Chapter 18 The EnvironmentSection 1 – Global ChangeSection 2 – Effects on EcosystemsSection 3 – Solving Environmental Problems

Acid RainAcidified precipitation caused by nitric

and sulfur-rich air pollutionBurning fossil fuels

Sulfur and nitric acid in atmosphere combined with water vapor falls to Earth and joins the water cycle

How acidic is the precipitation?Drops the pH from 7.0 to 4.0-4.5

What is the impact of acid rain?

Effects of Acid Rain

Largest affect is on aquatic ecosystemsHigh levels of nitric and sulfuric acid are

toxic to organism Toxicity can affect all organisms in a food

chain from producers to large predatorsThe soils of nearby areas can become too

acidic and plants start to become vulnerable to death if they cannot adapt to the new pH

PesticidesChlorinated hydrocarbons broken downThe process is slow and the toxins

accumulate in fatty tissues of animalsBiological Magnification:

Molecules move up the food chain as organisms are consumed

DDTNow banned due its threat to the bird population in 1972

Ozone LayerA protective, upper layer of the

atmosphere that reduces the amount of UV rays that hit the Earth’s surface

Ozone HoleThe concentration of O3 is lower over

AntarcticaExpected to have started becoming less

concentrated from 1978 and onDecrease in concentration has led to

more UV exposure and diseases

Causes of the Ozone HoleMain cause: Chlorofluorocarbons (CFCs)Chlorofluorocarbons (CFCs)

Created in 1920s as stable and harmless coolants

Present in fridges, Styrofoam, air conditioners and aerosol cans Presently banned in the US

Began escaping into the atmosphere breaking down the O3

Cl bonds reacted with oxygen – producing less O3

Global TemperaturesTemperatures have a typical pattern of

increase then decrease for about a centuryEffected by sunspot cycles

Since 1950’s the temperatures have only been increasing

Global WarmingPeriods of steady increase usually followed by

cold periodsHuman activities have contributed to larger

cycles of global warming

The Greenhouse EffectGreenhouse Gases

Water vapor, carbon dioxide, methane and nitrous oxideThese gases insulate the planet

The Greenhouse EffectBonds in carbon dioxide absorb heat radiating off the Earth and this heat is trapped by the atmosphere

As carbon dioxide levels increase, more heat is being absorbed by the atmosphere

Loss of ResourcesNonrenewable resources are being used

at faster rates – leaving a path of destruction in its wake

Effects of Loss of ResourcesExtinction of speciesLoss of TopsoilGround-water Pollution and Depletion

Extinction of SpeciesHuman activities like cutting down parts

of rainforests are leading to the next mass extinction

Approximately 10% of the species are subject to extinction

The worst possible outcome is loss of over 1/5th of the rainforests species

The loss of species can affect not only the ecosystem, but the possible benefit of those species to human kind.

Loss of TopsoilReplacement of topsoil is impossible –

about a centimeter is lost every yearThe causes are from turning the soil to

eliminate weeds, overgrazing and poor agricultural practices

These methods cause water and wind to remove soil from the area

Since 1950 – 1/3rd of the topsoil has been lost

Ground-water Pollution and Depletion

AquifersPorous rock reservoirs that hold ground water

Ground-water is a precious resource that is being used by the buckets at rates that are too large for consumption

Another portion of ground water is being polluted by chemical wastes

Removing of wastes is impossible

Growth of the Human PopulationFundamental causes of destructionAverage Global birth rate = 1,000/yearAverage death = 9 per 1,000/ yearPopulation exceed 6 million in 1999US rate is decliningThird world countries increasingProjected stable 9.7 million by 2050Will our resources support us until then?

Worldwide EffortBegan in 1990s

First Problem: PollutionInternational consensus decided to

reduce or eliminate use of CFCsUS started a ban DDT

Some countries followed suitSewage treatment plantsScrubbers – smoke stacksReduce car use – eco-friendly cars

United States EffortPollution Effective EffortsLaws Forbidding Pollution

Strict standards about what is released into the atmosphere

Clean Air Act of 1990Pollution Tax

To be effective the tax amount must equal the cost of the pollution

Gas tax is most popular

Five Steps to SuccessAssessment

Using data and observations – scientists make ecosystem models

Risk AnalysisModels are used as a trial and error

systemPlug in a disruption and understand the

consequenceFormulate a solution and check possible

progress

Five Steps to SuccessPublic Education

Informing the main cause of the problem of possible alternatives

Also can use the public for ideasPolitical Action

Power of persuasion and a group of followers

Follow-ThroughCollect data over time to evaluate the

progress and report to public

The Nashua River(New England)

Problem:Polluted by mills starting in 1900s

Solution (1966):Marion Stoddart and politicians start a group to finance a water treatment plantIndustrial dumping is now banned

Progress:As of 1990, the river has recovered and abilities to swim are intact

Lake Washington(Seattle)

Problem:Water treatment plan discharge into the lake between 1940 to 1953Blue-green algae started to grow with the new presence of nutrients

Solution:In order to clean-up the lake, taxes financed trunk sewers that divert sewage to Puget Sound

Progress:As 1961, clean bill of health and full of life

Lake Erie Algal blooms

What Can You Do?Conserve energy by walking to

locations, use public transportation or carpool

Energy inventory at home Educate yourself about the environmentRecycle and upcycleCompost