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Water Resources
The Hydrologic Cycle
• Water occurs as a solid, liquid and gas
• Amount of water is fixed
• The places where water resides are called
Reservoirs
• Water constantly moves from one
reservoir to another
The Hydrologic Cycle: Pathways
• Evaporation
• Evapotranspiration
• Condensation
• Precipitation
• Runoff
• Infiltration/Percolation
RESERVOIRS
Comparison of
the amount of
water supply
held in each of
the major
reservoirs
If the total
earth’s water
supply was a 55
gallon drum
Groundwater
• What happens to precipitation once it
reaches the ground
– infiltration
– percolation
• Water filling pore space, cracks &
crevices in rocks- Porosity
• Aquifer- Geologic unit that can store,
transmit and yield appreciable amounts
of water
Porosity and Permeability
• Porosity
– % of rock or sediment that is open (void
spaces)
– ability to hold water
• Permeability- ability to transmit water
Movement of ground water
• Moves in response to differences in water
pressure & elevation
• Velocity influenced by
– Slope of water table
– Permeability
Groundwater Movement
• Darcy’s Law
– Q= KA (h1-h2)/(l)
– Where Q is discharge; A= BxW
– K is hydraulic conductivity
– (h1-h2)/(l) is hydraulic gradient
Cone of Depression
After pumping in a well stops, the water level slowly recovers its
previous level and the cone of depression disappears
Water Use:
Trends in population and freshwater withdrawals
by source, 1950-2000.
Trends in total water withdrawals
by water-use category, 1950-2000
Water Pollution
Water Pollution
• Degradation of water quality
– Biological
– Chemical
– Physical
– Based on the intended use of the water
• Attainment vs. non-attainment
•
Clean Water Act Sec.304(a)(1) :
The Administrator, after consultation with appropriate
Federal and State agencies and other interested persons,
shall develop and publish, within one year after the date of
enactment of this title (and from time to time thereafter
revise) criteria for water quality accurately reflecting the
latest scientific knowledge
• (A) on the kind and extent of all identifiable effects on health
and welfare including, but not limited to, plankton, fish,
shellfish, wildlife, plant life, shorelines, beaches, esthetics,
and recreation which may be expected from the presence of
pollutants in any body of water, including ground water;
• (B) on the concentration and dispersal of pollutants, or their
byproducts, through biological, physical, and chemical
processes; and
• (C) on the effects of pollutants on biological community
diversity, productivity, and stability, including information on
the factors affecting rates of eutrophication and rates of
organic and inorganic sedimentation for varying types of
receiving waters.
Common Sources of Groundwater
Pollution/Contamination
• Leaks from storage tanks and pipes
• Leaks from waste disposal sites (landfills)
• Seepage from septic systems
• Accidental spills
• Agricultural activities
• Intrusion of salt water
• Mine spoils and tailings
• Irrigation
• Injection wells
• Acid mine drainage
• Runoff- urban, industrial, agricultural
Water Pollutants
• Biological Oxygen Demand
• Pathogenic Organisms
• Nutrients
• Oil
• Chemicals
• Heavy Metals
• Radioactive materials
• Sediments
• Thermal Pollution
Pollution and Environmental
Health
World Health Organization(WHO); World
Resources Institute(WRI); United States
Environmental Protection Agency (USEPA);
United States Geological Survey(USGS);
Botkin & Keller
Contamination, Pollution and
Toxicity
• Any material that is above
background level in the environment
(introduced)
• Any material that is above
background level in the environment
and that causes a deleterious effect
on humans and ecosystems
Units of Measurement
• Depending on whether it is found in water,
soil or air
• Reported as percent (%), ppm, ppb, ppt
(parts per million, billion or trillion)
– 0.01% = 100ppm = mg/kg or mg/L
– Milligram (mg) (1/1,000 g)
– Microgram (mg) (1/1,000,000g)
• Reported as either volume, mass or
weight
There are two very distinct
question sets
• Will a given material harm the
environment?
• Will a given material harm us?
Factors Influencing Toxicity
• Additive 2 + 2 = 4
• Synergistic 2 + 2 = 10
• Antagonism 2 +2 = 0
Spectrum of Toxic Dose
Agent LD50 (mg/kg)
Ethanol 10,000
NaCl 4,000
Ferrous Sulfate 1,500
DDT 100
Strychnine sulfate 2
Nicotine 1
Tetrodotoxin 0.1
Dioxin (TCDD) 0.001
Botulinus 0.00001
What determines the impact
of Exposure?
• Length of, period of, time
• Concentration - dose
• Recurrence – is contact repeated
• Frequency of recurrence – daily/yearly
• Life cycle sensitivity differences - infant/adult
• Physical condition of victim – robust/sickly
• Presence of other hazards - synergism
Point vs. Non-Point Sources
• As authorized by the Clean Water Act, the
National Pollutant Discharge Elimination System
(NPDES) permit program controls water pollution
by regulating point sources that discharge
pollutants into waters of the United States
• Point sources are discrete conveyances such as
pipes or man-made ditches
• Industrial, municipal, and other facilities must
obtain permits if their discharges go directly to
surface waters
• In most cases, the NPDES permit program is
administered by authorized states
Point vs. Non-Point Sources
• Non-point source (NPS) pollution, unlike
pollution from industrial and sewage
treatment plants, comes from many diffuse
sources
• NPS pollution is caused by rainfall or
snowmelt moving over and through the
ground
• As the runoff moves, it picks up and carries
away natural and human-made pollutants,
finally depositing them into lakes, rivers,
wetlands, coastal waters, and groundwater
Non-Point Source Pollutants
• 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 are also sources of non-
point source pollution
Federal Water Legislation
• Refuse Act 1899
• Federal Water and Pollution Control
Act 1956
• Fish and Wildlife Coordination Act 1958
• National Environmental Policy Act 1969
• Water Quality Improvement Act 1970
• Federal Water Pollution Control Act
(Clean Water Act) 1972
Water Quality Standards
• Under §303(c) of the Clean Water Act a water
quality standard is described as comprising:
(1) the designated beneficial uses (aquatic
life, wildlife, recreation, fishing, agriculture,
water supply, etc.) of a water body and (2) the
criteria (numeric and narrative) necessary to
protect these uses. States and Tribes are
required by CWA §303(c)(2)(B) to adopt
criteria for CWA §307(a) toxic pollutants for
which EPA has published CWA §304(a)
criteria, and/or recommendations and
methodology based on the latest science.
Federal Water Legislation
• Comprehensive Environmental Response,
Compensation and Liability Act (CERCLA)
1980
• Hazardous and Solid Waste Amendments
to the Resource Conservation and
Recovery Act (RCRA) 1984
• Water Quality Act 1987
• Safe Drinking Water Act 1996
Water Quality Standards
• Maximum Contaminant Level- MCLs
– Based on toxicity
– Usually lethal dose (LD50) for some target
organism or toxic dose (TD50)
• Maximum Contaminant Level Goal-
MCLGs
Primary Drinking Water Standards
Contaminant MCL (mg/L) Problems
Arsenic 0.05 Highly toxic
Lead 0.015 Highly toxic
Mercury 0.002 Kidney, Nervous System
Fluoride 4 Skeletal Damage
Asbestos 7 million fibers/L >10mm Benign Tumors
Lindane 0.004 Kidney, Nervous System,
Liver
2,4D 0.07 Kidney, Nervous System,
Liver
Benzene 0.005 Cancer
Trichloroethylene 0.005 Probable Cancer
Vinyl Chloride 0.002 Cancer risk
Fecal Coliform 1 cell/100ml Pathogen
Categories of Pollutants
• Biological- Infectious Agents
• Heavy Metals
• Organic compounds
• Particulates
• Radiation
• Thermal
Biological Hazards
• Of all the environmental hazards humans
encounter, the most formidable adversaries
remain the microorganisms -- viruses,
bacteria, protozoa, and parasitic worms
• Up to 17 million deaths per year are
attributable to these infectious and parasitic
agents, almost all in the developing world,
along with hundreds of millions of cases of
illnesses
Why consider infectious
diseases "environmental" in
origin?
• Cholera and other diarrheal diseases are
associated with inadequate access to clean water
and sanitation and poor hygiene
• Diarrhea is spread by both bacteria and viruses
through contaminated food or water, and these
disease-causing agents represent one of the most
widespread health problems in the world
• Diarrhea killed roughly 2.5 million people in 1996,
according to World Health Organization, most of
whom were children under age 5
Inadequate Water Supplies
• Creates conditions rife for transmitting
diarrhea
• An estimated 2.9 billion people lack access to
adequate sanitation
• Roughly 1.4 billion people do not have
access to safe drinking water
• This situation has persisted despite
investments of more than US$100 billion
during the International Water and Sanitation
Decade
Infectious Agents
• In 1993, the United States experienced the largest
outbreak of diarrhea in recent history
• Affecting more than 400,000 people
• The municipal water supply of Milwaukee,
Wisconsin, was contaminated by Cryptosporidium
parvum from farm animal wastes
• This protozoan parasite has been wreaking havoc in
countries across Europe as well, raising new
concerns about the safety of drinking water in some
of the world's most affluent countries.
Chemical Hazards in the
Environment
• Exposure to chemical agents in the
environment -- in air, water, food, and soil
-- has been implicated in numerous
adverse effects, from cancer to lung
disease to brain damage to birth defects
• Some evidence is ironclad; some is
suggestive at best
Heavy Metals
• Metals with high atomic mass
• Arsenic, Cadmium, Chromium, Lead,
Mercury, Nickel, Platinum, Selenium,
Silver, Vanadium (others)
• Used in industrial processes and by-
products of mining, smelting, fossil fuel
burning, etc.
• Can have direct physiological effect or
can Concentrate in fatty tissue
(bioaccumulation)
Copper mining and smelting in the Copper Basin of the SE US
Ducktown, TN- Burra Burra Mine
Mercury
• Mercury has been well known as an environmental
pollutant for several decades
• As early as the 1950’s it was established that emissions of
mercury to the environment could have serious effects on
human health
• Inorganic mercury (Hg2+) will undergo bacterial activity and
be converted to the more toxic methyl mercury ([CH3Hg]+)
• Early studies demonstrated that fish and other wildlife from
various ecosystems commonly attain mercury levels of
toxicological concern when directly affected by mercury-
containing emissions from human-related activities
• Human health concerns arise when fish and wildlife from
these ecosystems are consumed by humans (Minamata,
Japan)
• In the U.S. widespread mercury contamination in
streams, wet-lands, reservoirs, and lakes
• To date, 33 states have issued fish consumption
advisories because of mercury contamination
• These continental to global scale occurrences of
mercury contamination cannot be linked to
individual emissions of mercury, but instead are
due to widespread air pollution
• When scientists measure mercury levels in air
and surface water, however, the observed levels
are extraordinarily low
Why do fish from some remote areas have
elevated mercury concentrations, when
contamination levels in the environment are so
low?
• Mercury biomagnifies from the bottom to the top of the food
chain
• Even at very low input rates to aquatic ecosystems that are
remote from point sources, biomagnification effects can result
in mercury levels of toxicological concern
• The bioaccumulation effect is generally compounded the
longer an organism lives, so that larger predatory game fish
will likely have the highest mercury levels
• Adding to this problem is the fact that mercury concentrates in
the muscle tissue of fish
• Unlike organic contaminants (PCBs and dioxins) which
concentrate in the skin and fat, mercury cannot be filleted or
cooked out of consumable game fish
Synthetic Organic Chemicals
• Carbon based molecular structure
• Often contain reactive chlorine
• Manufactured as pesticides, herbicides,
insecticides or as insulator oil (PCB)
• 20 million produced and about 100,000
produced commercially
• Persistent in the environment
• Soluble in fat and accumulate in tissue
Synthetic Organic Chemicals
• "Over increasingly large
areas of the United
States spring now comes
unheralded by the return
of birds, and the early
mornings are strangely
silent where once they
were filled with the
beauty of bird song.“
• Rachael Carson, Silent
Spring 1962
DDT
• Dichloro-
diphenyltrichloroethane
• World Health Organization
credits DDT with reducing
disease
• 1945-1960, used to control
agricultural pests as well as
disease-carrying insects
(Malaria)
– Venezuela
• 1943 -8,171,115 cases
• 1958 –800 cases
– Taiwan
• 1945- 1,000,000 cases Jones Beach on Long Island, NY
• 1969- 9 cases
Cancer
• Cancers may take 10 to 40 years to develop,
and many factors may contribute to the
appearance of the disease in a particular person
• Accordingly, chemical risks tend to be described
in terms of the numbers of people exposed -- for
instance, 1.4 billion urban dwellers exposed to
air quality that exceeds health guidelines, as
WHO estimates
Thermal Pollution
• Release of heat into atmosphere or water
ways
– Acute (i.e. fires from agricultural burning)
– Chronic (i.e. hot water releases from electric
power plants)
• Change biological and physico-chemical
composition of streams
Toxicity Testing
• Despite widespread public concern over
chemical safety, toxicity testing remains
inadequate
• For the vast majority of chemicals in
widespread use, no toxicity testing results
are available in the public record
Hazards
• Of the other potential effects of chemical hazards, such as
infertility, birth defects, immune system impairment, or
brain damage, even less is known.
• In the United States, for instance, the chief agency for
chemical evaluation spent nearly US$29 million on testing
chemicals for cancer in 1991, but just about $6 million for
both genetic and reproductive effects
• Testing for other health concerns, such as immune system
effects or endocrine disruption, lags even further behind
• United States provides an apt example: according to a
recent study, 86 percent of chemicals in widespread use
have not been tested for immunotoxicity, and 67 percent
have not been tested for neurotoxicity
• This focus on cancer means that other important and
preventable risks may be overlooked
Remediation of Groundwater
• Extraction Wells
– “Pump and Treat” by filtration, oxidation or air
stripping
• Vapor Extraction
• Bioremediation
– Injection of nutrients and oxygen to
encourage microorganism growth
• Permeable Treatment Beds
CHEMICAL TREATMENT
Other Methods of Remediation
• Natural attenuation.
– Natural attenuation defines the natural
occurring processes in the subsurface
environment such as dilution, volatilization,
biodegradation, adsorption and chemical
reactions with subsurface compounds that
contain the spread of pollution and reduce the
concentration and amount of pollutants at
polluted sites.
