Sources and Types of Pollution
A groundwater pollutant (오물) is any
physical (물질의),
chemical (화학의),
biological (생물학의), or
radiological (방사선학의) substance or matter (물질) in groundwater.
Groundwater pollution can be from
a point pollution source (점오염원), or
a nonpoint pollution source (비점오염원).
Point source pollutants come from a single place, eg. pipes, ditches, channels, sewers, tunnels,
and containers of various types.
Nonpoint source pollution is spread over a wide land area, not from one place.
The pollution can be
physical, such as soil or other things in the water, (even heat) or it can be
chemical (which includes radiological substances), or it can be from
living things.
http://www.epa.gov/safewater/publicoutreach/landscapeposter.html
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The pollutants can get into the groundwater by
natural (자연의) activities (활동), or
human activities (인간 활동의), such as
waste disposal (폐기물 처분),
mining (광업), and
agriculture (농업).
The pollution from natural activities is usually small.
Human activities are the biggest cause of groundwater pollution.
The chemical pollution can include
Organic compounds – 유기화합물
Inorganic compunds – 무기화합물 such as
nitrates (질산염) and
phosphates (인산염), and
Elements and ions - 원소 and 이온 such as
boron, calcium, arsenic, sodium, iron, cadmium, chromium, mercury and other
trace metals.
(B, Ca, As, Na, Fe, Cd, Cr, Hg, etc).
Waste disposal includes the disposal of liquid waste and solid waste.
Liquid waste from homes
Liquid waste from homes, eg septic tanks (정화조), put the most wastewater into the ground.
They release filtered sewage effluent (유출물) into the ground.
Chemicals used to clean septic systems may be polluting.
Septic tanks
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High concentrations of
BOD (생화학적 산소요구량)
COD (화학적 산소 요구량)
Nitrate (질산염)
organic chemicals (유기화합물)
bacteria (박테리아, 세균)
Viruses (바이러스)
go into groundwater.
Land application of sewage effluent and sludge is the largest contributor to groundwater
contamination.
Treated wastewater and sludge are sometimes used to recharge groundwater or provide
nutrients that fertilize the land and stimulate plant growth.
Putting sewage effluent onto land can cause similar problems to septic tanks.
In urban areas there are lots of spilt oils and other chemicals.
They can infiltrate with the water into the ground and cause groundwater contamination of
shallow aquifers.
Many of the organic and inorganic chemicals in industrial wastewater effluent and sludge are
difficult to break down.
These contaminants can leak through the bottom of a dam.
Sometimes these are injected into an injection well into the ground.
Buried waste is leached by rain water and surface water or by groundwater contact with the fill.
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Leachate
If rain falls on piles of materials or wastes a leachate (침출수) can be made which infiltrates into
the groundwater.
The leachate can transport heavy metals, salts, and other inorganic and organic chemicals to
pollute groundwater.
Storage and Transport of Commercial Materials
Leaking storage tanks and spills can pollute groundwater.
Gasoline and home oil fuel tanks probably
contribute the most to groundwater contamination.
These tanks and pipelines can rust or break and leak.
Leakage happens often from bare steel tanks that
are not protected against rust.
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Even a small leak can be a big threat to groundwater quality.
Gasoline and petroleum products contain hydrocarbon components such as benzene, toluene,
ethylbenzene, and xylene (BTEX) which are easily dissolved in groundwater and can poison
people.
source
xylenes
benzene
MTBE
One liter of gasoline is enough to make one million liters of groundwater unusable.
Vapors and other compounds can be trapped in the pore spaces of the unsaturated zone.
They continue to pollute the groundwater when it rains or when the groundwater table goes up
and down.
Spills of chemicals onto the ground can move downward and contaminate groundwater.
Chemicals can be washed by rain runoff and moved to the subsurface where they pollute the
groundwater.
Groundwater can be contaminated by the drainage from mines and by oil and gas mining
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operations.
Oil and gas mining operations can make a large amount of wastewater.
The wastewater is usually held in surface dams or pumped into deep wells.
The chemicals in the wastewater, such as ammonia, boron, calcium, dissolved solids, sodium,
sulfate, and trace metals, can pollute groundwater.
Fertilizers (비료) are the main cause of groundwater contamination beneath farm lands (농지).
Fertilizers contain nutrients (영양소) such as nitrate, phosphate (인산염), and potassium (칼륨).
They are spread on farm land to fertilize the land and help plant growth.
Some of these nutrients infiltrate the soil and reach the groundwater table.
Phosphate and potassium fertilizers are easily adsorbed on soil particles.
Nitrates can poison human babies and animals.
Pesticides, herbicides, and fungicides used for killing animal pests, plants, and fungus can cause
groundwater contamination.
Some farms, especially animal farms, create their own waste which needs to be disposed of.
These wastes also can pollute the groundwater.
They cause similar problems to fertilizers, but have the additional problem of containing viruses
and bacteria.
Revision and More Types of Pollution
http://techalive.mtu.edu/meec/module04/title.htm
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Contaminants are separated into four main categories:
Physical
Biological
Inorganic chemicals
Organic chemicals
These categories may overlap sometimes. eg a biological organism might make organic chemicals
and the organisms have a physical effect on the water.
Contaminants can have effects at very small concentrations.
Measure amounts of contaminants in concentration.
ppm and ppb and ppt, which are parts per million and parts per billion and parts per
trillion.
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.
ppt is the amount of contaminant units in 1,000,000,000,000 (1 trillion) units of groundwater.
http://techalive.mtu.edu/meec/module04/GWContaminationBasics1.htm
Very small concentrations of some groundwater contaminants could have serious health effects.
Different kinds of contaminants have different concentration limits.
It is necessary to find out both the specific type of contaminant and the concentration of the
contaminant.
http://techalive.mtu.edu/meec/module04/GWContaminationBasics3.htm
Contamination Movement
As contamination moves it disperses.
The concentration decreases as it moves farther away from the source of the pollution.
So there are different concentrations of contaminants at different points in the aquifer.
The representation of these different concentrations is called a contamination plume.
http://techalive.mtu.edu/meec/module04/ContaminationMovement.htm
Area of Contamination
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A contaminant may be released into the groundwater for only a short time and in a very small
area, but as it disperses the contaminant can affect a very large area and number of people.
http://techalive.mtu.edu/meec/module04/AreaofContamination.htm
Plumes can be very irregular
http://techalive.mtu.edu/meec/module04/PlumeExample.htm
Watch this example and answer these questions:
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Where is the source of the contamination?
Is the source continuous or a one-time event?
Based on the direction of the plume, which way is the groundwater moving?
How far does the contamination travel in 16 years?
What important areas of the city are affected by the contamination?
Finding Contaminants
Look at the history of the site.
See if a nearby river is contaminated or what possible above-surface sources exists.
To find the contaminant plume drill test wells or use other technology to find concentrations at
different points underground.
http://techalive.mtu.edu/meec/module04/PlumeSourceGame.htm
Some specific contaminants.
Sites to search for contaminants
http://www.clu-in.org/contaminantfocus/default.focus/sec/General_Contaminant_Information/cat/Overview/
http://www.clu-in.org/contaminantfocus/default.focus/sec/General_Contaminant_Information/cat/Overview/
has a large list of sites, including
http://www.nature.nps.gov/hazardssafety/toxic/entry.cfm
Suspended Solids
Organic and inorganic particles in water are termed suspended solids
May be distinguished from colloids, particles that do not settle readily
Measured by filtering a water sample, drying and weighing the filter
Suspended Solids
Problems
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sedimentation
may exert oxygen demand
primary transport mechanism for many metals, organics and pathogens
aesthetic
complicates drinking water treatment
Sources
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storm water
wastes
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erosion
Pathogenic Organisms
Many organisms that cause human or animal diseases colonize the intestinal tract but can live for
a period of time outside the body
Carriers (who may or may not exhibit disease symptoms) excrete these intestinal tract organisms
in very large numbers
When water is contaminated by excreta, the organisms can be transmitted to those who contact
the water
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Toxic and Hazardous Substances
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Heavy metals
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Other inorganic elements
Acids/bases
Oxidants/reductants
Chlorination by-products
Combustion by-products
Volatile organic compounds
Hydrophobic organic compounds
Endocrine disruptors
Surfactants
Petroleum Additives
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Pesticides
Volatile Organic Compounds
Petroleum constituents:
benzene and substituted benzenes
CH3
CH3
CH2CH3
CH3
Benzene
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Toluene
Ethylbenzene
m-Xylene
in gasoline, diesel fuel, heating oil
most easily transported, slow degradation, toxic
Oxygenated gasoline additives
CH3
CH3
C O CH3
CH3
Methyl tertiary butyl ether (MTBE)
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added to gasoline to improve air quality
very soluble, resistant to degradation, toxic
attempt to solve one problem caused another (spills)
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Chlorinated solvents
C1 and C2 aliphatics
Cl
Cl
C
Cl H
Cl
Cl
Cl
H C Cl
Cl
C C H
C C
H
Cl
Cl
Cl H
carbon tetrachloride
chloroform
1,1,1-trichloroethane
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H
H
vinyl chloride
widely used in degreasing, dry cleaning, extraction
somewhat soluble, volatile, difficult to degrade
Hydrophobic Organic Compounds
Polycyclic aromatic hydrocarbons (PAHs)
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naphthalene
anthracene
pyrene
benzo[a]pyrene
phenanathrene
potent carcinogens, tend to associate with particles
also combustion by-products
Hydrophobic Organics/ Chlorinated Aromatics
Chlorinated Pesticides
Polychlorinated dibenzodioxins (PCDDs)
Cl
O
Cl
Cl
O
Cl
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)
Polychlorinated biphenyls (PCBs)
Cl
Cl
Cl
Biphenyl
2,3',4-trichlorobiphenyl
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Some Other Categories
Trihalomethanes
Explosives and Propellants
Phenolics
Aldehydes
Organometallics
Asbestos
Arsenic
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Occurs naturally in rock and soil
Released to groundwater under some conditions
Health effects include cardiovascular diseases, skin cancer, nervous system effects,
and kidney disease
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Major problem in Bangladesh
Drinking water standard being lowered in U.S.
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