LECTURE 26 CH 23 PATHWAYS OF ELEMENTS IN THE ECOSYSTEMAnswers to ASSIGNMENT from Tuesday LectureUse: U of I’s Nutrition Analysis Tool 2.0: http:www.nat.illinois.edu/mainnat.html1) ideal calories for height, weight, body build, physical activity _______2) calories consumed from plants _______ from animals _______ 3) % from animals ___________ total calories _______4) amount of ecologically equivalent calories consumed relative to a vegetarian total calories = ______ plant calories = ______ = ecological equivalent plant calories animal calories = ______; (_____ x 10) = ______= ecological equivalent animal calories total ecologically equivalent calories = ________ My diet/vegetarian diet = _______/______ = _____ X more ecologically equivalent caloriesthan vegetarian e.g. total calories = 2100; plant calories = 1449 = ecological equivalent plant calories animal calories = 651; (651 x 10) = 6510 = ecological equivalent animal calories total ecologically equivalent calories = 7959 My diet/vegetarian diet = 7959/2100 = 3.8 X more ecologically equivalent caloriesthan vegetarianMAJOR CONCEPTS1. Energy transformation and element cycling are intimately linked.2. A model of ecosystems includes linked compartments (pools): air; organisms; soil/rock; water3. Nutrients move from source compartments to sink compartments; the rate of movement = flux4. The water cycle is physical, not chemical.5. The carbon cycle is closely tied to the flux of energy through the biosphere.6. Nitrogen exists in many oxidized and reduced forms in its cycling.7. The phosphorous cycle involves little change in chemistry; a very large pool in rock; P is ‘lost’ to inactive sediments in oceans/lakes; its cycle is geological in time scale.8. Sulfur exists in many oxidized and reduced forms in its cycling.9. C, N, and S cycles differ greatly under aerobic vs. anaerobic conditions.10. Microorganisms assume significant and diverse roles in N, P, S cycles.I. Elements and their uses in organisms CHO: organic compounds and water N, P, S: proteins, amino acids Ca, P: bones, exoskeleton, cell membranes Fe, Mg: pigments, enzymes (e.g. hemoglobin, chlorophyll K, Na: ionic balance, neural transmissionII. Matter cycles/is reused; energy flows; not reused 483-4Energy transformations and element cycling are intimately linked 23.1, 23.2III. Features of ecosystems Size; boundaries Temporal scaleIV. General model of ecosystems 484-5 23.3 Linked compartments (boxes) (pools) (air; organisms; soil/rock; water) Rate of movement between compartments (arrows) (fluxes) Sinks: boxes with input/output increasing Sources: boxes with input/output decreasing Residence time varies among pools and cyclesV. Water cycle 486-7 23.4 Physical model, not chemical Balance of fluxesVI. Carbon cycle 487-490 23.5 A. Tied to energy flux; solar-powered B. Processes 23.6 Assimilation; dissimilation; redox reactions 483-4 Photosynthesis, respiration, methanogenesis Exchange of CO2 between air and oceans Sedimentation of carbonates 23.7 C. Human alterations: fossil fuel burning; tropical deforestation as new fluxes 482 The “missing sink”: sources>sinks Elevated CO2 experiments: Are plants limited by [Co2]? 492-3 Fig. 2, 3 Can plants sequester more carbon? Does increased CO2 act as fertilizer? D. Geological time scale changes in cycle 490-1 23.9, 23.10 E. Variation in flux and pools among biomesVII. Nitrogen cycle 493-6 23.11 Many oxidized/reduced forms Importance of microbes Nitrogen fixation 23.12 Nitrification Denitrification VIII. Phosphorus cycle 497-8 23.14 Little change in chemistry; form = (PO4-3) Large lithosphere pool; no atmospheric pool Lost to inactive sediments in oceans/lakes Cycle is geological in time scale Importance of mycorrhizae in phosphorus uptakeIX. Sulfur cycle 500-1 23.17Many oxidized/reduced forms Importance of microbesX. Microorganisms assume diverse roles in element cycles 501-2Summary: 1-12, 14,
View Full Document
Unlocking...