BIOGEOCHEMICAL CYCLES ‘Fundamentals’ of biogeochemical cycles • All matter cycles...it is neither created nor destroyed... • As the Earth is essentially a.
Download ReportTranscript BIOGEOCHEMICAL CYCLES ‘Fundamentals’ of biogeochemical cycles • All matter cycles...it is neither created nor destroyed... • As the Earth is essentially a.
BIOGEOCHEMICAL CYCLES ‘Fundamentals’ of biogeochemical cycles • All matter cycles...it is neither created nor destroyed... • As the Earth is essentially a closed system with respect to matter, we can say that all matter on Earth cycles . • Biogeochemical cycles: the movement (or cycling) of matter through a system by matter we mean: elements (carbon, nitrogen, oxygen) or molecules (water) so the movement of matter (for example carbon) between these parts of the system is, practically speaking, a biogeochemical cycle The Cycling Elements: macronutrients : required in relatively large amounts "big six": carbon , hydrogen , oxygen , nitrogen , phosphorous sulfur other macronutrients: potassium , calcium , iron , magnesium micronutrients : required in very small amounts, (but still necessary) boron (green plants) copper (some enzymes) molybdenum (nitrogen-fixing bacteria) ATMOSPHERE LITHOSPHERE HYDROSPHERE ECOSPHERE 5 of the most important cycles are the water, carbon, nitrogen, sulfur, and phosphorus. HYDROLOGIC CYCLE Condensation Rain clouds Transpiration Transpiration from plants Precipitation to land Precipitation Runoff Surface runoff (rapid) Evaporation Precipitation Evaporation from land Evaporation from ocean Precipitation to ocean Surface runoff (rapid) Infiltration and Percolation Groundwater movement (slow) Ocean storage HYDROLOGIC CYCLE CONNECTS ALL OF THE CYCLES AND SPHERES TOGETHER HUMAN IMPACTS TO WATER CYCLE 1. Water withdrawal from streams, lakes and groundwater. (salt water intrusion and groundwater depletion) 2. Clear vegetation from land for agriculture, mining, road and building construction. (nonpoint source runoff carrying pollutants and reduced recharge of groundwater) 3. Degrade water quality by adding nutrients(NO2, NO3, PO4) and destroying wetlands (natural filters). 4. Degrade water clarity by clearing vegetation and increasing soil erosion. Water Quality Degradation MARINE CARBON CYCLE Diffusion between atmosphere and ocean Carbon dioxide dissolved in ocean water photosynthesis Combustion of fossil fuels aerobic respiration Marine food webs Producers, consumers, decomposers, detritivores incorporation death, into sediments sedimentation uplifting over geologic time sedimentation Marine sediments, including formations with fossil fuels Figure 4-29a Page 78 TERRESTRIAL CARBON CYCLE Atmosphere (most carbon is in carbon dioxide) Combustion of fossil fuels volcanic action photosynthesis Terrestrial rocks weathering combustion of wood (for aerobic clearing land; or for fuel respiration Land food webs producers, consumers, decomposers, detritivores Soil water (dissolved carbon) leaching runoff death, burial, compaction over geologic time sedimentation Peat, fossil fuels Explain Natural Sources of Carbon •Death of plants and animals •Animal waste •Atmospheric CO2 •Weathering •Methane gas from cows (and other ruminants) •Aerobic respiration from terrestrial and aquatic life Sources of Carbon from Human Activity •Burning wood or forests •Cars, trucks, planes •Burning fossil fuels such as coal, oil and natural gas to produce heat and energy. Carbon in Oceans • Additional carbon is stored in the ocean. • Many animals pull carbon from water to use in shells, etc. • Animals die and carbon substances are deposited at the bottom of the ocean. • Oceans contain earth’s largest store of carbon. 14 CO2 emissions from fossil fuel (billion metric tons of carbon equivalent) 13 High projection 12 11 10 Low projection 9 8 7 6 5 4 3 2 1 0 1850 1900 1950 Year 2000 2030 Figure 4-30 Page 79 Slide 38 IMPORTANCE OF CARBON CYCLE CARBON IS THE BACKBONE OF LIFE! The Nitrogen Cycle Sources • • • • • • Lightning Inorganic fertilizers Nitrogen Fixation Animal Residues Crop residues Organic fertilizers Forms of Nitrogen • • • • • • • Urea CO(NH2)2 Ammonia NH3 (gaseous) Ammonium NH4 Nitrate NO3 Nitrite NO2 Atmospheric Dinitrogen N2 Organic N Global Nitrogen Reservoirs Nitrogen Reservoir Atmosphere Metric tons nitrogen 3.9*1015 Actively cycled Ocean soluble salts Biomass 6.9*1011 5.2*108 Yes Yes Land organic matter Biota 1.1*1011 2.5*1010 Slow Yes No Roles of Nitrogen • Plants and bacteria use nitrogen in the form of NH4+ or NO3• It serves as an electron acceptor in anaerobic environment • Nitrogen is often the most limiting nutrient in soil and water. Nitrogen is a key element for • amino acids • nucleic acids (purine, pyrimidine) • cell wall components of bacteria (NAM). Nitrogen Cycles • • • • • Ammonification/mineralization Immobilization Nitrogen Fixation Nitrification Denitrification N2 N2O NH4 NO2 R-NH2 NO NO2 NO3 Which of the following is not part of the Nitrogen Cycle? A) Ammonification B) Nitrification C) Denitrosation D) Nitrogen Fixation E) Denitrification In what form(s) do plants and bacteria use nitrogen? A) NH4+ B) NH3 C) NO3D) A and C E) All of the above What is the molecular formula for ammonium? A) NH4+ B) NH3 C) NO3 D) NO2 E) none of the above Ammonification or Mineralization N2 N2O NH4 NO2 R-NH2 NO NO2 NO3 Mineralization or Ammonification • Decomposers: earthworms, termites, slugs, snails, bacteria, and fungi • Uses extracellular enzymes initiate degradation of plant polymers • Microorganisms uses: • Proteases, lysozymes, nucleases to degrade nitrogen containing molecules • Plants die or bacterial cells lyse release of organic nitrogen • Organic nitrogen is converted to inorganic nitrogen (NH3) • When pH<7.5, converted rapidly to NH4 • Example: Urea NH3 + 2 CO2 Immobilization • The opposite of mineralization • Happens when nitrogen is limiting in the environment • Nitrogen limitation is governed by C/N ratio • C/N typical for soil microbial biomass is 20 • C/N < 20 Mineralization • C/N > 20 Immobilization Nitrogen Fixation N2 N2O NH4 NO2 R-NH2 NO NO2 NO3 Nitrogen Fixation • Energy intensive process : • N2 + 8H+ + 8e- + 16 ATP = 2NH3 + H2 + 16ADP + 16 Pi • Performed only by selected bacteria and actinomycetes • Performed in nitrogen fixing crops (ex: soybeans) Microorganisms fixing • • • • • Azobacter Beijerinckia Azospirillum Clostridium Cyanobacteria • Require the enzyme nitrogenase • Inhibited by oxygen • Inhibited by ammonia (end product) Rates of Nitrogen Fixation N2 fixing system Rhizobium-legume Nitrogen Fixation (kg N/hect/year) 200-300 Cyanobacteria- moss 30-40 Rhizosphere associations Free- living 2-25 1-2 Immobilization is the opposite of which process in the cycle? A) Mineralization B) Nitrification C) Immobilization D) Nitrogen Fixation E) Denitrification What process takes place when nitrogen is limiting in the environment? A) Mineralization B) Nitrification C) Immobilization D) Nitrogen Fixation E) Denitrification Which has the highest rate of nitrogen fixation? A) Rhizobium-legume B) Cynaobacteria-moss C) Rhizosphere associations D) Free-living E) Azobacter Applications to wetlands • • • • • Occur in overlying waters Aerobic soil Anaerobic soil Oxidized rhizosphere Leaf or stem surfaces of plants Bacterial Fixation • Occurs mostly in salt marshes • Is absent from low pH peat of northern bogs • Cyanobacteria found in waterlogged soils Nitrification N2 N2O NH4 NO2 R-NH2 NO NO2 NO3 Nitrification Two step reactions that occur together : • 1rst step catalyzed by Nitrosomonas 2 NH4+ + 3 O2 2 NO2- +2 H2O+ 4 H+ • 2nd step catalyzed by Nitrobacter • 2 NO2 + O2 2 NO3 • Optimal pH is between 6.6-8.0 • If pH < 6.0 rate is slowed • If pH < 4.5 reaction is inhibited In which type of wetlands do you thing Nitrification occurs? Denitrification N2 N2O NH4 NO2 R-NH2 NO NO2 NO3 Denitrification • Removes a limiting nutrient from the environment • 4NO3 + C6H12O6 2N2 + 6 H20 • Inhibited by O2 • Not inhibited by ammonia • Microbial reaction • Nitrate is the terminal electron acceptor Looking at the Nitrogen cycle through the eye of NH4 Denitrication is inhibited by A) NH3 B) NH4+ C) NO2D) O2 The second step of Nitrification is catalyzed by A) Nitrosomonas B) Clostridium C) Azobacter D) Nitrobacter E) Beijerinckia Which pH is within the optimal range for nitrication? A) 1.5 B) 4.6 C) 7.1 D) 8.7 E) 10.9 Surfac e water Low [NH4] Oxidized layer Reduce d soil layer Slow Diffusion Biodegradati on C/N <20 C/N >20 [NH4] HIGH Surfac e water nitrificatio n Low [NH4] Oxidized layer Reduce d soil layer Slow Diffusion [NH4] HIGH [NO3] high N2 Surfac e water Oxidized layer Reduce d soil layer [NO3] high Leaching [NO3] Low Denitrification PHOSPHOROUS CYCLE mining excretion FERTILIZER GUANO agriculture uptake by autotrophs MARINE FOOD WEBS weathering DISSOLVED IN OCEAN WATER uptake by autotrophs leaching, runoff DISSOLVED IN SOIL WATER, LAKES, RIVERS death, decomposition sedimentation death, decomposition weathering settling out uplifting over geologic time MARINE SEDIMENTS ROCKS LAND FOOD WEBS HUMAN IMPACTS TO PHOSPHOROUS CYCLE 1. Humans mine LARGE quantities of phosphate rock to use in commercial fertilizers and detergents. Phosphorous is NOT found as a gas, only as a solid in the earth’s crust. It takes millions to hundreds of millions of years to replenish. 2. Phosphorous is held in the tissue of the trees and vegetation, not in the soil and as we deforest the land, we remove the ability for phosphorous to replenish globally in ecosystems. 3. Cultural eutrophication – ad excess phosphate to aquatic ecosystems in runoff of animal wastes from livestock feedlots, runoff of commercial phosphate fertilizers fro cropland, and discharge of municipal sewage. IMPORTANCE OF PHOSPHOROUS CYCLE • 1.Phosphorous is an essential nutrient of both plants and animals. • 2. It is part of DNA molecules which carry genetic information. • 3. It is part of ATP and ADP) that store chemical energy for use by organisms in cellular respiration. • 4. Forms phospholipids in cell membranes of plants and animal cells. • 5. Forms bones, teeth, and shells of animals as calcium phosphate compounds. SULFUR CYCLE Water Sulfur trioxide Acidic fog and precipitation Sulfuric acid Ammonia Oxygen Sulfur dioxide Ammonium sulfate Hydrogen sulfide Plants Volcano Dimethyl sulfide Industries Animals Ocean Sulfate salts Metallic sulfide deposits Decaying matter Sulfur Hydrogen sulfide HUMAN IMPACTS TO SULFUR CYCLE Approximately 1/3 of all sulfur emitted into atmosphere comes from human activities. • 1. Burning sulfur containing coal and oil to produce electric power (SOx = acid deposition). • 2. Refining petroleum – (SOx emissions) • 3. Smelting to convert sulfur compounds of metallic minerals into free metals (Cu, Pb, Zn) • 4. Industrial processing. IMPORTANCE OF SULFUR CYCLE 1. Sulfur is a component of most proteins and some vitamins. 2. Sulfate ions (SO4 2- ) dissolved in water are common in plant tissue. They are part of sulfur-containing amino acids that are the building blocks for proteins. 3. Sulfur bonds give the three dimensional structure of amino acids. 4. Many animals, including humans, depend on plants for sulfur-containing amino acids. The Oxygen cycle 1. The Phosphorus Cycle takes A. Short time B. 20 years to fully cycle through C. 100 years to cycle through D. Geological Timescal 2. What percentage of sulfur is emmited buy human activity? A. .01% B. 20% C. 33.3% D. 66.7% E. Over 90% 3. The vast majority of oxygen in the ecosphere is in A. Outer space B. Lithosphere C. Atmosphere D. Hydrosphere PHOTOSYNTHESIS Photosynthesis: occurs within the chloroplasts of green plants. The photosynthetic membranes are arranged in flattened sacs called the thylakoids. 6CO2 + 12H2O C6H12O6 + 6O2 + 6H2O light (reactants) Function: Chemical energy Storage for cell use (products) CELLULAR RESPIRATION Cellular Respiration occurs in light simultaneously with photosynthesis. It occurs in the cytoplasm and mitochondria. It is the reverse reaction of photosynthesis. Function = chemical energy release C6H12O6 + 6O2 + 6H2O chemical energy 6CO2 + 12H2O+ Primary Productivity Connection • Gross Primary Productivity (GPP) – the rate at which an ecosystem’s producers capture and store a given amount of chemical energy as biomass in a given period of time. • Net Primary Productivity (NPP) – the rate at which all the plants in an ecosystem produce net useful energy; equal to the difference between energy produced through photosynthesis and energy used for cellular respiration. “GOOD OZONE UP HIGH” PHOTOCHEMICAL SMOG “BAD OZONE DOWN LOW” OZONE DEPLETION ACID DEPOSITION CULTURAL EUTROPHICATION Cultural Eutrophication & Anoxia • Eutrophication: natural process; over 1000’s of years, lakes fill in with sediment, become marshes then dry land • Cultural Eutrophication: same process, but speeded enormously by loading with “limiting nutrients” (typically P, sometimes N) ROCK CYCLE HUMAN IMPACTS ON THE ROCK CYCLE • 1. Humans are excavating minerals and removing rock material. It takes millions of years for rock to form. • 2. Humans remove sediments for building materials. This removes sediments that may form sedimentary rocks in the future. • 3. Humans are filling in wetlands (peatlands), area that will form future coal beds. 1. Which part of the atmosphere is the ozone layer right above? A. Stratosphere B. Troposphere C. Mesosphere D. Thermosphere 2. How long does it take rock formations to form? A. 1,000 years B. 10,000 years C. 100,000 years D. 1,000,000 years E. 10,000,000 years 3. What is cultural eutrophication good for? A. Fish B. Dissolved Oxygen in the lake C. algae D. clear lake Works Cited 1. http://science.pppst.com/carboncycle.html 2. westernreservepublicmedia.org/earthmotion3/image s/Carbon_Cycle.ppt 3. clima-dods.ictp.it/d3/annalisa/ocean_sv/lecture1.ppt 4. www.geology.wmich.edu/Koretsky/envs2150/Pcycl e_1.ppt