Transcript water - Highland Local Schools

WATER
WATER
• Sixty-six percent of a human being is
water.
• Seventy-five percent of the human brain is
water.
• Seventy-five percent of a living tree is
water.
WATER
• There is the same amount of water on Earth today as
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there was 3 billion years ago.
70% of the Earth is covered by water
97% of water on Earth is salt water
Three percent of the water on Earth is freshwater
5 Great Lakes contain at least 95% of fresh surface
water in US and 20% of the world’s fresh surface water
77% is frozen in icecaps
Only 1 % is available for human consumption.
WATER
HUMAN USES INCLUDE:
• Agriculture
• Drinking
• Bathing
• Cooking
How do you use water on a daily basis?
WATER
The water we require comes from two
sources:
1. Surface Water
2. Ground Water
WATER POLLUTION
Water Pollution - any chemical, biological,
or physical change in water quality that
has a harmful effect on living organisms
and makes water unsuitable for desired
uses
WATER POLLUTION
• Classes/Categories of water pollution
• Disease Causing Agents (pathogens):
i.e., bacteria, viruses, protozoa, and
parasitic worms from domestic sewage
from human and animal wastes
• Oxygen Demanding Wastes: organic
wastes that can be decomposed by
aerobic bacteria which depletes oxygen
WATER POLLUTION
• Water-Soluble Inorganic Materials: water-soluble
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nitrates and phosphates, can cause excessive growth of
algae and other aquatic plants that die and deplete the
oxygen content (kills fish)
Organic Chemicals: threatens human, animal and
aquatic plant life, i.e., oil, gas, plastic, pesticides,
detergents, ext.
Sediments or Suspended Matter (largest class):
particles of soil/solid that stay suspended in water and
made the water cloudy, reduces photosynthesis and
disrupts food webs and clogs harbors, reservoirs,
channels and artificial lakes
WATER POLLUTION
• Water-Soluble Radioactive Isotopes:
in tissues and organs and cause birth
defects, cancer and genetic damages
• Thermal Pollution: rise in water temp
b/c of heat absorbed in water to cool
power plants: lowers water and makes
organisms more vulnerable to disease
WATER POLLUTION
• Genetic Pollution: deliberate or accidental
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addition of nonnative species disrupts aquatic
systems and crowd out natives: reduces
biodiversity: principal way they are introduced =
intake and ballast from ships
Fecal Coliform: Good indicator for quality of
drinking and swimming water is the number of
coliform bacteria present in 100-mL sample
– WHO recommends 0 colonies for drinking
– EPA recommends max of 200 colonies for swimming
– Avg. person excretes 2 billion bacteria a day
WATER POLLUTION
How do we test for pollution?
• We detect water pollution through chemical
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analysis, using living organisms as indicator
species, computer models of aquatic life zones
Air and water pollution through chemical
analysis, using living organisms as indicator
species, computer models aquatic life zones
(saves $)
WATER POLLUTION
How are our freshwater resources polluted?
Point sources of water pollution have a
specific location (pipes, ditches, sewers):
fairly easy to find and monitor: developed
countries = controlled: developing =
uncontrolled
WATER POLLUTION
How are our freshwater resources polluted?
• Nonpoint sources of water pollution can’t be traced to
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1 site (large land areas, runoff, surface flow)
In US, sediment, inorganic fertilizer, manure, salts
dissolved in water and pollutants = 64% of mass of
pollutants in streams and 57% entering lakes
Storm water causes 33% of contaminates in lakes and
estuaries
WATER POLLUTION
Pollution of Streams and Lakes
Pollution of streams - Flowing streams and
rivers recover rapidly from degradable, oxygen
demanding wastes and excess heat by a
combination of dilution and bacterial decay
(natural process which works as long as streams
aren’t overloaded w/ pollutants: doesn’t get rid
of slowly degradable and nondegradable
pollutants)
WATER POLLUTION
• Oxygen sag curve: depends on stream’s
volume, flow rate, temperature, pH level
and volume of incoming degradable
wastes
• Extracting drinking water downstream
rather that upstream (what we do now)
would improve water quality
WATER POLLUTION
• Pollution control laws from the 1970s have
increased the quality and number of
wastewater treatment plants
• Ohio’s Cuyahoga River (Cleveland):
prompted city, state + federal officials to
enact laws limiting the discharge of
industrial wastes
WATER POLLUTION
• In developing countries waste water
treatment is almost nonexistent (Soviet
Union: Eastern European countries)
• More than 2/3 of India’s water is polluted
• 54 out of 78 monitored streams in China
are polluted and 20% of its rivers are too
polluted to use for irrigation
WATER POLLUTION
Pollution of Lakes
• In lakes, reservoirs, and ponds, dilution is
less effective than in streams
• Stratified layers, volumes of water w/ little
flow (reduces levels of dissolved oxygen)
• Flushing and changing of water in lakes
and large artificial reservoirs takes b/t 1
and 100 years
WATER POLLUTION
• More vulnerable to contamination by plant
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nutrients, oil, pesticides, and toxic substances:
destroy bottom life, and fish and birds that feed
on contaminated aquatic organisms
Thousands of waterfowl and fishes died at the
Kesterson National Wildlife Refuge in the San
Joaquin Valley in CA due to selenium
contaminated water flowing into the lakes
WATER POLLUTION
Eutrophication: natural enrichment of lakes
Cultural Eutrophication: process of human activities
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accelerating the input of nutrients
Animal wastes fertilizes cropland and is stored in pits and
lagoons that can pollute the air
1996: more that 40 animal waste spills killed 670,000
fish in Iowa, Minnesota and Missouri
Hot weather and droughts produces more bacteria
1/3 of the 100,00 medium-large lakes and 85% of the
large lakes near modern population centers in the US
suffer from some sort of cultural eutrophication
WATER POLLUTION
Prevention of cultural eutrophication = advanced
waste water treatment which bans/ limits the amount of
phosphates in detergents, soil conservation, and land
use control
Cleanup methods = dredging bottom sediments,
removing excess weeds, controlling plant growth w/
herbicides and algaecides, pumping air thorough lakes
and reservoirs
• Prevention is more effective and usually cheaper in the
long run than pollution control
• Seattle’s Lake Washington = success story from
eutrophication when sewage was diverted into Puget
Sound
TYPES AND EFFECTS OF WATER
POLLUTION
TYPES AND EFFECTS OF WATER
POLLUTION
• Infectious Agents
– Main source of waterborne pathogens is untreated and
improperly treated human waste.
• Animal wastes from feedlots and fields is also an important source
of pathogens.
– In developed countries, sewage treatment plants and pollutioncontrol devices have greatly reduced pathogens.
• Drinking water generally disinfected via chlorination.
– At least 2.5 billion people in less developed countries lack
adequate sanitation, and about half of these lack access to clean
drinking water.
Oxygen-Demanding Wastes
• Water with an oxygen content > 6 ppm will support desirable
aquatic life.
• Water with < 2 ppm oxygen will support mainly detritivores and
decomposers.
• Oxygen is added to water by diffusion from wind and waves, and by
photosynthesis from green plants, algae, and cyanobacteria.
• Oxygen is removed from water by respiration and oxygenconsuming processes.
• Biochemical Oxygen Demand - Amount of dissolved oxygen
consumed by aquatic microorganisms.
• Dissolved Oxygen Content - Measure of dissolved oxygen in the
water.
• Effects of oxygen-demanding wastes on rivers depend on volume,
flow, and temperature of river water.
• Oxygen Sag - Oxygen levels decline downstream from a pollution
Oxygen Sag
Plant Nutrients and Cultural
Eutrophication
• Oligotrophic - Bodies of water that have
clear water and low biological productivity.
• Eutrophic - Bodies of water that are rich in
organisms and organic material.
– Eutrophication - Process of increasing nutrient
levels and biological productivity.
• Cultural Eutrophication - Increase in biological
productivity and ecosystem succession caused by
human activities.
Inorganic Pollutants
• Metals
– Many metals such as mercury, lead, cadmium, and nickel are highly
toxic.
• Highly persistent and tend to bioaccumulate in food chains.
– Lead pipes are a serious source of drinking water pollution.
– Mine drainage and leaching are serious sources of environmental contamination.
• Nonmetallic Salts
– Many salts that are non-toxic at low concentrations can be mobilized by
irrigation and concentrated by evaporation, reaching levels toxic to
plants and animals.
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• Leaching of road salts has had detrimental effect on many ecosystems.
Acids and Bases
– Often released as by-products of industrial processes.
Organic Chemicals
• Thousands of natural and synthetic
organic chemicals are used to make
pesticides, plastics, pharmaceuticals,
pigments, etc.
• Two most important sources of toxic
organic chemicals in water are:
– Improper disposal of industrial and household
wastes.
– Runoff of pesticides from high-use areas.
• Fields, roadsides, golf courses
• Human activities have
Sediment
© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Shoreline Erosion
accelerated erosion rates
in many areas.
– Human-induced erosion and
runoff contribute about 75
billion metric tons of
suspended solids to world
surfaces each year.
• Sediment can either be
beneficial (nourish
floodplains) or harmful
(smother aquatic life).
From MM S Today 3(4) 1993, Minerals Management Service, U.S. Department of Interior.
Pollution
• Thermal
Raising or lowering
water temperatures from normal levels
can adversely affect water quality and aquatic life.
– Oxygen solubility in water decreases as temperatures increase.
• Species requiring high oxygen levels are adversely affected by warming
water.
• Industrial cooling processes often use heat-exchangers to
extract excess heat, and then discharge heated water back
into original source.
– Thermal Plume
• Produce artificial environments which attract many forms of wildlife.
– Can lead to large die-offs if plume disappears for extended period of time.
WATER QUALITY TODAY
• Areas of Progress
– Clean Water Act (1972) established a National
Pollution Discharge System which requires a
permit for any entity dumping wastes in
surface waters.
• In 1999, EPA reported 91.4% of all monitored river
miles and 87.5% of all accessed lake acres are
suitable for their designated uses.
– Most progress due to municipal sewage treatment
facilities.
Water Quality Today
Areas of Progress
• In 1998, EPA switched regulatory
approaches. Rather than issue standards
on a site by site approach, the focus is
now on watershed-level monitoring and
protection.
– States are required to identify waters not
meeting water quality goals and develop total
maximum daily loads for each pollutant and
each listed water body.
Remaining Problems
• Greatest impediments to achieving
national goals in water quality are
sediment, nutrients, and pathogens,
especially from non-point discharges.
– About three-quarters of water pollution in the
US comes from soil erosion, air pollution
fallout, and agricultural and urban runoff.
• Single cow produces 30 kg manure/day.
– Some feedlots have 100,000 animals.
Remaining Problems –
US Impaired River Miles
Surface Waters in Other
Countries
• Sewage treatment in wealthier countries
of Europe generally equal or surpass the
US.
• In Russia, only about half of the tap water
supply is safe to drink.
• In urban areas of South America, Africa,
and Asia, 95% of all sewage is discharged
untreated into rivers.
• Two-thirds of India’s surface waters are
Groundwater and Drinking
Water
• About half the US population, and 95% of rural
residents, depend on underground aquifers for drinking
water.
– For decades, groundwater was assumed impervious to pollution
and was considered the gold standard for water quality.
• Estimated 1.5 million Americans fall ill from fecal contamination
annually.
• EPA estimates 4.5 trillion liters of contaminated water
seep into the ground in the US every day.
– MTBE - Gasoline additive, and suspected carcinogen, is present
in many urban aquifers.
– In agricultural areas, fertilizers and pesticides commonly
contaminate aquifers and wells.
Groundwater Pollution
• Ocean
Estimated 6Pollution
million metric tons of plastic bottles, packaging
material, and other litter tossed from ships into the ocean
annually.
– Few coastlines in the world remain uncontaminated by oil or oil
products.
WATER POLLUTION CONTROL
• Source Reduction
– Cheapest and most effective way to reduce
pollution is avoid producing it or releasing it
into the environment.
• Studies show as much as 90% less road salt can
be used without significantly affecting winter road
safety.
• Soil Conservation
• Banning phosphate detergents
WATER POLLUTION CONTROL
Dioxin concentration in herring gull eggs on Scotch
Bonnet Island In Lake Ontario
Human Waste Disposal
• More than 500 pathogenic bacteria,
viruses, and parasites can travel from
human or animal excrement through
water.
• Natural Processes
– In many areas, outdoor urination and
defecation is the norm.
• When population densities are low, natural
processes can quickly eliminate waste.
Municipal Sewage Treatment
• Primary Treatment - Physical separation of large solids from the waste
stream.
• Secondary Treatment - Biological degradation of dissolved organic
compounds.
– Effluent from primary treatment transferred into trickling bed, or aeration tank
• Effluent from secondary treatment is usually disinfected (chlorinated) before release
into nearby waterway.
• Tertiary Treatment - Removal of plant nutrients (nitrates and phosphates)
from secondary effluent.
– Chemicals, or natural wetlands.
• In many US cities, sanitary sewers are connected to storm sewers.
– Heavy storms can overload the system, causing by-pass dumping of raw
sewage and toxic runoff directly into watercourses.
Municipal Sewage Treatment
Water Remediation
• Containment methods confine liquid
wastes in place, or cap surface with
impermeable layer to divert water away
from the site.
• Extraction techniques are used to pump
out polluted water for treatment.
– Oxidation, reduction, neutralization, or
precipitation.
• Living organisms can also be used
WATER LEGISLATION
• Clean Water Act (1972)
– Goal was to return all US surface waters to
“fishable and swimmable” conditions.
• For Point Sources, Discharge Permits and Best
Practicable Control Technology are required.
– Set zero discharge for 126 priority toxic pollutants.
Clean Water Act (1972)
• Areas of Contention
– Draining or Filling of Wetlands
• Many consider this taking of private land.
– Un-funded Mandates
• State or local governments must spend monies not
repaid by Congress.
Other Water Legislation
• Safe Drinking Water Act
• CERCLA (1980)
– SARA (1984)
• Great Lakes Water Quality Agreement (1972)
• London Dumping Convention (1990)
• BUT: Laws are only as good as:
– To the degree they are not weakened.
– To the degree they are funded.
Units for Measuring Water Quality
PARTS PER MILLION
Most dissolved substances
found in water are measured
in parts per million (ppm) or
even smaller amounts. This
means that for every one
million parts (units) of water
there is a certain number of
parts of the substance.
It is also expressed as milligrams
per liter. There are 1000 milliliters
in a liter and 1000 milligrams in a
gram. For example, a dissolved
oxygen reading of 8 ppm means
there are 8 milligrams of oxygen
for every 1000 milliliters of water.
8/1000 gram  1000 milliliters =
8/1,000,000 (8 parts per million)
Concentrations of certain
substances are also measured
in parts per billion, parts per
trillion and so on. These are
very small amounts but certain
substances can be harmful
even at these very low
concentrations.
Water Quality Indicators
We will now take
a look at the
water quality
indicators.
ALKALINITY
Alkalinity refers to the water’s
ability to neutralize acids.
Alkalinity is
produced by
minerals such as
limestone.
Limestone is a type of ocean
sediment composed of calcium
carbonate.
Limestone bedrock areas often
have caves and sinkholes, known
as Karst.
Water with low
alkalinity is
usually acidic.
Ammonia
Ammonia is produced by the decay
of organic matter and animal
waste.
Ammonia is toxic to most aquatic
life, especially at high pH.
Bacteria readily convert ammonia
to nitrate.
(a plant nutrient)
Ammonia
Ammonia is a
form of
nitrogen and
part of the
Nitrogen
Cycle.
BACTERIA
Most bacteria are important in
nutrient and other organic cycles.
Excess nutrients
cause algal blooms.
As algae die and
decay, the high
bacterial load
rapidly consumes
dissolved oxygen.
Certain types of bacteria
indicate animal and human
waste pollution.
Escherichia coli are coliform
bacteria found in the intestines
of warm-blooded organisms.
Most strains are harmless but
one E. coli strain can cause
severe diarrhea and kidney
damage.
DISSOLVED OXYGEN
Dissolved oxygen
is a product of
photosynthesis
and diffusion.
The warmer the water, the less
oxygen it can hold.
DISSOLVED OXYGEN
Most organisms
need at least 5 or
6 ppm of oxygen
in order to
survive.
Even cold water rarely contains
more than 15 ppm. Summer is
often a time of oxygen stress for
aquatic organisms.
CONDUCTIVITY
Conductivity measures the water’s
ability to conduct an electrical
current.
Pure water is a poor
conductor.
CONDUCTIVITY
The addition of dissolved
solids, especially salts,
increases the conductivity of
water.
Electrical current is measured
using a conductivity meter.
HARDNESS
Hardness refers to the
concentration of calcium and
magnesium in water.
Hard water has high
concentrations of these elements.
Soft water has low concentrations.
Water hardness often originates
from limestone.
HARDNESS
Area of the U.S. with limestone
bedrock have hard water.
Hard
Water
NITRATE
Nitrate is a primary
plant nutrient.
Nitrate is water
soluble and moves
easily from surface
to groundwater.
Excess nitrate causes algal
blooms that reduce water quality.
Under normal conditions, the
nitrogen cycle keeps the amount of
available nitrogen in balance with
the demands. However, excessive
use of fertilizers and nutrient rich
sewage release have created a
surplus of nitrate. The result is
eutrophication from excess algae
and bacteria with reduced dissolved
oxygen.
PESTICIDES
These chemicals are very
complex.
Effects on aquatic
organisms – Moderately
to highly toxic to
mammals, molluscs,
aquatic insects,
amphibians and fish.
pH
pH is the measure of the hydrogen
ion (H+) concentration.
The pH scale is zero to 14. Seven
is neutral, below seven is acidic,
and above seven is basic (or
alkaline).
Most aquatic organisms exist
within a pH range of 5.5 to 9.5.
Carbon dioxide reacts with water to
form a weak acid called carbonic acid.
pH tolerance
for most
aquatic life
Phosphate
Phosphate’s concentrations
in clean water is generally
low; however, phosphorus is
used extensively in fertilizer
and other chemicals.
Phosphate
The primary sources of
phosphates to surface water
are detergents, fertilizers,
and natural mineral
deposits.
Phosphate
High levels of phosphate
can over stimulate the
growth of aquatic plants
and algae.
This in turn, will cause high
DO consumption and death
to fish and many aquatic
organisms.
Salinity
Salinity refers to the salt
concentration in water,
mostly sodium chloride.
Salinity is historically
measured in parts
per thousand (ppt)
or grams per liter.
Salinity
Saltwater can cause problems when
it replaces fresh groundwater near
the coastal areas.
Sediment
Erosion causes
loose soil to
enter the
waterways
Sediment
Suspended sediment blocks
sunlight to plants and reduces
dissolved oxygen.
As sediments settle, they can
smother bottom (benthic)
organisms.
TEMPERATURE
Temperature is measured in
Fahrenheit and Celsius degrees.
Temperature can be measured
using field thermometers but
digital probes are much more
accurate.
Most aquatic organisms live
within a temperature range of
+32º F (+0º C) to 90º F (32º C).
Rapid temperature change and
temperature extremes can stress
aquatic organisms.
Temperature affects the oxygencarrying capacity of water.
14
Dissolved Oxygen (ppm)
12
10
8
6
4
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Winter
Summer
As the water warms, the
amount of dissolved
oxygen decreases.
TOTAL DISSOLVED SOLIDS (TDS)
TDS is the measure of the
material dissolved in water.
This measure is related to
hardness, salinity and
conductivity.
Hard water has more TDS than
soft water.
TOTAL SUSPENDED SOLIDS
(TSS)
TSS is the measure of the
sediment suspended in the
water.
TSS is related to turbidity.
Water with high TSS usually has
high Total Dissolved Solids (TDS)
as well.
TURBIDITY
Turbidity refers
to water clarity.
Sediments
suspended in
the water
increase
turbidity.
A secchi disk is one type of
instrument used to measure
turbidity.
TOXIC CHEMICALS
Toxic chemicals usually come
from industry and energy
production.
The effects are often not known
until years after they have entered
the environment.
Toxic chemicals include heavy
metals (lead, mercury),
organic compounds (DDT,
PCB), inorganic substances
(arsenic) and others.