Biodiversity Loss, Human Impact on Ecosystems & Resources Notes

Unit L: Biodiversity Loss, Human Impact on Ecosystems & Resources

Human Population Growth and Resource Demand

• As the human population grows, the demand for Earth's resources increases.

Pressure on Earth's Natural Resources

• The growing human population exerts pressure on Earth’s natural resources.

Renewable Resources

• Renewable Resources are resources that can be replaced at the same rate that it is consumed.
  • Examples: wind, biomass, geothermal, hydroelectric, & solar energy.
  • Using these resources impacts the environment.
  • Burning biomass increases $CO_2$ emissions.

Nonrenewable Resources

• Nonrenewable resources are natural resources that are used faster than the rate at which they can be replaced.
  • Examples: minerals, nuclear materials (uranium & plutonium), fossil fuels (oil, coal, petroleum, natural gas).
  • Extraction methods such as mining, drilling, hydraulic fracturing can damage ecosystems and cause harm to humans.

Renewable Resources Becoming Nonrenewable

• If renewable resources are not used carefully, they can become nonrenewable.
  • Examples:
    • Polluting drinking water.
    • Cutting down too many trees without allowing them to regenerate.
• Maintaining this balance is critical as the population continues to grow.

Fossil Fuel Emissions and the Biosphere

• Fossil fuel emissions affect the biosphere.

Pollution

• Pollution is any undesirable factor added to the air, water, or soil.
  • Can be: microscopic air particles, waste products from factories & sewers, and household chemicals.
• Harmful effects may be immediate or delayed and accumulate over time.
• Disrupts the function of ecosystems.

Smog

• Smog is a type of air pollution that forms from the burning of fossil fuels.
• Chemical compounds released combine to form smog when sunlight interacts with pollutants in the air.
• Two components of smog:
  • Particulates: very small dust, metal, & unburned fuel that can be inhaled before settling to the ground.
  • Ground-level ozone:
    • In the presence of sunlight, nitrogen dioxide ($NO<em>2$) and oxygen ($O</em>2$) react to produce ozone ($O_3$) and nitrogen monoxide ($NO$).
    • $NO<em>2 + O</em>2 \rightarrow O_3 + NO$
    • This ozone stays close to the ground and is harmful to living organisms.
• Ozone in the stratosphere acts as a shield to protect us from harmful UV rays.
• Smog can be harmful to human health.

Acid Rain

• Acid rain is caused by fossil fuel emissions.
  • Produced when pollutants in the water cycle cause rain pH to drop.
  • Water in the atmosphere reacts with sulfur dioxide ($SO<em>2$) and nitrogen oxides ($NO</em>x$) to form sulfuric and nitric acids.
• Can lower the pH of a lake or stream and harm trees.

Climate Change

• Air pollution is changing Earth’s biosphere, leading to climate change.
• The levels of atmospheric carbon dioxide rise and fall over time.
• High levels of carbon dioxide are typical of Earth’s warmer periods.
• Low levels of carbon dioxide are typical of Earth’s cooler periods, including ice ages.

Greenhouse Effect

• The greenhouse effect occurs when $CO<em>2$, $H</em>2O$, and $CH_4$ molecules absorb radiant energy from Earth’s surface and slow the release of energy from the atmosphere back into space.
• How it works:
  1. Sunlight penetrates Earth’s atmosphere.
  2. Energy is absorbed and reradiated as heat.
  3. Greenhouse gases absorb longer wavelengths.
  4. Greenhouse gas molecules rerelease infrared radiation.
  5. Results in warmer temperatures.

Global Warming

• Global warming refers to the trend of increasing global temperatures.
• Over the past 100 years, Earth’s global temperature has risen 0.6 º C.
• Scientists infer that increased levels of greenhouse gases are the cause of this increase.
• Scientists are investigating human impact and global biosphere effects of this warming trend.
• Global temperature fluctuations are normal parts of Earth’s climate cycle.

Water Pollution

• Pollution of Earth’s freshwater supply threatens habitat and health.
• Indicator species are animals, plants, or microorganisms used to monitor changes in our environment or the overall “health” of that ecosystem.
• Pollution can put entire freshwater and marine ecosystems at risk.
• Chemical contaminants such as sewage, trash, acid rain, fertilizers, & pesticides can make their way to rivers, lakes, aquifers, and oceans.
• A change in the chemistry of these water reservoirs can cause a lasting negative effect on our water supply.

Sources of Water Pollution

• Point source pollution: discharged from a single source.
  • Example: waste-release pipe from a factory.
• Non-point source pollution: many different sources that are difficult to identify.
  • Example: excess fertilizer from farmlands and homes.

Biomagnification

• Pollutants can be water or fat soluble.
• Water-soluble pollutants exit organisms through their waste.
• Fat-soluble pollutants stay in the body fat of an organism.
• Biomagnification: Pollutants can move up the food chain.
  • Predators eat contaminated prey.
  • Pollution accumulates at each stage of the food chain.
  • Top consumers, including humans, are most affected.

Water Management

• Biggest advancement for human health is sanitation and wastewater technology.
• Wastewater treatment filters and treats water to make it clean enough to return to rivers, lakes, and oceans to become part of the water cycle.
  • Removes organic material, scum, oil, and grease.
  • Kills bacteria and other harmful organisms.
  • Makes water safe to drink.
• Building dams benefit humans but hurts ecosystems.
• Temperature changes can cause changes in water quality found in reservoirs.

Biodiversity

• The impact of a growing human population threatens biodiversity.
• Biodiversity is the amount of variety of life on Earth.
• Healthy biodiverse ecosystems:
  • Clean our water.
  • Purify our air.
  • Maintain our soil.
  • Regulate the climate.
  • Recycle nutrients.
  • Provide us with food.
• All species, including humans, are adversely affected by the loss of species diversity.

Habitat Loss

• Loss of habitat eliminates species.
• Habitat loss due to agriculture, deforestation, & development.
• Clearing land – habitat loss can lead to extinction.
• Habitat fragmentation occurs when a barrier forms and prevents an organism from accessing its entire home range.
  • Reduces access to food/mates/shelter.
  • Places organisms at risk of getting run over.
• Solution: Habitat corridors can solve habitat fragmentation.

Introduced Species

• Introduced species can disrupt stable relationships in an ecosystem.
• Invasive species is any kind of living organism that is not native to an ecosystem and causes harm.
  • They can harm the environment, the economy, or even human health.
• An introduced species is invasive and is one that is brought to an ecosystem by humans, accidentally or on purpose.
  • Can exploit and push native species out.
  • Do well due to lack of predators.
  • Can cause a negative economic impact in a region.

Impacts on Land

• Deforestation, building cities, raising livestock and growing crops damage land.
• These activities cause loss of plants leaving soil behind.
• This leads to soil erosion – soil washed away by moving water, wind, and other agents.
• Soil erosion can lead to:
  • Land that is less fertile (missing nutrients).
  • Damage to the quality of the water in rivers, lakes, and the ocean due to runoff.
  • Disease-causing bacteria/pathogens spreading to other areas.
• If soil is damaged enough, desertification occurs – areas become desert-like over time.
• Mining can be:
  • Subsurface: looking for minerals, oil, coal below the surface
  • Surface: remove rock and soil on the surface to expose minerals

Conservation Methods

• Conservation methods can help protect and restore ecosystems.

Protecting Habitats & Species

• State and National Parks set aside public lands to be preserved in a natural state.
• Protecting endangered species protects individual species that are near extinction by protecting their habitat.
  • All species living in that habitat become protected.
• Sustainable fishing and hunting practices reduce overharvesting and conserve species populations.
  • Aim is to keep fish/wildlife populations at a sustainable level while providing food for humans.
  • Reduce harvesting.
  • Reduce net catches/use special types of nets.
  • Have certain times of the years for certain fish.
  • Fish size requirements

Habitat Conservation: Umbrella Species

• Umbrella species are species selected for making conservation-related decisions; these species indirectly protect the many other species that make up the ecological community of its habitat.

Engineering Solutions and Sustainable Development

• Engineering solutions help solve problems, such as the need for more renewable energy.
• Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

Converting Energy

• Petroleum, natural gas, and coal products are the primary energy source in the USA.
  • They emit greenhouse gases when burned.
• Nuclear power plants use nuclear fission to produce electricity and emit nuclear waste.
  • This waste must be stored properly or it will leak radioactive material.
• Renewable energy does not emit greenhouse gases nor radioactive waste.

Converting Waste Into Energy

• Landfills are a solution for storing human waste but it releases $CH_4$ as organic waste decomposes.
  • $CH<em>4$ has a 25% greater impact on the climate than $CO</em>2$.
  • Reduction of $CH_4$ is beneficial because it reduces the amount of trapped heat in the atmosphere.
• Waste-to-energy incinerators burn waste at high temperatures, producing steam to generate electricity.
  • They emit other greenhouse gases and pollutants.
• Making biofuel from waste – reused vegetable oil to power motor vehicles
• Ethanol is another biofuel made from corn or agriculture by- products
  • Growing agriculture for biofuels does have an environmental impact
  • Biofuels emit fewer greenhouse gases
• Anaerobic digestion of biomass uses microorganisms to break down organic substances in the absence of $O_2$.
  • Produce a mixture of gases called biogas ($CO<em>2$ and $CH</em>4$) that can be harvested instead of released into the atmosphere.
  • The residue that remains is called digestate and can be used as fertilizer.

Improving Solar Energy Efficiency

• Solar panels harvest sunlight and convert it into electrical energy by the movement of electrons.
• Silicon and hydrocarbons are used as the semiconductor.
• Expensive to make and install.

Engineering & Conservation

• Preventing deforestation:
  • The current rate is unsustainable.
  • Impacts the world because forests are carbon sinks.
  • Reduces biodiversity with loss of habitats.
  • Interrupts the water cycle, reduces water quality, & reduces $O_2$ production.
• Solutions: Reuse, Reduce, & Recycle
  • Decrease wood products in building and construction.
  • Find wood alternatives.
  • Use alternative plants like bamboo which grows rapidly.

Invasive Species Management

• Methods used to remove invasive species include:
  • Burning (plants only)
  • Chemical herbicides (plants only)
  • Grazing (plants only)
  • Physical removal (both plants and animals)
  • Hunting
  • Fishing
  • Trapping

Sustainable Fishing & Hunting Practices

• Federal and state regulations include:
  • Catch size
  • Season length
  • Age & sex of the animal
  • Catch limits
  • Allowable equipment
• Also reduces bycatch – any fish captured during commercial fishing that is not the target species (turtles and dolphins).