Transcript Chapter 5 Water Quality Chapter Headings • • • • • • Water Pollution Basic Parameters of Water Inorganic Chemicals Organic Chemicals Waterborne Diseases Water Quality Management.

Chapter 5
Water Quality
Chapter Headings
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Water Pollution
Basic Parameters of Water
Inorganic Chemicals
Organic Chemicals
Waterborne Diseases
Water Quality Management
Water Pollution
• Water pollution can affect
– Surface waters
– Ground waters
• Can occur naturally but is usually due to
man’s activities
• US waters have improved significantly
since the Clean Water Act Amendments
were passed in 1972
• But many waters still don’t meet standards
Point Source Pollution
• Contamination
discharged through a
pipe or other discrete,
identifiable location
• Relatively easy to
quantify and evaluate
impact
• Historically, the focus
of regulation
Water. 1993. National Geographic Special Edition
Point Sources
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Factories and sewage treatment plants
Landfills
Abandoned mines
Underground and above-ground storage
tanks
• Required to have permits under Clean
Water Act
Point Sources
• 2009 article on number of permit violations
by state in NY Times
• http://www.nytimes.com/interactive/2009/0
9/13/us/0913-water.html
Nonpoint Source Pollution
• Contamination from a
diffuse source
• Difficult to measure
• Not required to have
permits under Clean
Water Act
• Focus of recent
regulatory efforts
Soil erosion from a farm field
Gary Hawkins, UGA
Nonpoint Sources
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Lawns, gardens, and golf courses
Agricultural and forestry practices
Construction activities
Stormwater runoff
Chapter Headings
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Water Pollution
Basic Parameters of Water
Inorganic Chemicals
Organic Chemicals
Waterborne Diseases
Water Quality Management
Basic Parameters of Water
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Temperature
Dissolved oxygen (DO)
pH
Turbidity
Temperature
• Temperature affects physical, chemical,
and biological processes in water
– Chemical example: DO decreases as
temperature increases
– Biological example: fish seek thermal refuges
• Temperature affected by depth
– Causes lake turnover
• Loss of streamside shade trees causes
temperature to increase
Dissolved Oxygen
• Atmosphere consists of 21% O2
• Water consists of <1% O2
• When water and atmosphere come into
intimate contact, O2 tends to diffuse into
water
– Occurs as water passes over riffles, rapids,
and falls and to a lesser extent in still water
• Aquatic plants also pump O2 into water
– During daytime when they are undergoing
photosynthesis
Dissolved Oxygen
• Fish depend on DO in
water
– O2 diffuses from water
to blood in gills
• When DO
concentrations in
water drop below 5
parts per million
(ppm) most fish have
trouble
www.fishdoc.co.uk
pH = -log10(H+)
If H+ = 10-3 moles then pH = 3
If H+ = 10-11 moles then pH = 11
Turbidity
• Clarity of water
• Measured as light
penetration in
nephelometric
turbidity units (NTU)
• Also measured with a
Secchi disk
– Record the depth at
which you can no
longer see the banded
colors on the disk
Secchi disk depth comparison from clear (left) to murky (right)
http://earthobservatory.nasa.gov/Study/WaterQuality/water_quality2.html
Secchi disk depth for Lake Tahoe: http://terc.ucdavis.edu/research/clarity.html
Chapter Headings
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Water Pollution
Basic Parameters of Water
Inorganic Chemicals
Organic Chemicals
Waterborne Diseases
Water Quality Management
Inorganic Chemicals
• Compounds that do not contain carbon (C)
• Originally defined as compounds that do
not originate in plants or animals
• Metals, minerals, and nutrients1
1book
lists nutrients under organic compounds but
most nutrients are in the inorganic form
Minerals
• All surface and groundwaters contain minerals
• At high concentrations they can cause adverse
effects
• Salt: any compound that dissolves in water
– Most common salt is sodium chloride (NaCl)
– Salinity: the presence of excess salts in water or in
soil
– Saline water is undrinkable
– Saline soils make water uptake difficult for plants and
microbes
– Aquatic plants and animals sensitive to salinity
(oysters in Apalachicola Bay)
Colorado River and Salt
• U.S. irrigation and water withdrawals
cause Colorado River salinity to be very
high by the time it reaches Mexico
• 1974 law requires average annual salt
concentration <115 ppm at border
• Battery of wells at border
– 13-mile long 5-mile wide area
– Pump low salinity groundwater into river to
dilute salt concentrations
Colorado River Basin Salinity
Control Project
http://www.usbr.gov/projects/Project.jsp?proj_Name=CRBS
CP+-+Protective+and++Regulatory+Pumping+Unit++Title+I
Nutrients
• Major minerals important in animal and
plant nutrition:
– Nitrogen, phosphorus, potassium, calcium
• Trace elements also required
– Iron, zinc, manganese, etc.
• At high concentrations in streams, lakes,
estuaries, and oceans they can cause
problems
Nutrients: Nitrogen
• Nitrogen (N) an important plant nutrient
• Takes several forms in nature
– Nitrogen gas (N2)
– Nitrate (NO3-)
– Ammonia gas (NH3)
– Ammonium (NH4+)
– Organic forms
Nutrients: Nitrogen
• Nitrate in drinking water is a pollutant
• When ingested by babies in milk formula
– Causes methemoglobinemia or blue baby syndrome
– Converts to nitrite (NO2-) which interferes with oxygen
transport in the blood
– Baby suffocates
• Drinking water standard is <10 ppm nitrate
• Very mobile in soil and leaches easily to
groundwater
• Sources: manures, fertilizers, sewage
Nutrients: Phosphorus
• Not very mobile in soils
– Usually doesn’t leach to groundwater
• Instead it runs off into streams
– Dissolved in runoff or
– Attached to eroded sediment particles
• Not harmful to humans directly
• Sources: manures, fertilizers, sewage,
detergents
• P was banned from detergents in 1990’s
Eutrophication
• High levels of N and P can cause excessive
algal growth in fresh and salt water bodies
– Called eutrophication or algal blooms
• Microbes that decompose dead algae use oxygen and lower
DO
• Low DO stresses fish and other aquatic life, eventually
causing fish kills
– P causes eutrophication in freshwater
• Concentrations above 0.1 ppm (streams) and 0.01 ppm
(lakes) can trigger algal blooms
Eutrophication
• Lake in Canada
• Divided by plastic curtain
• For 8 years
– Nitrogen added each year
to one side
– Nitrogen and phosphorus
added to other side
• Every year there was an
algal bloom in response
to adding phosphorus
Lake Erie Algal Bloom 2011
Toledo 2014
Cartoon from Aug 8, 2014 Columbus Dispatch newspaper
Toledo 2014
http://www.nytimes.com/2014/08/05/us/lifting-bantoledo-says-its-water-is-safe-to-drinkagain.html?module=Search&mabReward=relbias%3Ar
%2C{%222%22%3A%22RI%3A14%22}&_r=0
Phosphorus concentrations in the Chattahoochee below Atlanta
Nutrients and Marine Waters
• Algal growth in marine waters is controlled
primarily by N
– P can be important at certain times of the year
• Estuaries (which are intermediate between
fresh and marine waters in terms of
salinity) are affected by both N and P
Gulf of Mexico Hypoxia
• Nitrogen (and to a lesser extent P) from
the Mississippi River watershed are
causing algal blooms and low DO
(hypoxia) in the Gulf of Mexico each
summer
• Dead zone at lower depths kills aquatic
species including shrimp
• http://www.nytimes.com/interactive/2010/0
4/28/us/20100428-spill-map.html?ref=us
Chapter Headings
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Water Pollution
Basic Parameters of Water
Inorganic Chemicals
Organic Chemicals
Waterborne Diseases
Water Quality Management
Organic Chemicals
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Compounds that do contain carbon (C)
Often large complex molecules
May be natural or man-made (synthetic)
Synthetic compounds may last for a long
time in the environment
– Natural decomposing processes are unable to
break down these complex molecules
Organic Chemicals
• Many synthetic organic chemicals are
carcinogens:
– Benzene (C6H6), commercial solvent
– Carbon tetrachloride (CCl4), in fire extinguishers,
solvents, and cleaning agents
– Polychorinated Biphenyls (PCBs), used as a coolant
in electrical transformers
• Pesticides are synthetic organic chemicals used
to kill unwanted pests
– Can be harmful to humans and wildlife
Organic Chemicals: Pesticides
• Silent Spring by Rachel
Carson published in 1962
– Showed that pesticides
such as DDT spread in the
environment and had
unintended victims
– DDT caused thinning of
egg shells of eagles
– Resulted in the banning of
DDT in U.S.
• http://www.youtube.com/
watch?v=aycQKk4qn_Y
Start at 2:03
Organic Chemical: MCMH
• Charleston WV spill
– http://www.nytimes.com/2014/01/12/us/thewait-continues-for-safe-tap-water-in-westvirginia.html?ref=us&_r=0
• What is MCHM
– http://en.wikipedia.org/wiki/4Methylcyclohexanemethanol
Chapter Headings
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Water Pollution
Basic Parameters of Water
Inorganic Chemicals
Organic Chemicals
Waterborne Diseases
Water Quality Management
Waterborne Diseases
• Early concerns regarding water quality caused
by waterborne diseases
– Plagues in the Middle Ages
– Cholera epidemic in 1848-1849 caused
53,000 deaths in London
• Connection between disease and water was
unknown until shown by Dr. John Snow
– 1854 Broad Street Pump study
• At that time cholera and other diseases thought
to be spread in the miasma (foul air)
Dr. John Snow
• Epidemic started on Aug 28
• Found that cholera cases were
clustered around a community
water pump at Broad Street in
London
– 500 deaths in 10 days in
that area
• Water came from a deep well
but cesspool next to the well
leaked down outside of well
casing
• Advised that the pump handle
be removed at a parish
meeting on Sep 7
Dr. John Snow
• Sewers in London
discharged to Thames
River
– Designed to get rid of
surface water
– Illegal to discharge
waste into sewers
before 1815
• Cesspools beneath each
house or building stored
waste
– Emptied by night soil
men who took it to
surrounding farms
Dr. John Snow
• Flushing toilets (water
closets) used in public
restrooms at Great
Exhibition of 1851 in London
– Became popular in
1850’s
• These overwhelmed the
cesspools and existing
sewers
• Many of the public water
pumps were supplied by
companies that took water
from the Thames River
Dr. John Snow
Dr. John Snow
Replica of Broad Street
pump with handle
removed outside the
John Snow pub
Several blocks from true
location of Broad Street
pump
www.ph.ucla.edu/epi/snow
Dr. John Snow
John Snow Pub on Broadwick Street
(formerly Broad Street)
Original well located behind back wall
Dr. John Snow
• John Snow’s work led
to development of
new sewer system
with large tunnels that
ran parallel to river
and intercepted older
sewer lines that had
discharged to river
• Large tunnels
discharged farther
downstream the
Thames River
Waterborne Diseases
Also a cholera epidemic in Chicago in 1885
Waterborne Diseases
• Microorganisms include
– Viruses – bits of DNA or RNA
– Bacteria – single cell organisms
– Other – protozoa, worms, blue-green algae
• Examples of microorganisms that are
pathogens (disease-causing organisms)
– Escherichia coli (E. coli) – bacterium
– Giardia – protozoa
– Cryptosporidium – protozoa
E. Coli
• E. coli are a common bacteria in the human
intestines
– Aid digestion, harmless
– Used as an indicator organism
• One strain of E. coli (0157:H7) is lethal, however
– In a town in Ontario in 2000, 2,300 people became ill
and 7 died when the water supply became
contaminated with 0157:H7
– Attributed to contamination from cattle manure
Indicator Organisms
• Too costly and dangerous to test water for
individual pathogens
• Instead we test for indicator organisms
– Harmless but indicate fecal origin
• Common indicator organism
– Fecal coliform bacteria – most common today
– E. coli – (not the 0157:H7 toxic strain) will
probably replace fecal coliform
Indicator Organisms
• Standard for drinking water in Georgia is
<1 fecal coliform per 100 mL
• Standard for streams and lakes is <200
fecal coliforms per 100 mL
Fecal coliforms in the Chattahoochee below Atlanta
Chapter Headings
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Water Pollution
Basic Parameters of Water
Inorganic Chemicals
Organic Chemicals
Waterborne Diseases
Water Quality Management
Water Quality Management
• We try to manage water quality so that waters
don’t become contaminated (pollution prevention)
– Costly and risky to rely only on treatment of drinking
water (cryptosporidum oocysts unaffected)
– Reduce impact on wildlife
• Book calls this Fate and Transport
– The movement and ultimate disposition of pollutants
• Water quality management programs focus on
ground water and surface water
Groundwater Management
• Pollutants usually move horizontally in a
plume away from the source in
groundwater
• Concentration decreases as pollutant gets
farther away from source
– Pollutant may break down with time
– Mixing with uncontaminated groundwater
causes dilution
• Pollutants may be more or less mobile
– Depends on adsorption to soil and rock
Groundwater Management
• Movement of plumes
is estimated by a
combination of
– Groundwater
monitoring wells
– Groundwater
computer models
www.uky.edu/KGS
Groundwater Management
• U.S. EPA Superfund Program established
in 1980
• Purpose to clean up highly contaminated
point-sources of pollution
• Currently there are more than 1,200 sites
in the U.S.
– 80% involve groundwater contamination
Groundwater Management
• Classic movie (and
book) on point-source
groundwater
contamination
• Groundwater
contamination by a
leather plant
appeared to cause
leukemia outbreak in
New England
community
Surface Water Management
• States set their own water quality
standards
– EPA has final approval
• EPA encourages a watershed approach
to surface water quality management
– Partnerships or stakeholder involvement that
gets everyone involved
– Management based on science and data
Surface Water Management
• Example is the Total Maximum Daily Load
(TMDL) program
– Watershed-scale management plans must be
developed for lakes and rivers that don’t meet
state water quality standards
• Focus on point and non-point sources of
pollution
• In Georgia, over 600 waters listed
– Most common pollutant is fecal coliforms
Lake Okeechobee TMDL
Lake Okeechobee TMDL
• Lake has experience algal blooms since mid1980’s
• Caused reduced DO levels and fish kills
• Due to increasing P concentrations in runoff
from dairies
– 49 dairies in watershed in 1980’s
– Legislature passed Dairy Buy-Out bill in 1987
– In 1997 there were 23 dairies left, all in compliance
with new law
• Historical loading has resulted in lake bottom
sediments high in P
– Diffusion from sediment = sum of all external loads
Lake Okeechobee TMDL
• TMDL developed in 2001
• Estimated TP (total P) concentration of 40
ppb would prevent algal blooms
• Load would have to be reduced from 640
metric tons per year to 140 metric tons per
year to achieve this concentration
• TMDL = 140 metric tons per year
Sediment TMDLs
Many rivers have TMDLs
for excessive sediment
loads
September 2, 2011
Connecticut River a week
after Hurricane Irene
caused torrential rains in
Vermont mountains
Surface Water Management
• Water sampling is important part of
surface water quality management
– Only way to know if a river or lake meets the
water quality standard
– Also used to determine if clean up plan is
working
• Federal and state agencies take samples
• Also volunteer groups (Adopt-a-Stream)
Surface Water Management
• Example of local volunteer group is Upper
Oconee Watershed Network (UOWN)
– http://www.uown.org/
– Quarterly monitoring of Upper Oconee River
– Annual River Rendezvous
– Maintain a database
Chapter Summary
• Pollutants come in many forms (inorganic,
organic, nutrients, microorganisms)
• Point and nonpoint sources of pollution
• Pollutants usually come from human
activity
• Water quality management programs
focus on groundwater and surface water