Theflowsofenergyarekeytohowthebiosphereworks,heraldingbacktothedaysofVernadsky.Thislecturewilldiscussenergyandtheroutesitflowsthroughthebiosphereasusedbyplants,microbesandhigherorganisms.Captureofsolarenergyiskey,butsomemicrobiallifeareabletoextractchemicalenergyfromtheirenvironmentbyredox.Energyfixedandstoredascarboncompoundsiseventuallycycledthroughfoodwebsfeedinglowerandlowertrophiclevels.

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Wonderfulbook.IfyouhaveEmetoreadforpleasureandcuriositysakeIrecommendthisbookforallbiospherians.

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ThesearesomeoftheoverarchingquesEonsassociatedwiththelinksbetweenEnergyandtheBiosphere.Canyouthinkofothersthatcomefromyourlifeexperiencesorinterests?

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hKp://www.phibetaiota.net/wp-content/uploads/2014/04/energy-six-forms.jpg

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Itisa‘tongueincheck’statementtogetyouraKenEon.Buttherearemanytruthstoit,especiallybylinkingPhysicsandBiology.Modernsciencecannotaffordtoworkinsilosofonlyphysicsoronlybiology.Thetwofieldsofbiologyandphysicsmustinteract,togetabeKerappreciaEonabouthowthebiosphereworks.Lifeissustainablebecauseitre-cyclesmaterialandisabletoextractasmuchenergyoutofthesystemaspossible,throughmulEpletrophiclevels.EvoluEonispowerfulasitenablesorganismstodevelopstructuresandfuncEonsthatareopEmizedfortheirenvironment.ThisisnottosaymulEplewaysareviable,justwalkthroughthedesert.ButitdoessaythatcertainformsandfuncEonsarenotviable.100mtallredwoodtreesdon’tgrowinthedesert,forexample.ThefirstpartofthisstatementcametomindwhenIwasinIndiaridingajitney.ObservingautomoEvechaoseverywhereIaskedthedriverwhereIcouldfindtheseatbelt.ThetaxidriverseemedinsultedandquesEonedmytrustinhisdrivingability.Iretorted‘Iwanttoberestrainedbecauseinthecaseofanaccident,because‘Physicswins’‘;Isurelydidnotwanttogetprojectedthroughthewindshieldifhecametoanabruptstop.Seriously,thebasisforthisstatementcomesfromobservaEon,researchand

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Theseexamplesclearlystatethehowphysicssetslimitsonmetabolism,formandfuncEon

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ExamplesonhowBiologydoesit…otherwiseallyouhaveisdeadrocksrollingdownhills.Thisisnotlife.

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ExamplesofthelinksbetweenEnergyandWorkandtheUnitsassociatedwiththeseterms.Ifyouforget,gobacktofirstprinciples.WorkisforceEmesdistance.WeknowfromdroppingarockthataforceismassEmesacceleraEon.AndweknowthatanacceleraEonisthechangeinvelocitywithEme(meterpersecondpersecond)

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EnergyFuelsMetabolism

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ParkNobel

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hKps://dr282zn36sxxg.cloudfront.net/datastreams/f-d%3A7c60c5dca8db65ef72d28224ee8a5f6de5be626ee1f049e9a2f67266%2BIMAGE_THUMB_POSTCARD%2BIMAGE_THUMB_POSTCARD.1d%3A7c60c5dca8db65ef72d28224ee8a5f6de5be626ee1f049e9a2f67266%2BIMAGE_THUMB_POSTCARD%2BIMAGE_THUMB_POSTCARD.1

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I’vecometoviewtheprocessoflife,likeabaKery.TheflowofelectronsfromchemicalenergydrivesthisbaKeryandtheflows,gainsandlossesofelectronsareassociatedwithREDOX.WhendeeismoreexpertonthistopicandwillcoveritmoreandbeKerwithdecomposiEon.

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QuesEoninclassaboutunits,permoleculeorpermole.WorkingthroughthecomputaEonswefindGibbsFreeenergyisJoulespermole

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HereitisenoughtoshowhowadeptlifeisatextracEngenergyfromitsenvironment.KnowingthesedifferentroutesandhowactswithineachboxisimportantOnefracEonofthebiosphereisdominatedbythephototrophs,thosewhoeatsunlight.TheotherfracEonisdominatedbyChemotrophs.TheyeitherderiveenergyfromorganicmaKerorareLithotrophsandableto‘eat’chemicalenergystoredinminerals.ItisimportanttoRecallandRemembertheChemicalEnergyusedbyOrganoTrophsUlEmatelycamefromPhotoTrophsandtheSun.Burginetal2011FronEersEcology

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ProfBanfieldwillcoverthistopicingreatdetailonherlectureonCarbonMetabolism.LightEnergysplitswaterandelectronsarereleased,andoxygenisformedGenerallessonsatthisstageare:lightenergyisusedtosplitwaterreleasing4electronsandproducingOxygen.Theseelectronsaretransportedandinter-convertedintobiochemicalenergycompounds,ATPandNADPH,thatulEmatelyleadtothefixaEonofCO2;energyisstoredinchemicalcompounds,sugars,andtherespiraEon(oxidaEon)ofthesesugarsprovideenergyformetabolismandthefoodchangesofprimary,secondaryandterEaryconsumers.

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AnexampleofthestoichiometryofthephotosyntheEccarbonreducEon(PCR)andthephotosyntheEccarbonoxidaEon(photorespiraEoncycles).Inthiscase,itisscaledwithinaninputof3CO2moleculesTheenzymeribulose-1,5-bisphosphatecarboxylase(Rubisco)catalyzesthereacEonbetweengaseouscarbondioxideandribulose-1,5-bisphosphate(RuBP).ProductofthereacEonaretwomoleculesof3-phosphoglycericacidforeachCO2moleculeC5O3H8(PO4

2-)2+CO2->2C3O3H4PO42-

RUBISCOhasanaffinityforbothCO2andO2,withthelaterleadingtophotorespiraEon,alossofCO2.TherateofcompeEEveoxygenfixaEonisaproporEonaltotheoxygenconcentraEonEmetheraEoofoxygenaEon(Vo)tocarboxylaEon(Vc).AtambientcondiEonsVo/Vcisabout0.27(2EmestheCO2compensaEonpointdividedbyCO2;~2x38/280).InpracEceforeachCO2consumedbycarboxylaEon0.5CO2EmesVo/VcarelostbyphotorespiraEon;

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WealwaysseetheNetreacEons,egCH2O+O2=CO2+H2O.ButitisimportanttoexploretheRedoxHalfreacEonsandseehowmanyelectronsarebeingshuKledbackandforth,asthesedrivetheulEmateenergeEcs.Weseewerelease500kJpercarbonhydrateand3000kJperglucosemolecule,thesugarfixedbyphotosynthesis.

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AdaptedfromBurgin.Withampleoxygen,OrganicCisconsumedandCO2andH2Oareproduced.IfO2isdepleted,NitratebecomestheelectronacceptorandN2gasandCO2isproduced.NextFe(III)gainsanelectron,formingFe(II)andCO2.LowestinEnergyyieldisSO4–asanelectronacceptor.H2SandCO2areformed

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MegonigalandHines

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Conceptual models of redox-associated mechanisms for generaEng self-potenEals:(a)classicalgeobaKerymodel [axerSatoandMooney,1960;Reviletal.,2010]and(b)biogeobaKerymodel[axerNaudetandRevil,2005;Reviletal.,2010].IFTHISIMAGEHASBEENPROVIDEDBYORISOWNEDBYATHIRDPARTY,ASINDICATEDINTHECAPTIONLINE,THENFURTHERPERMISSIONMAYBENEEDEDBEFOREANYFURTHERUSE.PLEASECONTACTWILEY'SPERMISSIONSDEPARTMENTONPERMISSIONS@WILEY.COMORUSETHERIGHTSLINKSERVICEBYCLICKINGONTHE'REQUESTPERMISSIONS'LINKACCOMPANYINGTHISARTICLE.WILEYORAUTHOROWNEDIMAGESMAYBEUSEDFORNON-COMMERCIALPURPOSES,SUBJECTTOPROPERCITATIONOFTHEARTICLE,AUTHOR,ANDPUBLISHER.

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InthislessonweconcentrateontheuElizaEonofsolarenergyatfieldandfarmscales.Inessence,howmaychemicalenergyisstoredthroughfieldphotosynthesisgiventheabundantamountsofenergydiscussedabove?And,howmuchcarboncanbeextractedfromtheatmospherebytheseprocesses?ThesecalculaEonsareforsolarradiaEonfluxdensityaveragedacrosstheEarth’ssurface,161Wm-2;simplisEcasitisrespecttothehemispherethatincludesoceans,anddoesnotconsiderthegeographicaldistribuEonofland,sunlightandplantsPSEfficiency,adaptedfromBoltonandHall1991

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OnlyasmallporEonofincidentsunlightisactuallycaptureandconvertedtobiomass.Hence,biofuelsmaybealessefficientalternaEvetocapturingsunlightthansolarpanels.AndthisfigureignorestheaddiEonallossofrespiraEonduetogrowthandmaintanence.

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For1MJofsunlightabout1%ofthatenergywillbeproducedintothebiomassofprimaryproducers.About1to10%ofthisenergywillbeusedbyprimaryconsumers,herbivores,likeinsects,caKle,grazers,etc.Evenlessenergyisdispensedtosecondaryconsumerswhomayeattheprimaryconsumersanddetritus.EvenlessenergyislexfortheterEaryconsumers,whomayresideatthetopoftheinvertedfoodpyramid

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Less and Less energy is available at higher and higher Trophic Levels, Less energy, less mass…but larger individuals. The classic textbook example of the inverted pyramid for aquatic systems is misleading. The large whales and sharks at the top are actually sustained by large pools of plankton and krill that have short life times and fast turn over (2 to 6 days). It is more appropriate to consider the mass of this primary productive over the course of a year than its mass at a give instant. And it is more appropriate to consider the mass of large carnivores and mass of small primary producers over a large area..then there is coherency between the pyramids of energy and the pyramids of biomass Global integrated chlorophyll biomass is 4 to 5 Tg.. Phytoplankton turn over every 2 to 6 days! Ocean NPP is ~50 Pg/y Behrenfeld,M.J.,R.T.O/'Malley,D.A.Siegel,C.R.McClain,J.L.Sarmiento,G.C.Feldman,A.J.Milligan,P.G.Falkowski,R.M.Letelier,andE.S.Boss.2006.Climate-driventrendsincontemporaryoceanproducEvity.N

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Thebeautyofcomplexsystemsisthataspectsoftheirbehaviorcanbepredictedbypowerlaws.Sothereis‘order’and‘rules’amongchaos.Inthiscasethereareonlysomanyindividualssustainableonaplotofland,giveacertainsize.Youcaneitherhavealotofsmallindividualsorafewlargeindividualsforunitareaofland.Thisisanexampleoftheself-organizingandpredicEveaspectofcomplexsystems.PredicEonsfollowsapowerlaw,withlog-logscaling,withaknownslope,orpowerlawexponent,inthiscase-4/3.

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Themetabolicenergy,B,neededtosustainmetabolismscaleswiththemassoftheorganismtothe¾powerMaxKleiberwasazoologistatUCDavis.Itookmycoursesonbiologyandbotany,asanundergrad,inKleiberHall.Sadly,Idon’trecallweweretoldofhisimpactonsciencethen.

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Exampleofthe‘Universality’ofKleiber’slawover21ordersofmagnitudeofmass

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Exampleofthemutualconstraintsofsizeandmass,onlylargethingscanhavemuchmass

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FromSchlesinger’sbook

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