ECOL 1000 1nd EditionExam # 2 Study Guide Lectures: 15 - 26Lecture 15Nuclear energy comes in 2 forms: fission and fusiono Fission: breaking apart Atoms bombarded with neutrons which breaks atom into 2 smaller pieces whichreleases energy and more neutrons Chain reaction Uranium is bombarded with neutrons, starting a chain reaction Heat transforms water into steam which powers turbines that generate electricity Used in the U.S.o Fusion: joining together Fuse hydrogen isotopes together results in helium, energy, and neutron No toxic byproducts Not practically feasible at this timeFuel assemblies: fuel rods grouped together, help control the nuclear reaction by absorbing neutronsProblems with nuclear powero Cost-it takes billions of dollars to build new plants For about 30 yrs nuclear power plant construction was halted but there is a new plant under construction in GAo Waste produced during mining-mine tailings Contaminates watero Waste heat from reactors-especially once-through cooled systems Must release heat into the environment Back into the water or as steam Some power systems have water that goes in circulates once and then goes backouto Water use-800-2000 gallons per megawatt houro Waste produced from reactorDisposal of nuclear wasteo Cooled rods can be transported for reprocessing or disposal-that’s what they do in France USA doesn’t want to do that because a byproduct is plutonium-a major source of nuclear weaponso Reprocessed fuel rods must be stored for 10,000 yearso No commercial reprocessing areas exist in the USLecture 16 Biomass Fuels: include Bioenergy and Traditional Fuelso Advantages Carbon neutral (no net release of carbon dioxide into the atmosphere) Lower nitrates and sulfates Abundant Widely distributed Produced domesticallyo Disadvantages Carbon neutral Costs associated with transport, processing, fertilizers, water Increase food pricesBioenergy: energy contained in firewood and other plant matter, can be derived from solar energyTraditional Fuels: wood, charcoal, and animal shitWind Power: 2/3 of wind power in the US comes from Texas, California, Iowa, Minnesota, and Washingtono Advantages No fuel needed (no drilling, wastes, etc) No pollutants released Domestic energy source Not subject to disruptions of single energy planso Disadvantages Bird and bat deaths (interfere with bird movement) Aesthetics? Intermittent wind (not continuously available) Windy areas not usually near urban areasUsing biomass to create auto fuel can drive food prices upLecture 17- Hydropowero Advantages  Fossil fuel not needed No pollutants emitted-lessens acid rain Energy cheap to produce (after expense of plant construction) Power produced can be matched to demand Flood control Water retention (recreation & water supply)o Disadvantages  Effect on environment and human communities Toxins forming Ecosystem alteration & flow changes Peak flows are no longer seasonal (ecosystems are used to seasonal flooding) Sediment accumulation & transport altered Temperature and oxygen in stream changedThree Gorges Dam: dam in China that produces 16% of global demand of electricity but displaced many peopleDisadvantages of Impoundment plants (dams)- Fish populations can be impacted if fish cannot migrate upstream past the impoundment dams- Impact water quality and flow, can cause low dissolved oxygen levels which may harm riverbank habitats- Can be affected by drought- Impact the local environment and may compete with other uses for the land- Dams do not allow the rivers to flood and spread nutrients to the surrounding areasLecture 18Solar power: o Solar Advantages Free and renewable No emissions Roof installations/ space 20,000 jobs now and increasing 35% per yearo Solar Disadvantages High startup costs Costs of electricity Daylight requirements Geographical limitations Hazardous materials used in constructionSolar power currently accounts for a small fraction of our electricity needs, although is growing each yearGeothermal energy: heat energy generated and stored in Earth that does not originate from theSuno Advantages Reliable and inexpensive Pollution free Ground source heat pumps GSHP use 30-70% less energy than conventional methodso Disadvantages Ecosystem disturbance (Yellowstone National Park) Replenishment rates of ground heat High start up costs Geographic limitations (California, Nevada, Hawaii, and Utah)Ocean Energy- Fracking: pumping the fracturing fluid into the wellbore at a rate that exceeds that of thefracture gradient of the rocko Produces wasteo Natural gas is drilled from Marcellus bedrock, contaminates water- Ocean energy uses kinetic energy from tides and waves and tidal turbinesLecture 19Case Study: Paul Cox- Biodiversity in the Samoan rainforest- Biodiversity: variety among organisms and ecological systems at all levels of organization Genetic diversity: variations in the genes among individuals of the same species Outbreeding vs. Inbreeding- Outbreeding maximizes genetic diversity Species diversity: the variety of species present in an area; includes the number of different species that are present as well as their relative abundance- Endemic species: organisms that are found only in specific localities Ecological diversity: the variety of habitats, niches, trophic levels, and community interactions- Coral reefs support many species o Species level biodiversity increases moving towards the tropicso There have never been more species on earth than there currently areo Insects have the greatest number of specieso The “Red Queen Hypothesis”: why plants continually evolve new chemical and physical defenseso Many of the global diversity hotspots around the world are located on islands because populations of island species are isolatedLecture 20Reasons for high tropical biodiversity- Diversity increases without limit over time- Diversity reaches an equilibrium in which factors adding species balance factors removing species, in the tropics, factors adding species occur at a faster rate than factors removing species- Trees and amphibians are influences by the moisture gradient from east to west- Reptiles are influenced by the temperature gradient from south to northDiversity has both regional and local componentso Can be measured at a variety of