Download Ground Water, Carbon Cycle and Ocean

(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
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)
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.
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.
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.
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.
Recharge is the process by which ground
water is replenished. A recharge area is
where water from precipitation is transmitted
downward to an aquifer.
Ground water occurs in aquifers under two conditions:
A confined aquifer is overlain by a confining bed, such as an
• Confined
impermeable layer of clay or rock.
• Unconfined
An unconfined aquifer has no confining bed above it and is
usually open to infiltration from the surface.
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.
Springs
This corresponding
and seeps will
zone
only(orcontinue
cone) ofto
flow
depression
as long can
as the
often
water
form
table
in the
is higher
area
than
beingthey’re
depleted
aquifers
by a are.
well that people
have dug into the water table.
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.
• Precipitation
• Runoff
• Infiltration
• Evaporation
• Transpiration
(evapotranspiration)
• Condensation
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 time is the
average amount of time Things that can affect residence time:
• Number of people relying upon aquifer for a
that a particle (which in
source of freshwater.
this case, is a water
• Amount of recharge available (rainfall)
molecule) spends in a
• Presence of confining units (such as shale or
particular system (which
clay)
in this case, is an
aquifer).
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,
The level of the water table can naturally and bar charts show.
change over time also, due to
• Changes in weather cycles and
What does it mean to be
precipitation patterns,
• Stream flow
“sustainable”?
• Geologic changes
• For a resource (water) to be
Some human induced changes include:
It must supply us
Excessive pumping or drawdown. can lower the sustainable,
water table so
• Overuse much that the wells no longer supply water—theywith
can "go
dry." we need today;
what
• Increase in impervious surfaces
• Tomorrow
like roads and paved areas over
• And do it in such a way, that
recharge zones
the resource does not
Is sustainability possible?
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 lithosphere contains a great deal of
limestone, which is essentially made of calcium
carbonate…CaCO3
Chalk is also calcium carbonate.
• The cryosphere
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.
Both the hydrosphere and the atmosphere can carbon sinks
as well.
• Hydrosphere
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.
• Atmosphere
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.
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;
The exchange of gases in aerobic life, CO2 for O2
• Photosynthesis;
The process whereby CO2 is turned into carbohydrates, such as glucose
• Combustion;
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)
• Decomposition
The process whereby organic things are broken down into constituent particles. The process
consumes Oxygen, and gives off CO2.
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.
How do rising temperatures affect algal growth?
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.
How do rising temperatures affect corals?
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.
We’ve already learned that increased temperatures You can easily see the
between
can lead to increased evaporation…which leads to correlation
SSTs and hurricane
intensity in the graph
increased precipitation…and sometimes this
precipitation comes in the form of sever weather, or below.
Globally, Earth is experiencing an
increased hurricane intensity.
extinction event, and an extreme drop
Warm air has a far greater
in biodiversity.
energy and instability than cold Warmer temperatures have decreased
the productivity of the ocean, and
air, relatively speaking. It is for
terrestrial biomes as well. This
that reason, that we only see
hurricanes forming in the Atlantic decrease has led to a decrease in
species…so ecosystems are less able
during the summer months, from to rebound after experiencing some
June-November
change.