BILD Biochemical cycles

BILD Biochemical cycles - BILD 3 12 May 2008 BIOGEOCHEMICAL...

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BILD 3 12 May 2008 Woodruff: biogeochemical cycles 1 1 BIOGEOCHEMICAL CYCLES SUN P H C NUTRIENT --------------- DECOMPOSERS POOL (reservoir) ATMOSPHERE SOIL OCEANS LITHOSPHERE 2 Chemical Cycling • Gaseous carbon, oxygen, sulfur, nitrogen occur in the atmosphere and cycle globally • Less mobile elements such as phosphorus, potassium, calcium cycle on a more local level • Cycling involves organic and inorganic reservoirs • Living organisms play critical roles in most cycles in reservoir transfer processes LE 54-16 Fossilization Reservoir a Reservoir b Reservoir c Reservoir d Organic materials available as nutrients Organic materials unavailable as nutrients Inorganic materials available as nutrients Inorganic materials unavailable as nutrients Living organisms, detritus Coal, oil, peat Atmosphere, soil, water Minerals in rocks Assimilation, photosynthesis Burning of fossil fuels Weathering, erosion Formation of sedimentary rock Respiration, decomposition, excretion 4 Biogeochemical Cycles • In studying cycling of water, carbon, nitrogen, and phosphorus, ecologists focus on five factors: 1. Each chemical’s biological importance 2. Forms in which each chemical is available or used by organisms 3. Major reservoirs for each chemical 4. Key processes driving movement of each chemical through its cycle 5. The living organisms responsible for key links in the cycle LE 54-17a Transport over land Precipitation over land Evaporation from ocean Precipitation over ocean Net movement of water vapor by wind Solar energy Evapotranspiration from land Runoff and groundwater Percolation through soil WATER CYCLE ATMOSPHERE 0.001% 6 WATER CYCLE Approx. 500 g water are transpired for each gram of terrestrial primary productivity (>10 17 g/yr). Transpiration therefore accounts for 93% of terrestrial evapotranspiration Total precipitation: 378 x 10 18 g/yr Atmospheric pool: 13 x 10 18 g/yr Therefore water in atmospheric pool recycles 29 times/year (11-14 days)
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BILD 3 12 May 2008 Woodruff: biogeochemical cycles 2 LE 54-17b Cellular respiration Burning of fossil fuels and wood Carbon compounds in water Photosynthesis Primary consumers Higher-level consumers Detritus Decomposition CO 2 in atmosphere CARBON CYCLE ATMOSPHERE 0.03% 8 CARBON CYCLE Transit time of atmospheric C is approx 8 years CO 2 absorbs or reflects long wavelength infrared light It does not absorb or reflect the longer wave lengths entering the atmosphere but it does reflect back to earth the infrared radiant energy emanating from the surface of the sunlit earth. This energy warms the air. More atmospheric CO 2 will trap more energy and cause more warming. This is the so-called Greenhouse Effect. 9
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This note was uploaded on 12/03/2008 for the course BILD 3 taught by Professor Wills during the Spring '07 term at UCSD.

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BILD Biochemical cycles - BILD 3 12 May 2008 BIOGEOCHEMICAL...

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