Organic compounds contain C and H CO NH2 C6H12O6 Carbon Carbon cycle Campbell p 1211 2 Campbell p 1209 Inorganic CO2 NH4 NO3Available to biota Unavailable1 2 Unavailable until mined 3 4 Phosphorus cycle No gaseous atmospheric component 5 6 Nitrogen cycle more complex than P cycle Phosphorus Fig 27 3 Krebs P residence time algae days weeks animals days years soils months millenia ocean sediments millions of years The Nitrogen Cycle 7 8 http www physicalgeography net fundamentals 9s html Human activities fossil fuel combustion synthetic fertilizers cultivation of legumes industrial meat production have more than doubled the natural input rate of fixed 9 bioavailable nitrogen Vitousek 1997 10 Vitousek 1997 Ecol Applicns V Smil 1997 Scientific American Curious fate of Franz Haber German chemist awarded Nobel Prize 1919 for ammonia synthesis Haber Bosch synthesis of ammonia from nitrogen and hydrogen combined at high temps and pressures explosives for WWI but world fertilizers soon thereafter allowing human population to exceed 6 billion Haber Bosch fertilizer relaxed a limiting factor and elevated human carrying capacity but was and is subsidized by cheap oil Tg Teragrams 10 12 g The Haber process is the synthesis of ammonia using magnetite 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 11 The hydrogen required is produced from methane also developed weaponized chlorine gas used in WWI hoping to limit overall suffering by bringing about a quicker resolution to 12 the war Ecosystem efficiency organic production nutrient flux mass time t mass time t Importance of forest cover in retaining N high in the landscape Hubbard Brook Experiment Gene Likens p 1214 Campbell deforested stream Tree cutting completed Losses during floods control 13 Stream Ecosystem efficiency organic production nutrient flux mass time t mass time t Ecosystem retention reducing fluxes through basin Retentive ecosystems with short spiral lengths are more efficient more biotic production per nutrient flux downstream They also protect downstream water bodies from eutrophication flow Stream spiraling Newbold Webster downstream transport with periodic cycling by local biology Biological backflows backflows 15 storage Watershed health public health impacts on downstream water bodies and nearshore marine waters output Marsh building important on Gulf Coast input storage 16 Why should we care N2 input 14 output Retention storage elements vegetation wetlands denitrification woody debris large fauna upstream migrations etc increase residence time shorten spiral lengths decrease rate of losses of nutrients from ecosystems 17 18 Coastal Zone Color Scanner Nimbus 7 satellite Inverted pyramid of Trophic level Biomass Ecosystem goods and services Pfiesteria piscicida N C Clean water and fish Dinoflagellate Sewage and volatilized NH3 from industrial pig farms suppress sustain Burkholder and Glasgow 1997 19 20 State change bottom heavy trophic pyramid dominated by cyanobacteria in a eutrophied lake 21 22 www resalliance org Where is the system now and how will it change Rain Uptake and evapotranspiration Soil moisture Trees roots leaves Growth Negative feedback stabilizing 23 Scheffer et al 2000 LIDAR data from NCALM 24 More Rain Greenhouse warming Erosion Erosion Landslides Exposed soil surface Vegetation stripping Vegetation Exposed soil surface Vegetation stripping Positive feedback tips towards eroding unstable slope state Positive feedback tips towards eroding unstable slope state 25 26 Greenhouse warming creates droughts that kill vegetation increasing dust that darkens glaciers accelerating their melt that decrease water supplies ATV tracks 27 Terrestrial nutrient and soil retention degraded by wind erosion in desert after loss of desert crusts 28 Positive fdbks destabilizing Earth s response to global warming System set of interacting entities Feedback modification of a system by its results or effects Oxidation of ancient carbon stored in arctic ecosystems with melt of permafrost terrestrial ecosystems leading to an increase of atmospheric CO2 levels Amplifying positive destabilizing feedback induces further change in a system in the same direction as the initial perturbation Stabilizing negative corrective feedback diminishes the effect of a change by counteracting it with a change in the opposite direction Higher albedo of sea ice and seasonal snow cover Darker earth and sea surfaces absorb more sunlight leading to further warming 29 Acidification of the ocean elevating CO2 concentration will lower ocean pH interfering with the ability of ocean biota to produce and sequester 30 calcium carbonate Spahini et al Science 2005 Vostok Antarctic ice core archived climate and atmospheric composition over past four glacial cycles over past 420 Kyr Greenhouse warming oxidation of peat stored in permafrost More atmospheric CO2 New Antarctic Core spans 8 cycles 4 more than previously available over past 740 Kyr CO2 emission This ice is about 491 0000 years old Positive feedback 31 32 Evidence of global warming The concentration of CO2 in air today is higher than it has been in the last 650 000 years and probably since it has been in the last 50 my CO2 ppm Before 1850 274 1958 Keeling 316 2005 370 2075 est Glacier shrinkage on mountains around the globe Satellite balloon measurements show lower atmosphere is warming at similar rate to surface Permafrost melting in Arctic Acceleration of Greenland deglaciation due to moulins Warming of upper layers of the ocean 540 Melting of Greenland Ice Sheet would elevate sea34level 20 33 Are modern humans the first to change climate Steppe grass Mossy tundra Terry Chapin Distribution of tundra today Sergei Zimov and woolly rhinoceros bone in Siberia Pleistocene Park 35 12 000 years ago vegetation changed across all of Beringia Siberia Alaska from steppe grass to mossy tundra Most scientists assume this was due to climate change but no paleorecord of this 36 sediment or ice cores Moss tundra is a good insulator so permafrost shallow soils waterlogged and hypoxic Grasses dry up soils support more productivity and floral diversity Siberian ponies pastured downslope from grass refuges on hills extend steppe
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