Earth Systems

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Chapter 8

• Earth Systems

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Hybrid Electric Vehicles
Although they reduce our consumption of liquid
fossil fuels, HEV do come with environmental
trade-offs. They require scarce metals for the
motors and the batteries.
Mining of these metals have severe environmental
impacts such as adding acid, as well as harmful
levels of metal to waterways, erosion of soil,
and creates habitat destruction.
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Earths Resources

• Most of the elements that we have on earth
• came from when the earth was first formed 4.6
  billion years ago.
• They were distributed unevenly around the globe.
• Earths elements settled into place based on
  their mass leading to distinct vertical zonation.

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Earths Layers
The core is made up of Ni and Fe. The inner core
is solid and the outer core is liquid. The mantle
contains magma that slowly circulates in
convection cells. The asthenosphere is composed
of semi-molten, ductile rock. The Lithosphere, is
a brittle outermost layer of the planet about
100km thick. It includes the solid upper mantle
as well as the crust. Over the crust lies the
thin layer of soil that allows life to exist on
the plant. The crust and the overlying soil
provide most of the chemical elements that
compromise life.
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Earth contains a finite supply of mineral
resources

• We cant extract indefinitely!
• Since we have already mined the most easily
  obtainable minerals, more energy must be used to
  extract the remaining resources.

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Mineral Distribution around the world
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Earth is constantly changing

• The core of the earth is very hot as a result of
  radioactive decay of various isotopes such as K,
  U, and Th which releases heat.
• The heat causes plumes of magma to well upward
  from the mantle to the lithosphere and create hot
  spots.
• The heat from the core also creates convection
  cells in the mantle that drives change and
  creation and renewal of Earths materials in the
  Lithosphere.

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Earths Tectonic Plates
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Theory of Plate Tectonics

• World continents were originally one land mass
  Pangaea
• Earths Lithosphere is divided into plates, most
  of which are in constant motion.
• The tectonic cycle is the sum of the processes
  that build up and break down the lithosphere.
• Oceanic plates lie beneath the oceans
• Continental plates lie beneath landmasses.

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Convection and Plate Movement

• Oceanic plates are more dense and rich in Fe.
• Continental plates contain SiO2, which is less
  dense than Fe. So they are lighter than the
  oceanic plates and typically rise above them.
• Both plates float on top of denser material below
  them and move by convection cells in the Earths
  mantle.
• As the plates move, the continents slowly drift.

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Convection Plate Movement
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Tectonic Plates
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Seafloor Spreading

• As Oceanic plates move apart, rising magma forms
  new oceanic crust on the seafloor at the
  boundaries between those plates.
• When Oceanic plates meet Continental plates, old
  oceanic crust is pulled downward beneath the
  continental lithosphere and the heavier oceanic
  plate slides underneath the lighter continental
  plate subduction

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Consequences of Plate Movement

• As the Continents drifted over time, many changes
  occurred climate changes, geographic barriers
  formed, species evolved or went extinct, some
  continents broke apart, islands formed, volcanoes
  formed, volcanic islands formed.

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Geologic Time Scale
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Type of Plate Contact

• Divergent plate boundaries when plates move away
  from each other. Magma reaches the Earths
  surface and pushes up and out creating new rock
  seafloor spreading.
• Convergent plate boundariesplates move towards
  each other and collide, creating mountain ranges
  (Andes)
• Transform fault boundary when plates move
  sideways past each other.

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Type of Plate Boundaries
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A fault zone in California is created where
movement of the plates has occurred and rock near
the plates margin fractures
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Earthquakes

• Earthquakes occur when the rocks of the
  Lithosphere rupture unexpectedly along a fault.
• The epicenter is the exact point on the Earths
  surface directly above the location where the
  rock ruptures.
• Sometimes volcanic eruptions and earthquakes are
  observed at the same time, along the plate
  boundaries where tectonic activity is high. Ring
  of Fire, around the Pacific Ocean.

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Locations of Earthquakes and Volcanoes
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Haiti Earthquake 2010 kills 200,000
The Richter Scale measures the largest ground
movement that occurs during an earthquake. The
scale is logarithmic, like the pH sale. So a 7.0
on the scale is ten times stronger than a
6.0. This earthquake registered as 7.0 in
magnitude
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Volcanic Eruptions

• Spew ash into the air that contains SiO2.
• Dust, rock or lava , and cinder may cause a loss
  of life, habitat destruction and alteration and
  reduction in air quality.

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THE ROCK CYCLE
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Rocks

• The substance that the lithosphere is made of,
  contains one or more minerals (solid chemicals
  with uniform or crystalline structures that form
  under pressure and heat).
• Rocks can form from molten magma, by compression
  of sediments, and by exposure of rocks and other
  materials to heat and pressure

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Igneous Rocks

• Form directly from molten magma
• Classified by their chemical composition as
  either basaltic (dark colored-with high amounts
  of Fe, Mg, and Ca, and is the dominant rock type
  in oceanic plates or granitic(lighter colored-
  composed of feldspar, mica and quartz, Si, Al, K,
  Ca and is the dominant rock type in continental
  plates)
• Intrusive- forms within Earth as magma, rises up,
  and cools in place underground.
• Extrusive-forms when magma cools above the
  surface rapidly, so minerals have little time for
  crystals to form resulting in obsidian.

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Sedimentary Rocks

• Form when sediments (mud, sand and gravel) are
  compressed by overlying sediments.
• Takes a long period of time to form
• Ex sandstone, conglomerate and mudstone
• Contain the fossil record of our past, with
  plant and or animals
  remains
• that are compressed over eons

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Metamorphic Rock

• Forms when sedimentary rocks, igneous rocks, or
  other metamorphic rocks are subjected to high
  temperatures and pressures.
• Ex Slate, marble, and anthracite

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Weathering

• Physical Weathering- the mechanical breakdown of
  rocks and minerals by water, wind, or variations
  in temperature. It can also be caused by plant
  roots and burrowing animals. It produces a
  greater surface area for chemical weathering
  processes to work on.
• Chemical Weathering-the break down of rock and
  minerals by chemical reactions, the dissolving of
  chemical elements from rocks, or both. It
  releases essential nutrients from rocks making
  them available for use by plants and animals.
  Acid rain promotes chemical weathering of certain
  minerals in the soil.

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Erosion

• Erosion is the physical removal of rock fragments
  from a landscape or ecosystem.
• This can occur by wind, water and ice transport
  materials downslope under the force of gravity.
  Organisms that burrow under he soil can also
  cause erosion.
• Once the material has traveled a certain distance
  it accumulates and deposition occurs.
• Erosion can be accelerated by deforestation,
  overgrazing, road building and unmanaged
  construction activity.

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Soil Formation is the 3rd part of the geologic
cycle.

• Soil is a mixture of geologic and organic
  components.
• Soil has many functions plant growth, primary
  filter of water, provides habitat for bacteria,
  algae, fungi, insects and other animals, breaks
  down organic material and recycles nutrients that
  benefit plants and filters chemical compounds.

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Soil Formation

• Is formed over thousand of years as a result of
  weathering of rocks and the accumulation of
  detritus from the biosphere.
• Young soil has less organic matter and fewer
  nutrients than a more mature soil.
• There are 5 factors that determine the properties
  of soil the parent rock, climate, topography,
  organisms and time.

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SOIL FORMATION
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• Parent Material- the type of rock of which it was
  composed of. Quartz-sand parent material produces
  nutrient poor soil. Soil that has CaCO3 will have
  an abundant supply of Ca , have a high pH and
  support a high agricultural productivity.
• Climate-soil does not develop well in
  temperatures below freezing because organic
  matter cant decompose well then. Soil formed in
  the tropics, is accelerated due to rapid
  weathering of rocks and minerals, leaching of
  nutrients, and the decomposition of organic
  detritus.

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• Topography- the surface slope and the arrangement
  of a landscape. Soil that forms on a steep slope
  is subject to erosion.
• Organisms-Plants remove nutrients from the soil
  and excrete organic acids that speed chemical
  weathering. Animals that burrow earthworms,
  gophers, voles, mix the soil distributing organic
  and mineral matter.
• Time-As soil ages, and has organic matter in it
  over time, they become deep and fertile.

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SOIL HORIZONS
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Soil Horizons (Layers)

• O Horizon- at the surface of many soils, this
  layer contains organic detritus in various stages
  of decomposition. Pronounced in forest soils and
  in grasslands.
• A Horizon- topsoil, a mixture of organic
  material and minerals.
• E Horizon-only found in some acidic soils(beneath
  the O or A horizon), a zone of leaching or
  eluviation, Fe and Al are and dissolved organic
  acids are transported through here and deposited
  in the B horizon where they accumulate.

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• B Horizon-subsoil, composed of mineral
  material(metals) with little organic matter. If
  nutrients are present in the soil, they will be
  found here.
• C Horizon- always occurring below the B horizon,
  it is similar to the parent material. This
  horizon contains the least weathered soil.

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SOIL PROPERTIES
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Physical Properties of Soil

• Texture- determined by the percentage of sand,
  silt and clay (mineral particles of different
  sizes).
• Porosity- how quickly soil drains, depends on
  texture (Best agricultural soil is a mixture of
  sand, silt and clay which allows for water
  drainage and retention).Clay is useful where
  contminants need to be contained and wont allow
  them to leach into groundwater.

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Soil Porosity
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Chemical Properties of Soil

• Clay particles are neg. charged and attract pos.
  charged mineral ions that are adsorbed(held on
  the surface) by the particles. These minerals can
  be released and used as nutrients by plants. This
  ability is called cation exchange capacity (CEC)
  or nutrient holding capacity. If a soil is more
  than 20 clay, its water retention is too high
  and the soil is waterlogged and the roots of
  plants become O2 deprived. A balance must exist.

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pH of soil

• Ca, Mg, K and Na can neutralize soil acids such
  as Al and H2. Therefore they are considered
  bases.
• Soil acids are detrimental to plant growth
• Soil bases promote plant growth and are essential
  for plant nutrition.
• Base saturation- is a measure of the proportion
  of soil bases to soil acids ().
• Soils with high CEC and high base saturation is
  likely to support high productivity.

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Biological Properties of Soil

• Fungi, Bacteria and Protozoans are detritivores,
  which consume dead plant and animal tissues and
  recycle the nutrients they contain. Some bacteria
  fix nitrogen
• Rodents and Earthworms contribute to soil mixing
  and breakdown of large organic material.
• Snails and Slugs eat plant roots and some
  aboveground parts of the plant.

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Crustal Abundance

• The average concentration of an element in the
  Earths crust. O2, Si, Al and Fe make up 88 of
  the crust. However, the composition varies from
  location to location.
• Ores are concentrated accumulations of minerals
  from which economically valuable materials can be
  extracted. Most ores contain metals Cu, Ni, Al.
  They are formed by a variety of processes.
• The reserve -is the known quantity of the
  resource that can be economically recovered.

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S.W. VIRGINIA 2003 STRIP MINING FOR COAL
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Open Pit Mining
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MOUNTAIN TOP REMOVAL
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Placer Mining
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Subsurface mining
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Types of Mining and their effects

• Environmental issues can include erosion,
  formation of sinkholes, loss of biodiversity, and
  contamination of soil, groundwater and surface
  water by chemicals from mining processes. In some
  cases, additional forest logging is done in the
  vicinity of mines to increase the available room
  for the storage of the created debris and
  soil.28 Contamination resulting from leakage of
  chemicals can also affect the health of the local
  population if not properly controlled.29
  Extreme examples of pollution from mining
  activities include coal fires, which can last for
  years or even decades, producing massive amounts
  of environmental damage.