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14 Cards in this Set
- Front
- Back
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Energy flows
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A small fraction of solar radiation is fixed by photosynthetic organisms, but once energy is dissipated as heat, it is never recovered by ecosystem (except as passive energy savings for transport - e.g. ocean or air currents driven by heat and used by organisms.)
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Materials cycle
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Atoms created in stars are used again and again, end up in different pools, and fluxes transfer atoms between pools.
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Turnover time
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The amount of time a molecule stored before it is used again. If the system is in equilibrium, energy storage = energy expenditure.
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Effect of pollution
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Global dimming reducing evaporation rates, because carbon in the clouds reduces water storage capability.
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Phosphorus cycle
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Transfers are so efficient because phosphorus so wanted. Eventually, though, phosphorus gets subsumed into the earth, and with tectonics rearranging, it can be part of sea floor, or in deep lithosphere, for millions of years, until mountains emerge.
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Nitrogen cycle
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Plant with symbiosis with nitrogen fixing bacteria, fixed as ammonia, bacteria take it up, some low-oxygen bacteria convert nitrate into gas, who give it back to atmosphere. (Nitrogen fixation is a gain process, and denitrofication is a loss process)
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Eutrophic
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Nutrient rich, likely to produce or harmful algal blooms (cyanobacteria, toxic dinoflagellates).
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Mesotrophic
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Intermediate nutrient concentrations.
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Oligotrophic
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Low nutrient concentrations, very clear water ("good" water quality for humans and fish)
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Bioaccumulation
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Toxins like DDT, we are exporting to third world economies, TBC's, and other toxins that accompany ingestion aren't completely released.
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Biomagification
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Higher trophic levels accumulate more toxins because they ingest more numerous amounts of the lower trophic levels which ingest these toxins.
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What stabilizes blue water state?
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-nutrient sequestration in long-lived top predators
-upslope moving of nutrients by mobile scavengers and predators -frequent scour and flushing -land conversion, water use |
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What stabilizes eutrophic state?
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-internal nutrient cycling enhanced by hypoxia
-loss of higher trophic levels due to hypoxia and inedible algae -more bank erosion with loss of rooted terrestrial vegetation -nitrogen fixation by cyanobacteria that dominate under high P |
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Health of ecosystem
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If predators arrive, the ecosystem is often "healthier" with longer food aquatic chains.
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