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APES Review! 4/24/08 Introduction Environment, biotic, abiotic Thomas Malthus and Paul Ehrlich: predicted massive population increases and subsequent problems Environmental science is about sustainability, which requires us to live in such a way as to maintain Earth’s systems for the foreseeable future Designing Experiments have a hypothesis that you want to test Make sure to have a control group that is not tested in order to compare Only test 1 variable at a time! Basic Information Properties of water: – strong cohesion (helps transport of chemicals) – can resist temperature change – Solid form is less dense than liquid (ice floats) – Bonds well (dissolves many molecules) pH scale: <7= acid, >7=base Basics on Energy Potential energy is energy of position and kinetic energy is energy of motion First law of thermodynamics: the total energy of the universe remains constant – Ex) the potential energy of the water behind a dam equals the kinetic energy of its eventual movement Second law of thermodynamics: the nature of energy will change from a more ordered to less ordered state – As we burn a log, the energy is released as heat and light, becoming more disorganized Basics on Energy Photosynthesis: plants, or autotrophs, convert sunlight energy and CO2 into glucose and O2 Cellular respiration: all organisms convert glucose into ATP energy and CO2 Energy Basics Energy efficiency: the amount of energy that is useful from one step to the next – A coal power plant is 38% efficient – Beef cattle are 7% efficient, chickens are 33% Productivity is the amount of biomass that is produced by a community Basic Ecology Information A species is a group of organisms with similar enough genetic makeup to be able to reproduce successfully A population is an interbreeding group of organisms that lives in the same area A community is a group of interdependent populations An ecosystem is composed of biological communities and their physical surroundings The biogeochemical cycles The carbon cycle 1. photosynthesis captures CO2 to form glucose. animals eat glucose 2. cellular respiration converts glucose into CO2 3. CO2 is captured and dissolved by the oceans 4. Organisms use the carbonate ion to form sediments 5. When organisms die, they may be compressed into fossil fuels 6. Fossil fuels are burned to produce CO2 The biogeochemical cycles The nitrogen cycle 1. Nitrogen fixation converts nitrogen gas into ammonia through bacterial action 2. Nitrogen gas can form NO2 through combustion and later combined with water to form acid rain 3. Nitrification turns ammonia into nitrite and nitrate ions 4. Nitrates are used by plants to form proteins 5. Plant proteins are eaten by animals 6. Animals decompose to form ammonia through ammonification The biogeochemical cycles The phosphate cycle – There is no gaseous phase unlike other cycles 1. Phosphates are used in plants and animals 2. Decaying organic matter puts phosphates in soil – This is often used as fertilizers 3. Animals and plants pick up phosphates to use The biogeochemical cycles The sulfur cycle 1. Sulfur is used to construct proteins 2. Living cells are compressed into fossil fuels, which release SO2 when combusted 3. SO2 combines with water vapor to form acid rain 4. Sulfate ions are taken in by plants to form proteins 5. Volcanic eruptions produce sulfides The biogeochemical cycles The water cycle – Characterized by changes in the physical state, rather than chemical reactions – Powered by solar energy and by gravity – A large amount of water is stored as groundwater in aquifers The biogeochemical case studies Wastewater treatment and nitrogen – Plants need to be careful to have bacteria convert all the ammonia into nitrate ions, which are later removed Earth Systems and Global Processes Convection is the circulation of material that occurs when the density of material is changed upon warming or cooling – Energy from the Earth’s core heats the mantle, which then rises and cools as it contacts the crust—this drives tectonic action – Ocean currents are also driven by differences in temperature and salinity Earth Systems and Global Processes Convection in the atmosphere – Energy from the sun from is as UV light and is mostly absorbed by ozone; eventually all energy is reradiated as infrared radiation More solar energy hits the equator than other regions – Coriolis effect—circular air movements that create surface winds Plate tectonics Plate tectonics describes the movements of the Earth’s lithospheric plates – Divergent boundaries occur where magma is pushed up and new crust is produced; produces rift valleys and sea floor spreading – Convergent boundaries occur when two plates meet and one dives under the other through subduction; forms mountains and trenches – Transform boundaries occur when two plates slide past each other; causes earthquake faults The rock cycle Igneous rocks are formed from magma that has solidified Sedimentary rocks are formed through weathering and deposition – Mechanical weathering takes place when a force is applied to break up a rock – Chemical weathering takes place through chemical reactions, often with water Metamorphic rocks are formed as other rocks are exposed to heat or pressure Soil Soil is formed from small particles of rock and minerals Soil composition – Clay: very fine particles, impermeable to water – Silt: fine particles that result from weathering – Sand: course particles from weather; high water permeability – Humus: organic material in topsoil – Loam: a mixture of the other types, good for agriculture Soil Soil profiles show the different layers of material Soil conservation: Soil Conservation Act – Erosion occurs when soil is moved; occurs through water, wind, and salinization – Decrease erosion through no-till farming, trees to break wind, monitor soil nutrients, decrease irrigation The atmosphere Mostly nitrogen, then oxygen, then water vapor and other gases Layers: troposphere < tropopause < stratosphere < mesosphere < thermosphere/ionosphere Weather is caused by temperature, pressure, and moisture Global Climate Changes Milankovitch cycles: changing of Earth’s orbit around the sun, exposing different latitudes to different amounts of sunlight over time Volcanic eruptions: put huge amounts of ash into the atmosphere, blocking sun El Nino: as water moves in the surface of equatorial waters, it is heated and evaporates, causing increased moisture – Causes different amounts of moisture and precipitation Global Climate Changes Greenhouse effects: the increased amounts of greenhouse gases causes more infrared radiation to be captured – Increased burning of fossil fuels has made more CO2 than our natural processes can absorb Effects of Global Climate Change Reduces artic sea ice, increases the level of the sea Glaciers are melting, causing less freshwater runoff for human use High ocean levels will flood major population centers Spreads the range of disease-causing organisms Causes migration of plant and animal species Coral reefs undergo bleaching Permafrost is melting Causes more energetic storms Species Interactions Food webs: producers—primary consumer—secondary consumer—tertiary consumer—decomposers Keystone species have a particularly strong impact on ecosystems – Often a large, tertiary consumer Succession shows the pattern of restoration when an ecosystem is disturbed Species Interactions The niche is a species’ ecological role – The niche is determined by competition Predation: the process by which individuals of one species hunt and kill Parasitism: one organism depends on another for nourishment or other benefit while causing the host harm Herbivory: animals feed on the tissues of plants Species Interactions Mutualism: two or more species benefit from the interaction with one another Symbiosis: physical close mutualitistic association – Ex) plant roots and fungi, bacteria in intestine Amensalism: one organism is harmed and the other is unaffected Commensalism: one species benefits and the other is unaffected Evolution Evolution is the process of change in a population over time – Evolution occurs through the process of natural selection, where the best genetically adapted individuals survive and reproduce – Proposed by Charles Darwin The result of evolution is speciation – Allopatric speciation is a result of geographic barriers Extinction The disappearance of a species from Earth is called extinction – Extinctions occur when rapid environmental change occurs and species cannot adapt – There have been 5 mass extinctions on Earth – The K-T extinction occurred when the dinosaurs were wiped out The Biomes Biomes: a major region classified by its dominant plant type – Tundra: few trees, extreme cold, frozen ground (permafrost) – desert: very low moisture, adapted plants, small animals – grassland: medium rainfall, grazing animals – Savannahs: tropical grasslands – Chaparral: dry ecosystem with low woody trees The Biomes – Temperate deciduous forest: trees loose leaves every fall; even precipitation – Taiga: boreal forests with long, snowy winters and conifer trees – Temperate rainforest: heavy rainfall; many coniferous trees – Tropical rainforest: heavy rainfall; warm year-round; high biodiversity The Biomes Pelagic marine ecosystems: open ocean; phytoplankton→zooplankton→small fish →top carnivores Benthic marine ecosystems: near the bottom of the sea – Coral reefs: mutualistic relationship between algae and marine inverterates, as well as great biodiversity The Biomes Benthic marine ecosystems – Mangrove swamps: occur near the shore where salt-adapted trees grown with their roots in the water; tropical zones – The abyss: great depths of the ocean – Estuaries and salt marshes: interface between ocean and rivers; brackish water; high biodiversity – Intertidal zones: regions between low and high tides The Biomes Coastal ecosystems – Supratidal zone: beach area – Barrier islands: islands created by wave action Streams and rivers: major source of nutrients comes from terrestrial sources Lakes and ponds: vary in nutrient levels Wetlands – Provide essential habitats – Reservoir for flood waters – Natural water treatment process Biodiversity Genetic biodiversity refers to the variety of genes within a population Species biodiversity refers to the number of species in an ecosystem – Benefits: helps ecosystem stability, medicines, aesthetic value, etc Ecosystem biodiversity refers to the variety of biome types Endangered Species Generally have characteristics that make it vulnerable – Logistic population growth Long life span, large body, carnivore, low reproductive rate – Requires a large amount of land per animal – Specialist species – Low genetic diversity – Competes for resources with a dominant species – Low tolerance for pollution and/or human activity Introduced Species Invasive species are non-native organisms that alter communities substantially and become dominant – No limiting factors to regulate their population – Often difficult to remove or control – Often on islands Protecting Biodiversity The Endangered Species Act National parks and forests Wetland protection/range management Wildlife corridors between parks land reclamation Captive breeding programs in zoos Biodiversity case studies Wolves restored to Yellowstone park Overharvesting for seafood markets Silent Spring shows the impact of pesticides on biodiversity Population Definitions Fertility: a measure of the actual number of offspring produced Fecundity: the physical ability of an organism to reproduce Natality: the production of new individuals Morbidity: level of illness in a population Mortality: measure of actual number of individuals that die Population Definitions Survivorship: the number of people in a given age bracket who remain alive Life expectancy: probable number of years an individual will survive Life span: longest length of life reached total growth rate: sum increases to the population Population Growth Growth = (birth + immigration) – (death + emigration) Exponential growth: when a population increases by a fixed amount (j-curve) Logistic growth: population rises sharply at first but then levels off (s-curve) – Levels off when a population reaches its carrying capacity Doubling Time = 70 / % growth Biotic Potential K-selected species are large, slow reproduction, lots of parental care – Ex) humans, mammals, etc R-selected species are small, short-lived, with quick reproduction – Ex) insects, rodents Characteristics of populations Population size Population density Population distribution: random, uniform, or clumped Sex ratios Age structure Birth and death rates: survivorship curves Factors that affect human population size Increase size – – – – Social factors: status, comfort, pride Financial factors: source of labor, security Fertility factors: high infant mortality Cultural factors: producing an heir, etc Reduce size – Personal freedom and educational opportunities for women – Socioeconomic status – Materialism Human Age Structure Diagrams Demographic Transition Evolution of populations from high birth/ death rates to low birth/death rates Stage 1: high birth and death rates – Little access to birth control, high infant mortality Stage 2: high birth rates, death rates fall— high population growth – Improved medical care and sanitation – Better food distribution Demographic Transition Stage 3: birth and death rates fall— population growth is constant – Increased birth control, wealth increases, higher education Stage 4: low birth and death rates—steady population size Air Pollutants Primary pollutants: harmful to humans in the form in which they are emitted Secondary pollutants: become toxic after they are released – Ex) ozone Nitrogen oxides Description: formed when N2 is combusted at high temps Sources: ½ from anthropogenic sources, mostly automobiles Effects: acid rain, causes increased plant growth (eutrophication and decreased dissolved oxygen) Sulfur oxides Description: has that damages tissues Sources: combustion of coal Effects: acid rain, causes breathing difficulties Carbon oxides Description: CO2 and CO most common Sources: burning fossil fuels Effects: CO2 causes global warming, CO is toxic to humans Volatile Organic Compounds (VOCs) Description: easily vaporized and can react for form ground-level ozone Sources: cleaning fluids, paints, oil, etc Effects: can be carcinogens, irritants, neurotoxins, etc Particulate Matter Description: solid or liquid particles suspended in the air; includes ash, dust, smoke, etc Effects: irritates the lungs, may be toxic Metals and Halogens Description: lead and mercury are the most concerning metals, and CFCs are important halogens Sources: atmospheric lead comes from gasoline, mercury comes from coal power plants, CFCs from coolants Effects: lead and mercury lead to brain damage – Mercury will bioaccumulate – CFCs decrease ozone protection Photochemical oxidants Description: secondary pollutants that are synthesized with the aid of solar energy – Includes ozone Sources: often nitrogen oxides Effects: ozone is highly reactive when in the troposphere and causes lung damage Indoor Air Pollutants Asthma triggers: secondhand smoke, dust, etc Toxic building materials: VOCs, heavy metals, asbestos Radon gas: radioactive gas that is produced within the Earth and enters homes Carbon monoxide: decreases oxygen levels in tissues; created by incomplete combustion of fuel Human Water Use agriculture > industrial > municipal Dams can be used to control water flow and to produce electricity Water diversion projects change the flow of rivers and bring water to cities Water pollutants Pathogens: highest threat to human health Oxygen-demanding wastes: the addition of nutrients or human wastes allows algae to grow; then they die, the organisms that decompose them use up the oxygen in the water – Biological Oxygen Demand (BOD) is a good estimate of the load of oxygen-consuming organisms Inorganic wastes: suspended particles and dissolved ions such as acid deposition Water Pollutants Suspended particles: includes sediment from erosion and runoff Dissolved ions: includes heavy metals and calcium Heavy metal ions: usually extremely toxic and may bioaccumulate Toxic organic wastes: may come from dumps or fuel, as well as natural sources such as red tides Thermal pollution: decreases dissolved oxygen levels; often comes from power plants Removing toxic wastes Physical methods: vaporization, filtration, UC disinfection, reverse osmosis Chemical methods: acid neutralization, precipitation, or hydrolysis Biological methods: bioremediation, wetlands, bacterial decomposition Water pollution control Clean Water Act – Make all waters “fishable and swimmable” – Require discharge permits of major polluters – Identify toxic pollutants and remove them Reduce emissions of nitrogen and sulfur dioxides Modify agricultural practices to reduce runoff Treat wastes more effectively Decrease silt runoff from urban areas Reverse river channelization Land Use Tragedy of the commons: personal good supersedes the public good – Garrett Hardin – Case study: Easter Island—used all of the public resources until they were gone – Case study: overharvesting of fish or deforestation Ecological Footprint: the sum total of the impact a human has on the Earth, including the resources used Land Reuse Conservation: not using and protecting resources Preservation: providing a reserve of resources for the future Restoration: bringing a damaged ecosystem back to its natural condition Remediation: using chemical, biological, or physical methods to remove pollutants Reclamation: using large water projects to bring water to otherwise un-arable lands Mitigation: finding as solution to a problem Human Nutritional Needs Undernourishment—getting fewer calories than needed to survive – Famines are massive incidents of undernourishment, often caused by political or economic upheaval, or environmental devastation Overnutrition—in the US we eat an average of 1000 extra calories per day Human Nutritional Needs Malnourishment—inability to acquire adequate vitamins and nutrients – Kwashiorkor—lack of protein – Anemia—lack of iron; prohibits oxygen traveling in tissues – Goiter—iodine deficiency – Vitamin A deficiency—harms vision – Scurvy—vitamin C deficiency Land Degradation Desertification: converting farmable grassland into non-arable desert – Often occurs when land is over farmed and organic material is removed Erosion: soil is moved Fertilizer Use: adds inorganic materials to soil – Often causes water pollution Energy use: depends on fossil fuels Land Degradation Pesticide use – Toxicity to nontarget species (animals and humans) – Pest resistance – Types: inorganic, chlorinated hydrocarbons (DDT), organophosphates, botanic pesticides – Integrated pest management (IPM) uses a variety of management techniques Mining Extraction – Surface mining—dig an open mine, displacing large amounts of soil – Subsurface mining—underground mines; more risks to miners – Well—used for liquid or gaseous deposits Processing – Gold is extracted by spraying with solvent, often toxic cyanide – Uranium is processed, creating huge amounts of toxic waste – Aluminum extraction from bauxite ore requires large amounts of energy Mining Reclamation The Surface Mining Control and Reclamation Act requires that coal mining operations reclaim sites after mining Involves the return of the overburden (land removed) – Then, topsoil must be put down and plants grown – Tailings must be removed to stop toxic and acidic runoff Skipped pgs 123-144—human health Skipped pg 181-182—sewage treatment 195-205 (building and urbanization) Energy chapter