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Abstract
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?Writeafterfinishingmostofmanuscript
?<200wordsor<18lines
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ABSTRACT
Halogenatedfumigantsaresomeofthemostheavilyusedpesticides
worldwide.Anumberofstudieshaveshownthatfumiganttransformationin
soiliscorrelatedwithsoilorganicmattercontent.However,relativelylittleis
knownaboutthemechanismsoffumigantinteractionwithsoilorganicmatter.
Inthisstudy,weused
14
C-labelled1,3-dichloropropene(1,3-D)andmethyl
bromide(MeBr)tocharacterizetheirincorporationintosoilorganicmatterand
theassociationofboundradioactivitywiththedifferentorganicmatter
components.The
14
Cactivityofboundresiduesincreasedwithtime,and
reached38-49%for1,3-Dand37-42%forMeBrafter72dofincubationat
25oC.Moreboundresidueswereproducedfor1,3-DthanforMeBrinthesame
soils.Thedistributionof
14
Cactivityinsoilhumicsubstancesfollowedthe
orderoffulvicacids>>humin>humicacids.Theseobservationssuggestthat
incorporationintosoilorganicmatteristhepredominantpathwayfor
transformationofhalogenatedfumigantsinsoil,andfulvicacidsarelikelythe
mostsignificantsinkofallsoilorganicmatterfractions.Itisfurtherspeculated
thatboundresiduesformedasaresultofalkylationoforganicmatterbythe
fumigantsthroughnucleophilicreplacement.
ABSTRACT
Chiralpesticidescurrentlyconstituteabout25%ofallpesticidesused,andthis
ratioisincreasingasmorecomplexstructuresareintroduced.Chiralityoccurs
widelyinsyntheticpyrethroidsandorganophosphatesthatarethemainstayof
moderninsecticides.Despitethegreatpublicconcernsassociatedwiththeuse
ofinsecticides,theenvironmentalsignificanceofchiralityincurrentlyused
insecticidesispoorlyunderstood.Inthisstudy,weresolvedenantiomersofa
numberofsyntheticpyrethroidandorganophosphateinsecticidesonchiral
selectivecolumns,andevaluatedoccurrenceofenantioselectivityinaquatic
toxicityandbiodegradation.Dramaticdifferenceswereobservedbetween
enantiomersintheiracutetoxicitytofreshwaterinvertebratesCeriodaphnia
dubiaandDaphniamagna,suggestingthattheaquatictoxicityismostly
attributabletoonlyaspecificenantiomerintheracemate.Infieldsediments,the
(–)enantiomerofcis-bifenthrinorcis-permethrinwaspreferentiallydegraded,
resultinginrelativeenrichmentofthe(+)enantiomer.Enantioselective
degradationwasalsoobservedduringincubationofsedimentsunderlaboratory
conditions.Enantioselectivityintheseprocessesisexpectedtoresultin
ecotoxicologicaleffectsthatcannotbepredictedfromourexistingknowledge,
andmustbeconsideredinfutureriskassessmentandregulatorydecisions.
Introduction
?Mostdifficulttowrite
?WriteafterM&M
?Keypoint:justify“why”
?Aimlow,aimsmall,aimspecific
?Thoroughunderstandingofpublishedstudies
?Fairevaluationofexistinginformation
?Startwithproblems,sources,bigpictureissues,…(1
st
paragraph)
?Followedbyspecificreview
?Donotundermineotherresearchers!
?Onlyincludeuseful/relevantstudies
?Always“praise”previousfindings
?Followedbyagaporanuncleartopic
?Followedby“Inthisstudy,we…”,or“Themainobjectiveofthisstudy
was…”
?Endbythepotentialusefulnessoftheexpectedinformation:“The
resultsfromthisstudymaybeused…”
?About4paragraphs;<2pages!
INTRODUCTION
Halogenatedhydrocarbonsformthemajorityofsoilfumigants.Inparticular,methyl
bromide(bromomethane,MeBr)hasbeenheavilyusedforseveraldecadesduetoitsbroad
spectrumofactivityagainstnematodes,arthropods,weeds,fungi,andbacteria.However,the
potentialcontributionofMeBrtostratosphericozonedepletionwillresultinacompleteMeBr
phase-outin2005intheU.S.andotherindustrializedcountries(1).Mostoftheprobable
chemicalalternativesarealsohalogenatedfumigants.Theseinclude1,3-dichloropropene(1,3-
D)andchloropicrin,whicharealreadyinwidespreaduse,andmethyliodide(iodomethane,
MeI)andpropargylbromide(bromopropyne,PBr),whicharebeingconsideredaspotential
alternatives(2-4).Allofthesecompoundshaveveryhighvaporpressures,andhavebeen
showntoquicklyvolatilizeaftersoilincorporation(5-8).Atmosphericemissionoffumigantsis
anenvironmentalorhealthhazard,becausemanyfumigantsareacutelytoxicandpotentially
carcinogenic(7).Evaluationoffumigantemissionsandmechanismshasattractedgreat
researchinterestoverthelastdecade.Transformationinsoilhasbeenidentifiedasthemost
importantprocessinreducingfumigantemissions(9).
Fumiganttransformationcanbemediatedbybothchemicalandmicrobialprocesses(10-
12).Forhalogenatedfumigants,therateoffumiganttransformationhasbeenshowntodepend
closelyonsoilorganicmattercontent(10,13-16).Forinstance,transformationofMeBr,1,3-
D,andMeIwasmorerapidinsoilswithhigherorganicmattercontentorafteramendmentof
organicmaterialssuchascompost,andtheenhancedtransformationoccurredalsoinsterilized
soils(13-14,17).Alltheseobservationssuggestthatsoilorganicmatterisinvolvedinthe
abiotictransformationoffumigantsinsoil.Inseparatestudies,Papierniketal.(15-16)showed
thattransformationofPBrorMeBrproceededatsimilarratesinsterileandnon-sterilesoils,
andlittlepropargylalcoholormethanolwasproducedfromthetransformation.This
impliesthatabioticprocessespredominatedfumiganttransformation,andhydrolysis
wasnotthemaintransformationpathway.Inarecentstudy,usingsolid-state13C
NMR,TaoandMaciel(18)observedbondinteractionsbetweenMeBrandwholesoil
samplesorsoilorganicmattercomponents.Whilethestudyoffereddirectevidenceto
thehypothesisthatMeBralkylatedorganicmatterinsoil,theactualcontributionbythis
pathwaytotheoverallabiotictransformationwasnotknown.
Themainobjectiveofthisstudywastoevaluatetheroleoforganicmatterin
fumiganttransformationinsoilbyfollowingtheformationanddistributionofnon-
extractableorboundresidues.Boundresiduesaredefinedasthefractionofpesticides
thatisnon-extractableafterexhaustiveextraction(19).Boundresiduescommonly
occurasaresultofirreversibleinteractionsbetweenpesticidesandsoilorganicmatter.
Thefumigants1,3-DandMeBrwereusedasthetestcompoundsinthisstudy.The
samemechanismsshouldapplyalsototheotherhalogenatedfumigantsofsimilar
structures,includingMeI,PBr,andchloropicrin.
Introduction
Thesignificanceofmolecularchiralityiswidelyrecognizedinlifesciences(1,2).A
lesserknownfactisthatmanymodernpesticidesalsocontainchiralstructuresandthusconsist
ofenantiomers(3,4).About25%ofcurrentlyusedpesticidesarechiral,andthisratiois
increasingascompoundswithmorecomplexstructuresareintroducedintouse(3).
Enantiomersofthesamecompoundhaveidenticalphysical-chemicalproperties,thusappearing
asasinglecompoundinstandardanalysis.Foreconomicreasons,chiralpesticidesaremostly
usedasmixturesofenantiomers,orracemates.However,enantiomersareknowntoselectively
interactwithbiologicalsystemsthatareusuallyenantioselective,andmaybehaveasdrastically
differentcompounds.Theroleofenantioselectivityinenvironmentalsafetyispoorly
understoodforpesticides,andtheknowledgegapisreflectedinthatthegreatmajorityofchiral
pesticidesareusedandregulatedasiftheywereachiral,thatis,assinglecompounds.
Studiesonchiralpesticidesstartedtoappearintheearly1990s(4,5-12).Studiessofar
showthatmicrobialdegradationofchiralpesticidesiscommonlyenantioselective.Asone
enantiomerispreferentiallydegraded,theenantiomerratio(ER),definedastheratioof(+)-
enantiomerover(–)-enantiomer,increasinglydeviatesfromtheoriginalvalue(typically1.0)
(8,9).EnantioselectivitywasfoundtoresultinchangesofERofα-HCHalongthepolarbear
foodchain,causingERtoincreasefromabout1.0incodto2.3inliversamplesofpolarbear
(10).InthebraintissueofsealsaroundIceland,oftenonly(+)-α-HCHwasfound,while(–)-α-
HCHwasabsent,givingindefinitelylargeERvalues(5,13).Enantioselectivityhasalsobeen
observedunderlaboratoryconditionsforthesoildegradationofsomechiralherbicidesand
fungicides,includingmetolachlor,metalaxyl,anddichlorprop(4,8,14).
Mostenvironmentalresearchonchiralpesticideshasthusfarbeenlimitedtoa
fewlegacychlorinatedinsecticideswhoseusewasdiscontinueddecadesago,andsome
herbicidesorfungicides.Littleisknownaboutcurrentlyusedchiralinsecticides.Many
currentinsecticideshavehighactivityagainstnon-targetorganismsandarealsochiral.
Inparticular,twoclassesofinsecticides,syntheticpyrethroids(SPs)and
organophosphates(OPs),areacutelytoxictoawiderangeofaquaticorganismsattrace
levels(15,16).Contaminationofsurfaceaquaticecosystemsbythesecompoundsisa
greatenvironmentalconcern(17,18).AllknownSPshavechiralstructuresandcontain
4or8enantiomers(19),whilemanyOPsarealsochiral,consistingtypicallyof2
enantiomers(20).However,althoughthesecompoundsareinwideuse,
enantioselectivityintheirenvironmentalbehaviorisalmostunknown(21).
Inthisstudy,wedevelopedchiral-selectivechromatographicmethodstoseparate
andisolateenantiomersfromanumberofSPsandOPs.Individualenantiomerswere
usedforcharacterizingtheirdifferencesinacutetoxicitytotwoindicatoraquatic
invertebrates,CeriodaphniadubiaandDaphniamagna.Enantioselectivitywasfurther
evaluatedforSPsduringtheirbiodegradationinsedimentsunderfieldandlaboratory
conditions.
Materials&Methods
?Easiesttowrite
?Writefirst
?Structure/arrangement
?Sub-headings:
?Add“experiments”…
?Chemicals(1paragraph;nostructures;noproperties)
?Soils(source,properties,briefdescriptionofhandling
andanalysis)
?GrouptreatmentssotheycorrespondtoResultsand
Discussion
?Infoonexactsteps,wordbyworddescription
?Avoidgeneralstatements
?Details,details,details!
?Writesothatotherpeoplecanrepeat!
M&M
?Flowchart:
?Chemicals:names,fullchemicalnames,purity,sources
?companynamewithout“Inc.”or“Co”,city,state
abbreviation
?Soils/sediments:source,handling(size,airdrying),
properties(OM,pH,texture),analysis
?Scientificnamesforsoils
?Specifictreatments/experiments
?Chemicalanalysis
?Maybecombinedintoexperiments
?Spelloutterms(HPLC,GC,…)whenfirstused;abbreviate
thereafter
?Exactconditions:temperatures,flowrate(doublecheck)
?Retentiontimes
?Calibrationmethods
?Recoveries,detectionlimits
MATERIALSANDMETHODS
Soils.Twodifferenttypesofsoilwereusedinthisstudy,aChualarloam(fine-
loamy,mixed,thermicArgixerol)fromSalinas,California,andaWaukegansiltloam(finesilty,
oversandyorsandy-skeletal,mixed,mesicTypicHapludoll)fromRosemont,Minnesota.The
basicsoilpropertieswereanalyzedbeforethestudy(Table1).Thesoilorganiccarboncontent
wasdeterminedusingtheWalkley-Blackmethod(20),andparticlesizesweredeterminedusing
thehydrometermethod(21).Thesesoilswerepassedthrougha2-mmsievewithoutair-drying
andstoredat4oCbeforeuse.
Chemicals.Methylbromide(>99%purity)wasobtainedfromtheGreatLakes
ChemicalCompany(WestLafayette,IN).Carbon-14labelledMeBrwithaspecificactivityof
3.1mCimmole-1andradiochemicalpurityof>97%wassynthesizedbytheNewEngland
NuclearCo.(Boston,MA).Thestandardof1,3-D(48%cisisomerand49%transisomer)was
purchasedfromChemService(WestChester,PA).Carbon-14labelled1,3-Dwithspecific
activityof1.11mCimmole-1andradiochemicalpurity98.6%wasprovidedbyDow
AgroSciences,LLC(Indianapolis,IN).
IncubationExperiments.Themoistsoilsampleswerepre-incubatedfora
weekatroomtemperaturetorevivesoilmicrobialactivity.Topreparethespikingsolutions,both
14
C-labelledandunlabelledMeBror1,3-Dweredissolvedinethyl…
Preparationof
14
C-boundResidueSamples.Thesoilsampleswerethawed
atroomtemperatureandtransferredto50-mlcentrifugetubes,followedbyaerationinafume
hoodovernighttoremoveanyuntransformedparentcompoundorvolatile…
Fractionationof
14
C-boundResidues.Boundresiduesderivedfromtheprevious
incubationexperimentswerefractionatedintofulvicacids(FA),humicacids…
RadioactivityMeasurement.TheradioactivityinHAandFAfractionswas
measureddirectlyonaPackardTri-Carb1600TRLiquidScintillationAnalyzer(Packard
InstrumentCompany,IL)aftermixingwith5mlUltimaGoldCocktail(Packard,CT).
CombustionofsolidsampleswascarriedoutonanOX-500biologicaloxidizer(R.J.Harvey
InstrumentCorp.,Hillsdale,NJ).Thetotaltimeofoxidationwas4min,andthetemperaturewas
900oC.The
14
CO2evolvedfromcombustionwastrappedin15mlCarbon-14Cocktail(Harvey,
Hillsdale,NJ),andtheradioactivitywasdeterminedbyLSC.Theefficiencyof14CO2recovery,
asdeterminedbycombusting
14
Cstandards,wasdeterminedtobe>97%.A5-minuteintervalwas
usedforallsamplesforradioactivitycountingbyLSC.
MaterialsandMethods
Chemicals.Analyticalstandardsofracemic(Z)-cis-bifenthrin[>96%,2-methylbiphenyl-3-
ylmethyl(Z)-(1RS)-cis-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-
dimethylcyclopropanecarboxylate)],fonofos[99.4%,O-ethylS-phenyl(RS)-
ethylphosphonodithioate],andprofenofos[>93.7%,O-4-bromo-2-chlorophenyl…
ChromatographicSeparationandAnalysis.Enantiomerswereresolvedandisolated
onanAgilent1100Serieshighpressureliquidchromatography(HPLC)(Wilmington,DE)with
chiralcolumns.Aftertestingwithasuiteofcommerciallyavailablecolumns,resolutionofSP
enantiomerswasachievedonaSumichiralOA-2500Icolumn(SumikaChemicalAnalysis
Service,Osaka,Japan),using99.5%hexaneand0.5%1,2-dichloroethaneasthemobilephase.
ResolutionofOPenantiomerswasachievedonaChiralcelOJcolumn(DaicelChemical
Industries,Tokyo,Japan)using98%hexaneand2%ethanol(containing5%methanoland5%
isopropanol)asthemobilephase.Theinjectionvolumewas20μlandtheUVwavelengthfor
detectionwas230±15nm.Thepolarity(i.e.,rotationsign)oftheresolvedenantiomerswas
determinedbyanin-linelaserpolarimeterdetector(PDR-Chiral,LakePark,FL).Thelight
sourceforthechiraldetectorwasalaser(675nm)andthecellpathwas50mm.Theresolved
enantiomerswereindividuallycollectedattheHPLCoutlet,evaporatedtodryness,andusedin
aquatictoxicitybioassays.Concentrationsweredeterminedusingpeakarea,byassumingthe
sameresponsefactorforenantiomersoriginatingfromthesamecompound.…
AquaticToxicityAssays.Enantioselectivityinaquatictoxicitywasevaluatedthrough96-
hacutetoxicityassaysusingCeriodaphniadubiaandDaphniamagna.Theoverallprocedurefor
thetestwassimilartotheEPAguidelines(22).TestanimalsweresuppliedbyAquatic
Biosystems(FortCollins,CO).Briefly,testsolutions(15mL)containingagiven…
AnalysisofFieldSediments.Sedimentscontainingresiduesofcis-bifenthrinand
cis-permethrinwerecollectedatasitenexttoanurseryinsouthernCalifornia,andwereusedfor
evaluationofchangesinERasaresultofnaturalattenuation.Thedriedsedimentwas
accumulatedfromsurfacerunoffoverafouryearperiod.Samplesweretakenusing…
IncubationExperiments.EnantioselectivityinSPdegradationwasfurtherevaluated
throughincubationexperiments.Sedimentsampleswerecollectedfromasedimentationpondand
arunoffchannelatanurserysiteinsouthernCalifornia.Thepondsedimentcontained0.65%
organiccarbonand5%clay,whilethechannelsedimentcontained6.4%organiccarbonand19%
clay.Comparedtosedimentsusedintheaboveexperiment,sedimentsfromthesedimentation
pondandchannelwerenewlydeposited.Thesedimentsweresampledfromthesurfacelayer(0-5
cm)andusedwithoutair-dryingtopreservetheoriginalmicrobialactivity.Fivegrams(dry…
ResultsandDiscussion
?Relativelydifficulttowrite
?Thinkthroughwhat’simportant
?CombineResultsandDiscussion
?Breakinto2-3sectionswithheadings
?Someresultsfollowedbysomediscussion
?Followedbyextrapolation
?Avoidpurespeculation!
?Leavemajorconclusionstotheend
?Usereferencesforargument(2-4references)
?Usetopicsentences
RESULTSANDDISCUSSION
Massbalance.Inthisstudy,therecoveryof
14
Cactivityafterorganicmatterfractionation
rangedfrom86±4.0%to112.7±7.9%for1,3-D-derivedboundresidues,andfrom82.5±2.8%to
109.9±7.2%forMeBr-derivedboundresidues.…
Totalboundresiduesinsoil.Figure1showsaccumulationofboundresiduesinthe
WaukegansiltloamandtheChualarloamaftertreatmentof
14
C-labelled1,3-DorMeBr.…
Betweenthetwofumigants,thefractionofboundresidueswasslightlygreaterfor1,3-
DthanforMeBrinthesamesoilsateachincubationtime.Thiswasconsistentwiththe
observationthatMeBr…
Compositionofboundresidues.Boundresiduesof
14
C-labelled1,3-DandMeBrwere
fractionatedintoFA,HA,andhuminusingthestandardproceduresfororganicmatterfractionation
(Figures2-4).…
The
14
CboundresiduesinhuminfractionwasapparentlyhigherintheChualarsoilthan
intheWaukegansoilthroughouttheincubationperiod.Theactivitywithhuminappearedto…
ThemoredominantdistributionofboundresiduesintheFAfractionovertheHAor
huminfractionwasinconsistentwiththeobservationbyTaoandMacielfor(18).Usingsoil
componentsisolatedpriortoMeBrexposure,TaoandMaciel(18)showedthattherewasformation
of
13
CH3O-moietiesbetweenMeBrandHAorhumin,butnotbetweenMeBrandFA.…
Therapidincorporationoffumigantsintosoilorganicmattersuggeststhatfumigants
maybeinactivatedthroughthisprocess.Previousstudieshaveshownthatthebiologicalactivityof
mosthalogenatedfumigantsiscausedbytheirabilitytoalkylateessentialbiological
macromoleculessuchasproteinsandDNA(28).Therefore,interactionoffumigantswithsoil
organicmatter,e.g.,alkylationofFAandotherorganicmattercomponents,shouldrenderthe
fumigantfragmentinactiveduetothelossofthenucleophile(i.e.,BrinMeBrandClatthe
saturatedcarbonin1,3-D).Theincreaseinradioactivitywiththehuminfractionovertimefurther
suggeststhatthe
14
Cwasnolongerassociatedwiththeoriginalcompound,butbecameanintegral
partofthesoilorganicmatter.Therefore,incorporationintosoilorganicmattermaybeconsidereda
detoxificationprocessforsoilfumigantssuchasMeBrand1,3-D.
(significance,application,neededresearch…)
RESULTSANDDISCUSSION
EnantiomerSeparationandAnalysis.Resolutionofenantiomerswashighly
column-specificinbothHPLCandGCanalyses.InHPLCanalysis,completeseparationwas
achievedonlyonSumichiralOA-2500IforSPenantiomersandonChiralcelOJforOP
enantiomers(Table1).InGCanalysis,separationwasachievedonlyonaBGB-172columnfor
cis-bifenthrinandcis-permethrin.Utilizingthecurrentconditions,the(+)enantiomerofSPs
consistentlyelutedpriortothe(–)enantiomeron…
EnantioselectivityinAquaticToxicity.Theacuteaquatictoxicitywasmeasured
forindividualenantiomersandracematesusingC.dubiaandD.magnaasthetestanimals(Table
2).FromtheLC50valuesfortheracemate,allinsecticidespossessoutstandingtoxicityagainstC.
dubiaorD.magna,withLC50<1μgL-1.However,thereconsistentlywasasignificant
differenceinLC50betweenthetwoenantiomersofthesamecompound.Invariably,whenone
enantiomershowedhighactivity,theotherenantiomerexhibitedactivitythatwasdrasticallylower.
FortheselectedSPs,the(+)enantiomerwasmoreactivethanthe(–)enantiomerby17-38times
(Table2).The(–)enantiomerincis-permethrinandtrans-permethrinwassoinactivethatonlya
thresholdof6μgL-1wasobtainedfortheLC50againsteitherC.dubiaorD.magna.Fromthe
LC50valuesmeasuredforindividualenantiomers,itwasestimatedthatthe…
EnantioselectivityinDegradation.Enantioselectivityindegradationwasevaluatedforthe
selectedSPsbystudyingchangesinERduringdegradationunderfieldandlaboratoryconditions.
Analysisofagedfieldsedimentsamplesshowedthatallsamplescontainedrelativelyhighlevelsof
bifenthrinandpermethrin.TheERincommercialformulationswascloseto1.0forcis-bifenthrin
(1.02)andcis-permethrin(0.99).TheaveragedERvalueforcis-bifenthrin(1.02)remainedcloseto
1.0inthesurfacesediment(0-15cm),butincreasedto1.11inthe15-30cmlayer,andfurtherto…
EcotoxicologicalImplications.Occurrenceofenantioselectivityineitherdegradation
ortoxicityalonewouldhavelimitedenvironmentalsignificance.Forinstance,iftwoenantiomersof
achiralcompoundhavethesameaquatictoxicity(i.e.,non-enantioselective),changesinERalone
willnotresultindifferenteffectsontheorganism,asthecombinedtoxicitywouldremain
unchangedinrelationtotime.Conversely,ifenantioselectivityoccursonlyintoxicitybutnotin
degradation,ERwillremainunchangedovertimeandtheecotoxicologicaleffectsarepredictable
fromtheracemate.Althoughpreviousstudiesshowedthatlegacychiralinsecticidesandsomechiral
herbicidesorfungicidescouldundergoenantioselectivedegradationintheenvironment,the
ecotoxicologicalsignificancewasnotrevealed,becauseenantioselectivityinecotoxicitywasnot
simultaneously…Furtherstudiesareneededtocharacterizeinteractionsofenvironmentalfactors,
suchassoil/sedimentproperties,vegetationtypes,Redoxconditions,andmicrobialstructureswith
enantioselectivityinthebehaviorofchiralpesticides.BothSPsandOPshaveothermodesof
toxicologicaleffects,butitisunknownifenantioselectivityalsooccursinthoseprocesses.…Given
thewidespreaduseoftheseinsecticides,amorecomprehensiveunderstandingofthesignificanceof
enantioselectivityisimperativeforimprovingriskassessmentandregulationofthesepesticides.
Conclusions
?Omitofpossible
?IncorporateintolastparagraphofResults&
Discussion
?Offersa“closure”
?Startwithmostsignificantfindings,notwhat
wasdone;
?Followedby“significance”
?Endbymentioningfutureneededresearch
?Alwaysoneparagraph;about?page.
Asdemonstratedinthisstudy,ahighlyvaluableapplicationofSPMEmaybe
itsuseforimprovingKdmeasurementforstronglyadsorbingcompounds.Many
importantenvironmentalpollutantsdisplaystrongadsorptionpotentialsonsedimentsand
soils.TheseincludePCBs,PAHs,DDTandotherchlorinatedinsecticides,synthetic
pyrethroidinsecticides,amongothers.AccuratemeasurementofKdforthese
compoundsmayimprovethepredictionoftheirreleasefromacontaminatedsediment
bedintotheoverlayingwater,oroftheireliminationfromawatercolumnbyadsorption
tothesuspendedsolidsandthebulksediment.However,themajorityoftheKdvalues
forthesecompoundspublishedinthescientificliteraturewereobtainedusingmethods
thatdonotproperlydistinguishthedissolvedandDOM-adsorbedforms.Itwillbeof
greatpracticalimportancetorevisitthesecompounds,andevaluatethepotential
underestimationintheirKdvaluesusingsuchmethodsasSPME.
References
?15-25references
?AvoidInternetcitations!
?Avoidtextbooks
?Representativepublications
?Relevantpublications
?Consistentformat
?Crosscheck!
?Toarrange/formatattheveryend
Tables&Figures
?Tablesarepreferred
?1-4tables,5-2figures
?Avoidlargetables,butmaystackfigures
?Usecorrectformat
?Includer
2
,SD,S.E.valuesintables
?Useerrorbarsinfigures
?Maketableandfigurecaptionsstand-alone(selfexplaining)
?Tables,followedbyfigurecaptions
?Nocaptionsonfigurepages
?“printable”quality(fontsize,symbolsize,linethickness,height-
widthratio4:5)
?UseSigmaPlotorothergraphicsoftwareforfigures
?AvoidusingExcel
FinalTouches
?Correctalltypos!
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?Startlong,andthengraduallycondense
?Convertcopiedsentencesintoyourownwords!
?Trimextra,non-essentialwords
?Payattentiontoformatdetails(useofbold,italics,table
andfigurecaptionformat,keywords?...)
?Usearecentarticlefromthesamejournalasexample
?Readacoupleoftimesadayfor3-4daysoruntilyouare
happywithityourself
?Practicemakesamaster!
ResponsetoReview
Comments
?Sitonthemforafewdays
?Sincereattitude
?Compromise
?Beprofessional
?Considereverycomment
?Pointtopoint
?ListresponsesinReviewer#1,Q1,Q2,…;Reviewer#2,
Q1,Q2,…
?Showtrueeffort
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