Week 1 - Introduction to Groundwater
Water in three states: liquid, solid (ice), and
water vapor in the air. Clouds are water
droplets, condensed from vapor-saturated air.
Water changes from one state to another. So water can be solid, liquid or gas.
Water also moves.
We call this the Water Cycle.
http://ga.water.usgs.gov/edu/watercyclekoreanhi.html
cycle – 주기
http://ga.water.usgs.gov/edu/watercycleprint.html
circulation – move around something like a circle.
Here is an animation of the Hydrologic Cycle
http://techalive.mtu.edu/meec/module01/HydrologicScene.html
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1.72, Groundwater Hydrology Lecture Packet 1 Prof. Charles Harvey http://ocw.mit.edu/NR/rdonlyres/Civil-and-Environmental-Engineering/1-72Fall2005/4F444E12-8746-459D-A6BD-1F42F7498903/0/1_72_lecture_1.pdf
Here is a quiz about the Hydrologic Cycle
http://techalive.mtu.edu/meec/module01/HydrologicQuiz.html
Here is an animation about Evaporation.
http://techalive.mtu.edu/meec/module01/Evaporation.html
Here is an animation about Evapotranspiration.
http://techalive.mtu.edu/meec/module01/Transpiration2.html
Groundwater is an important source of freshwater.
A lot of water is used for agriculture 농업
56% is used by animals and plants
20% is lost when the water is moved
24% flows back into the stream or ground
A lot of water is used for making electricity. This is
87% of all industrial water use
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Water can dissolve many things.
Water consists of two atoms of hydrogen and one of oxygen, - a chemical formula of H2O.
Water can dissolve at least small amounts of almost all substances that it contacts.
Ground water usually has the large amounts of dissolved solids.
The composition and concentration of substances dissolved in unpolluted ground water depend on
the chemical composition of precipitation, on the biologic and chemical reactions on the land
surface and in the soil, and on the composition of the aquifers and confining beds through which
the water moves.
The concentrations of substances dissolved in water are in units of weight per volume.
In the International System (SI), the most commonly used units are milligrams per liter.
A milligram equals 1/1,000 (0.001) of a gram,
a liter equals 1/1,000 of a cubic meter,
1 mg/L equals 1 gram m -3.
and
so
The concentration of most substances dissolved in water is small.
The weight per weight unit commonly used is parts per million (ppm).
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Natural inorganic constituents commonly dissolved in water that are most likely to affect use of the water.
Substance
Major natural sources
Effect on water use
Important
concentration
(mg/L3)
Bicarbonate (HCO3)
and carbonate
(CO3)
The solution of carbonate rocks
by water containing carbon
dioxide.
150-200
Calcium (Ca) and
magnesium (Mg)
Soils and rocks containing
limestone (CaCO3), dolomite
(CaMgCO3), and gypsum (CaSO4).
Small amounts from igneous and
metamorphic rocks
In inland areas, from seawater
trapped in sediments at time of
deposition. In coastal areas,
from seawater in contact with
freshwater in productive
aquifers.
Both sedimentary and igneous
rocks. Not widespread
Control the ability of water to neutralize strong acids
Bicarbonates of calcium and magnesium decompose in
steam boilers and water heaters to form scale and
release corrosive carbon dioxide gas. With calcium and
magnesium, can cause carbonate hardness
Main cause of hardness and of boiler scale and deposits
in hot-water heaters.
in large amounts, increases corrosiveness of water and,
in combination with sodium, gives water a salty taste
250
In low concentrations, reduces tooth decay, at higher
concentrations, causes color of teeth.
07-1.22
Chloride (Cl)
Fluoride (F)
25-50
Iron (Fe) and
manganese (Mn)
Iron present in most soils and
rocks; manganese less widely
distributed.
Stain laundry and are bad in food processing, dyeing,
bleaching, brewing, and other industrial processes
Fe>03,
Mn>0.05
Sodium (Na)
Same as for chloride.
See chloride.
In large concentrations, may affect persons with heart
disease, and other medical problems. Sodium may damage
irrigated crops
69 (irrigation)
20-170 (health)
Sulfate(SO4)
Gypsum, pyrite (FeS), and other
rocks containing sulfur (S)
compounds
Low concentrations give water a bitter taste and higher
concentrations have a laxative effect
With calcium, forms a hard calcium carbonate
scale in steam boilers
300-400
(taste),
600-1,000
(laxative)
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Pollution of Groundwater
Pollution of ground water is any loss of quality of the water because of what people do.
Most pollution of ground water comes from:
 the disposal of wastes
o on the land surface,
o in shallow holes including septic tanks, or
o through deep wells and mines;
 the use of fertilizers and other agricultural chemicals;
 leaks in sewers, storage tanks, and pipelines; and
 animal feedlots.
The size of any pollution problem depends on:
 the size of the area affected and the amount of the pollutant involved,
 the solubility, toxicity, and density of the pollutant,
 the mineral composition and hydraulic characteristics of the soils and rocks through which
the pollutant moves, and
 the effect or potential effect on ground-water use.
Affected areas range in size from:
 point sources, such as septic tanks, to
 large urban areas having leaky sewer systems and
 numerous municipal and industrial waste-disposal sites.
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Nearly all substances are soluble to some extent in water.
Many chemical wastes are highly toxic even in very small concentrations.
Contamination Basics: Concentration
We need to know both the type and amount of contaminant in the groundwater system. We can
measure amounts of contaminants in ppm and ppb, which are parts per million and parts per
billion.

ppm is the amount of contaminant units in 1,000,000 (1 million) units of groundwater.

ppb is the amount of contaminant units in 1,000,000,000 (1 billion) units of groundwater.

pph (parts per hundred), is the amount of contaminant units in 100 units of groundwater.
We call it percent, %. (1pph = 1/100 =1%)
This animation gives an idea of the different concentrations.
http://techalive.mtu.edu/meec/module04/Concentration.html
Which is a larger concentration, 1 ppm or 1 ppb?
Effects of Contamination
Why do we care if there was only 1ppm (1/1,000,000) of a particular contaminant? It seems like
too small of a number to matter.
With groundwater contaminants, both chemical and biological, a very small concentration of
contaminant could still lead to serious health effects. Different kinds of contaminants have
different concentration limits at which they start to effect us or the environment. In dealing with
groundwater contamination problems, it is necessary to find out both the specific type of
contaminant and the concentration of the contaminant.
In this animation vary the concentration of different contaminants in the groundwater. Check out
Mr. Blue's reactions to the contaminants. Mr. Blue reacts in the same way a healthy person would
to these chemicals. A person who is not as healthy, such as an older person or a small child, might
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suffer the effects even more.
http://techalive.mtu.edu/meec/module04/ContaminationEffects.html
Which chemical needs to exist in the least concentration in the groundwater in order to avoid
hurting someone?
Density
The density of a liquid substance - that is, the weight per unit volume of the substance relative to
that of water - affects its underground movement.
 Densities range from:
o petroleum products that are less dense than water
o other substances that are denser than water.
 Substances less dense than water float at the top of the saturated zone;
o if, like petroleum, they are immiscible, they will spread in all directions as a thin
layer.
 Substances denser than water move downward through the saturated zone to the first
extensive confining bed.
Contaminant Movement
Contaminants can enter the groundwater by seeping in from the surface or by flowing in from
another part of the aquifer. Once in the aquifer they move with the groundwater flow.
As contamination moves it disperses. This means that the concentration decreases as it moves
farther away from the source of the pollution. For that reason there are different concentrations
of contaminants at different points in the aquifer.
The minerals and physical characteristics of soils and rocks through which pollutants move may
affect the pollutants in several ways.
If a pollutant enters the ground at a "point," it will be dispersed longitudinally and laterally in
granular materials so that its concentration will be reduced in the direction of movement.
The visual representation of these different concentrations is called a contamination plume. How
the plume looks depends on the type of contamination source, the specific contaminant(s), where
the aquifers are located, and different soils in that area.
These animations show the two main categories of plumes based upon their source.
Here are two animations of the Dispersal of a Pollutant from a Point source
http://techalive.mtu.edu/meec/module04/OneTimePlume.html (Click Play)
http://techalive.mtu.edu/meec/module04/ContinuousPlume.html (Click Play)
Organic Substances
Organic substances and other biodegradable materials can be broken down both by oxidation and
by bacterial action in the unsaturated zone.
Soil, especially clays and organic matter, may absorb trace metals and some complex organic
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pollutants and reduce their concentration as they move through the underground environment.
The hydraulic characteristics of the soils and rocks determine the path taken by and the rate of
movement of pollutants.
Substances dissolved in water move with the water except when they are tied up or delayed by
adsorption.
The movement of pollutants is most through the most permeable zones; the farther their point of
origin from a ground-water discharge area, the deeper they move into the ground-water system
and the larger the area affected.
The factors related to the movement of pollutants must be carefully considered in the selection of
waste-disposal sites, animal feedlots, and sites for other activities that may cause ground-water
pollution.
Here is an animation to allow you to Pick the Best Site for a New Well
http://techalive.mtu.edu/meec/module06/WellSiting.htm
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Review
Match the letters with the name.
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