First Law of Thermodynamics
energy is neither created nor destroyed, but may be converted from one form to another.
Second Law of Thermodynamics
when energy is changed from one form to another, some useful energy is always degraded into lower quality energy (usually heat).
radiation w/enough energy to free electrons from atoms forming ions, may cause cancer (ex. gamma, X-rays, UV).
Natural radioactive decay
unstable radioisotopes decay releasing gamma rays, alpha & beta particles (ex. Radon).
the time it takes for 1⁄2 of the mass of a radioisotope to decay. A radioactive isotope must be stored for approximately 10 half-lives until it decays to a safe level.
2 isotopes of light elements (H) forced together at high temperatures till they fuse to form a heavier nucleus. Happens in the Sun, very difficult to accomplish on Earth, prohibitively expensive.
Soil Conservation Methods
conservation tillage, crop rotation, contour plowing, organic fertilizers.
in arid regions, water evaporates leaving salts behind. (ex. Fertile crescent, southwestern US)
Hydrologic Cycle Components
evaporation, transpiration, runoff, condensation, precipitation, and infiltration.
Salt Water Intrusion
near the coast, overpumping of groundwater causes saltwater to move into the aquifer.
El Nino Southern Oscillation, trade winds weaken & warm surface water moves toward South America. Diminished fisheries off South America, drought in western Pacific, increased precipitation in southwestern North America, fewer Atlantic hurricanes.
"Normal" year, easterly trade winds and ocean currents pool warm water in the western Pacific, allowing upwelling of nutrient rich water off the West coast of South America.
because atmospheric N cannot be used directly by plants, it must first be converted into ammonia by bacteria.
does not exist as a gas; released by weathering of phosphate rocks, it is a major limiting factor for plant growth. Phosphorus cycle is slow, and not atmospheric.
plants convert CO2 (atmospheric carbon) into complex carbohydrates (glucose C6H12O6).
oxygen consuming producers, consumers & decomposers break down complex organic compounds & convert C back into CO2.
Energy Flow through Food Webs
10% of the usable energy is transferred to the next trophic level. Reason: usable energy lost as heat (2nd law of Thermodynamics), not all biomass is digested & absorbed, predators expend energy to catch prey.
development of communities in a lifeless area not recently inhabited by life (ex. lava flow, retreating glacier).
life progresses where soil remains (ex. clear-cut/burned forest, old farm, vacant lot).
relationship in which one organism (the parasite) obtains nutrients at the expense of the host.
reproductive strategy in which organisms reproduce early, bear many small, unprotected offspring (ex. insects, mice).
reproductive strategy in which organisms reproduce late, bear few, cared for offspring (ex. humans, elephants).
"human population cannot continue to increase. Consequences will be war, famine & pestilence (disease)."
(rule of 70) doubling time equals 70 divided by percent growth rate. (ex. a population growing at 5% annually doubles in 70 ÷ 5 = 14 years)
Replacement Level Fertility
the number of children a couple must have to replace themselves (averages 2.1 in more developed nations, 2.7 in less developed nations).
death rate (infant mortality) lower, birth rates remain high, better health care, population grows fast.
Age Structure Diagrams
broad base → rapid growth; narrow base → negative growth; uniform shape → zero growth
Non-Point Source (Area/Dispersed Source)
source spread over an area such as agricultural/feedlot runoff, urban runoff, traffic.
Primary Sewage Treatment
first step of sewage treatment; eliminates most particulate material from raw sewage using grates, screens, and gravity (settling).
Secondary Sewage Treatment
second step of sewage treatment; bacteria breakdown organic waste, aeration accelerates the process.
Biological Oxygen Demand, amount of dissolved oxygen needed by aerobic decomposers to break down organic materials.
rapid algal growth (algal bloom) caused by an excess of nitrogen & phosphorus, blocks sunlight, causing the death/decomposition of aquatic plants, decreasing dissolved oxygen (DO), suffocating fish.
Corporate Average Fuel Economy standards enacted into law in 1975, established fuel efficiency standards for passenger cars and light trucks. The fuel economy ratings for a manufacturer's entire line of passenger cars must currently average at least 27.5 mpg for the manufacturer to comply with the standard.
sources include burning fossil fuels and car exhaust. Effects include reduced visibility, respiratory irritation. Methods of reduction include filtering, electrostatic precipitators, alternative energy).
(NOx) Major source is auto exhaust. Primary and secondary effects include acidification of lakes, respiratory irritation, leads to smog and ozone. Reduced using catalytic converters.
Secondary pollutant, NO2 + UV → NO + O; O + O2 → O3, with VOCs. Causes respiratory irritation and plant damage. Reduced by reducing NO emissions and VOCs.
(SOx) Primary source is coal burning. Primary and secondary effects include acid deposition, respiratory irritation, plant damage. Reduction methods include: scrubbers, burn low sulfur fuel.
(CO2) Sources include the combustion of fossil fuels. Effects: greenhouse gas-contributes to global warming. Reduction accomplished by increased fuel efficiency (gas mileage), mass transit (reduction).
(CO) Sources include incomplete combustion of fossil fuels. Effects: binds to hemoglobin reducing bloods ability to carry O2. Reduction accomplished by catalytic converters, oxygenated fuel, mass transit (reduction).
Most significant: H2O, CO2, methane (CH4), CFCs. Trap outgoing infrared energy (heat) causing earth to warm.
a vital process, required for life to exist on Earth. If accelerated, bad, leads to global warming.
Effects of Global Warming
rising sea level (due to thermal expansion not melting ice), extreme weather, droughts (famine), and extinctions.
caused by CFCs, methyl chloroform, carbon tetrachloride, halon, methyl bromide all of which attack stratospheric ozone. Negative effects of ozone depletion include increased UV, skin cancer, cataracts, and decreased plant growth.
problems include leachate, which is solved using a liner with a collection system; methane gas, which may be collected and burned; and the volume of garbage, which may be compacted and/or reduced.
Advantages-volume of waste reduced by 90% and waste heat can be used. Disadvantages-toxic emissions (polyvinyl chloride, dioxin), scrubbers and electrostatic precipitators needed, ash disposal.
In Natural Ecosystems
50-90% of pest species are kept under control by: predators, diseases, parasites.
Major Insecticide Groups
chlorinated hydrocarbons—ex. DDT; organophosphates—ex. malathion; carbamates—ex. aldicarb
saves lives from insect transmitted disease, increases food supply, and increases profits for farmers. Cons: genetic resistance, ecosystem imbalance, pesticide treadmill, persistence, bioaccumulation, and biological magnification.
Natural Pest Control
better agricultural practices, genetically resistant plants, natural enemies, and biopesticides, sex attractants.
Genetically Modified Organisms (GMOs)
new organisms created by altering the genetic material (DNA) of existing organisms; usually in an attempt to remove undesirable or create desirable characteristics in the new organism.
steam, from water boiled by fossils fuels or nuclear energy, or falling water is used to turn a generator.
Petroleum (Crude Oil) Formation
microscopic aquatic organisms in sediments converted by heat & pressure into a mixture of hydrocarbons.
cheap, easily transported, high-quality energy. Cons: reserves depleted soon, pollution during drilling, transport and refining, land subsidence, burning oil produces CO2.
prehistoric plants buried un-decomposed in oxygen-depleted water of swamps/bogs converted by heat and pressure.
consists of a core, control rods, moderator, steam generator, turbine, containment building.
first layer of atmosphere 0-10 miles above the Earth's surface. Contains weather, greenhouse gases (bad ozone).
second layer of atmosphere 10-30 miles above the Earth's surface. Contains protective ozone layer (good ozone).
Inversion Layer (Temperature Inversion)
a warm layer of air above a cooler layer traps pollutants close to the Earth's surface.
one of the most toxic human-made chemicals. Stable, long-lived, by-product of herbicide production enters environment as fallout from the incineration of municipal and medical waste and persists for many years.
PCBs (Polychlorinated Biphenyls)
Stable, long-lived, carcinogenic chlorinated hydrocarbons. Produced by the electronics industry.