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Biogeochemical cycle and impact of anthropogenic activity by shashi shekhar singh SES,JNU,New Delhi
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Biogeochemical cycle and impact of anthropogenic activity by shashi shekhar singh SES,JNU,New Delhi

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Presented on 20/11/2012

Presented on 20/11/2012

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  • Over the past three decades, considerable understanding has been accumulated about the patterns and magnitudes of the circulation of these critical elements. Humans are altering these cycles and it is essential to understand the changes induced by anthropogenic activity.
  • Over the past three decades, considerable understanding has been accumulated about the patterns and magnitudes of the circulation of these critical elements. Humans are altering these cycles and it is essential to understand the changes induced by anthropogenic activity.
  • Figure 3.26 Natural capital: simplified model of the hydrologic cycle.
  • Figure 3.27 Natural capital: simplified model of the global carbon cycle. Carbon moves through both marine ecosystems (left side) and terrestrial ecosystems (right side). Carbon reservoirs are shown as boxes; processes that change one form of carbon to another are shown in unboxed print. QUESTION: What are three ways in which your lifestyle directly or indirectly affects the carbon cycle? (From Cecie Starr, Biology: Concepts and Applications, 4th ed., Pacific Grove, Calif.: Brooks/Cole, © 2000)
  • Figure 3.31 Natural capital: simplified model of the phosphorus cycle. Phosphorus reservoirs are shown as boxes; processes that change one form of phosphorus to another are shown in unboxed print. QUESTION: What are three ways in which your lifestyle directly or indirectly affects the phosphorus cycle? (From Cecie Starr and Ralph Taggart, Biology: The Unity and Diversity of Life, 9th ed., Belmont, Calif.: Wadsworth © 2001)
  • Figure 3.32 Natural capital: simplified model of the sulfur cycle. The movement of sulfur compounds in living organisms is shown in green, blue in aquatic systems, and orange in the atmosphere. QUESTION: What are three ways in which your lifestyle directly or indirectly affects the sulfur cycle?
  • Transcript

    • 1. Presented byShashi Shekhar Singh SES,JNU,New Delhi
    • 2.  Identify and describe the flow of nutrients in each biogeochemical cycle Explain the impact that humans have on the biogeochemical cycles
    • 3.  An ecosystem survives by a combination of energy flow and matter recycling.
    • 4. Nutrient Cycles: Global Recycling Global Cycles recycle nutrients through the earth’s air, land, water, and living organisms. Nutrients are the elements and compounds that organisms need to live, grow, and reproduce. Biogeochemical cycles move these substances through air, water, soil, rock and living organisms.
    • 5. Biogeochemical cycles are cycling of chemical elements or nutrients from the abiotic environment to organism and then back to the abiotic environment.The pathway by which chemical circulate through ecosystem involve both living (biotic) and nonliving (geological) components.Involvedorganism (bio), environmental geology (geo) & chemical changes (chemical)
    • 6. Most important are: The water cycle The carbon cycle The phosphorus cycle The Sulfur cycle The nitrogen cycle The circulation of chemicals in these biogeochemical cycles and interactions between cycles are critical for the maintenance of terrestrial, freshwater and marine ecosystems. Global climate change, temperature, precipitation and ecosystem stability are all dependent upon biogeochemical cycles
    • 7. There are strong forces of attraction between molecules of waterWater exists as a liquid over a wide temperature rangeLiquid water changes temperature slowlyIt takes a large amount of energy for water to evaporateLiquid water can dissolve a variety of compoundsWater expands when it freezes.
    • 8. Water Cycle Rain clouds Condensation Transpiration Evaporation Precipitation Transpiration to land from plantsPrecipitation Precipitation Evaporation Surface runoff from land Evaporation Runoff from ocean Precipitation (rapid) to oceanInfiltration and SurfacePercolation runoff (rapid) Groundwater movement (slow) Ocean storage
    • 9. 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.
    • 10.  Mining Fossil Fuels Clearing Vegetation: www.pewclimate.org/ images/figure4.gif
    • 11. Phosphorous Cycle mining Fertilizerexcretion Guano agriculture uptake by weathering uptake by autotrophs autotrophs Marine Dissolved leaching, runoff Dissolved Land Food in Ocean in Soil Water, Food Webs Water Lakes, Rivers Webs death, death, decomposition decompositionsedimentation settling out weathering uplifting over geologic time Marine Sediments Rocks
    • 12.  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.
    • 13. Sulfur Cycle Sulfur Water Acidic fog and Sulfuric acid precipitation trioxide Ammonia Ammonium Oxygen sulfateSulfur dioxide Hydrogen sulfide Plants Dimethyl Volcano sulfide Industries AnimalsOcean Sulfate salts Metallic Decaying matter Sulfur sulfide deposits Hydrogen sulfide
    • 14. 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
    • 15. Nitrogen Cycle Legume nodule bacteria needs 10g of glucose to fix 1g of nitrogen whereasfree living bacteria require 100g of glucose to fix same amount (Odum 1983)
    • 16. We alter the nitrogen cycle by: Adding gases that contribute to acid rain (Smil, 2000) Adding nitrous oxide to the atmosphere through farming practices (Vitousek et al., 1997) which can warm the atmosphere and deplete ozone (Chapin et al. 2002). Contaminating ground water from nitrate ions in inorganic fertilizers Releasing nitrogen into the troposphere through deforestation.
    • 17. Effects of Human Activities on the Nitrogen Cycle Ecosystem processes can increase with nitrogen fertilization,but anthropogenic input can also result in nitrogen saturation, which weakens productivity and can kill plants (Vitousek et al., 1997) → algae blooms Decreases in biodiversity both over land and in the ocean can result if higher nitrogen availability increases nitrogen- demanding species (Aerts and Berendse 1988) NH3 in the atmosphere has tripled as the result of human activities. It acts as an aerosol, decreasing air quality and clinging on to water droplets (acid rain).
    • 18. Thank You