karen M. Roy2, Barry P. Baldigo1, Howard A. Simonin3, Sophia I. Passy4, Robert W. Bode3, and Susan B. Capone5

1 U.S. Geological Survey.

2 New York State Department of Environmental Conservation.

3 Retired, formerly New York State Department of Environmental Conservation.

4 The University of Texas at Arlington.

5Adirondack Lakes Survey Corporation.

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