Unit 2B Human Impact on the Biosphere

Chapter 6 in the textbook

6.1 – A Changing Landscape

Development

6.2 Using Resources Wisely

1. Soil Resources

• Soil is needed to grow crops (for food!)

• Healthy soil has nutrients, few salts, and can hold moisture while allowing extra water to drain

• Healthy soil is created over long periods of time by interactions between soil and the plants growing in it

Soil Erosion

• The removal of soil by water and wind

• Roots of growing plants normally hold soil in place and prevent erosion

• If plants are removed, erosion can occur more easily

• Also, erosion carries away nutrients that make the soil healthy

Desertification

• The process of turning farmland into desert that occurs due to farming, overgrazing, drought, and climate change.

Deforestation

• The loss of forests• Forests hold soil in place

and absorb CO2

• Without forests, soil erosion can occur and there will be more CO2 in the atmosphere.

• Sometimes forests can grow back, but it can take centuries

2. Atmospheric Resources

• We need oxygen from the air to breathe

• Ozone (O3) in the upper atmosphere absorbs UV rays, protecting us from skin damage that causes cancer.

• Greenhouse gases (carbon dioxide, methane, and water vapor) hold heat in the atmosphere to regulate Earth’s temperature

Air Pollution• Burning fossil fuels (coal, oil, natural gas)

release pollutants (harmful materials) into the air

• This can affect breathing, and change climate

Forms of Air Pollution

A. Smog-

- Gray-brown haze formed from chemical reactions between air pollutants

- Harmful when breathed in

Forms of Air Pollution (cont.)

B. Acid Rain-

- Two of the elements released into the air by the burning of fossil fuels are nitrogen and sulfur

- When combined with water vapor, these become acids, and fall as acid rain (below pH of 5.0)

- Can kill plants and change the chemistry of the soil

Forms of Air Pollution (cont.)

C. Greenhouse gases-

- In addition to nitrogen and sulfur, burning fossil fuels also releases carbon into the air as CO2

- Burning forests also release CO2

- CO2 is a greenhouse gas

- Excess greenhouse gases cause global warming because they trap heat in the atmosphere

Forms of Air Pollution (cont.)

D. Particulates-

- Microscopic particles of ash and dust released by industries and diesel engines

- Can be breathed into the lungs and cause health problems

3. Freshwater Resources

• We rely on fresh water for drinking, industry, transportation, energy, and waste disposal

• Only 3% of Earth’s water is fresh (most of that is frozen at earth’s poles)

• Freshwater ecosystems should be protected

Water Pollution

• Water pollutants come from factories, oil spills, automobiles, (etc.), or can be washed off the ground by rain.

• Most pollutants come from industrial and agricultural chemicals, and residential sewage.

Positive Synergy

• Occurs when two pollutants have little effect on their own, but multiply each others effect when combined

Industrial and Agricultural Chemicals

• Rainwater washes waste chemicals, fertilizers and pesticides into the water supply.

• Excess fertilizer in the water can lead to eutrophication

• When organisms (like primary producers) in the water pick up chemicals, their bodies can’t get rid of them, so they store them in their cells.

• When the consumers eat the producers, they eat and store the chemicals too.

Biological Magnification

• As chemicals stored in organisms travel up the food chain, they become more concentrated in the bodies of the organisms

• This process is called biological magnification

Biological Magnification (cont.)

• The higher the trophic level, the greater the concentration of chemicals

• Roughly 10 times greater at each trophic level

• This can cause serious problems for wildlife, and even for humans who eat fish

6.3 Biodiversity

Biodiversity-

• The variety of all forms of life in the biosphere.

• Three types: ecosystem diversity, species diversity, and genetic diversity.

1. Ecosystem Diversity- The variety of habitats, communities, and ecological processes in the biosphere.

2. Species Diversity- the number of different species in the biosphere

3. Genetic Diversity- all of the variations in genetic information (genes) carried by the organisms of the biosphere.

3 Types of Biodiversity

Threats to Biodiversity

• Human activities can alter biodiversity by causing the extinction of certain species.

1. Altered habitats: changing or removing a habitat to farm or build on the land

- Habitat fragmentation- splitting an ecosystem into pieces by developing an area

2. Hunting: killing animals for food, sport, or to sell body parts (like skin, fur, tusks, etc.)

3. Invasive species (also called “introduced” or “exotic”): non-native organisms brought into an ecosystem.

4. Pollution: forms of pollution can affect the ability of new generations to survive.

- Pesticides can prevent birds from laying eggs

- Acid rain can make water more acidic, affecting the survival of aquatic organisms

5. Climate Change: the increase in global temperature.

- species are adapted to survive in a certain temperature range.

- it is uncertain how disruptive climate change will be to the biodiversity on Earth.

Conserving Biodiversity

1. Protect Individual Species- placing endangered species into zoos or aquariums where they can safely reproduce.

- The goal is to later place the organisms back into the wild.

Conserving Biodiversity (cont.)

2. Preserving Habitats and Ecosystems- protect the areas where organisms live.

- Ecological Hot Spots- places with large numbers of species and habitats that are in danger of extinction.

Conserving Biodiversity (cont.)

3. Incentives to change behavior-

- US government offers tax credits to people who put up solar panels or buy hybrid cars

- Industries are paid money when they release less pollution

6.4 Meeting Ecological Challenges

Renewable Resources• Resources that can be

produced or replaced quickly after they have been used.

Examples: 1. Trees- can grow back (relatively)

quickly after they have been cut down.

2. Sun, wind, water, geothermal (all can be used for energy)

3. Biomass- garbage, wood, waste, plants, landfill gases (all can be reused for energy)

Nonrenewable Resources

• Resources that can not be replenished within a reasonable amount of time after they have been used.

Examples:1. Fossil Fuels- coal, oil, natural

gas- Take millions of years to form- Once they are used up, they

will be gone forever

These resources are “finite”!!

Ecological Footprint• Refers to the human impact on the

environment• Describes the total land and water

needed to provide for an individual and make harmless its wastes

• Takes into account what is needed to provide energy, food, water, and shelter, and to absorb wastes like sewage and greenhouse gases

Comparing Footprints

• It is hard to calculate the exact size a footprint for a person, country, or the world

• Estimated footprint sizes show that Americans have a footprint 4 times larger than the global average

Comparing Footprints

Sustainability

• The ability to use resources in a responsible way, thinking about the future

Examples: 1. leave stems and roots from crops to prevent erosion2. Replant trees3. Sewage treatment to protect the water4. Plants roots filter water in the ground, so maintain the

land that the water runs through5. Remove cars that pollute excessively from the road6. Remove excess chemicals from gasoline7. Use more renewable resources than nonrenewable

A Sustainable Future-

• Means how to face ecological challenges so that our resources are not gone or unhealthy in the future

• How do scientists face ecological challenges?

1. Recognize the problem2. Determine the causes3. Show us how to change our behavior to help

or fix the problem