Prentice Hall EARTH SCIENCE

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Prentice Hall EARTH SCIENCE

• Tarbuck Lutgens

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Distribution of Earths Water
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The Water Cycle
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? Much of the water in soil seeps downward until
it reaches the zone of saturation.
? The zone of saturation is the area where water
fills all of the open spaces in sediment and
rock.
Groundwater is the water within this zone.
The water table is the upper level of the
saturation zone of groundwater.
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? Movement
Groundwater moves by twisting and turning
through interconnected small openings.
The groundwater moves more slowly when the
pore spaces are smaller.
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? Movement
Porosity
- The percentage of pore spaces
- Determines how much groundwater can be stored
Permeability
- Ability to transmit water through connected
pore spaces
- Aquifers are permeable rock layers or
sediments that transmit groundwater freely
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Features Associated with Subsurface Water
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? A spring forms whenever the water table
intersects the ground surface.
? Hot Springs
Water is 69ºC warmer than the mean air
temperature of the locality.
Water is heated by cooling of igneous rock.
? Geysers
Intermittent hot springs
Water turns to steam and erupts.
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Geyser Eruption Cycle
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? A well is a hole bored into the zone of
saturation.
An artesian well is any formation in which
groundwater rises on its own under pressure.
Pumping can cause a drawdown (lowering) of
the water table.
Pumping can form a cone of depression in the
water table.
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Cone of Depression
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? Overuse and contamination threatens groundwater
supplies in some areas.
Treating it as a nonrenewable resource
Land subsidence caused by its withdrawal
Contamination
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Groundwater Supplies are Finite!!

• The High Plains Aquifer is an example of
• Severe groundwater depletion.
• Even if pumping were to stop now, it would
• take thousands of years to replenish the
• groundwater.

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San Joachim Valley, CA

• The marks of the utility
• pole illustrate the sinking
• of 13,400 sq. km over 9
• meters because of
• the withdrawl of
• groundwater for irrigation
• subsidence.

www.aegweb.org/.../ subsidence_Poland.jpg
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High Plains Aquifer

• About 27 percent of the
• irrigated land in the US overlies
• this aquifer system.
• It yields about 30 percent of
• the nation's ground water used
• for irrigation.
• It provides drinking water to
• 82 percent of the people who
• live within the aquifer boundary. 2

http//en.wikipedia.org/wiki/Ogallala_Aquifer
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Groundwater Contamination
Common Sources of Water Pollution

• Sewage from septic tanks.
• Farm wastes
• Inadequate or broken sewers
• Fertilizers, Pesticides, and Highway Salts
• Chemicals and Industrial Materials leaking from
• Pipelines
• Storage tanks
• Landfills
• Holding Tanks

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Groundwater Contamination
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Groundwater Contamination

• Harmful bacteria in aquifer
• may be purified by
• Mechanical filtration
• Chemical oxidation
• Assimilation by other organisms

http//openlearn.open.ac.uk/file.php/2457/T210_1_0
14i.jpg
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Groundwater Contamination
LANDFILLS Solid Waste Disposal

• Open Air Dumps
• used in US up until 1970, now illegal (standard
  in rest of world)
• release toxins in air and groundwater
• Attract vermin, breed disease
• Sanitary
• Dig hole, line w/ clay and plastic liner, cover
  w/ dirt daily
• Promotes decomposition, reduces vermin disease
• Still may leak, check groundwater constantly

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Open-air rubbish dump on coastline, Barrow,
Alaska, USA
This dump site in such fragile environment is
polluting groundwater and spoils the tundra.
http//www.gettyimages.com/detail/450076-001/Stone
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Sanitary Landfill
http//seagrant.uaf.edu/nosb/papers/2004/images/se
lawikfig2.jpg
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Sanitary Landfill
http//blog.pennlive.com/lvbreakingnews/2008/01/ch
rinlandfill.JPG
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US WASTES FACTS

The US produces more wastes per person than any
other nation in the world (10 to 100 X more!!!)
Over 200 metric tons/year!! 60 of our wastes
end up in landfills, 20 is incinerated, and 20
is recycled. The US is guilty of
eco-terrorism a. We are the World Leaders of
e wastes (500 tons/month) b. We export 80 to
Africa and China c. Children harvest the metal
for sale and wade through the toxic wastes for
food. Also contaminates water supply. d. One
desktop 9 to 12 pounds of lead, mercury,
arsenic, and radioactive isotopes and may also
contain a few grams of silver, gold, and
copper. (source NCSU/Bruck)
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LANDFILL VIDEO
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? A cavern is a naturally formed underground
chamber.
? Erosion forms most caverns at or below the
water table in the zone of saturation.
? Travertine is a form of limestone that is
deposited by hot springs or as a cave deposit.
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Dissolving of Groundwater Creates Caverns
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? Characteristics of features found within
caverns
Formed in the zone of aeration
Composed of dripstone
Formed from calcite deposited as dripping
water evaporates
Common features include stalactites (hanging
from the ceiling) and stalagmites (growing upward
from the floor).
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? Formed by dissolving rock at, or near, Earth's
surface
? Common features
Sinkholessurface depressions
- Sinkholes form when bedrock dissolves and
caverns collapse.
Caves and caverns
? Area lacks good surface drainage.
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Sinkhole Formation
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Water Contamination

• Point Source Pollution-pollution that comes from
  a known/specific location
• Nonpoint Source Pollution- does NOT have a
  specific point of origin

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Point Source Pollution

• The term "point source" means any discernible,
  confined and discrete conveyance, including but
  not limited to any pipe, ditch, channel, tunnel,
  conduit, well, discrete fissure, container,
  rolling stock, concentrated animal feeding
  operation, or vessel or other floating craft,
  from which pollutants are or may be discharged

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Continued
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Nonpoint Source Pollution

• Excess fertilizers, herbicides and insecticides
  from agricultural lands and residential areas
• Oil, grease and toxic chemicals from urban runoff
  and energy production
• Sediment from improperly managed construction
  sites, crop and forest lands, and eroding
  streambanks
• Salt from irrigation practices and acid drainage
  from abandoned mines
• Bacteria and nutrients from livestock, pet wastes
  and faulty septic systems
• Atmospheric deposition and hydromodification

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Wastewater Treatment

• https//www.youtube.com/watch?vpRaptzcp9G4