Human Impact Chapter 5

Loss of Biodiversity Biodiversity - variety of life in an area

Tropical regions contain two-thirds of all land species

Number of mammals, for example:

• Canada - 163

• U.S. - 367

• Mexico - 439

Importance of biodiversity

food webs and ecosystem balance

02 for humans

diverse diets, clothing and building materials

medicines

Endangered Species in GA

Purple pitcher plant

Sarracenia purpurea

Loggerhead Sea

Turtle

Caretta caretta

Black right whale

Eubalaena glacialis

Red-cockaded

woodpecker

Picoides borealis

Endangered Species in GA

Loss of Biodiversity

Possible causes

Habitat loss

Habitat fragmentation

Habitat degradation (by pollution)

Solutions

• Habitat Preservation through

• National and State Parks

• W.M.A (Wildlife Management Areas)

Biomagnification

Biomagnification

toxins become more concentrated as

it moves up the trophic levels

Example is DDT insecticide

Dichloro-diphenyl-trichloroethane

Collects in fatty (adipose) tissues of

animals

Biomagnification

History of DDT

Developed and used during WWII

small tins given to soldiers to combat lice & malaria

Heavily used in U.S. from 1940s to 1970s

even sprayed in public areas to kill mosquitoes

Banned from U.S. in 1972, but continues to be used

in other countries

History of DDT

Rachel Carson

DDT a serious problem…decline in bird (top of food chain)

populations (thin egg shells)

Silent Spring written by Carson helped to bring about formation

of EPA and banning of DDT

Bird populations showed dramatic recovery

Even today, traces of DDT have been found in every organism

tested - even in human breast milk throughout world

Land Resource Depletion

What happening?

Plowing removes the roots that hold the

soil in place, increasing the rate of soil

erosion.

SOIL EROSION – is the wearing away

of surface soil by water and wind.

Desertification – the process of turning

once productive areas into deserts from

a combination of farming, overgrazing,

and drought.

Land Resources

Why is it a problem?

Soil is a renewable resource, however it can be permanently damaged if mismanaged

What is being done?

Contour plowing- fields plowed across the slope of the land

Leaving stems and roots of the previous year’s crops in place to hold soil.

Planting trees

Land Resource Depletion

Deforestation - loss of forest which leads to severe erosion

Water Resources

What is happening? Pollution such as OIL SPILLS threatens our water supply.

Improperly discarded chemicals can enter streams and

rivers.

Domestic sewage entering our water ways can cause an

increase in bacteria growth.

Overfishing - fish stocks in many fisheries are being

harvested faster than they reproduce.

Water Resources

Why is this a problem?

Fresh water is used daily for everything from drinking and

washing to watering crops and making steel.

Although water is a renewable resource, the total supply of

fresh water is limited.

What is being done?

Conservation by: drip irrigation and consumer

awareness of conservation

Water Resources (Oceans)

What is happening?

Overfishing - fish stocks

in many fisheries are being

harvested faster than they

reproduce.

o Why is this a problem?

o People depend on the

ocean as a major source

of protein, both from

finfish and from

shellfish.

o With the amount of fish

caught each year

increasing, the fish

cannot reproduce fast

enough to keep up.

o Disrupts ecosystem

(food web)

Water Resources

What is being done?

Limiting the catch of fish

Certain fishing grounds

have been temporarily

closed

Aquaculture - farming

of aquatic organisms

Air Resources

What is happening?

Smog

a mixture of chemicals that occurs as a gray-brown haze in the

atmosphere

This is due primarily to automobile exhausts and industrial

emissions.

Pollutant - a harmful material that can enter the biosphere

through air, land, or water

The burning of fossil fuels can release pollutants that cause

smog and other problems in the atmosphere.

What is Acid Rain and

What Causes It?

"Acid rain" is a broad term used to describe several ways that acids fall out of the atmosphere. A more precise term is acid deposition, which has two parts: wet and dry.

Wet deposition refers to acidic rain, fog, and snow. As this acidic water flows over and through the ground; it affects a variety of plants and animals.

Dry deposition refers to acidic gases and particles. About half of the acidity in the atmosphere falls back to earth through dry deposition. The wind blows these acidic particles and gases onto buildings, cars, homes, and trees. Dry deposited gases and particles can also be washed from trees and other surfaces by rainstorms.

What is Acid Rain and

What Causes It?

Prevailing winds blow the compounds that cause both wet and dry acid deposition across state and national borders, and sometimes over hundreds of miles.

Scientists discovered, and have confirmed, that sulfur dioxide (SO2) and nitrogen oxides (NOx) are the primary causes of acid rain.

In the U.S., about 2/3 of all SO2 and 1/4 of all NOx come from electric power generation that relies on burning fossil fuels like coal.

Acid rain occurs when these gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds. Sunlight increases the rate of most of these reactions. The result is a mild solution of sulfuric acid and nitric acid.

Air Resource Depletion

Air Resources

Why is it a problem?

This leads to toxins that enter the mouth, nose and lungs

causing health problems over the long term.

Gases released from the burning of fossil fuels combine with

water vapor to form ACID RAIN

Acid rain kills plants and changes the chemistry of soils

What is being done?

Technology to control emissions from factory smokestacks

Strict automobile emission standards and clean air regulations

Global Warming

Global Warming

Some warming is good

if not for the ozone and atmosphere, Earth would be -18˚C

Warming is due to greenhouse gases in the atmosphere trapping in heat

Estimated increase of 2˚C by end of 21st century

Even 1.3˚C affects polar ice cap melting

Sea levels could rise 100 m, gradually going in 150 km or more

Green House Effect

Natural situation in which

heat is retained in the

earth’s atmosphere by

green house gasses

Examples: carbon

dioxide, methane, water

vapor, and other gasses

Global Warming

Global Warming

Why is this a problem?

Polar ice caps will continue to melt and could rise

enough to flood some low lying coastal areas.

Storms and other weather disturbances could

become more frequent and severe.

Heat favors rodents, weeds, and insects that

reproduce and spread quickly.

Ozone Depletion

Ozone layer is composed of 03 in lower stratosphere.

Stratospheric Ozone The stratosphere, or "good" ozone layer extends upward from about 6 to 30 miles and protects life on Earth from the sun's harmful ultraviolet (UV) rays

This natural shield has been gradually depleted by man-made chemicals like chlorofluorocarbons (CFCs).

A depleted ozone shield allows more UV from the sun to reach the ground, leading to more cases of skin cancer, cataracts, and other health problems.

Ozone Depletion

Ozone Depletion

Ozone Depletion

Why is this a problem?

The ozone layer absorbs a great deal of harmful

UV rays before it reaches the earth’s surface.

As the ozone layer is depleted, UV exposure can

cause sunburns, cancer, eye damage and

decreases an organism’s resistance to disease.

Ozone Depletion Solutions

Reduce the amount of CFC’s use.

Most CFC’s are banned

1987 The Montreal Treaty

reduction of CFC’s and eventual ban the

CFC production.