chapter_08 - Recycling of the Elements: Carbon &...

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Unformatted text preview: Recycling of the Elements: Carbon & Nutrient Cycles Carbon Chapter 8 Dr. Emily Berndt Fundamentals of the Climate System EAS 253 I. Overview I. a. The recycling of the elements among The components of the Earth System is a key to the continual functioning of Earth key b. Carbon is most essential c. The Carbon cycle is a hierarchy of The subcycles that operate on different time scales scales II. Systems approach to the Carbon Cycle Carbon II. Systems approach to the Carbon Cycle II. a. The life cycle of a carbon atom is repeated The nearly 500 times before a leak occurs nearly i. Soil erodes and is transported to ocean by Soil rivers rivers ii. Sediments settle to seafloor iii. Carried into subduction zone Converted to CO2 Included in metamorphic or sedimentary rocks iv. Could spend millions of years in a rock v. Weathering releases CO2 as inorganic carbon reacts with O2 reacts b. Terrestrial organic carbon cycle may b. Terrestrial operate on short and long time scales operate II. Systems approach to the Carbon Cycle Ic. Carbon Reservoir Dynamics I. c. Carbon Reservoir Dynamics i. 1. 2. Mantle reservoirs near earth’s surface Carbon in methane Carbon in sedimentary rock ii. iii. How does the system of reservoir respond to perturbation (i.e. CO2 from fossil fuels) fossil Reservoirs 1. 2. 3. 4. Temporary repositories for material that flows through them Size changes in response to changes in inflow and outflow Characterized by amount of material that it is holding at a particular time Mass, volume, moles per unit time System components are constant with time Balance between inflow and outflow Average length of time in a substance spends in a given reservoir at steady Average state state RT= size at steady state/ inflow/ outflow Helps to monitor the recycling of elements Indicator of how long it takes reservoir to respond to imbalances in flow Characteristic response time- residence time defined at steady state when a Characteristic system is not in steady state system A disturbance from steady state it diminishes to about 38% (1/e) of its original size in one disturbance characteristic response time characteristic iv. Steady state 1. 2. v. Residence time 1. 2. 3. 4. 5. Carbon Reservoirs Carbon Seasonal Fluctuations in Atmospheric CO2 Atmospheric Carbon Reservoir Atmospheric Effect of Changes on CO2 Effect concentration on the photosynthetic rate of plants photosynthetic II. Systems approach to the Carbon Cycle II. d. Oxidized and Reduced Carbon i. - Oxidized carbon – carbon combined with oxygen Skeletons atmospheric CO2 rust on iron more inert ii. Reduced carbon – carbon combined with other Reduced carbon atoms, hydrogen, or nitrogen carbon organic carbon chemically reactive III. Short-Term Organic Carbon Cycle III. a. Involves processes on daily to seasonal time scales i. Photosynthesis ii. Respiration iii. Decomposition b. The key is the conversions of inorganic carbon to organic carbon through The photosynthesis photosynthesis c. Impact on the Global Cycle i. Primary productivity 1. Amount of organic carbon produced by photosynthesis (time/ area) Amount 2. Depends on population of primary producers 2. ii. Primary Producers -Plants 1. 2. i. Some species are more productive Chemical reaction between CO2 and H2O form organic matter and form oxygen oxygen Consumers use energy other organisms create via photosynthesis III. Short-Term Organic Carbon Cycle III. c. Marine Organic Carbon Cycle on short time scales i. Producers and consumers 1. 2. - Phytoplankton are producers Live in photic zone Upper 100m of ocean 3. Zooplankton are consumers Transfer of CO2 and nutrients to the deep ocean and Settling of organic matter Decomposition in deep water ii. Biological pump 1. 2. 3. Balanced by upwelling Impact on ocean chemistry a. b. Surface waters are depleted of carbon, phosphate, and nitrate Stopping the pump -Oceans become more uniform in composition -Few 1,000 years Shells of phytoplankton Shells diatom coccolithophorid radiolarian foraminifer The Marine Biological Pump The IV. The Long-Term Organic Carbon Cycle Carbon a. On longer time scales, the processes a. must be closely in balance must b. Geological processes become important b. controls of atmospheric CO2 controls c. Carbon burial in sedimentary rocks d. Weathering of organic carbon in d. sedimentary rocks sedimentary Short-term & Long-term organic carbon cycles carbon V. The Inorganic Carbon Cycle V. ...
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This note was uploaded on 04/11/2011 for the course EAS 253 taught by Professor Dr.emilyberndt during the Spring '11 term at Saint Louis.

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