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1、4THEGLOBALNITROGENCYCLEBessWardDepartmentofGeosciences,PrincetonUniversity,Princeton,NJ08540USA4.1IntroductionTheseinvolvethediscoveryofpreviouslysuspected,butunknownprocesses,aswellasthediscoveryofnewThegeobiologyofnitrogenisdominatedbylargeinertand
2、diversemicrobesinvolvedinmanyofthenitrogenreservoirsandsmallbiologicalfluxes.Thelargestreser-cyclefluxes.voirsarenitrogengas(intheatmosphereanddissolvedintheocean)andsedimentarynitrogen(sequesteredin4.2Geologicalnitrogencyclecontinentalcrust).Because
3、mostorganismscannotuti-lizegaseousnitrogen,wedistinguishbetweenfixedNitrogenisanessentialelementforlifeonEarthandthenitrogencompounds(whichcontainnoN–Nbonds)fourthmostabundantelement(afterC,OandH)inthethatarebiologicallyavailable,andthedinitrogengase
4、sbiosphere(livingplusdeadorganicmatter)atabout(NandNO)thatarelargelyinaccessibletoorganisms.0.3%byweight.Unliketheothermajorbiologically22Fluxesintoandoutofthefixednitrogenpoolsareimportantelements,nitrogen(N)isaminorconstituentbiologicallycontrolled
5、,andmicrobescontroltheratesofoftheEarth’scrust,averaging50ppmincontinentaltransformationsandthedistributionofnitrogenamongcrust(Wedepohl,1995).Freshigneousrockscontaininorganicandorganicpools.essentiallynonitrogen(e.g.freshvolcaniclava),soPossiblymor
6、ethananyotherbiologicallyimportantnitrogeninrocksisultimatelyderivedfromtheatmos-element,theglobalnitrogencyclehasbeenperturbedbyphereviabioticandabioticnitrogenfixation.Thepro-anthropogenicactivities.TherateofindustrialnitrogencessofNsequestrationin
7、rocksinvolvesaccumulationfixationnowapproximatelyequalsthenaturalrate,oforganicmatterinlowenergymarineenvironments,resultinginatwo-tothreefoldincreaseinthetotalwhereisitslowlydecomposedandtheammoniumthatinventoryoffixedNonthesurfaceoftheEarththroughi
8、sliberatedpartitionsintoclayminerals.Inhighenergyagriculturalfertilizerapplications(Gallowayet al.,2004).environments,claysandorganicmatterdonotNitrogenoxidesentertheatmosphereviafossilfuelaccumulateandthecoarsergrainedsandsdonotacquirecombustionandc
