Review straight from the slides

Ozone Depletion

CFCs are man-made substances found in coolants and aerosols.  In the stratosphere under UV light one of the three Cl- molecules can come off, which reacts with Ozone (O₃) to create O₂ + ClO. This depletes the ozone layer.  Other free O- molecules interact with the ClO to create O₂  and Cl-, which causes the cycle to repeat itself.  

Tropospheric Ozone Depletion

• In the troposphere, NO₂ from cars reacts in sunlight to form NO + O-.  

• The lone oxygen will react with  O₂ to form Ozone (O₃) in the troposphere, which is BAD.

Ozone is: “Good up high (in the stratosphere), bad nearby (troposphere)

• This NO will go on to react with VOC (Volatile Organic Compounds) to form Photochemical Oxidants.  

• Photochemical Oxidants combined with Ozone will create Photochemical smog.

Importance of Wetlands

• Threatened by drainage and development

• Ecosystem services provided include

  • Maintain drinking quality

  • Flood control

  • Water filtration

  • Commercial fisheries

  • Recreation

  • Wildlife habitat (contributes to food or ecotourism)

The Nitrogen Cycle

Nitrogen Fixation

The process where certain bacteria convert nitrogen gas from the air into a form plants can use.

• Example: Rhizobium bacteria in legume roots help plants get nitrogen.

• Importance: Provides essential nitrogen for plant growth.

N₂ + 3H₂ → 2NH₃

Ammonification

The process where organic nitrogen from dead organisms is converted into ammonia by decomposers like bacteria. Plants can then use this ammonia to make proteins.

• Example: Bacteria break down organic nitrogen compounds in dead organisms into ammonia. For instance, in soil, bacteria decompose dead plants and animals, releasing ammonia as a byproduct.

• Importance: It converts organic nitrogen from dead organisms into ammonia, which plants can use for growth.

organic nitrogen compounds → NH3

Nitrification

The process where bacteria convert ammonia into nitrites, then into nitrates.

• Example: Ammonia is converted to nitrite by Nitrosomonas bacteria, then to nitrate by Nitrobacter bacteria in soil. For instance, in agricultural fields, ammonia from fertilizers is transformed into nitrate, which plants can absorb for growth.

• Importance: Creates essential nutrients for plants. This process makes nitrogen available for plant uptake, promoting growth and productivity in ecosystems.

NH3 → NO3-

Assimilation

The process where plants and animals take up nitrogen compounds like nitrates from the soil to build proteins and other essential molecules for growth and development.

• Example: Plants absorb nitrate or ammonium ions from the soil and incorporate them into their proteins, DNA, and other organic molecules.

• Importance: It converts inorganic nitrogen into organic forms like proteins, DNA, and chlorophyll, making nitrogen available for living organisms.

Incorporation of NH3 and NO3- into biological tissues

or

NH4+ + 2O2 -> NO3- + H2O + 2H+

Dentrification

The process where bacteria convert nitrates in the soil back into nitrogen gas, releasing it into the atmosphere.

• Example: Bacteria convert nitrates in soil back into nitrogen gas, releasing it into the atmosphere.

• Importance: Converts nitrates back into nitrogen gas, completing the nitrogen cycle and replenishing the atmosphere with nitrogen.

NO3 → N2

Soil Components

O Horizon

Organic matter in various stages of decomposition

A Horizon (topsoil)

Zone of overlying organic material mixed with underlying mineral material

E Horizon

Zone of leaching of metals and nutrients; occurs in some soils beneath either the O horizon or the A horizon

B Horizon (subsoil)

Zone of accumulation of metals and nutrients

C Horizon (subsoil)

Least-weathered portion of the soil profile, similar to the parent material

Vocab

Horizon: Each layer of soil

Soil profile: The cross-section of soil as a whole

(up to six major horizons may occur in a soil profile)

Topsoil: inorganic and organic material most nutritious for plants

Leaching: Dissolved particles move down through horizons

Climate Change

Some greenhouse gasses are produced by human activity:

• Burning of fossil fuels

• Agricultural practices

• Deforestation

• Landfills

• Industrial production

Carbon Dioxide

Although carbon dioxide is not the most potent greenhouse gas, it is extremely abundant

• It is a major contributor to global warming

• Human activities have boosted atmospheric concentrations from 280 ppm to 383 ppm

• At their highest levels in more than 650,000 years

Impacts of the Increase in Greenhouse Gases

• Melting of polar ice caps (in Greenland and Antarctica)

• Melting of many glaciers around the world

• Melting of permafrost

• Rising of sea levels due to the melting of glaciers and ice sheets and as the water warms it expands

• Heat waves

• Cold spells

• Change in precipitation patterns

• Increase in storm intensity

• Shift in ocean currents

Ocean Acidification

• Coral reefs can be bleached due to the increase in water temperature

  • This affects coral symbiotes and makes them more susceptible to diseases

Ocean Acidification: The other CO2 problem

• Surface waters have increased in acidity by 30% since 1800

• Could reach dangerous levels before 2050

• CO2 combines with water to form carbonic acid (H2CO3)

• Threatens corals, snails, and other organisms with shells

Organisms

• Organisms are adapted to their environments, so they are affected when those environments change

• Global warming modifies temperature-dependent phenomena

  • Timing of migration and breeding change

• Spatial shifts in the range of organisms

  • Animals and plants will move toward the poles or upward in elevation

  • 20-30% of all species will be threatened with extinction

• Plants act as carbon sinks; fewer plants means more CO2 in the atmosphere

Solutions

Mitigation: Pursue actions that reduce greenhouse gas emissions, in order to lessen the severity of future climate change

• Renewable energy sources, farm practices to protect soil integrity preventing deforestation

Adaptation: Accept climate change is happening and pursue strategies to minimize its impacts on us

• Criticized as sidestepping

Both are necessary

Carbon Offset: A voluntary payment to another entity intended to enable that entity to reduce the greenhouse emissions that one is unable or unwilling to reduce oneself

• Becoming popular among utilities, businesses, universities, governments, and individuals trying to achieve carbon neutrality, where no net carbon is emitted

• Carbon offsets fall short

  • A lack of oversight to make sure that the offset money accomplishes what it is intended for

Chem Review

pH

pH is a measure of the amount of H+ and OH- ions in a solution

Acids have a higher concentration of H+ and Bases have a higher concentration of OH-

The pH scale is logarithmic, so each value is 10x greater than the next higher value

Formation of Acids in the Environment

NOx (from cars) + H2O → HNO3 (Nitric acid)

SOx (from coal) + H2O → H2SO4 (Sulfuric acid)

CO2 (from fossil fuels) + H2O → H2CO3 (Carbonic acid)

The formation of an acid causes the pH to decline

• Environments that become acidic from acid rain or acid mine drainage may be remedied by adding a base such as limestone. Acid rain results in the loss of nutrients from soil (clay is attracted to the acid and releases metals) and metals such as AL3+ may be leached out of the soil and runoff into groundwater. Acid rain leads to general forest decline.

• The ocean becomes acidic due to carbonic acid from excess release of CO2 from burning fossil fuels. Ceasing the use of fossil fuels will help prevent the problem, but there is remediation - you can not add enough limestone to raise the pH of the ocean.

Dissolved Oxygen

Gases dissolve better in cooler-temperature liquids. As temperature increases, less gas dissolves. As temperatures decrease, more gas dissolves. As temperatures warm or cool due to climate change, more or less oxygen can be dissolved in the waters. Cooler temperature waters hold more dissolved oxygen (DO) while warmer waters hold less. This can impact an organism’s range of tolerance. As our oceans warm, they absorb and store less CO2 and less DO. If sediment erodes and runs off into a waterway, the dark soil absorbs sunlight, warming the waters and causing DO to decline.

Electricity

• The flow of electrons in a wire

• Can be generated from almost any energy source

  • Energy sources spin a turbine

  • The turbine turns a generator

    • A bundle of wires spins around a magnet or vice versa

Air Pollution

Tropospheric Ozone and Photochemical Smog Formation

Tropospheric Ozone Formation:

• Formed by reactions of nitrogen oxides and volatile organic compounds in the presence of sunlight.

• Precursor pollutants are released from human activities like vehicle emissions.

Photochemical Smog Formation:

• Results from the interaction of sunlight with pollutants like nitrogen oxides and volatile organic compounds.

• Leads to the formation of ground-level ozone and other harmful compounds.

Solutions

• Decreased use of fossil fuels

• Improved efficiency

• Use of electrostatic precipitators and scrubbers

Dams

Much of hydropower in recent years has been from enormous dams

• Human Displacement

• Ecosystem Destruction

• Wildlife Losses

• Large-Scale Flooding Due to Dam Failures

• Sedimentation

• Herbicide Contamination

• Evaporative Losses

• Nutrient Flow Retardation

Rotting of submerged vegetation kills fish, acidifies water, produces greenhouse gases

Schistosomiasis - a human disease caused by a parasitic fluke that lives in snails, which like the slow-moving water behind dams

Eutrophication

Eutrophication Process:

1. Excessive Nutrients: Nutrient runoff enters water.

2. Algal Bloom: Nutrients promote algal growth.

3. Algae Die-off: Algae die, sink, and decompose.

4. Oxygen Depletion: Decomposition reduces oxygen.

5. Dead Zone Formation: Low oxygen levels harm aquatic life.

Biochemical Oxygen Demand - the amount of dissolved oxygen consumed by aquatic microorganisms. 

• Used as a test for organic waste contamination.

Dissolved Oxygen Content - a measure of dissolved oxygen in the water

• The effects of oxygen-demanding wastes on rivers depend on river water's volume, flow, and temperature.

Oxygen Sag - Oxygen levels decline downstream from a pollution source as decomposers metabolize waste materials

Biochemical Oxygen Demand - The amount of dissolved oxygen consumed by aquatic microorganisms. 

• Used as a test for organic waste contamination.

Dissolved Oxygen Content - a measure of dissolved oxygen in the water

• The effects of oxygen-demanding wastes on rivers depend on the volume, flow, and temperature of river water.

Oxygen Sag - Oxygen levels decline downstream from a pollution source as decomposers metabolize waste materials

• During hot weather or drought

• Dense growths of algae and cyanobacteria

Impacts of Eutrophication

The level of nitrates discharged from the Mississippi River into the Gulf of Mexico tripled since the 1950s

• This causes severe depletion of dissolved oxygen

Food web disruption

• Many species cannot migrate away from the area and die

  • Which causes deaths of seabird and marine mammal species that depend on dying fish and shellfish

Human Factors

• Dredging and straightening increase the flow of nutrients

• Removal of wetlands that act as filters for pollutants

Can only be repaired with:

• Time

• Small areas that can be aerated

Prevented by:

• Education

• Riparian zones

• Plant ground cover or crops to absorb fertilizer

• Sustainable agriculture practices

Landfills

Solid Waste Management Terms:

• Groundwater Monitoring: Monitoring water quality to prevent contamination.

• Methane Collection: Capturing methane gas from waste for energy.

• Solid Cap: Covering waste to prevent water infiltration.

• Open Cell: Waste disposal area without liners.

• Leachate: Liquid formed by water passing through waste.

• Leachate Collection: System to collect and treat leachate.

• Closed Cell: Waste disposal area with liners.

• HDPE Liner: High-density polyethylene liner to contain waste.

• Gravel: Used for drainage in waste disposal areas.

• Clay: Natural material used for sealing waste containment areas.

The Carbon Cycle

The Carbon Cycle: The process through which carbon is exchanged between the atmosphere, oceans, soil, and living organisms.

Importance: It regulates the Earth's climate by balancing carbon dioxide levels in the atmosphere, supports plant growth through photosynthesis, and is essential for the survival of all living organisms.

Processes of the Carbon Cycle

• 1. Photosynthesis

  • Plants absorb CO2 from the atmosphere

  • Convert CO2 into glucose through photosynthesis

• 2. Respiration

  • Organisms release CO2 back into the atmosphere

  • Breakdown of glucose for energy

• 3. Decomposition

  • Decomposers break down dead organic matter

  • Release CO2 back into the atmosphere

• 4. Combustion

  • Burning of fossil fuels releases CO2 into the atmosphere

  Carbon Reservoirs

  • 1. Atmosphere

    • Contains CO2 in the form of a greenhouse gas

  • 2. Oceans

    • Absorb and store large amounts of CO2

  • 3. Plants and Soils

    • Store carbon through photosynthesis and decomposition

  • 4. Fossil Fuels

    • Coal, oil, and natural gas store carbon from ancient plant and animal remains

  Human Impact on the Carbon Cycle

  • 1. Deforestation

    • Reduces the ability of plants to absorb CO2

  • 2. Burning Fossil Fuels

    • Increases CO2 levels in the atmosphere

  • 3. Industrial Activities

    • Release large amounts of CO2 into the atmosphere

Impacts of Industrial Agriculture

Water Issues

• Groundwater depletion from irrigation

• Pollution from fertilizer and pesticide runoff

• Sediment pollution from eroding soil particles

• Pollution from animal wastes (livestock factories)

• Enrichment of surface water from fertilizer runoff and livestock wastes

Air Pollution

• Pesticide sprays

• Soil particles from wind erosion

• Odors from livestock factories

• Greenhouse gases from the combustion of fossil fuels

• Other air pollutants from the combustion of fossil fuels

Land Degradation

• Soil erosion

• Loss of soil fertility

• Soil salinization

• Soil pollution (pesticide residues)

• Waterlogged soil from improper irrigation

Loss of Biological Diversity

• Habitat fragmentation (clearing land and draining wetlands)

• Monocultures (lack of diversity in croplands)

• Stressors from air and water pollution

• Stressors from pesticides

• Replacement of many traditional crop and livestock varieties with just a few

Increases in Greenhouse Gases

Thermal Expansion of Seawater

Water expands as it heats up, and oceans have been absorbing most of the heat trapped by greenhouse gases released by fossil fuel burning, deforestation, and animal farming.

• Example: If a container of seawater is heated, it will increase in volume as the temperature rises, demonstrating the principle of thermal expansion.

• Effects: Warming waters caused as much sea level rise from 2002 through 2014 as the melting of all the glaciers and Greenland Antarctic ice sheets combined.

Climate Change Increases Diseases Transmitted Through Insects

Rising global temperatures can lengthen the season and increase the geographic range of disease-carrying insects.

• Example: As temperatures warm, mosquitoes and other warm-weather vectors can move into higher altitudes and new regions farther from the equator

• Effects: For instance, in some regions in the United States, warming is lengthening the season for Zika-carrying mosquitoes.

Increased rainfall, flooding, and humidity create more viable areas for vector breeding, allowing breeding to occur more quickly, as eggs hatch faster in hotter climates.

• Cause and Effect: Officials braced for increased risk for Zika and West Nile virus infections after the massive flooding event in Louisiana in August 2016, which increased the breeding habits for Aedes mosquitoes.

Carbon Sequestration

Biological Carbon Sequestration

Biological carbon sequestration is the storage of carbon dioxide in vegetation such as grasslands or forests, as well as in soils and oceans

• The most common/most known form of carbon sequestration

Geological Carbon Sequestration

Geological carbon sequestration is storing carbon dioxide in underground geologic formations, or rocks. Typically, carbon dioxide is captured from an industrial source, such as steel or cement production, or an energy-related source, such as a power plant or natural gas processing facility, and injected into porous rocks for long-term storage.

• Happens naturally during the carbon cycle

Technological Carbon Sequestration

Scientists are exploring new ways to remove and store carbon from the atmosphere using innovative technologies. Researchers are also starting to look beyond the removal of carbon dioxide and are now looking at more ways it can be used as a resource.

Biodiversity

Biodiversity in an ecosystem includes genetic, species, and habitat diversity.

Population Bottleneck

The more genetically diverse a population is, the better it can respond to environmental stressers. Aditionally, a population bottleneck can lead to loss of biodiversity.

Population bottleneck is a sharp reduction in the size of a population due to environmental events or human activities, leading to a loss of genetic diversity.

Biodiversity Importance

Diverse communities are generally more resilient to to disturbance than otherwise similar, but less diverse communities. A diverse community is one that would likely have overlaping niches. If one species is lost, another one may serve a similar role in the community.

• Ecosystems with a larger number of species are more likely to recover from disrupters.

Habitat Loss

Without maintenance of very large blocks of inter-connected forest, there is a clear risk that hundreds of species could become extinct. Larger mammals such as elephants are particularly affected because of the vast, particular areas needed to survive.

• Loss of habitat leads to a loss of specalist species, followed by a loss of generalist species. It also leads to reduced numbers of species that have territorial requirements.

Ecological Tolerence

The range of conditions, such as temperature, salinity, flow rate, and sunlight an organism can endure before injury or death results.