Environmental Science Midterm 2013 Fall

11 Pages
465 Views
Unlock Document

Department
Environmental Science
Course
EESA01H3
Professor
Carl Mitchell
Semester
Fall

Description
Environmental Science Mid-term Notes Lecture 2 The Base Cause of Environmental Degradation My opinion (probably the same as most Environmental Scientists: World population growth, consumption, far above what we can be replaced Our Future: Cornucopians vs. Cassandras Cornucopia: horn of plenty – Human ingenuity will see us through our environmental problems via new technologies and the such. Cassandra: mythical princess of Troy who prophesized about dire future scenarios – All is lost because of our impact on the environment. IPAT(S) Model • 1974: Paul Ehrlich and John Holdren I P A T S
 • Impact is largely POLLUTION, RESOURCE DEPLETION, or both. Population = individuals need space and resources Affluence = greater per capita resource use Technology = increased exploitation of resources or ways of better dealing with our need for resources Sensitivity = how sensitive an area is to human pressure The First Humans Oldest known homonid (human-like) fossils: Ethiopia: 4.1 Doubling Time ln(2)´100 70 tD= = growthrate(%) growthrate(%) • The number of years it takes, given a specific rate of increase, for a number (such as population to double.)   1979 China growth rate = 2.8% (popl’n at )me: 1B) Current global growth rate = 1.2% (now: ~6.9B) Current Canada growth rate (natural and net immigration together) = 0.9% (now: 33.5M) Carrying Capacity • “The maximum population size of a species that a given environment can sustain.” • Limiting factors • Births ≈ deaths • Earth’s carrying capacity? Between 10 million and 33 billion. Cultural Revolution/Paleolithic Period: • Development of tools; stone, bone, wood – (Note animal tool use – crows) Environmental Science Mid-term Notes • Omnivorous diet • Manipulation of fire • Development of speech and communication • Toolmaking: – Ethiopia: 2.6 My bp – Tanzania: 1.75 My bp • Little evidence of population at time. Agricultural Revolution: • Start ~ 10-12,000 years bp • Transition from nomadic hunter-gatherer to settled farmer (environmental manipulation to meet needs) • Consequences: – Reduction of area needed per person – 500 X population density – Excess of food production over minimum – Whole population need not be in food production or acquisition – Establishment of settlements – Social structures – priests – accountants – salesmen – “Fertile Crescent” – note soil salinization & collapse of society • Easier to meet needs (food, safety, ease of raising children) = population increase Industrial Revolution • Began mid-1700’s (Great Britain) • Transition from rural, basic farming to manufacturing, urban society and massive use of energy • Consequences: • Improved sanitation and medicine • Major advance in agriculture (powered machinery-driven) leads to increases in food production • Greater supply of energy, resources, labour • Accumulation of wealth and market for manufactured goods Medical-Technological Revolution • We are in the middle of this one • Characteristics: • Developments in medicine and pharmaceuticals • Improved sanitation • Global communication • Green Revolution (agriculture advances) Environmental Science Mid-term Notes • Consequences: • People live longer, healthier lives • Gap between rich and poor widened Demography: The study of human population - Considerations: • Population size • Population density and distribution • Age structure • Sex ratios • Birth, death, immigration, and emigration rates ^Shape a population’s environmental impact. In the United Arab Emirates and Qatar, the ratio is closer to 200 to 100. Such ratios are bound to lower population growth rates. • It has occurred in Europe, U.S., Canada, Japan, and other nations over the past 200-300 years • The transition could fail in cultures that – Place greater value on childbirth – Grant women fewer freedoms – Factors Affecting Population Growth Education and the status of women (family planning), Poverty, Disease, (HIV/AIDS) Lecture 3 Difficult to find closed system Open system: ex. Automobile inputs and outputs energy, matter Closed system: inputs energy, outputs energy Negative feedback loops: output from system becomes input to a system, moving system in opposite direction (don’t let things change too much)  Ex. Rabbit and lynx population depleting and growing in a cycle Positive feedback loops: output from system exacerbates the system response by moving it further toward one extreme  Ex. Sea ice melting Emergent properties: characteristics of a system not evident (perceivable) from its components alone or individually  The rate (amount per time) if energy (joules) received at a surface called power (Js ^-1). This is Watt (W) Environmental Science Mid-term Notes  Power per surface area is an Energy Flux measured in W m^-2  The rate of energy emitted by a substance is governed by the Stefan-Boltzmann Law Solar constant: the rate at which isolation is received at the outer atmosphere of Earth Environmental Systems • Ecosystems • Hydrologic Cycle (next class) • Global Energy Balance (next class) • Biogeochemical Cycles: – Carbon Cycle – Nitrogen Cycle – Phosphorus Cycle – Sulphur Cycle – Mercury Cycle and lots of others Ecosystem: All organisms and nonliving entities that occur and interact in a particular area at the same time – Includes abiotic and biotic components – Energy flows and matter cycles among these components – Generally, the smallest ecologically “self-sufficient” space • BIG POINT: Energy enters, flows through, and exits this system, but matter is cycled within it. Conversion of Energy to Biomass in Ecosystems • Biomass: organic material that makes up living organisms. • Autotroph: an organism that produces complex organic compounds from sunlight and inorganic molecules (i.e., plants and some bacteria). • Gross Primary Production (GPP): Overall conversion of solar energy into chemical energy by autotrophs. • Respiration: metabolism. • Net Primary Productivity (NPP): Energy remaining after respiration, that goes toward accumulating biomass. • Net Ecosystem Productivity (NEP): NPP minus heterotrophic respiration and herbivory. Key Chemical Equations: Photosynthesis occurs in the presence of light and chlorophyll: Respiration involves the use of accumulated carbon to produce needed energy (below is the aerobic process): Environmental Science Mid-term Notes NPP vs. NEP • NEP = NPP – Ecosystem Respiration • Ecosystem respiration includes both the respiration of carbon above the surface and from soil. Factors Affecting NEP: 1. Nutrients • Nutrients (especially macronutrients like nitrogen and phosphorus) can be limiting factors for productivity. • Nitrogen usually limiting factor in marine systems, usually phosphorus in freshwater systems. 2. Oxygen Aerobic respiration: Energy Produced = 2872 kJ per mol glucose Biogeochemical Cycles • Earth is a “closed” system. Open to energy, but matter “cycles” (is circulated) within it over and over again (some VERY minor exceptions). • Matter circulates between pools or reservoirs. • The volume of material moving among reservoirs per unit time (a rate) is called a flux. • Fluxes are not necessarily stable (e.g., we have greatly affected the flux of C to the atmosphere). • Residence time (T ): Rverage amount of time a molecule or atom stays in a pool. • Sources vs. Sinks. • Lots of feedbacks in biogeochemical cycling. Importance of Nitrogen • 78% of atmosphere th • 6 most abundant element on earth • Key ingredient in proteins and DNA • Essential nutrient for plant growth Key Processes in the N Cycle • Nitrogen Fixation: combination of nitrogen gas (N ) with 2ydrogen to form ammonia (NH ) an3 subsequently, the biologically available and soluble ammonium ion (NH ). 4 • Two driving processes: lightning and nitrogen-fixing bacteria. • Nitrification: Conversion of NH to N4 and then2NO by specializ3d bacteria. Plants take up NO . - 3 - • Denitrification: Conversion of NO back 3o N gas by s2ecialized bacterial Environmental Science Mid-term Notes communities. Human Alteration of N Cycle • Doubling of nitrogen fixation. Due to Haber-Bosch process (fertilizer production) and increased production of legumes (soybeans). • Increased atmospheric N O 2greenhouse gas) and other NO (produxe smog). Due to fossil fuel burning and animal waste decomposition. • Depletion of micronutrients (Ca, K) from soils (N fertilizers make them more mobile and they flush out). • Acid rain. • Eutrophication  devastating to fisheries (especially coastal marine fisheries). • Increased plant growth and carbon storage. Eutrophication: The process of nutrient over-enrichment, blooms of algae, increased production of organic matter, and ecosystem degradation Importance of Phosphorus • Key component of cell membranes, DNA, and ATP (energy). • Often limiting nutrient for autotroph growth. • Biogeochemical cycle is largely restricted to lithosphere and hydrosphere (NOT atmosphere). • Cycle is largely driven by: – solubilization – precipitation – assimilati
More Less

Related notes for EESA01H3

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit