EVS 207 Final Review

Earth’s Compositional Layers

• Crust

  • Thinnest and outermost layer of Earth

  • Can be oceanic or continental

  • Oceanic crust is thinner but more dense than continental crust

• Mantle

  • Thickest section of Earth, subdivided into different zones with different properties

• Core

  • Innermost section

  • Divided into liquid outer portion and solid inner portion; densest materials

Earth’s Mechanical Layers

• Lithosphere

  • Rigid/brittle outer shell of Earth

  • Composed of both crust and uppermost mantle

  • Makes up Earth’s tectonic plates

• Asthenosphere

  • Plastic zone on which the lithosphere floats

Basics of Plate Tectonics

• The Earth’s lithosphere is divided into plates that move relative to each other.

• Rock along plate boundaries undergoes intense deformation as the plates move (towards, away, or along) their neighboring plates.

• As plates move, so do continents that form part of the plates.

• The map of the Earth’s surface is constantly changing due to plate movement

Earth’s Plates

• Some plates are entirely oceanic lithosphere, while others are made of both oceanic and continental lithosphere.

The Three Types of Plate Boundaries

• Divergent boundary – two plates move away from each other

• Convergent boundary – two plates move towards each other

• Transform boundary – two plates slide past each other

Divergent Boundary

• Two plates move away from each other; seafloor spreading produces new seafloor at a mid-ocean ridge.

• As seafloor spreading progresses, the ocean basin widens and continents move apart.

Convergent Boundary

• Two plates move toward one another. The downgoing plate sinks beneath the overriding plate because it is more dense; this process is called subduction.

Continental Volcanic Arc

• Subduction along the edge of a continent produces a continental volcanic arc.

• Note that sediments on the down-going slab are scraped off to form an accretionary prism.

Island Arc Formation

• When subduction involves two oceanic plates, a volcanic island arc forms on the overriding plate.

Transform Boundaries

• At a transform boundary, plates slide past one another along a vertical fault plane.

• No new plate forms, and no old plate is consumed.

• Example: Transform fault

San Andreas (Transform) Fault

• Some transform boundaries cut continental crust. For example, across the San Andreas fault, the Pacific Plate moves northwest relative to the North American Plate.

Hot-Spot Volcanoes

• Hot-spot volcanoes are probably a consequence of mantle plumes.

• As a plate drifts over the hot spot, a chain of extinct volcanoes (a hot-spot track) forms.

Modern Evidence of Plate Motion

• Plate motion can be measured using satellites, radar, lasers and global positioning systems (GPS).

Ring of Fire

• The rim of the Pacific Plate is called the “ring of fire” because of the high level of volcanic activity that occurs as the plate interacts with surrounding plate boundaries.

The Rock Cycle

• Representation of how rocks are formed, broken down, and processed in response to changing conditions

• Processes may involve interactions of geosphere with hydrosphere, atmosphere and/or biosphere

• Arrows indicate possible process paths within the cycle

3 Categories of Rocks

• Igneous

  • Form from the solidification of molten rock (magma)

• Sedimentary

  • Form from pieces of sediment created by weathering of pre-existing rocks

• Metamorphic

  • Form from increased temperature, pressure, and stress applied to pre- existing rocks

Minerals and Rocks

• Mineral definition:

  • Fixed chemical composition

  • Inorganic

  • Naturally occurring

  • Crystalline structure

  • Solid

• Rocks are an aggregate of one or more minerals

Weather, Climate & Climate Change

• Weather – describes what the atmosphere is doing over short timescales; extremely variable (it is hot and dry or cool and rainy today)

• Climate – the average weather pattern in a region over long periods of time, usually 30+ years; fairly consistent year to year (NE Ohio experiences four seasons) but variable on a large scale

• Climate Change – climate has fluctuated in the past and will continue to do so

  • average weather conditions (temperature, precipitation, cloudiness, winds, relative humidity, etc)

  • frequency of weather extremes

  • anthropogenic – influence of humans on the natural world

Atmosphere Energy Budget

• of the solar energy that reaches the atmosphere:

  • About one-quarter is reflected by clouds and the atmosphere.

  • Another quarter is absorbed by water vapor, carbon dioxide, ozone and a few other gases.

  • About half reaches the earth’s surface.

  • The amount that reaches the surface directly impacts the temperature that we experience

Solar Energy Balance

• Incoming solar energy: 100

• Reflected solar energy: 30

  • Reflected by clouds and atmosphere: 25

  • Reflected from surface: 5

• Absorbed by atmosphere and clouds: 25

• Absorbed by surface: 45

• Reradiated from clouds and atmosphere: 66

• Condensation in water: 4

• Convection currents: 5
  -Latent heat: 24

• Reradiated from surface: 12

• Conduction, ocean currents: 0

• Outgoing infrared energy: 70

• Greenhouse effect: 88

• Reabsorbed: 104

Albedo

• albedo: percentage of radiation reflected from a surface

  • light-colored objects have a high albedo and reflect more energy (snow, white paint, clouds)

  • dark-colored objects have a low albedo and reflect less energy (asphalt, dark soils)

• Global average is 30% reflection

Greenhouse Effect

• If all of Earth’s radiation energy was lost, its average surface temperature would be well below freezing (-19°C)

• Much of the Earth’s long-wave radiation is absorbed by gases in the atmosphere (greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide)

• This absorption of radiation heats the atmosphere and sends radiation back towards Earth’s surface, heating it up (Greenhouse Effect)

• act as a blanket – trap heat and keep it close to the surface

Greenhouse Gases

• Gases in the atmosphere that absorb some of the Earth’s outgoing radiation and in return release some of this energy back to the Earth, causing the surface to warm (greenhouse effect)

• Without the natural greenhouse effect, the Earth would be too cold for us to survive

• Carbon Dioxide – emissions have doubled from 1970 to 2010

  • Fossil-fuel burning is the major human caused source of carbon dioxide.

• Methane – wetlands and rice paddies are natural sources

  • Absorbs more energy than CO_2.

• Nitrous Oxide – vehicle engines, agriculture processes are major sources.

  • Highly effective at capturing heat energy.

• Hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) are synthetic chemicals used in a variety of industrial production processes such as semiconductor manufacturing.

Global Warming - Greenhouse Effect

• Sunlight (radiant energy) is absorbed at surface.

• Some heat radiated from Earth is absorbed by greenhouse gases.

• Some of this heat is transferred back to Earth's surface.

  Measuring Climate Change

  • Carbon Dioxide concentrations

    • Indirectly measured through historical ice cores

  • Global surface temperatures

  • Thickness and cover of Arctic sea and land ice

  • Sea level

  Glacial-interglacial Climate Change Record from Ice Cores

  • This slide shows a graph of the changes in N2O (ppb), CO2 (ppm), CH_4 (ppb), and \Delta T (K) over the past 800,000 years.

  Ecological/Carbon Footprint

  • How does your lifestyle contribute to greenhouse gas emissions?

  • How many Earth’s would be used up if everyone lived like you do?

  • What are some ways that you can reduce your carbon footprint?

    • Drive less

    • Eat less meat

    • Buy local

    • Get a roommate

    • Buy fresh

    • Conserve energy (turn out the lights)

  What Is Air Pollution?

  • Various chemicals (gases, liquids, or solids) present in the atmosphere in high levels that can harm humans, other organisms, or materials

  • Examples:

    • Gases: SO2, NOX, CO

    • Liquids: acid rain

    • Solids: particulate matter (PM2.5 and PM10)

  Conventional Pollutants: Air Quality Index

  • Environmental Protection Agency (EPA) establishes an AQI for six major air pollutants regulated by the Clean Air Act. Each of these pollutants has a national air quality standard set by EPA to protect public health:

    • ground-level ozone (O_3)

    • particle matter (PM2.5 and PM10)

    • carbon monoxide (CO)

    • sulfur dioxide (SO_2)

    • nitrogen oxides (NO_x)

    • lead

  What Is Water Pollution?

  • Water Pollution – any physical, biological, or chemical change in water quality that adversely affects the health of humans and other living organisms or significantly affects the desired (or designated) uses of water bodies

  • Types of Water Pollution:

    • Sewage, disease-causing agents, sediment, inorganic nutrients, organic compounds, inorganic chemicals, radioactive substances, and thermal pollution

  Sources of Water Pollution

  • Point Sources: Discharge pollution from specific locations

    • Discrete and identifiable

    • Factories, power plants, sewer outfalls

    • Can be monitored and regulated

  • Non-Point Sources: Scattered or diffuse, having no specific location of discharge

    • Often highly episodic with irregular timing

    • Agricultural fields, road salt application, lawns/gardens, golf courses, construction sites, parking lots

    • Difficult to monitor and/or regulate

  • Atmospheric Deposition: contaminants carried by air currents or precipitation into watersheds or directly onto surface water

  Major Categories of Water Pollution

  • Category A: Causes Health Problems

    • Infectious agents: Bacteria, viruses, parasites, from Human and animal excreta

    • Organic chemicals: Pesticides, plastics, detergents, oil, gasoline, from Industrial, household, and farm use

    • Inorganic chemicals: Metals, salts, from Industrial effluents, household cleansers, surface runoff

    • Radioactive materials: Uranium, thorium, cesium, iodine, radon, from Mining and processing or ores, power plants, weapons production, natural sources

  • Category B: Causes Ecosystem Disruption

    • Sediment: Soil, silt, from Land erosion

    • Plant nutrients: Nitrates, Phosphates, from Agricultural and urban fertilizers, sewage, manure

    • Oxygen-demanding wastes: Animal manure, plant residues, from Sewage, agricultural runoff, paper mills, food processing

    • Thermal: Heat, from Power plants, industrial cooling

  Why is stream health important?

  • Water is critical to sustaining life on Earth

  • Maintaining stream health is a vital part of sustaining biological diversity in aquatic ecosystems

  How is stream health measured?

  • Stream health/water quality is measured according to physical, chemical, and biological indicators

    • Physical: velocity of water current, temperature, pH, TSS (total suspended solids)

    • Chemical: dissolved oxygen, nitrogen compounds, total soluble phosphates

    • Biological: macroinvertebrates (organisms lacking a backbone that live on the bottom of the stream bed and can typically be seen without a microscope)

  Dissolved Oxygen (DO)

  • Amount of oxygen dissolved in water is important because oxygen is necessary for respiration by aquatic organisms

  • Different organisms require different amounts of DO to survive

    • Trout need about 6.5 ppm and sludge worms can live in 0 ppm

  • High DO = good water quality; Low DO = poor water quality

  Factors Influencing Dissolved Oxygen (DO)

  • Temperature: cold water holds more DO than warm water

  • Turbulence: a riffle (shallow section of a stream or river with rapid current and a surface broken by gravel, rubble or boulders) allows atmospheric oxygen to mix into water whereas deep shallow pools do not allow mixing

  • Presence of suspended and dissolved organic matter (from human and animal waste as well as dead and decaying plants and animals): cause an increase in decomposer bacteria that use oxygen in water to metabolize organic compounds

  • Respiration by aquatic organisms and photosynthesis: plants perform photosynthesis (produce oxygen) only during sunlight hours but perform respiration (consume oxygen) 24/7

  Riffle vs Pool:

  • Riffle: Rocks & Pebbles

  • Pool: Silt

  Phosphates and Nitrogen Compounds

  • Their presence in the water can indicate pollution.

  • Sources include:

    • Fertilizer runoff from lawns, golf courses, and agriculture

    • Insecticides, pesticides, herbicides used in landscaping

    • Animal waste

    • Sewage treatment plant effluent

    • Household detergent

    • Atmospheric deposition

  Human Impact on DO Levels

  • Organic wastes from human sewage

  • Concentrated animal feeding operations

  • Industry runoff

  • Runoff of fertilizer from farms and lawns (seasonal differences? rural vs urban?)

    • Increase in decomposer bacteria use oxygen in water to metabolize organic compounds

    • Nutrients stimulate growth of aquatic plants and photosynthetic organisms

    • Photosynthesis only occurs during sunlight but respiration continues 24 hours so increased presence of organisms that use photosynthesis reduces DO content; when these organisms die the decomposer bacteria will consume more oxygen

  Biochemical Oxygen Demand (BOD)

  • Presence of organic matter results in growth of decomposer bacteria that use oxygen for aerobic respiration as they break down organic matter; this demand for oxygen is known as BOD

  • Downstream from a pollution source, the DO content initially decreases and then rises as part of the oxygen sag curve; the BOD has an inverse relationship as it rises initially before slowly falling as the organic material is decomposed

  Oxygen Sag Curve

  • Clean Zone: Normal clean water organisms (Trout, perch, bass, mayfly, stonefly), DO at 8 ppm

  • Decomposition Zone: Trash fish (carp, gar, Leeches). DO decreases

  • Septic Zone: Fish absent, fungi, Sludge worms, bacteria. BOD increases and DO sag at 2 ppm

  • Recovery Zone: Trash fish (carp, gar, Leeches). BOD decreases and DO increases.

  • Clean Zone: Norma clean water organisms (Trout, perch, bass, mayfly, stonefly) DO at 8 ppm

  Kinds of Energy

  • Fossil fuels: a natural fuel formed in the geological past from the remains of living organisms (Coal, natural gas, oil)

  • Nuclear energy: use of nuclear reactions that release nuclear energy to generate heat, which is then used in steam turbines to produce electricity in a nuclear power plant (Fission, fusion, decay)

  • Renewable energy: collected from resources which are naturally replenished on a human timescale (sunlight, wind, rain, tides, waves, and geothermal heat).

  What is Renewable Energy?

  • Energy that comes from sources that can be replenished, renewed, or reused (Biomass, solar energy, wind, geothermal energy, hydroelectric power)

  • As of 2022 provided nearly 22% of electricity generation in the US, and around 13% of all energy consumption (industrial, transportation, residential, commercial)

  Solar Energy

  • Radiant light and heat from the Sun harnessed using a range of technologies such as solar heating, photovoltaics, solar thermal energy, solar architecture and artificial photosynthesis.

  • Most abundant source of renewable energy

  • Drawback: Requires a high amount of space and technology to be effective.

  Wind Energy

  • Use of air flow through wind turbines to mechanically power generators for electricity

  • Average wind speeds above 6.5 meters/second are considered suitable for wind turbines

  • Most wind turbines are situated 80+ meters high

  • Drawbacks: Must be positioned where wind is ever- present at sufficient speeds to be effective. Can block views and be detrimental to wildlife (bird migration).

  Biomass Energy

  • Numerous categories (Ethanol, Organic residues, Mill residues, Methane emissions)

  • Conversion of biomass to electricity requires about a metric ton of biomass to produce about 3500 kWh

  • Drawback: A large amount is required to be an effective long- term energy supply

  Geothermal Energy

  • Temperature gradient increases as one moves deeper beneath the Earth’s surface

  • Underground heat is relatively constant and can be trapped to heat water in a boiler system

  • Drawbacks: High-temperature fluids can be highly corrosive and require a detailed maintenance plan. Long-term supply of heat in that exact location is difficult to predict.