DOCSLIB.ORG

Nitrogen Biogeochemistry

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Nitrogen Biogeochemistry Nitrogen biogeochemistry Chlorophyll a, mg m‐3 0.01 0.1 1 10 Nitrogen species in nature Oxidation state ‐ 5nitrate, NO3 4nitrogen dioxide, NO2; N2O4 ‐ 3nitrite, NO2 2nitricoxide, NO 1 nitrous oxide, N2O 0nitrogen, N2 ‐1 hydroxylamine, NH2OH ‐2hydrazine, N2H4 + + ‐3 ammonium, NH4 , amines, R‐NH3 etc. Lam & Kuypers, Ann. Rev. Mar. Sci. 2011 The classical nitrogen cycle, 1934 Organic N Industrial and microbial N fixation Aerobic nitrification (ammonium oxidation and nitrite oxidation) Anaerobic Nitrate reduction denitrification to ammonium L.G.M. Baas Becking: Geobiologie (1934) Biogeochemical significance of nitrogen • Nitrogen is a nutrient – e.g., phytoplankton ≈ C106H175O42N16P… => assimilation/mineralization cycle • Nitrogen is used in microbial energy metabolism: ‐ ‐ NO3 is e acceptor for anaerobes, e.g. denitrification + ‐ NH4 is e donor for lithotrophs, e.g. nitrification => redox cycle • N2O is a greenhouse gas and ozone destroyer ‐ ‐ • NO3 /NO2 buffer H2S and, possibly, CH4 Nitrogen is essential for all life Trees: ~0.1% N Herbs: ~1% N Biomass N, e.g. in phytoplankton: 93% protein 7% nucleic acids Animals: ~10% N Phytoplankton: 5‐10% N Nitrogen in biomass Phytoplankton biomass Biomass N: 54.4% protein w. 16.3% N 93% protein 25% carbohydrate* 7% nucleic acids 16.1% lipid X% amino sugars 4% nucleic acids w. 16.6% N * bacteria have amino sugars (N‐acetyl‐glucose/galactose amine) in cell walls, crustaceans have amino sugar (chitin) in exoskeleton. Mineralization of C and N Anaerobic mineralization in closed 2008 incubation of sediment: Dalsgaard and Thamdrup Models of (aerobic) mineralization with microbial growth: al.2005 Canfield et Time (days) Time (days) Biogeochemical significance of nitrogen • Nitrogen is a nutrient – e.g., phytoplankton ≈ C106H175O42N16P… => assimilation/mineralization cycle • Nitrogen is used in microbial energy metabolism: ‐ ‐ NO3 is e acceptor for anaerobes, e.g. denitrification + ‐ NH4 is e donor for lithotrophs, e.g. nitrification => redox cycle • N2O is a greenhouse gas and ozone destroyer ‐ ‐ • NO3 /NO2 buffer H2S and, possibly, CH4 The nitrogen cycle is • Largely (micro‐)biological –exceptions: – atmospheric N fixation by lightning –NOx formations from combustion – atmospheric NOx transformations – Haber‐Bosch process –chemo‐denitrification • Largely restricted to biosphere and atmosphere –rock N important in some terrestrial ecosystems Fixed vs. free nitrogen (”water, water, every where, nor any drop to drink”) Nitrogen in the atmosphere 3.9 x 1021 g Microbial NN N fixation Microbial + ‐ NH4 , NO3 , Norg, etc. denitrification To help protect your privacy, PowerPoint has blocked automatic download o… Bioavailable / reactive / fixed N: 1.4 x 1018 g Redox chemistry N2 is unstable in oxic environments: 1 ‐ NO3 ‐ + N2 + 2.5O2 + H2O => 2NO3 + 2H ∆G0’ = –65 kJ/mol! 0.5 V , 0 N2 E 5 10 and in reduced sediments: 0 + N2 + 1.5CH2O + 3H2O + 0.5H => + ‐ 2NH4 + 1.5HCO3 ‐0.5 + NH4 ∆G0’ = –78 kJ/mol! pH Oceanic reactive nitrogen budget 160 Turn‐over time of oceanic nitrate 80 w.r.t. denitrification ~2000 y 0 1 ‐ y N input input Burial ‐80 Tg Diazotrophy Riverine denitrification ‐160 denitrification Atmospheric ‐240 Pelagic Benthic ‐320 Middelburg et al. (1996), Gruber and Sarmiento 2002, Brandes and Devol (2002), Codispoti et al. (2007) It all starts with N2 OXIC fixation N2 oxidation + NH4 Norg N2 fixation + NH4 N2 reduction ANOXIC oxidation state: ‐3 ‐2 ‐1 0 1 2 3 5 Microbial N fixation by nitrogenase + − N2 + 8H + 16MgATP + 8e → 2NH3 + H2 + 16MgADP + 16Pi Metal requirements: 4 Fe in Fe protein 30 Fe, 2 Mo in MoFe protein Synthesis involves ≈ 20 enzymes Irreversible inhibition by O2 Seefeldt et al. 2009, Ann. Rev. Biochem. Large diversity of diazotrophs Carpenter and Capone 2008, in Nitrogen Cycling in the Marine Environment Symbiotic N2 fixation in root nodules of legumes Root of soy bean with nodules Rhizobium in vesicles N fixation in soils is predominantly (75 – 95%) symbiotic N‐fixing cyanobacteria symbiotic Anabaena in water fern, Azolla toxic Nodularia N‐fixing cyanobacteria in the ocean Trichodesmium sp. mpi‐bremen.de ”Candidatus Atelocyanobacterium thalassa” a.k.a UCYN‐A inside Braarudosphaera sp. haptophyte ”Sawdust of the sea” Richelia sp. inside Hemiaulus sp. diatom www.whoi.edu Where is N2 fixed? Oligotrophic lake ≈0 Plankton Mesotrophic lake Benthos Eutrophic lake Rice paddy Saltmarsh Mangrove Seagrass bed Estuaries 2005 ≈90% of marine N fixation is pelagic N. Atlantic/N. Pacific al. ≈0 Open ocean Trichodesmium ≈0 0,1 1 10 100 1000 10000 ‐2 ‐1 N2 fixed, µmol m d after Canfield et High N2 fixation in dark sediments? ‐2 ‐1 N2 flux, Narragansett Bay, µmol m h Fulweiler and Heiss 2014, Oceanography Experimental quantification of N2 fixation Acetylene reduction assay: rate 15 Gross N2 incorporation 15 15 - 15 N N + 6e => 2R- NH2 rate Direct N2 flux measurements (mostly via N2/Ar) Net Where is N2 fixed? – natural terrestrial systems: µmol N m‐2 d‐1 180 135 Cleveland 90 et al. 2001 45 High evapotranspiration => high N2 fixation 0 rates corrected x 0.25 according to Vitousek et al. 2013 leguminous crops: 250 ‐ 5000 µmol N m‐2 y‐1 (Peoples et al. 1995) N fixation by the Haber‐Bosch process ≈ 2% of the world’s energy consumption Sutton et al. 2013 Global fixed nitrogen budget Anthropogenic N fixation Canfield et al. 2010 Nitrogen and marine eutrophication Global terrestrial fixed N budget DIN input vs. PP in estuaries 12 and coastal ecosystems Denitrification ? Denitrification Seitzinger and Harrison 2008 Nixon et al. 1996, Paerl and Piehler 2008 Atmospheric N deposition Galloway et al. 2008 Next step: N2 OXIC fixation N2 N2O oxidation Assimilation Ammonium Nitrite oxidation oxidation + NH OH ‐ ‐ NH4 2 NO2 NO3 Norg N2 fixation + NH4 N2 reduction ANOXIC oxidation state: ‐3 ‐2 ‐1 0 1 2 3 5 Nitrification 1) Ammonium oxidation 2) Nitrite oxidation + ‐ + ‐ ‐ NH4 + 1.5O2 NO2 + H2O + 2H NO2 + 0.5O2 NO3 ∆G0’ = ‐275 kJ mol‐1 ∆G0’ = ‐74 kJ mol‐1 Nitroso‐monas, ‐spira, etc. Nitro‐bacter, ‐spira, etc. Km(O2) ~ 10 µM Km(O2) ~ 50 µM • Obligately aerobic processes • Performed by specialized, autotrophic organisms • Efficiency of energy conservation < 10% => large turn‐over with small biomass • Ammonium oxidation generally rate limiting except at low PO2 • Results in acidification and leaching of nitrogen from soils • Releases N2O, particularly at low O2 levels Ammonium oxidation + ‐ + NH4 + 1.5O2 NO2 + H2O + 2H Nitrosomonas sp. + Nitrosopumilus sp. NH4 ‐oxidizing bacterium + NH4 ‐oxidizing thaumarchaeon –discovered~10 years ago + –Km(NH4 ) 2 µM –knownfor > 100 years + + – dominates in NH4 ‐poor systems –Km(NH4 ) 100 µM –7 mM + (e.g., unfertilized soil, open ocean) – dominates in NH4 ‐rich systems (e.g., wastewater treatment) Close coupling of ammonium and nitrite oxidation in a riverine sediment nmol cm-2 h-1 ‐ ‐ ‐1 NO3 , NO2 (µmol l ) Meyer et al. 2005, Appl. Environ. Microbiol. + High NH4 affinity – but slow growth. Nitropira inopiata dominates in, e.g., ground water sand filters Kitts et al. (2015) Anaerobic nitrification? + + ‐ NH4 N2 NH4 NO2 400 0 1 2468 ‐ ) + 4 200 NH ‐100 2468 (mol 0 kJ ‐200 G, ∆ ‐ ‐200 ‐300 NO2 N2 pH pH ‐ ”Feammox”: Feammox to NO2 is exergonic at pH>4! + + 2+ ‐ 6Fe(OH)3 + NH4 + 10H 6Fe + NO2 + 16H2O No robust evidence of either Fe(III) or + + 2+ Mn(IV)‐dependent NH4+ oxidation in 3Fe(OH)3 + NH4 + 5H 3Fe + N2 + 9H2O aquatic systems ‐ ‐ ‐ 2+ 2+ 2‐ [NO2 ], [HS ]: 1 µM; [NO3 ], [Mn ], [Fe ]: 10 µM; [SO4 ]: 10 mM, PN2: 1 atm Back to N2: N2 OXIC fixation N2 N2O oxidation Assimilation Ammonium Nitrite oxidation oxidation + NH OH ‐ ‐ NH4 2 NO2 NO3 Norg N2 fixation Denitrification + ‐ ‐ NH4 N2 N2O NO NO2 NO3 reduction ANOXIC oxidation state: ‐3 ‐2 ‐1 0 1 2 3 5 N2 OXIC fixation N2 N2O oxidation Assimilation Ammonium Nitrite oxidation oxidation + NH OH ‐ ‐ NH4 2 NO2 NO3 Norg N2 fixation Denitrification + ‐ ‐ NH4 N2 N2O NO NO2 NO3 N H NO 2 4 Anammox reduction ANOXIC DNRA oxidation state: ‐3 ‐2 ‐1 0 1 2 3 5 Denitrification ‐ ‐ + 5CH2O + 4NO3 2N2 +5 HCO3 + 2H2O + H • Many different facultative anaerobes ‐ • Four‐step reduction of NO3 : ‐ ‐ NO3 NO2 NO N2O N2 Nar/Nap Nir Nor Noz • Inhibited by O2 ≥ 2% air saturation • Electron donors organic C, H2, H2S or Fe2+ Denitrification as a modular process in permeable sediments Marchant et al. (2018) Environ. Microbiol. Coupled nitrification–denitrification in a riverine sediment nmol cm-2 h-1 ‐ ‐ ‐1 NO3 , NO2 (µmol l ) Coupled nitrification‐denitrification 10.8/13.5 = 80% of total Meyer et al. 2005, Appl. Environ. Microbiol. Relative contributions of N‐reducing pathways Skagerrak Aarhus Bay sediment sediment Denitrification Anammox Mae Klong DNRA OMZ Peru Estuary sed. water col. Thamdrup and Dalsgaard 2002, Lam et al. 2009, Dong et al. 2011 Anammox bacteria ”Candidatus Scalindua sp.” NO ‐ + NH + N + 2H O Hydrazine 2 4 2 2 ∆G°’ = ‐357 (N2H4) KJ/molCandidate genera: Kuenenia (1 species) Sludge, Brocadia (3 species) 2008 wastewater, al. soils, Anammoxosome Anammoxoglobus (1 species) freshwater Jettenia (1 species) Niftrik et Marine van Scalindua (4 species) environments div. freshwater habitats Ladderane Obligate anaerobes, anammoxidizers, lipids 0.2 µm and autotrophs Doubling time 1 –3 weeks! Active in freshwater and marine sediments, aquifers, sea ice, hydrothermal systems Relative importance of anammox in sediments Rivers/estuaries/marshes Nicholls & Trimmer, n=40 100 Freshwater Temperate coastal Arctic 80 Open ocean OMZ Peru Mn-rich production 2 60 Intact cores 40 2 20 9 % Ananmmox, % of N 0 0,1 1 10 100 1000 10000 Water depth, m Thamdrup (2012), amended Rates vs. depth Mean anammox contribution: 28% Trimmer & Engström 2010, in Nitrification Anammox in the global N cycle Total N2 production % anammox N2 from anammox Tg y‐1 Tg y‐1 Marine sediments 126 – 300 28 35 –84 Oxygen minimum zones 65 – 150 28 – 100 18 – 150 Marine total 191 – 450 28 –52 53 – 234 Soils 124 5? 6 Groundwater 44 25? 11 Rivers 35 10? 3.5 Lakes 30 15? 4.5 Land total 234 11? 26 Global total 425 – 684 19 –38 81 – 260 9 Global N2 inventory 3.9 x 10 Tg 6 Turn‐over time w.r.t.
Load more

Recommended publications
  • Human Alteration of the Global Nitrogen Cycle
    What is Nitrogen? Human Alteration of the Nitrogen is the most abundant element in Global Nitrogen Cycle the Earth’s atmosphere. Nitrogen makes up 78% of the troposphere. Nitrogen cannot be absorbed directly by the plants and animals until it is converted into compounds they can use. This process is called the Nitrogen Cycle. Heather McGraw, Mandy Williams, Suzanne Heinzel, and Cristen Whorl, Give SIUE Permission to Put Our Presentation on E-reserve at Lovejoy Library. The Nitrogen Cycle How does the nitrogen cycle work? Step 1- Nitrogen Fixation- Special bacteria convert the nitrogen gas (N2 ) to ammonia (NH3) which the plants can use. Step 2- Nitrification- Nitrification is the process which converts the ammonia into nitrite ions which the plants can take in as nutrients. Step 3- Ammonification- After all of the living organisms have used the nitrogen, decomposer bacteria convert the nitrogen-rich waste compounds into simpler ones. Step 4- Denitrification- Denitrification is the final step in which other bacteria convert the simple nitrogen compounds back into nitrogen gas (N2 ), which is then released back into the atmosphere to begin the cycle again. How does human intervention affect the nitrogen cycle? Nitric Oxide (NO) is released into the atmosphere when any type of fuel is burned. This includes byproducts of internal combustion engines. Production and Use of Nitrous Oxide (N2O) is released into the atmosphere through Nitrogen Fertilizers bacteria in livestock waste and commercial fertilizers applied to the soil. Removing nitrogen from the Earth’s crust and soil when we mine nitrogen-rich mineral deposits. Discharge of municipal sewage adds nitrogen compounds to aquatic ecosystems which disrupts the ecosystem and kills fish.
    [Show full text]
  • Nitrogen Metabolism in Phytoplankton - Y
    MARINE ECOLOGY – Nitrogen Metabolism in Phytoplankton - Y. Collos, J. A. Berges NITROGEN METABOLISM IN PHYTOPLANKTON Y. Collos Laboratoire d'Hydrobiologie CNRS, Université Montpellier II, France J. A. Berges School of Biology and Biochemistry, Queen's University of Belfast, UK Keywords: uptake, reduction, excretion, proteases, chlorophyllases, cell death. Contents 1. Introduction 2. Availability and use of different forms of nitrogen 2.1 Nitrate 2.2. Nitrite 2.3. Ammonium 2.4. Molecular N2 2.5. Dissolved organic N (DON) 2.6. Particulate nitrogen (PN) 3. Assimilation pathways 4. Accumulation and storage 4.1. Inorganic compounds 4.2. Organic compounds 5. Nutrient classification and preferences 6. Plasticity in cell composition 7. Overflow mechanisms: excretion and release processes 8. Recycling of N within the cell 9. Degradation pathways 9.1. Requirements for and roles of degradation 9.2. How is degradation accomplished? 9.3. Variation in degradation 9.4. Pathogenesis and Cell Death 10. From uptake to growth: time-lag phenomena 11. Relationships with carbon metabolism 12. Future directions AcknowledgementsUNESCO – EOLSS Glossary Bibliography SAMPLE CHAPTERS Biographical Sketches Summary Phytoplankton use a large variety of nitrogen compounds and are extremely well adapted to fluctuating environmental conditions by a high capacity to change their chemical composition.Degradation and turnover of nitrogen within phytoplankton is essential for many processes including normal cell maintenance, acclimations to changes in light, salinity, and nutrients, and cell defence against pathogens. The ©Encyclopedia of Life Support Systems (EOLSS) MARINE ECOLOGY – Nitrogen Metabolism in Phytoplankton - Y. Collos, J. A. Berges pathways by which N degradation is accomplished are very poorly understood, but based on work in higher plant species, protein degradation is likely to be of central importance.
    [Show full text]
  • Human Alteration of the Global Nitrogen Cycle: Causes And
    Published by the Ecological Society of America Number 1, Spring 1997 Causes andConsequences Human Alterationofthe Issues in EcologyGlobal NitrogenCycle: Photo by Nadine Cavender Issues in Ecology Number 1 Spring 1997 Human Alteration of the Global Nitrogen Cycle: Causes and Consequences SUMMARY Human activities are greatly increasing the amount of nitrogen cycling between the living world and the soil, water, and atmosphere. In fact, humans have already doubled the rate of nitrogen entering the land-based nitrogen cycle, and that rate is continuing to climb. This human-driven global change is having serious impacts on ecosystems around the world because nitrogen is essential to living organisms and its availability plays a crucial role in the organization and functioning of the worlds ecosystems. In many ecosystems on land and sea, the supply of nitrogen is a key factor controlling the nature and diversity of plant life, the population dynamics of both grazing animals and their predators, and vital ecologi- cal processes such as plant productivity and the cycling of carbon and soil minerals. This is true not only in wild or unmanaged systems but in most croplands and forestry plantations as well. Excessive nitrogen additions can pollute ecosystems and alter both their ecological functioning and the living communities they support. Most of the human activities responsible for the increase in global nitrogen are local in scale, from the production and use of nitrogen fertilizers to the burning of fossil fuels in automobiles, power generation plants, and industries. However, human activities have not only increased the supply but enhanced the global movement of various forms of nitrogen through air and water.
    [Show full text]
  • Carbon–Nitrogen Interactions in Idealized Simulations with JSBACH (Version 3.10)
    Geosci. Model Dev., 10, 2009–2030, 2017 www.geosci-model-dev.net/10/2009/2017/ doi:10.5194/gmd-10-2009-2017 © Author(s) 2017. CC Attribution 3.0 License. Carbon–nitrogen interactions in idealized simulations with JSBACH (version 3.10) Daniel S. Goll1,a, Alexander J. Winkler2,3, Thomas Raddatz2, Ning Dong3,5, Ian Colin Prentice4,6, Philippe Ciais1, and Victor Brovkin2 1Le Laboratoire des Sciences du Climat et de l’Environnement, IPSL-LSCE CEA/CNRS/UVSQ Saclay, Gif sur Yvette, France 2Max Planck Institute for Meteorology, Hamburg, Germany 3International Max Planck Research School on Earth System Modeling, Hamburg, Germany 4Department of Biological Sciences, Macquarie University, North Ryde, NSW 2109, Australia 5Faculty of Agriculture and Environment, Department of Environmental Sciences, University of Sydney, NSW 2006, Australia 6AXA Chair in Biosphere and Climate Impacts, Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot SL5 7PY, UK aformerly at: Max Planck Institute for Meteorology, Hamburg, Germany Correspondence to: Daniel S. Goll ([email protected]) Received: 17 December 2016 – Discussion started: 9 January 2017 Revised: 7 April 2017 – Accepted: 14 April 2017 – Published: 22 May 2017 Abstract. Recent advances in the representation of soil car- The strengths of the land carbon feedbacks of the re- −1 bon decomposition and carbon–nitrogen interactions imple- cent version of JSBACH, with βL D 0:61 Pgppm and γL D mented previously into separate versions of the land sur- −27:5 Pg ◦C−1, are 34 and 53 % less than the averages of face scheme JSBACH are here combined in a single version, CMIP5 models, although the CMIP5 version of JSBACH which is set to be used in the upcoming 6th phase of coupled simulated βL and γL, which are 59 and 42 % higher than model intercomparison project (CMIP6).
    [Show full text]
  • Biogeochemistry of Wetlands Nitrogen
    Institute of Food and Agricultural Sciences (IFAS) Biogeochemistry of Wetlands SiScience an dAd App litilications NITROGEN Wetland Biogeochemistry Laboratory Soil and Water Science Department University of Florida Instructor : Patrick Inglett [email protected] 6/22/20086/22/2008 P.W.WBL Inglett1 1 Nitrogen Introduction N Forms, Distribution, Importance Basic processes of N Cycles Examples of current research Examples of applications Key points learned 6/22/2008 P.W. Inglett 2 1 Nitrogen Learning Objectives Identify the forms of N in wetlands Understand the importance of N in wetlands/global processes Define the major N processes/transformations Understand the importance of microbial activity in N transformations Understand the potential regulators of N processes See the application of N cycle principles to understanding natural and man-made ecosystems 6/22/2008 P.W. Inglett 3 Nitrogen Cycling Plant biomass N N2 NH3 N2 N2O (g) Litterfall Nitrogen Fixation Volatilization Mineralization. Water - Nitrification + + NO3 NH4 Organic N NH4 Column AEROBIC - Plant Peat NO3 + + [NH4 ]s uptake accretion [NH4 ]s Denitrification ANAEROBIC Microbial + Organic N Biomass N Adsorbed NH4 N2, N2O (g) 6/22/2008 P.W. Inglett 4 2 Forms of Nitrogen Organic Nitrogen Inorganic Nitrogen + • Proteins • Ammonium (NH4 ) - • Amino Sugars • Nitrate N (NO3 ) - • Nucleic Acids • Nitrite N (NO2 ) • Urea • Nitrous ox ide (N2O) • Dinitrogen (N2) 6/22/2008 P.W. Inglett 5 N Transformations Solid Gaseous Phase: Phase: Particulate N N2 + Bound: NH4 N2O - - NO3 NO2 Aqueous Phase: + NH4 DON - DIN NO3 - Particulate N NO2 6/22/2008 P.W. Inglett 6 3 Reservoirs of Nitrogen Lithosphere 163,600 x 1018 g Atmosphere 3,860 x 1018 g Hydrosphere 23 x 1018 g Biosphere 0.28 x 1018 g 6/22/2008 P.W.
    [Show full text]
  • The Carbon Cycle Is Very Important to All Ecosystems, and Ultimately Life on Earth
    What is The Carbon Cycle? The carbon cycle is very important to all ecosystems, and ultimately life on earth. The carbon cycle is critical to the food chain. Living tissue contains carbon, because they contain proteins, fats and carbohydrates. The carbon in these (living or dead) tissues is recycled in various processes. Let's see how this cycle works using the simple sketch below: Human activities like heating homes and cars burning fuels (combustion) give off carbon into the atmosphere. During respiration, animals also introduce carbon into the atmosphere in the form of carbon dioxide. The Carbon dioxide in the atmosphere is absorbed by green plants (producers) to make food in photosynthesis. When animals feed on green plants, they pass on carbon compounds unto other animals in the upper levels of their food chains. Animals give off carbon dioxide into the atmosphere during respiration. Carbon dioxide is also given off when plants and animals die. This occurs when decomposers (bacteria and fungi) break down dead plants and animals (decomposition) and release the carbon compounds stored in them. Very often, energy trapped in the dead materials becomes fossil fuels which is used as combustion again at a later time. Nitrogen Cycle: Nitrogen is also key in the existence of ecosystems and food chains. Nitrogen forms about 78% of the air on earth. But plants do not use nitrogen directly from the air. This is because nitrogen itself is unreactive, and cannot be used by green plants to make protein. Nitrogen gas therefore, needs to be converted into nitrate compound in the soil by nitrogen-fixing bacteria in soil, root nodules or lightning.
    [Show full text]
  • The Nitrogen Cycle
    The Nitrogen Cycle Almost 80% of our atmosphere is made up of the element nitrogen bonded together as N2. This represents most of the nitrogen available on Earth. Ni- trogen is an important element used by all living things to make proteins, amino acids and the nucleic acids of DNA. Yet its gaseous form, N2, found – + in the atmosphere is not usable. It must be “fixed” into nitrates (NO3 ), ammonium (NH4 ) or urea (NH2)2CO to be taken up by plants. Animals can get their nitrogen by eating those plants and so it moves through the food webs. When nitrogen is fixed, it is absorbed by plants and then eaten by animals, who then expel it in their waste and eventually die and decompose (releas- ing more). The nitrogen is then released into the soil and then back into atmosphere – this is the Nitrogen Cycle. The Nitrogen Cycle can be broken down into 4 processes: Nitrogen fixing – Decay – Nitrification – Dentrification 1. Nitrogen Fixing is when gaseous nitrogen is “fixed” by either lightning (only up to about 8%), bacteria in the soil, or nitrogen-fixing bacteria in the root nodules of leguminous plants (like soy beans). 2. Decay - The nitrogen in plants is eaten by animals and broken down and expelled in the animals’ waste. Microorganisms further break it down into ammonia. 3. Nitrification - Some ammonia is absorbed by plants through their roots, but most is converted by nitrifying bacteria into nitrites and then nitrates. 4. Dentrification moves the nitrogen in the other direction back into the atmosphere. Dentrifying bacteria reduce nitrites and nitrates into nitrogen gas, releasing it back to the atmosphere to complete the cycle.
    [Show full text]
  • Carbon-Nitrogen Interactions Regulate Climate-Carbon Cycle Feedbacks: Results from an Atmosphere-Ocean General Circulation Model
    Biogeosciences, 6, 2099–2120, 2009 www.biogeosciences.net/6/2099/2009/ Biogeosciences © Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License. Carbon-nitrogen interactions regulate climate-carbon cycle feedbacks: results from an atmosphere-ocean general circulation model P. E. Thornton1, S. C. Doney2, K. Lindsay3, J. K. Moore4, N. Mahowald5, J. T. Randerson4, I. Fung6, J.-F. Lamarque7,8, J. J. Feddema9, and Y.-H. Lee3 1Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6335, USA 2Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543-1543, USA 3Climate and Global Dynamics Division, National Center for Atmospheric Research, Boulder, CO 80307-3000, USA 4Department of Earth System Science, University of California, Irvine, CA 92697-3100, USA 5Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY 14850, USA 6Department of Earth and Planetary Science, University of California, Berkeley, CA 94720-4767, USA 7NOAA Earth System Research Laboratory, Chemical Sciences Division, 325 Broadway, Boulder, CO 80305-3337, USA 8Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, CO 80307-3000, USA 9Department of Geography, University of Kansas, Lawrence, KS 66045-7613, USA Received: 28 January 2009 – Published in Biogeosciences Discuss.: 26 March 2009 Revised: 12 August 2009 – Accepted: 17 September 2009 – Published: 8 October 2009 Abstract. Inclusion of fundamental ecological interactions
    [Show full text]
  • The Carbon Cycle
    TEACHER GUIDE THE CARBON CYCLE MATERIALS PER GROUP: LESSON OVERVIEW: Activity 1 The carbon cycle is the biogeochemical cycle by which carbon is • Carbonated water (clear soda or exchanged among the biosphere, pedosphere, geosphere, hydro- seltzer water) sphere and atmosphere of Earth. Along with the nitrogen cycle • Hot water (50°C) and the water cycle, the carbon cycle comprises a sequence of • Cold water (5°C) events key to making Earth capable of sustaining life; it describes • Two 12 oz. plastic bowls the movement of carbon as it is recycled and reused throughout • Two small (3 oz.) clear plastic cups the biosphere. Activity 2 LESSON OBJECTIVES: • Vinegar Students will be able to: • Baking soda 1. Observe the density of carbon dioxide. • Universal indicator 2. Demonstrate the effect of temperature on the amount of car- • Water bon dioxide that will dissolve in water. • Water and indicator cup 3. Test the effect of carbon dioxide on the pH of water. • Baking soda and vinegar 4. Describe how these properties of carbon dioxide relate to the • Mini spoon carbon cycle. • Universal indicator pH color chart ESSENTIAL QUESTION: Activity 3 How does matter cycle through an ecosystem? • Bubble generator* • Dry ice (8 oz.) TOPICAL ESSENTIAL QUESTION: • 9 oz. plastic cup What is carbon’s role in life on Earth? • Water (enough to fill bubble generator half-full) • Plastic spoon TOTAL DURATION: • Dish soap (5 mL) 15-20 min. pre-lab prep time; 40-50 min. class time • Cotton glove SAFETY PRECAUTIONS: *A bubble generator can be purchased from • Avoid contact of all chemicals with eyes and skin.
    [Show full text]
  • Recycling Nitrogen and Sulfur in Grass-Clover Pastures
    Recycling Nitrogen and Sulfur in Grass-Clover Pastures 4.tj AGRICULTURAL EXPERIMENT STATION OREGON STATE UNIVERSITY CORVALLIS STATION BULLETIN 610 JUNE 1972 Contents Abstract 3 Introduction 3 The Nitrogen Cycle 3 The Sulfur Cycle 8 Summary 11 LiteratureCited 12 AUTHORS: M. D. Dawson is a professor of soils science and W. S. McGuire is a professor of agronomy, Oregon State University. ACKNOWLEDGMENTS: The authors are indebted to Viroch Impithuksa for conducting the carbon-nitrogen-phosphorus-sulfur (C:N:P:S) analyses and to J. L. Young for invaluable assistance in writing the manuscript. Recycling Nitrogen and Sulfur in Grass-Clover Pastures M. D. DAWSOTJ and W. S. McGuii Abstract Indeed, the soil-plant-animal chain is a fascinating intra-system where the Improved grass-clover pastures uti-nitrogen and sulfur cycles have practi- lized under high stockingsystems cal significance. epitomize conservation management at The management practicescom- its best. Under intensive grazing andpared are (1) unimproved, indigenous in spite of nitrogen (N) or sulfur (S) grasses, (2) fertilized grass-clover cut losses through leaching, volatilization, for hay, and (3) fertilized grass-clover or sales of meat and wool from the intensively grazed. The purpose of this farm, good management permits sym- bulletin is to review certain features bioticfixationofnitrogen and re-of soil-plant-animal interrelationships cycling of N and S in amounts needed as they influence soil nitrogen and sul- for top production. In the comparisons fur cycles under different management of management practicesinvolvingpractices in grass-clover pastures. unimproved indigenous grasses with (1) fertilized grass-clover cut for hay and (2) fertilized grass-clover inten- The Nitrogen Cycle sivelygrazed,thisbulletin reviews In western Oregon, annual yields of certainfeaturesof soil-plant-animal6,000 pounds and 12,000 pounds of interrelationships as they influence soildry matter per acre are common on nitrogen and sulfur cycles.
    [Show full text]
  • Century: Grand Challenges in the Nitrogen Cycle
    Feeding the World in the 21st Century: Grand Challenges in the Nitrogen Cycle National Science Foundation Arlington, Virginia November 9–10, 2015 PI: Nicolai Lehnert (Department of Chemistry, University of Michigan) Co-organizers: Gloria Coruzzi (Department of Biology, New York University) Eric Hegg (Department of Biochemistry and Molecular Biology, Michigan State University) Lance Seefeldt (Department of Chemistry and Biochemistry, Utah State University) NSF liaison: Timothy Patten (Division of Chemistry) Co-funded by the Chemical, Bioengineering, Environmental, and Transport Systems Division Funded under NSF Award Number 1550842 The nitrogen (N) cycle is one of the most important biogeochemical cycles on Earth, as nitrogen is an essential nutrient for all known life forms. Natural processes, driven mostly by microbes in association with leguminous plants, fix and deliver around 120 megatons per year of bioavailable nitrogen to the biosphere. Humans have greatly augmented these processes, mostly through the industrial Haber-Bosch process and planting of leguminous crops, contributing at least the same amount. It is estimated that around 40% of the human population depends on the human contribution to the nitrogen cycle. The purpose of this workshop, held November 9–10, 2015 at the National Science Foundation headquarters in Arlington, Virginia, was to identify ways that chemists can contribute to understanding and improving the nitrogen cycle in the context of agriculture and environmental management. Participants noted two major imbalances in the nitrogen cycle: insufficient bioavailable nitrogen in soils in the developing world, and too much inorganic nitrogen in the developed world. Lack of bioavailable nitrogen in the developing world leads to low crop yields and diets with insufficient protein.
    [Show full text]
  • A Reduced, Abiotic Nitrogen Cycle Before the Rise Of
    236 Appendix 1 A REDUCED, ABIOTIC NITROGEN CYCLE BEFORE THE RISE OF OXYGEN Ward, Lewis M, James Hemp, and Woodward W. Fischer. In preparation. Abstract: Nitrogen is a critical element for all known life, where it is used in essential biomolecules such as amino and nucleic acids. However, most nitrogen on Earth is found as relatively inert N2 in the atmosphere, and must be “fixed” to more bioavailable forms before it can be incorporated into biomass. Fixed nitrogen can further be interconverted between a range of oxidized and reduced forms in a complex web of biogeochemical reactions driven by diverse microorganisms in order to conserve energy in addition to using nitrogen for biosynthesis. This redox cycling is a function of the oxidation state of Earth surface environments, and therefore cannot be assumed to have been present on the early Earth, particularly before the evolution of oxygenic photosynthesis and oxygenation of the atmosphere. Here, we consider which steps in the modern nitrogen cycle may have been present on the early Earth before the introduction of molecular oxygen into biology and geochemistry. This includes incorporation of biochemical and phylogenetic evidence for the antiquity of microbial nitrogen metabolisms, as well as geochemical- and photochemical- model based estimates for abiotic processes. We conclude that before the evolution of oxygenic photosynthesis, the nitrogen cycle was largely abiotic, consisting of atmospheric and geological transformations of reduced nitrogen species. Depending on the productivity of the early biosphere, the nitrogen demand of the biosphere may have 237 been met by abiotic nitrogen fixation processes, consistent with a late origin of biological nitrogen fixation via the nitrogenase enzyme, or an early evolution of nitrogenase for cyanide uptake followed by later cooption for N2 fixation.
    [Show full text]