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VolcanogenicoriginofcenotesnearMtGambier,southeasternAustralia
Geomorphology,Volume119,Issues1-2,15June2010,Pages23-35
JohnA.Webb,KenG.Grimes,IanD.Lewis
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AbstractAbstract|Figures/TablesFigures/Tables|ReferencesReferences
Abstract
ThecenotesnearMtGambierarecircular,cliffed,collapsedolinescontainingwater-tablelakesupto125
mdeep,flooredbylargerubblecones.Theylieinaflat,coastalplaincomposedofmid-Tertiarylimestone.Mostofthedeepestcenotesareconcentratedintwosmallareaslocatedalongtrendssub-paralleltothemainjointdirectioninthelimestone.Thecenotesdonotconnecttounderwaterphreaticpassages,andwaterchemistrydataconfirmthattheyarenotpartofaninterconnectedkarstnetwork.Theyformedbycollapseintolargechambers(upto>
1millionm3)thatextended125
mormorebelowthelandsurface.Severalcenoteshaveactivelygrowingstromatolitesonthesub-verticalwallsthatstartedgrowingat
8000
yearsBP.
ThecavesthatcollapsedtoformthedeepMtGambiercenotesaremuchlargerthanshallowanddeepphreaticcavesinthearea,anddonotconnectintodeepphreaticsystems.Theywerenotformedbyfreshwater/seawatermixing,responsibleformanyofthewell-knownYucatancenotes,becausetheyarenotassociatedwithlocationsofthemixingzoneduringprevioushighsealevels,andaremuchlargerthancavespresentlyformingalongthemixingzonenearMtGambier.InsteaddissolutionwasmostlikelyduetoaprocesswherebyacidifiedgroundwatercontaininglargeamountsofvolcanogenicCO2ascendedupfracturesfromthemagmachambersthatfedthePleistocene–Holocenevolcaniceruptionsinthearea;
deepreservoirsofvolcanogenicCO2occurnearby.
CavedissolutioncouldhavebeenduetoreleaseofCO2duringtheMtGambiereruption
28,000
yearsago,followedbycollapsetoformcenotesduringthelowsealevelsoftheLastGlacialMaximum
20,000
yearsago.Thecenotesthenflooded
yearsagoassealevelrose,andstromatolitesbegantogrowonthewalls.
ArticleOutline
1.Introduction
2.Geomorphologicalsetting
3.Geologicalsetting
4.Climate
5.Hydrogeology
6.Karstfeatures
6.1.Cenotes
6.2.Phreaticcaves
6.3.Springs
7.Cenoteorigin
7.1.Collapseintocavitiesdissolvedinevaporitebeds
7.2.Progressivecollapseduetodissolutionbyunder-saturatedbasalwaters
7.3.Collapseintocavitiesformedbyphreaticprocesses
7.4.Collapseintocavitiesformedbyfreshwater/seawatermixing
7.5.CollapseintocavitiesdissolvedbyvolcanogenicCO2
8.Timingofdeep,volcanogeniccenoteformation
9.Conclusions
Acknowledgements
References
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270
Soilmanagementinrelationtosustainableagricultureandecosystemservices
FoodPolicy,Volume36,Supplement1,January2011,PagesS72-S87
D.S.Powlson,P.J.Gregory,W.R.Whalley,J.N.Quinton,D.W.Hopkins,A.P.Whitmore,P.R.Hirsch,K.W.T.Goulding
Requirementsforresearch,practicesandpoliciesaffectingsoilmanagementinrelationtoglobalfoodsecurityarereviewed.Managingsoilorganiccarbon(C)iscentralbecausesoilorganicmatterinfluencesnumeroussoilpropertiesrelevanttoecosystemfunctioningandcropgrowth.EvensmallchangesintotalCcontentcanhavedisproportionatelylargeimpactsonkeysoilphysicalproperties.PracticestoencouragemaintenanceofsoilCareimportantforensuringsustainabilityofallsoilfunctions.SoilisamajorstoreofCwithinthebiosphere–increasesordecreasesinthislargestockcaneithermitigateorworsenclimatechange.Deforestation,conversionofgrasslandstoarablecroppinganddrainageofwetlandsallcauseemissionofC;
policiesandinternationalactiontominimisethesechangesareurgentlyrequired.SequestrationofCinsoilcancontributetoclimatechangemitigationbuttherealimpactofdifferentoptionsisoftenmisunderstood.SomechangesinmanagementthatarebeneficialforsoilC,increaseemissionsofnitrousoxide(apowerfulgreenhousegas)thuscancellingthebenefit.Researchonsoilphysicalprocessesandtheirinteractionswithrootscanleadtoimprovedandnovelpracticestoimprovecropaccesstowaterandnutrients.Increasedunderstandingofrootfunctionhasimplicationsforselectionandbreedingofcropstomaximisecaptureofwaterandnutrients.Rootsarealsoameansofdeliveringnaturalplant-producedchemicalsintosoilwithpotentiallybeneficialimpacts.Theseincludebiocontrolofsoil-bornepestsanddiseasesandinhibitionofthenitrificationprocessinsoil(conversionofammoniumtonitrate)withpossiblebenefitsforimprovednitrogenuseefficiencyanddecreasednitrousoxideemission.Theapplicationofmolecularmethodstostudiesofsoilorganisms,andtheirinteractionswithroots,isprovidingnewunderstandingofsoilecologyandthebasisfornovelpracticalapplications.Policymakersandthoseconcernedwithdevelopmentofmanagementapproachesneedtokeepawatchingbriefonemergingpossibilitiesfromthisfast-movingareaofscience.Nutrientmanagementisakeychallengeforglobalfoodproduction:
thereisanurgentneedtoincreasenutrientavailabilitytocropsgrownbysmallholderfarmersindevelopingcountries.Manychangesinpracticesincludinginter-cropping,inclusionofnitrogen-fixingcrops,agroforestryandimprovedrecyclinghavebeenclearlydemonstratedtobebeneficial:
facilitatingpoliciesandpracticalstrategiesareneededtomakethesewidelyavailable,takingaccountoflocaleconomicandsocialconditions.Inthelongertermfertilizerswillbeessentialforfoodsecurity:
policiesandactionsareneededtomaketheseavailableandaffordabletosmallfarmers.Indevelopedregions,andthosedevelopingrapidlysuchasChina,strategiesandpoliciestomanagemorepreciselythenecessarilylargeflowsofnutrientsinwaysthatminimiseenvironmentaldamageareessential.Aspecificissueistominimiseemissionsofnitrousoxidewhilstensuringsufficientnitrogenisavailableforadequatefoodproduction.Applicationofknownstrategies(througheitherregulationoreducation),technologicaldevelopments,andcontinuedresearchtoimproveunderstandingofbasicprocesseswillallplayapart.Decreasingsoilerosionisessential,bothtomaintainthesoilresourceandtominimisedownstreamdamagesuchassedimentationofriverswithadverseimpactsonfisheries.Practicalstrategiesarewellknownbutoftenhavefinancialimplicationsforfarmers.Examplesofsystemsforpayingonegroupoflandusersforecosystemservicesaffectingothersexistinseveralpartsoftheworldandserveasamodel.
Introduction
Managingorganiccarboninsoil
Soilcarbon–quantity,structureandsoilfunctions
Soilcarbonandtheglobalcarboncycle
Emergingtopicsforresearchoraction
Optimisingsoilphysicalconditionsforcropgrowthinarangeofenvironments
Wateravailabilitytocropsandthephenomenonof“strongsoils”
Organicmatterandsoilphysicalproperties
Managingnutrientsindiverseenvironmentsandcroppingsystems
Situationsofnutrientshortage
Situationswithadequateorexcessnutrients
Understandingandoptimisingsoilbiologicalprocesses
Soilbiologicalprocessesandpopulations
Diversity-functionrelationships
Opportunitiesfromnewmethodologies
Root–soilinteractions
Releaseofcarboncompounds
Structureformation
Nutrientsintherhizosphere
Managementoftherhizosphere
Minimisingsoilerosionfromagriculturalland
Possiblebeneficialimpactsofbiocharonsoilpropertiesandcropgrowth
Developingpracticesandpolicies
Researchhighlights
►Wereviewsoilissuesrelevanttoglobalfoodsecurityandecosystemfunctioning.►Wesuggestactionsforeachissueincludingpolicies,communicationorresearch.►Organicmattercontentisessentialforimprovingmanysoilphysicalproperties.►Policiestomakefertilizersaffordableindevelopingcountriesareessential.►Practicestocutgreenhousegasemissionsfromintensifiedagricultureareneeded.
271
Under-representationofwomenandethnicminoritiesinvascularsurgeryrandomizedcontrolledtrials
JournalofVascularSurgery,Volume50,Issue2,August2009,Pages349-354
AndrewW.Hoel,AhmedKayssi,SomaBrahmanandam,MichaelBelkin,MichaelS.Conte,LouisL.Nguyen
Supplementarycontent
Objectives
Genderandethnicityarefactorsaffectingtheincidenceandseverityofvasculardiseaseaswellassubsequenttreatmentoutcomes.Althoughwellstudiedinotherfields,balancedenrollmentofpatientswithrelevantdemographicchar