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Earth and Space TEK:. (15)  Fluid Earth. The student knows that interactions among Earth's five subsystems influence climate and resource availability, which affect Earth's habitability . The student is expected to:.

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slide1

Earth and Space TEK:

(15)  Fluid Earth. The student knows that interactions among Earth's five subsystems influence climate and resource availability, which affect Earth's habitability. The student is expected to:

c)  quantify the dynamics of surface and groundwater movement such as recharge, discharge, evapotranspiration, storage, residence time, and sustainability;

(d)  explain the global carbon cycle, including how carbon exists in different forms within the five subsystems and how these forms affect life; and

(e)  analyze recent global ocean temperature data to predict the consequences of changing ocean temperature on evaporation, sea level, algal growth, coral bleaching, hurricane intensity, and biodiversity

slide2

Aquifers

Unconsolidated (not lithified) sand and gravel layers

Fractured Limestone

  • As you know from learning about the hydrologic cycle, water exists in three states on Earth…
    • Solid (ice)
    • Liquid (water in oceans, lakes, rivers, and streams, and)
    • Gas (water vapor in our atmosphere)

Conglomerate…larger particles means larger spaces… even more water storage capacity

Columnar Basalt

Sandstone aquifer discharge on cliff face

An aquifer is a body of saturated rock through which water can easily move. Aquifers must be both permeable and porous and include such rock types as sandstone, conglomerate, fractured limestone and unconsolidated sand and gravel. Fractured volcanic rocks such as columnar basalts also make good aquifers.

slide3

Infiltration: Importance to Aquifers

  • Infiltration moves water through gravity down through the soil.
    • If soils are dry, water is absorbed by the soil until it is thoroughly saturated. Sometimes, if rainfall comes too fast, and soil is too dry, it runs over the surface.
    • Any excess infiltration that is able to, begins to move slowly downward to the water table.
    • Once it reaches the water table, it is called ground water.
  • Ground water continues to move downward and laterally through the subsurface. Eventually it discharges through hillside springs or seeps into streams, lakes, and the ocean.
slide4

Dynamics of surface and groundwater

Recharge

Aquifers recharge when water is “added” to them. This most often occurs when rain water infiltrates down through the ground and is able to permeate the aquifer.

Rechargeis the process by which ground water is replenished. A recharge area is where water from precipitation is transmitted downward to an aquifer.

A confining bed is a geologic unit which is relatively impermeable. They can be made of slate, marble, or even clay. Confining beds, also referred to as aquitards, restrict the movement of ground water into and out of adjacent aquifers.

  • Ground water occurs in aquifers under two conditions:
    • Confined
    • Unconfined

A confined aquifer is overlain by a confining bed, such as an impermeable layer of clay or rock.

  • An unconfined aquifer has no confining bed above it and is usually open to infiltration from the surface.
slide5

Dynamics of surface and groundwater

Discharge

  • Groundwater can move through aquifers until it reaches an opening to the surface.
    • In a seep, the water reaches the surface over a large area.
    • In a spring, water flows from the earth at a small point.
    • Water in confined aquifers is generally under high pressure and can result in the production of an artesian spring.

Water can also be removed from aquifers by the activity of humans drilling wells. If rates of removal of water for human use exceed the very slow, natural rate of recharge, then the total amount of water in the aquifer is reduced which results in a lowering of the water table (aquifer depletion).

Lower water tables (such as occur in deserts) require deeper wells which greatly increases the cost of pumping water from aquifers and further depletes water from the already slow, natural rate of recharge.

  • Springs and seeps will only continue to flow as long as the water table is higher than they’re aquifers are.

This corresponding zone (or cone) of depression can often form in the area being depleted by a well that people have dug into the water table.

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Dynamics of surface and groundwater

Evapotranspiration

  • Precipitation
  • Runoff
  • Infiltration
  • Evaporation
  • Condensation
  • Transpiration (evapotranspiration)
slide7

Dynamics of surface and groundwater

Storage, Residence time, and Sustainability

Large amounts of water are stored in the ground. Aquifers are a huge storehouse of Earth's water and people all over the world depend on ground water in their daily lives.

Residence timeis the average amount of time that a particle (which in this case, is a water molecule) spends in a particular system (which in this case, is an aquifer).

  • Things that can affect residence time:
    • Number of people relying upon aquifer for a source of freshwater.
    • Amount of recharge available (rainfall)
    • Presence of confining units (such as shale or clay)
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Groundwater is Finite

We teach that freshwater is a renewable, yet exhaustible resource. This resource is “finite”, even thought it is cyclical. Water obeys the law of conservation of matter.

  • Describe what the pie, and bar charts show.
  • What does it mean to be “sustainable”?
    • For a resource (water) to be sustainable, It must supply us with what we need today;
    • Tomorrow
    • And do it in such a way, that the resource does not become depleted or polluted.
  • The level of the water table can naturally change over time also, due to
    • Changes in weather cycles and precipitation patterns,
    • Stream flow
    • Geologic changes
  • Some human induced changes include:
    • Overuse
    • Increase in impervious surfaces like roads and paved areas over recharge zones

Excessive pumping or drawdown. can lower the water table so much that the wells no longer supply water—they can "go dry."

Is sustainability possible?

slide9

Carbon in Earth Subsystems

Lithosphere and Cryosphere

  • Carbon is cycled on Earth through many processes, and can be found stored (sequestered) in many places also. A place where carbon is stored is called a “sink”.
  • Carbon may be found stored in:
    • The lithosphere
    • The cryosphere

The lithosphere contains a great deal of limestone, which is essentially made of calcium carbonate…CaCO3

Chalk is also calcium carbonate.

In the frozen cryosphere, carbon is stored within the tiny air spaces found in the ice. Carbon dioxide gas (CO2) is a portion of this gas.

slide10

Carbon in Earth Subsystems

Hydrosphere and Atmosphere

  • Both the hydrosphere and the atmosphere can carbon sinks as well.
    • Hydrosphere
    • Atmosphere

In the hydrosphere, dissolved CO2 is the result of cellular respiration in living aerobic organisms that inhabit the aquatic biomes of the Earth. Also, CaCO3 is the main ingredient in the shells of mollusks within this watery realm. When these creatures die, their shells sink to the ocean floor, and either dissolve, or become lithified (fossilized) in the sand and silt found there.

The most obvious carbon sink of all of the Earth’s subsystems is found here. Carbon Dioxide gas is in our atmosphere in trace amounts, but it is there! Again, it is largely the waste product of cellular respiration of terrestrial organisms.

slide11

Carbon in Earth Subsystems

Biosphere

  • There are many processes at work on Earth that serve to cycle carbon, or the movement of carbon atoms and molecules…the essential element to all organic things.
    • Respiration;
    • Photosynthesis;
    • Combustion;
    • Decomposition

The exchange of gases in aerobic life, CO2 for O2

The process whereby CO2 is turned into carbohydrates, such as glucose

The burning process, usually accompanied by a fuel (many times a hydrocarbon), production of light energy, and thermal energy and some sort of gaseous evolution. (CO2)

The process whereby organic things are broken down into constituent particles. The process consumes Oxygen, and gives off CO2.

slide12

Global Ocean Temperatures

Thermal Expansion and evaporation

  • Globally, sea-levels are changing due to thermal expansion, a property of water that allows it to increase in volume as it warms.
  • As we have already spoken of this, suffice it to say that this thermal expansion, more than global warming, is the cause for concern in beach-front communities around the Earth.

Continued rise in global temperatures, means increasing evaporation of water…which leads to increased precipitation…and increased hurricane patterns and severe weather as well.

slide13

Global Ocean Temperatures

Algal Growth and Coral Bleaching

How do rising temperatures affect algal growth?

How do rising temperatures affect corals?

Warming of the atmosphere, means warming of the aquatic biomes on Earth…both freshwater and marine. Warming water, means algal blooms. Algal blooms are not particularly dangerous, UNTIL the algae begins to die. Algae has a particularly short life-span, and when an excessive amount begins to die, DECOMPOSITION depletes the dissolved oxygen in the water. Depletion of dissolved oxygen means aquatic organisms will become stressed.

Perhaps the ocean organism most vulnerable to temperature change is coral. There is evidence that reefs will bleach (eject their symbiotic algae) at even a slight persistent temperature rise. Bleaching slows coral growth, makes them susceptible to disease, and can lead to large-scale reef die-off.

slide14

Global Ocean Temperatures

Hurricane Intensity and Biodiversity

We’ve already learned that increased temperatures can lead to increased evaporation…which leads to increased precipitation…and sometimes this precipitation comes in the form of sever weather, or increased hurricane intensity.

You can easily see the correlation between SSTs and hurricane intensity in the graph below.

Globally, Earth is experiencing an extinction event, and an extreme drop in biodiversity.

Warmer temperatures have decreased the productivity of the ocean, and terrestrial biomes as well. This decrease has led to a decrease in species…so ecosystems are less able to rebound after experiencing some change.

Warm air has a far greater energy and instability than cold air, relatively speaking. It is for that reason, that we only see hurricanes forming in the Atlantic during the summer months, from June-November