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Biogeochemical Cycles EQ: Identify and describe the flow of nutrients in each biogeochemical cycle. Explain the impact that humans have on the biogeochemical cycles. What does biogeochemical mean? • Bio • Geo • Chemical 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 Matter = 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 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 6 of the most important cycles are the water, carbon, nitrogen, sulfur, phosphorus and oxygen. 1. 2. 3. 4. 5. 6. Water Carbon Nitrogen Phosphorous Sulfur Oxygen I. The Water Cycle • Evaporation -Water changes from liquid to gas • Transpiration -Water evaporates from the leaves into the atmosphere. • Condensation - Water vapor (gas) turns into liquid water forming clouds. • Precipitation -Water droplets become large enough to fall to Earth -Rain, snow, sleet, or hail • Surface Runoff - Rain, snow, that flows into streams, rivers, or canals. 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 Effects of Human Activities on Water Cycle • We alter the water cycle by: – Withdrawing large amounts of freshwater. – Clearing vegetation and eroding soils. – Polluting surface and underground water. – Contributing to climate change. Water Quality Degradation II. The Carbon Cycle Where does carbon come from? 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. Fig. 3-27, pp. 72-73 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 Effects of Human Activities on Carbon Cycle We alter the carbon cycle by adding excess CO2 to the atmosphere through: Burning fossil fuels. Clearing vegetation faster than it is replaced. Figure 3-28 III. The Nitrogen Cycle • Where does nitrogen come from? Sources of Nitrogen • • • • • 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 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). Effects of Human Activities on the Nitrogen Cycle • We alter the nitrogen cycle by: – Adding gases that contribute to acid rain. – Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone. – Contaminating ground water from nitrate ions in inorganic fertilizers. – Releasing nitrogen into the troposphere through deforestation. Effects of Human Activities on the Nitrogen Cycle • Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined. Figure 3-30 IV. The Phosphorous Cycle 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. 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. Effects of Human Activities on the Phosphorous Cycle • We remove large amounts of phosphate from the earth to make fertilizer. • We reduce phosphorous in tropical soils by clearing forests. • We add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers. V. The Sulfur Cycle 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. 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 Effects of Human Activities on the Sulfur Cycle • We add sulfur dioxide to the atmosphere by: – Burning coal and oil – Refining sulfur containing petroleum. – Convert sulfur-containing metallic ores into free metals such as copper, lead, and zinc releasing sulfur dioxide into the environment. VI. The Oxygen Cycle The Oxygen cycle 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+ 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