Ecologicalriskassessmentofpestisideresiduesintaihu

EcologicalModelling222(2011)287–292ContentslistsavailableatScienceDirectEcologicalModellingjournalhomepage:∗,L.Huang,F.Y.LiStateKeyLaboratoryofPollutionControlandResourceReuse,SchooloftheEnvironment,NanjingUniversity,Nanjing210093,ChinaarticleinfoArticlehistory:Availableonline18August2010Keywords:EcologicalriskassessmentPesticideresiduesTaihuLakeWetlandabstractAsamajorecosystemtype,wetlandprovidesinvaluableecologicalservices.Environmentalpollution,especiallypesticidespollutionshouldbepaidmoreattentiontokeepwetlandshealthy.Basedontheriskquotientmethod,coupledwithaprobabilisticriskassessmentmodel,thispaperproposedamethodol-ogysuitableforecologicalriskassessmentofpesticideresiduesforwetlandecosystems.AsanimportantindustrializingandecologicallyvulnerableareainChina,theTaihuLakewetlandwaschosenforthecasestudy.TherisksofeightpesticidesinTaihuLakewetlandwereassessed,assinglesubstancesandinmix-tures.Theassessmentindicatesthatrisksoftherepresentativespeciesarenotsignificant.Ingeneral,theherbicideisfoundtobemoretoxicforalgae,whereasinsecticidesposemoreriskstozooplankton,insectandfish.Foreachpesticideinthewetland,theecologicalriskitposesisacceptable.Butthecombinedecologicalriskposedbymixturecanharmmorethan10%ofspeciesofthewetlandecosystem,mainlydominatedbydichlorvos,dimethoateandmalathioncontributions.TheseresultsimplythatpesticideresidueshavebeenposingpressuresontheecosystemoftheTaihuLakewetland.Itisrecommendedthatpropercountermeasuresshouldbeimplementedtoreducetherisks.©2010ElsevierB.V.Allrightsreserved.1.IntroductionWetlandisoneofthethreemajorecosystemtypesontheearth,andprovidesirreplaceableecologicalservicesfortheecosys-temandhumansociety.Butovertime,morethanhalfofthewetlandsdisappearafteryearsofbeingdrained,dredged,filled,leveled,andflooded(ZedlerandKercher,2005).Withrapidurban-izationandindustrialization,wetlanddegradationandlosshavebeenidentifiedinmanycountries,bothdevelopedanddevelop-ing(Tiner,1984;Hollandetal.,1995;Dahl,2000;Ralph,2003;ZedlerandKercher,2005).However,sincethelasthalfofthe20thcentury,thepreservationofwetlandsattractsmoreandmoreattentionastheirvaluetosocietyhasbecomemorefullyunder-stood(Stevensetal.,1995;DahlandAllord,1999;WoodwardandWui,2001).Studiesofwetlandprotectionareemerging.Yettheliteraturefocusesmainlyonthefunctioningofconstructedwetlands,ecologicalwaterdemandsandvegetationdevelopment(Spieles,2005;Chenetal.,2009;Cuietal.,2009).Infact,withrapidsocialandeconomicdevelopment,contaminationofwetlandsfromchemicalshasbecomeanurgentproblemworldwide.Duetoagriculturaluseandindustrialproduction,pesticideresiduesinwetlandshavecausedpotentialrisktotheecosystem.Organ-ismscaneasilybioaccumulate,biomagnifyorbiotransfercertain∗Correspondingauthor.Tel.:[phone];fax:[phone].E-mailaddress:[e-mail](J.Bi).pesticidestoconcentrationshighenoughtoinjuretheecosystempotentially,especiallythroughthetransmissionprocessinthefoodchain.Buttheattentionthatispaidtoenvironmentpollutionandthesubsequentecologicalriskinwetlandsisnotenough.Itiscriticalimportantforenvironmentalmanagersanddecision-makerstounderstandtheecologicalriskposedbypes-ticidecontaminationtothewetlandecosystem.Informationonsite-specificecologicalriskassessmentofpesticidecontaminationisofgreatimportanceforresourceagenciesandenvironmentalmanagerstoidentifyandprioritizekeystonesforwetlandprotec-tion.Accordingtothisneed,inthispaper,weintendtobuildaprocedureforecologicalriskassessmentofpesticidecontamina-tion,andapplyittoawetlandinTaihuLakeareainChinaforriskanalysisandmanagement.2.Materialsandmethods2.1.StudyareaandenvironmentalsamplesTaihuLake,thethirdlargestfreshwaterlakeinChina,islocatedinthesouthernendofYangtzeRiverDelta,andcoversapprox-imately2425km2.Withanaveragewaterdepthof1.89m,amaximumdepthof3.34mandavolumeof51.5×108m3,TaihuLakeisanimportantwetlandservingasawatersupplyforindustry,agriculturalirrigation,recreation,transportationandbiodiversitypreservation.However,withtherapideconomicgrowthsincethelate1970s,waterandsoilpollutionfromindustry,agriculture,and0304-3800/$–seefrontmatter©2010ElsevierB.V.Allrightsreserved.doi:10.1016/j.ecolmodel.2010.07.014288C.S.Quetal./EcologicalModelling222(2011)287–292Fig.1.TaihuLakeandthelocationofsamplingsites.urbanwastehasbeenincreasingsignificantlyinthearea.InMay,2007,anestimated4millionpeopleinWuxi,anindustrialcitylocatedalongthelake,weredeprivedofdrinkingwaterfornearlyaweek,asacarpetofalgaescumoragglomerateofbiologicaloriginmadelocallakewaterunusable(Guo,2007;Yangetal.,2008).Chinaisalargeproducerandconsumerofpesticides.PesticideslikeHCHandDDTwerewidelyusedfromthe1950suntiltheiruseswerebannedin1983(Lietal.,1999,2001;Qiuetal.,2004;Wangetal.,2005).TheagricultureintheTaihuLakewetlandareaishighlyproductive.Largeamountsofpesticideswereusedinthisareainthepast(Lietal.,1999).StudiesalsoshowedthatconcentrationsofpesticidesinTaihuLakeareawerestillmeasurableorevenhighinmostwater,soilandorganismsamples(Wan