1Campbell,p. 1209CO2NH4+NO3-CO (NH2) 2C6H12O6(Organic compoundscontain C and H)Available to biotaUnavailableInorganicCarbon2Carbon cycle (Campbell p. 1211)3Unavailableuntil mined456Phosphorus cycle: No gaseous, atmospheric component7Fig. 27.3,KrebsP residence time:algae: days-weeksanimals: days-yearssoils: months-milleniaocean sediments: millions of yearsPhosphorus8Nitrogen cycle: more complex than P cycle9http://www.physicalgeography.net/fundamentals/9s.htmlHuman activities (fossil fuel combustion, syntheticfertilizers, cultivation of legumes, industrial meat production)have more than doubled the natural input rate of fixed(bioavailable) nitrogen (Vitousek 1997).The Nitrogen Cycle10Vitousek 1997 Ecol. Applicns11Haber-Boschfertilizer relaxeda limiting factorand elevatedhuman carryingcapacity, but wasand is subsidizedby cheap oil.Tg = Teragrams = 10 12 g12The Haber process, is the synthesis of ammonia usingmagnetite, iron oxide, as the catalyst:N2 (g) + 3 H2 (g) 2 NH3 (g) (!H = !"2.4 kJ·mol!#)This is done at high pressures (15–25 MPa(150–250 bar)_ and temperatures (300 and 550 °C)passing the gases repeatedly over beds of catalyst. On each pass only about 15% conversion occurs,but any unreacted gases are recycled,so that eventually an overall conversion of 98%can be achieved.The hydrogen required is produced from methane.V. Smil 1997. Scientific American. Curiousfate of Franz Haber* German chemist,awarded Nobel Prize 1919 for ammoniasynthesis. Haber-Bosch synthesis of ammoniafrom nitrogen and hydrogen, combined at hightemps and pressures! explosives for WWIbut world fertilizers soon thereafter, allowinghuman population to exceed 6 billion….*also developedweaponizedchlorine gasused in WWI,hoping to limitoverallsuffering bybringing abouta quickerresolution tothe war.13Importance of forest cover in retaining N high in thelandscape—Hubbard Brook ExperimentGeneLikensp. 1214 CampbellTreecuttingcompletedcontroldeforestedstreamLosses during floods14Ecosystem efficiency:organic production/nutrient flux(mass time-t / mass time-t )Ecosystem retention—reducing fluxes through basin15Stream Ecosystem efficiency:organic production/nutrientflux(mass time-t / mass time-t )Stream spiraling (Newbold,Webster): downstreamtransport with periodic cyclingby local biologybackflowsflow16Retentive ecosystems with shortspiral lengths are more efficient-- more biotic production pernutrient flux downstream.They also protect downstreamwater bodies from eutrophicationBiologicalbackflows17storageinput outputstorageinput outputRetention (storage) elements: vegetation, wetlands(denitrification!), woody debris, large fauna, upstreammigrations, etc.)-- increase residence time, shorten spirallengths, decrease rate of losses of nutrients fromecosystemsMarsh building important on Gulf Coast!N218Why should we care?Watershed healthpublic health--impactson downstream waterbodies and nearshoremarine waters19Coastal Zone Color ScannerNimbus-7 satellitePfiesteria piscicida, N.C.SewageandvolatilizedNH3 fromindustrialpig farmsBurkholder andGlasgow 1997Dinoflagellate20Inverted pyramid of Trophic level Biomass-->Ecosystem goods and servicesClean water, and fish—suppresssustain21State change “bottom heavy” trophic pyramid dominated by cyanobacteria in a eutrophied lake?22www.resalliance.org23???!Where is the system now and how will it change…?(Scheffer et al. 2000)LIDAR data from NCALM?24RainTrees, roots leavesSoil moistureGrowthUptake and evapotranspiration-++Negative feedback (stabilizing)25More RainExposed soil surface LandslidesVegetationstrippingErosion ++Positive feedback (tips towardseroding unstable slope state)+26Greenhouse warmingExposed soil surface VegetationVegetationstrippingErosion ++Positive feedback (tips towardseroding unstable slope state)+27Greenhouse warming createsdroughts that kill vegetation,increasing dust that darkensglaciers accelerating their melt,that decrease water supplies…28Terrestrial nutrient and soilretention degraded by wind erosion indesert after loss of desert crustsATVtracks29System: set of interacting entitiesFeedback: modification of a system by its resultsor effectsAmplifying (positive, destabilizing) feedbackinduces further change in a system in the samedirection as the initial perturbationStabilizing (negative, corrective) feedbackdiminishes the effect of a change by counteractingit with a change in the opposite direction30 Positive fdbks destabilizing Earth’s response toglobal warming: * Oxidation of ancient carbon stored in arcticecosystems with melt of permafrost terrestrialecosystems, leading to an increase of atmosphericCO2 levels * Higher albedo of sea ice and seasonal snow cover.Darker earth and sea surfaces absorb more sunlight,leading to further warming. *Acidification of the ocean--elevating CO2concentration will lower ocean pH, interfering withthe ability of ocean biota to produce and sequestercalcium carbonate.31More atmospheric CO2 oxidation of peatstored in permafrostCOCO22 emissionGreenhouse warmingGreenhouse warming++Positive feedback+32Spahini et al. Science 2005Vostok (Antarctic) ice corearchived climate andatmospheric compositionover past four glacialcycles over past 420 Kyr.New Antarctic Core spans8 cycles, (4 more thanpreviously available) overpast 740 Kyr.This ice is about491,0000 yearsold33The concentration of CO2 inair today is higher than ithas been in the last 650,000years, and probably since ithas been in the last 50 my. CO2 (ppm)Before 1850 2741958 (Keeling) 3162005 3702075 (est.) 54034Evidence of global warming•Glacier shrinkage onmountains around the globe•Satellite, balloonmeasurements show loweratmosphere is warming atsimilar rate to surface•Permafrost melting inArctic•Acceleration of Greenlanddeglaciation due to moulins•Warming of upper layers ofthe oceanMelting of Greenland IceSheet would elevate sea level20’35Sergei Zimov and woolly rhinocerosbone in Siberia– Pleistocene ParkTerry ChapinAre modern humans the first to change climate?3612,000 years ago,vegetation changedacross all of Beringia(Siberia + Alaska) fromsteppe grass to mossytundra.Most scientists assumethis was due to climatechange, but nopaleorecord of thissediment or ice cores.Distribution of tundra todaySteppe grassMossy tundra37Zimov et al. (1995) hypothesized thatvegetation changed because human huntersarrived and exterminated a megafaunathat hadn’t co-evolved with a carnivoroussocial primate with projectile
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