Earth as a System

Life on EarthUnit 6StandardsSES1e . Identify the transformations and major reservoirs that make up the rock cycle, hydrologic cycle, carbon cycle, and other important geochemical cycles.SES6c. Explain how geological and ecological processes interact through time to cycle matter and energy, and how human activity alters the rates of these processes (e.g. fossil fuel formation and combustion)Earth as a SystemEarth system is a result of interaction between matter and energy.Matter anything having mass and volume. Made up of atomsEnergy ability to do work. Can be transferred by heat, light, vibrations, or electromagnetic waves.A system is described by the way that matter and energy are transferred within the system or to and from other systems.Closed energy and matter do not enter or leave Open energy and matter must be added or removedSection 2Earths Four SpheresMatter on Earth is in solid, liquid, and gaseous states. The Earth system is composed of four spheres that are storehouses of all of the planets matter.

The Atmospherea mixture of gases that surrounds a planet or moon

The atmosphere provides the air you breathe and shields Earth from the suns harmful radiation.

Earths Four Spheres, continuedThe Hydrosphere

hydrosphere the portion of Earth that is water

Water covers 71% of Earths surface.

Water in the hydrosphere occur in the form of oceans, lakes, rivers, streams, glaciers and ice sheets, and groundwater.

Earths Four Spheres, continuedThe Geosphere

geosphere the mostly solid, rocky part of Earth; extends from the center of the core to the surface of the crust

The geosphere includes all of the rock and soil on the surface of the continents and on the ocean floor.

The geosphere also includes the solid and molten interior of Earth.

Earths Four Spheres, continuedThe Biosphere

biosphere the part of Earth where life exists; includes all of the living organisms on Earth

The biosphere is composed of all of the forms of life in the geosphere, in the hydrosphere, and in the atmosphere, as well as any organic matter that has not decomposed.

The biosphere extends from the deepest parts of the ocean to the atmosphere a few kilometers above Earths surface.

Earths Energy Budget1st Law of Thermodynamics energy cannot be created or destroyed, only transferred between systems.Transfer of energy between Earths spheres are parts of the energy budgetCycles in the Earth SystemReservoir is a place where matter or energy is storedCycle is a group of processes in which matter and energy repeatedly move through a series of reservoirs.Hydrologic Cycle

10Oxygen Cycle

Carbon Cycle

Nitrogen Cyclenitrifyingbacterianitrifyingbacteriaammoniumammonificationdecomposersplantnitrogen-fixingbacteria in soilnitrogen-fixingbacteria in rootsnitratesnitrites

Phosphorus Cycle

Ecosystems of the BiosphereEcology is the study of the complex relationships between living things and their nonliving, or abiotic environment.

ecosystem is a community of organisms and their abiotic (nonliving) environment

An ecosystem may be as large as an ocean or as small as a rotting log. The largest ecosystem is the entire biosphere.

Section 3Ecosystems, continuedEcosystems are made up of Communities combinations of organisms that live in the same area and may or may not interact.Populations groups of the same organism living in a particular areaOrganisms each individual within a populationEcosystems, continuedOrganisms that make their own food are called producers. Most producers use energy from the sun to produce their own food.

Consumers are organisms that get their energy by eating other organisms. Consumers may get energy by eating producers or by eating other consumers.

Some consumers get energy by breaking down dead organisms. These consumers are called decomposers.

To remain healthy, an ecosystem needs to have a balance of producers, consumers, and decomposers.

Balancing Forces in Ecosystems, Energy Transfer

The ultimate source of energy for almost every ecosystem is the sun.

Producers, such as plants, capture solar energy by a chemical process called photosynthesis. This captured energy then flows through the ecosystem from the producers, to the consumers, and finally to the decomposers.

As matter and energy cycle through an ecosystem, chemical elements are combined and recombined. Each chemical change results in either the temporary storage of energy or the loss of energy.

The largest population that an environment can support at any given time is called the carrying capacityTrophic LevelsEnergy moves from one trophic level to another

SunProducerConsumerConsumerEnergy Pyramid

Balancing Forces in Ecosystems, continuedEnergy Transfer, continued

An energy pyramid is one way to see how energy is lost as it moves through the ecosystem.

Producers form the base of the pyramid. Consumers that eat the producers are the next level of the pyramid. Animals that eat those consumers form the upper levels of the pyramid.

As you move up the pyramid, more energy is lost at each level. Therefore, the least amount of energy is available to organisms at the top of the pyramid.

Balancing Forces in Ecosystems, continuedFood Chains and Food Webs

The sequence in which organisms consume other organisms can be represented by a food chain or by a food web.

food web a diagram that shows the feeding relationships among organisms in an ecosystemFood Chain

Population GrowthPopulations do not usually grow unchecked.Predators, disease, and resource availability will limit growth and eventually, the population may stabilize.Carrying capacity (K): the population size that an environment can sustain.Population Growth ModelsBiotic Potential ~ max rate at which a population could increase under ideal conditions (age reprod begins, life span, # of reprod periods, number of offspring capable Exponential model (blue) idealized population in an unlimited environment (J-curve) Logistic model (red) carrying capacity (K) ~ maximum population size that a particular environment can support (S-curve)

25Exponential Growth unrestrained no predation, parasitism, or competition, immigration or emigration, with limited resources (ex. Bacteria newly inoculated onto a petri dish)

Age Structure Diagrams Displays relative numbers of individuals at each age.

26Shows relative ages of individuals at each age

Kenya growing population (typical of developing countries) with many young and few old

United states slow growth (birth and death rates are about the same)Population Limiting FactorsDensity-dependent factors Increase as population increasescompetition predation stress/crowding waste accumulation Density-independent factors factors unrelated to the population densityEarthquakesweather/climateperiodic disturbances

Human Population Growth

Mineral ResourcesMineral resources can be either metals, such as gold, U, silver, Ag, and aluminum, Al, or nonmetals, such as sulfur, S, and quartz, SiO2ores a natural material whose concentration of economically valuable minerals is high enough for the material to be mined profitably. Example: gold, nickel

Energy ResourcesNonrenewable resource a resource that forms at a rate that is much slower than the rate at which it is consumed

Fossil Fuels

A nonrenewable energy resource that formed from the remains of organisms that lived long ago; examples include oil, coal, and natural gas

Most used comes from the burning of the hydrocarbons that make up fossil fuels.

When hydrocarbons are burned, the breaking of chemical bonds releases energy as heat and light.

Formation of Coal

Coal is the most commonly burned fossil fuel, formed during a complex process called carbonization.

Formation of Petroleum and Natural Gas

Petroleum and natural gas are mixtures of hydrocarbons.

These fossil fuels formed when heat and pressure caused chemical changes to the remains of microorganisms and plants.They are mined from permeable sedimentary rocks.

Crude oil, or unrefined petroleum, is also used in the production of plastics, synthetic fabrics and rubber, medicines, waxes, chemical fertilizers, detergents, shampoos, and many other products.

Coal is the most abundant fossil fuel in the world. Two-thirds of the known deposits of coal occur in the United States, Russia, and China.

Oil shale is a relatively abundant material that contains petroleum. But the cost of mining oil from shale is far greater than the present cost of recovering oil from other sedimentary rocks.

Nuclear Energy

nuclear fission the process by which the nucleus of a heavy atom splits into two or more fragments; the process releases neutrons and energy

The newly released neutrons begin a chain reaction by striking nearby nuclei, which causes those nuclei to split and release more neutrons and more energy.

If left uncontrolled, a fission reaction will escalate quickly and may result in an explosion. Controlled reactions produce heat that can be used to generate electricity.

A nuclear reactor is a specialized equipment in which controlled nuclear fission is carried out.

Currently, uranium-235, or 235U, is the only naturally occurring element used for nuclear fission.

The resulting chain reaction from nuclear fission causes the fuel rods to become very hot.

Water is pumped around the fuel rods to absorb and remove heat energy.

The water is then pumped into a second circuit, where it becomes steam and turns the turbines that provide power for electric generators.

A third water circuit carries away the excess heat and releases it into the environment.

Nuclear power plants burn no fossil fuels and produce no air pollution.

However, they produce harmful radioactive materials that have very long half-lives, wastes must be stored for thousands of years.

These waste products give off harmful doses of radiation that can destroy plant and animal cells and can cause harmful changes in the genetic material of living cells.Energy Resources (cont.)Renewable resource a natural resource that can be replaced at the same rate at which the resource is consumed

Geothermal energy the energy produced by heat with Earth

The resulting steam from water passing by nearby magma or hot gases related by magma, deep in the earth, produces a large amount of geothermal energy.

Engineers and scientists have harnessed geothermal energy by drilling wells to reach the hot water.

The steam and hot water are used as a source of heat and as sources of power to drive turbines, which generate electricity.

solar energy the energy received by Earth from the sun in the form of radiation

Solar energy can be converted to heat energy in many different ways.

In a passive system, sunlight enters the house and warms the building materials, which stores some heat for the evening.

An active system includes the use of solar collectors and photovoltaic cells to collect heat or convert solar energy into electricity.

hydroelectric energy electrical energy produced by the flow of water

Moving water is one of the oldest sources of energy. Energy can be harnessed from the running water of rivers and streams or from ocean tides.

Today, 11% of the electricity in the United States comes from hydroelectric power plants.

At a hydroelectric plant, massive dams hold back running water and channel the water through the plant. Inside the plant, the water spins turbines, which turn generators to produce electricity.

Hydroelectric Dam

biomass plant material, manure, or any other organic matter that is used as an energy source

Biomass is a major source of energy in many developing countries.

Bacteria that decompose the organic matter produce gases, such as methane that can be burned.

Liquid fuels, such as ethanol, also form from the action of bacteria on biomass.

More than half of all trees that are cut down are used as fuel for heating or cooking.

Wind energy is now being used to produce electricity in locations that have constant wind.

Wind farms may have hundreds of giant wind turbines that can produce enough energy to meet the electricity needs of entire communities.

Wind generators are not practical everywhere. Because the wind does not always blow, wind energy cannot be depended on as an energy source for every location.

Wind Power in the US

Resources and ConservationThe limited supply of fossil fuels and other traditional energy resources has inspired research into possible new energy resources.

Scientists are studying how the use of traditional energy sources affects Earths ecosystems.

They estimate that the worldwide coal reserves will last about 200 years, and within 20 years, humans will have used half of Earths oil supply.

We have also learned that mining can damage or destroy fragile ecosystems. Also, fossil fuels and nuclear power may add pollution to Earths air, water, and soil.

Environmental Impacts of MiningMining can cause a variety of environmental problems.

Mining may cause both air and noise pollution, water pollution, increased erosion and soil degradation, formation of sink holes, and the destruction to wildlife habitats.

Because fires in coal mines are difficult to put out, they are commonly left to burn out, which may take several decades or centuries.

Fossil Fuels and the EnvironmentFossil-fuel procurement affects the environment and contributes to air pollution.

Strip mining removes plants and topsoil. The exposed land often erodes quickly, creating runoffs of acid rain into nearby rivers and streams.

Burning coal releases large amounts of sulfur dioxide, SO2, into the atmosphere. When SO2 combines with water in the air, acid precipitation forms.

Pollution from transportation and industry releases carbon dioxide, CO2, into the atmosphere.

Global Climate ChangeIncreases in CO2 concentration may lead to global warming, an increase in average temperatures around the Earth

Because vegetation uses CO2 to make food, deforestation also affects one of the natural ways of removing CO2 from the atmosphere.

Even short-term changes in the climate may lead to long-lasting effects that may make the survival of life on Earth more difficult for both humans and other species.

Some of these potential climate changes include global warming, sea-level changes, and changes in wind patterns and precipitation.

Human ImpactBiological magnification: trophic process in which retained substances become more concentrated at higher levelsGlobal Warming: warming of planet due to atmospheric accumulation of carbon dioxideOzone depletion: effect of chlorofluorocarbons (CFCs) released into the atmosphereRainforest destruction Cause: Overpopulation?

49Human disruption of chemical cycles throughout the biosphere

Toxins industrial toxins enter the food chain. Any toxins, antibiotics, hormones, carcinogens, or teratogens (causing birth defects) that get into the food chain accumulate and remain in the higher level carnivores fatty tissues.

Global Warming Excessive burning of fossil fuels has caused concentrations of CO2 in the air to increase to such high levels that it causes the greenhouse effect (absorption of infrared radiation by CO2 and H2O in the air keeping the temperature of the earth steady) to increase causing the global temperature to increase. A 1 degree Celsius degree change could cause a polar ice caps to melt.

Depletion of the Ozone Layer Accumulations of chlorofluorocarbons (chemicals used for refrigeration and aerosol cans) have caused the formation of a hole in the protective ozone layer. This allows more ultraviolet light to reach the earth cause in increase in incidence of skin cancer worldwide. Lake Eutrophication abnormal nutrient content caused by runoff from pastures and lawns causing excessive growth of algae and other plants choking shallow areas. As large populations die, organic material accumulates on lake bottom and reduces lake depth and detrivores use oxygen as they decompose dead organic matter. Lower oxygen levels makes it impossible for fish to live. More fish die, decomposers expand activity and oxygen levels continue to decrease, more decomposing matter accumulates on the bottom and ultimately the lake disappears.

Acid Rain caused by pollutant in the air from combustion of fossil fuels. Nitrogen and sulfur pollutants in the air turn into nitric, nitrous, sulfurous, and surfuric acids, which cause the pH of rain to be less than 5.6. This causes the death of the organisms in lakes and damages ancient stone architecture.

Introduction of New Species moving species from one area to another:Killer Honeybee African honeybee a very aggressive subspecies of honeybee brought to Brazil in 1956 to breed a variety of bee that would produce more honey in the tropics than the Italian honeybee. African honeybees escaped by accident and have been spreading throughout the Americas. By 2000, 10 people were killed by these bees in the US.Zebra mussel fingernail sized mollusk native to Asia was discovered in a lake near Detroit in 1988. It is assumed it was accidentally carried by a ship from a freshwater port in Europe. With no local natural predator to limit its population, the mussel population exploded. Its presence has caused millions of dollars of damage to pipes in cities whose water is supplied by Lake Erie and it threatens several native species with extinction by outcompeting indigenous species.