Lecture 6 - Lecture 6 Biogeochemical Cycles Carbon Cycle 1...

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Lecture 6 Biogeochemical Cycles Carbon Cycle 1. Greatly influenced by living organisms 2. Atmospheric CO2 main source of carbon for terrestrial organisms 3. Only minimal amount of carbon is found in the atmosphere 4. Increasing concentrations of CO2 in the atmosphere may change climates and interfere with ecosystems 5. Carbon Dioxide is a nutrient BUT some scientists are convinced it is also a pollutant Nitrogen Cycle 1. Nitrogen makes up 78 % of the Earth's Atmosphere 2. Few organisms can use elemental (atmospheric) nitrogen 3. Organisms that convert elemental nitrogen into useable forms by green plants are called nitrogen fixing bacteria 4. Usable forms for plants are nitrites and nitrates 5. Lightning also converts elemental nitrogen to nitrates that are usable by green plants Phosphorus Cycle 1. Exists in rocks and soil as inorganic Phosphate 2. When weathering of rock occurs phosphates are released 3. Does not have a gas phase 4. Is recycled only if wastes containing phosphorus are deposited on the soil 5. There are deep sinks of phosphorus in oceans and the sinks remain for an extremely long time Sulfur Cycle
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1. Sulfur has many oxidation states from inorganic processes 2. Bacteria sequester sulfur in biogenic deposits or release it to the environment 3. Human activities release large quantities of sulfur from burning fossil fuels 4. Sulfur dioxide and sulfate aerosols cause health problems in humans 5. Sulfur dioxide damages building 6. Sulfur dioxide also damages vegetation 7. Sulfur forms absorb UV radiation and create cloud cover that cools cities and may be involved in the reduction of CO2, hence reducing the Greenhouse Effect. HYDROLOGIC CYCLE 1. Circulation of water as it evaporates from land, water, and organisms 2. Enters the atmosphere, condenses, and precipitates to the earth's surface. 3. Moves underground by filtration 4. Enters rivers, lakes, and seas as runoff 5. Moderates the earth's temperature 6. Plants play an important role in by absorbing groundwater and pumping it into the atmosphere by transpiration 7. Solar radiation drives this cycle through evaporation of the surface water Lecture 7A World Population is 6,369,686,884 1.17 % Gr. / year Earth Area: 510.072 million sq km Land: 148.94 million sq km Water: 361.132 million sq km
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Three Major Portions of the Earth's Surface 1. Atmosphere: "Air" N2, O2, CO2 A) Troposphere: sea level to 11 miles up B) Stratosphere: 11-30 miles up C) Ozone layer or shield: right above the stratosphere 2. Hydrosphere: Liquid water A) Fresh (non salt) water in lakes, ponds, streams, and polar ice caps B) Salt water (marine): oceans 3. Lithosphere: Earth's crust WEATHER: short term conditions in the troposphere in any given area CLIMATE: average long-term weather in any given area ECOLOGICAL TERMINOLOGY 1. Biosphere: all portions of the earth's surface where living organisms are found 2. ECOSYSTEMS: ALL POPULATIONS IN A GIVEN AREA (COMMUNITY) TO INCLUDE BIOTIC AND ABIOTIC ENVIRONMENT 3. Community: all populations that are found in a PARTICULAR habitat
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This note was uploaded on 04/20/2008 for the course SCI 1101 taught by Professor Jbrock during the Fall '07 term at Kennesaw.

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Lecture 6 - Lecture 6 Biogeochemical Cycles Carbon Cycle 1...

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