Transcript Chapter 20 Water Pollution

Chapter 20 - Water
Pollution
03/28/10
WATER POLLUTION
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IN THE EARLY 1800'S, IT WAS
NOT UNCOMMON FOR
GARBAGE TO BE DUMPED INTO
THE NEAREST RIVER OR LAKE.
SUCH DUMPING ALONG WITH A
COMPLETE LACK OF SANITARY
PRACTICES FREQUENTLY LED
TO EPIDEMICS OF
WATERBORNE DISEASES.
BY THE TURN OF THE CENTURY
EFFORTS WERE MADE TO
CONTROL THESE EPIDEMICS BY
FILTERING PUBLIC WATER
SUPPLIES. BY 1908, CHLORINE
WAS ADDED TO MUNICIPAL
WATER BEFORE IT ENTERED
THE WATER MAINS.
BY THE 1960'S
WATERBORNE DISEASES
HAD BECOME RELATIVELY
RARE IN THE USA.
ALTHOUGH THEY STILL
PLAGUE MANY LESS
DEVELOPED COUNTRIES.
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INFECTIOUS AGENTS:
WATER TRANSMITS DISEASE WHEN
IT CONTAIN WATERBORNE
PATHOGENS OR DISEASE
PRODUCING ORGANISMS. THOSE
PATHOGENS, WHICH CAN BE
VIRUSES, BACTERIA, PROTOZOA
OR PARASITIC WORMS, CAN CAUSE
DISEASES AS DYSENTERY, TYPHOID
FEVER AND CHOLERA.
INFECTION CAN BE SPREAD
DIRECTLY AS A RESULT OF
DRINKING OR SWIMMING IN
CONTAMINATED WATER OR
INDIRECTLY AS A RESULT OF
EATING FOOD THAT HAS BEEN
CONTAMINATED TROUGH FOOD
WEBS.
DETECTING THE PRESENCE OF
SPECIFIC PATHOGENS IS TIME
CONSUMING, COSTLY AND A
DIFFICULT PROCESS. WATER
THEREFORE, IS ANALYZED BY A
READILY IDENTIFIABLE GROUP
OF MICROORGANISMS CALLED
COLIFORM BACTERIA.
THESE ORGANISMS ARE
NORMALLY PRESENT IN THE
INTESTINAL TRACT OF
HUMANS AND ANIMALS,
LARGE NUMBERS OF
COLIFORM BACTERIA IN A
WATER SAMPLE INDICATE
RECENT CONTAMINATION BY
UNTREATED FECES.
COLIFORM BACTERIA EXCEEDING
2.2 ORGANISMS PER 100
MILLILITERS OF DRINKING
WATER REQUIRE MUNICIPALITY
TO EITHER CHLORINATE THE
WATER OR SEEK ALTERNATIVE
SOURCES OF WATER.
RECREATIONAL WATER HAS AN
UPPER LIMIT OF 200 COLIFORM
BACTERIA PER 100 MILLILITERS
OF WATER.
CHLORINATION OF PUBLIC
WATER SUPPLIES HAS
VIRTUALLY ELIMINATED
EPIDEMICS OF OFTEN
FATAL WATERBORNE
DISEASES IN DEVELOPED
COUNTRIES
AS BIOLOGICAL POLLUTION IN THE
FORM OF WATERBORNE DISEASES IN
THE DEVELOPED WORLD HAS
DIMINISHED, CHEMICAL POLLUTION
HAS INCREASED.
TODAY OUR WATER RESOURCES ARE
BEING ASSAULTED BY SUCH
CHEMICALS AS COMMERCIAL
FERTILIZERS, PESTICIDES,
DETERGENTS, TRACE QUANTITIES
OF METALS, ACIDIC MINE WASTE,
RADIOACTIVE SUBSTANCES, AND A
WIDE VARIETY OF INDUSTRIAL
CHEMICALS.
TODAY THERE IS GROWING
CONCERN THAT CHEMICAL
POLLUTANTS IN WATER MAY
BE CONTAMINATING OUR
FOOD AND DISRUPTING
AQUATIC ECOSYSTEMS BY
HINDERING THE LIFE CYCLE
OF AQUATIC ORGANISMS.
MOST WATER-POLLUTION
PROBLEMS STEM FROM LANDBASED ACTIVITIES WITHIN
DRAINAGE BASINS RATHER
THAN FROM WATER BASED
ACTIVITIES SUCH AS SHIPPING,
BOATING AND SWIMMING.
NATURAL POLLUTANTS:
NATURAL AREAS, SUCH AS
FORESTS, MARSHES, AND
GRASSLANDS, GENERALLY
CONTRIBUTE SMALL
AMOUNTS OF MATERIALS
TO WATERWAYS.
MANMADE POLLUTANTS:
AGRICULTURAL AREAS DEGRADE
WATER QUALITY IN SEVERAL WAYS:
EXCESSIVE SOIL EROSION WILL
INCREASE THE LOAD OF
SEDIMENTS. PESTICIDES,
FERTILIZERS AND ANIMAL WASTES
THAT ARE WASHED FROM FIELDS
AND ORCHARDS WILL RUN OFF INTO
STREAMS OR SEEP INTO THE
GROUNDWATER.
POINT AND
NONPOINT SOURCES
OF POLLUTION
POINT SOURCE
POLLUTION:
A CONCENTRATED SOURCE
OF WATER POLLUTION DUE
TO A DRAINPIPE FORM A
SEWAGE TREATMENT
PLANT OR INDUSTRIAL
SITE.
NON POINT SOURCES: A
DIFFUSED SOURCE OF
WATER POLLUTION DUE TO
AGRICULTURAL
APPLICATIONS. NON POINT
SOURCES ARE LOW
CONCENTRATIONS BUT
HIGH VOLUME
DISCHARGES.
Nonpoint Sediment from
Unprotected Farmland Flows into
Streams
NONPOINT SOURCES
Rural homes
Cropland
Urban streets
Animal feedlot
Suburban
development
POINT
SOURCES
Wastewater
treatment
plant
Factory
SEWER SYSTEM
DESIGN
STORM SEWER:
IN CITIES BUILDINGS AND PAVED
AREAS RENDER A LARGE PART OF
THE URBAN SURFACE
IMPERMEABLE TO RAINWATER
AND SNOWMELT. TO PREVENT
FLOODING LARGE STORM
SEWERS PIPES ARE USED TO
CHANNEL WATER RUNOFF TO
NEAREST RIVER, LAKE OR
OCEAN.
SANITARY SEWER:
A SECOND SMALLER SYSTEM OF
SEWERS PIPES CALLED A
SANITARY SEWER SYSTEM
CARRIES WASTES OR EFFLUENTS,
FROM HOMES AND COMMERCIAL
AREAS TO TREATMENT PLANTS.
IF THESE TWO SEWER
SYSTEMS ARE COMBINED
INTO ONE SYSTEM THIS TYPE
OF SYSTEM IS CALLED A
COMBINED SEWER SYSTEM.
OXYGEN-DEMANDING WASTES
MOST AQUATIC ORGANISMS
ACQUIRE THEIR OXYGEN FROM THE
SUPPLY THAT IS DISSOLVED IN THE
WATER. THE SUPPLY OF AQUATIC
OXYGEN CAN QUICKLY DIMINISH
WHEN ORGANIC WASTES
DECOMPOSE IN THE WATER.
OXYGEN IN WATER IS
DEPENDENT ON THE
PROCESSES THAT ADD
OXYGEN - TURBULENCE AND
PHOTOSYNTHESIS AND THOSE
THAT REMOVE OXYGEN RESPIRATION BY AQUATIC
ORGANISM
WHEN ORGANIC MATERIALS ARE
ADDED TO WATER A PROLIFERATION
OF OXYGEN CONSUMING
DECOMPOSERS MAINLY BACTERIA
AND FUNGI ARE ENCOURAGED.
THESE ORGANISMS REDUCE THE
OXYGEN SUPPLY AND DEPRIVE
OTHER AQUATIC ORGANISM LIKE
FISH OF OXYGEN.
UNDER NORMAL CONDITIONS THE
QUANTITY OF ORGANIC MATERIAL
IS SMALL AND THE AMOUNT OF
OXYGEN THAT IT UTILIZES IS
LIMITED. THE CONCENTRATION OF
DISSOLVED OXYGEN REMAINS
RELATIVELY CONSTANT AND AT A
LEVEL THAT IS HIGHER THAN 5
PPM
THIS LEVEL IS USUALLY
CONSIDERED TO BE CRITICAL FOR
THE SURVIVAL OF MOST FISH.
MOST WATER BODIES CAN
REMOVE NATURAL ORGANIC
WASTES WITHOUT DEPLETING
THE DISSOLVED OXYGEN LOWER
THAN 5 PPM (LAKE AND RIVERS
CAN NATURALLY CLEANSE
THEMSELVES).
THE AMOUNT OF DISSOLVED
OXYGEN THAT IS NEEDED TO
DECOMPOSERS TO BREAK
DOWN ORGANIC MATERIALS IN
A GIVEN VOLUME OF WATER IS
CALLED THE BIOCHEMICAL
OXYGEN DEMAND (BOD). BOD IS
A MEASURE OF THE LEVEL OF
ORGANIC CONTAMINATION IN
WASTEWATER.
SEWAGE-LADEN
WASTEWATER THAT ENTERS
A SANITARY SEWER SYSTEM
HAS AN AVERAGE BOD LEVEL
OF 250 PPM, BUT MOST
BODIES OF WATER LAKES
AND RIVERS ARE INITIALLY
LIKELY TO CONTAIN ONLY
ABOUT 8 PPM OF OXYGEN.
WHEN THIS SEWAGE
WASTEWATER IS ADDED TO
LAKE OR RIVER WATER,
THE LEVELS OF DISSOLVED
OXYGEN AT THE
DISCHARGE POINT IS
QUICKLY DEPLETED BY
MICROBIAL ORGANISMS,
WHICH BEGIN TO
DECOMPOSE THE WASTE.
THE DAILY WASTES OF JUST
ONE PERSON REQUIRES THE
DISSOLVED OXYGEN OF 2200
GALLONS OF WATER IF NO
OXYGEN WERE ADDED TO
IT.
WHEN EFFLUENTS THAT HAVE
HIGH LEVEL OF BOD ARE
RELEASED INTO A STREAM
OXYGEN LEVELS
DOWNSTREAM FOLLOW A
CHARACTERISTIC PATTERN
CALL AN OXYGEN SAG CURVE
animations\Water\river_pollution.swf
ORGANIC WASTE
DISCHARGES HAVE THEIR
GREATEST IMPACT ON
AQUATIC LIFE DURING
WARM SUMMER MONTHS,
WHEN THE STREAM FLOW
IS LOW AND LESS
DISSOLVED OXYGEN IS
PRESENT
IF A COMPLETE LOSS OF
OXYGEN OCCURS IN A BODY OF
WATER A CHANGE IN THE TYPE
OF DECOMPOSER BACTERIA
ALSO OCCUR - FROM AEROBIC
DECOMPOSERS (THOSE THAT
USE OXYGEN) TO ANAEROBIC
DECOMPSERS (THOSE THAT DO
NOT NEED OXYGEN).
AEROBIC DECOMPOSERS PRODUCE
MAINLY CARBON DIOXIDE, WATER,
NITRATE AND SULFATE THAT ARE
NOT USUALLY HARMFUL.
ANAEROBIC DECOMPOSERS
PRODUCE METHANE, AMMONIA
AND HYDROGEN SULFIDE. UNDER
ANAEROBIC CONDITIONS WATER
BECOMES A TURBID, DECAYING
MESS WITH BUBBLING METHANE
AND HYDROGEN SULFIDE.
Mississippi
River Basin
Ohio
River
Missouri
River
Mississippi
River
LOUISIANA
Mississippi
River
Depleted
Oxygen
Gulf of Mexico
Cooperstown
NEW YORK
PENNSYLVANIA
ATLANTIC
OCEAN
Harrisburg
NEW
JERSEY
MARYLAND
Baltimore
WEST
VIRGINIA
Washington
DELAWARE
Richmond
VIRGINIA
Drainage
basin
Norfolk
Chesapeake Bay
No oxygen
Low concentrations
of oxygen
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CULTURAL EUTROPHICATION
IF EXCESSIVE QUANTITIES OF PLANT
NUTRIENTS ARE DISCHARGED INTO A
LAKE, OCEAN BAY OR RIVER THE
NATURAL AGING PROCESSES OF
THOSE WATERWAYS ARE
ACCELERATED. IF THE
ACCELERATION IS FROM HUMAN
ACTIVITY THIS PROCESS IS CALLED
CULTURAL EUTROPHICATION.
CULTURAL EUTHROPHICATION
IS ONE OF THE MOST SERIOUS
PROBLEMS FACING MANY
BODIES OF WATER TODAY. IT
JEOPARDIZES THE USE OF
WATER FOR DRINKING,
RECREATION, SPORTS AND
COMMERCIAL FISHING,
AGRICULTURE AND INDUSTRY.
Discharge of untreated
municipal sewage
(nitrates and phosphates)
Discharge of
detergents
(phosphates)
Discharge of treated
municipal sewage
(primary and secondary
treatment: nitrates
and phosphates)
Dissolving of
nitrogen oxides
(from internal combustion
engines and furnaces)
Natural runoff
(nitrates and
phosphates)
Inorganic fertilizer runoff
(nitrates and phosphates)
Manure runoff
from feedlots
(nitrates, phosphates,
ammonia)
Lake ecosystem
nutrient overload
and breakdown of
chemical cycling
Runoff from streets,
lawns, and construction
lots (nitrates and
phosphates)
Runoff and erosion
(from cultivation,
mining, construction,
and poor land use
LIKE TERRESTRIAL PLANTS,
AQUATIC PLANTS REQUIRE
NITROGEN, PHOSPHORUS,
POTASSIUM AND OTHER
MINERALS NUTRIENTS. IN
AQUATIC SYSTEMS, THE TWO
NUTRIENTS THAT ARE MOST
COMMONLY ACT AS LIMITING
FACTORS ARE PHOSPHOROUS AND
NITROGEN IN THE FORM OF
EITHER NITRATE OR AMMONIA.
WHEN THESE LEVELS
NUTRIENTS INCREASE SOME
AQUATIC ORGANISM RESPOND
BY INCREASING IN NUMBER AND
SIZE. FOR EXAMPLE ALGAE
BLOOMS OCCUR WHEN
NUTRIENTS ARE EXCESSIVE IN
LAKES AND PONDS.
TOXIC SUBSTANCES:
AQUATIC ORGANISMS ARE
AFFECTED BY OXYGEN
CONSUMING POLLUTANTS AND
ADDED PLANT NUTRIENTS
BECAUSE THOSE SUBSTANCE
DIRECTLY OR INDIRECTLY ALTER
THE AMOUNTS OF OXYGEN
AVAILABLE TO THEM.
TOXIC SUBSTANCES, IN
CONTRAST, AFFECT
ORGANISMS ADVERSELY, AND
SOMETIMES FATALLY BECAUSE
THEY DISRUPT THE
METABOLISM OF THE
ORGANISMS AS A RESULT OF
INGESTION OR CONTACT.
OTHER WATER
POLLUTANTS
OIL POLLUTION:
OIL SPILLS KILL MOST OF
THE ORGANISMS THAT
BECOME COATED WITH OIL
AND CAN RESULT IN
CONTAMINATED WATER
FOR SEVERAL YEARS OR
LONGER.
SEDIMENT:
EROSION-CAUSED SEDIMENTS
FILL RESERVOIRS, LAKES,
HARBORS AND NAVIGATION
CHANNELS. SUSPENDED
SEDIMENTS IMPEDE
PHOTOSYNTHESIS AND CARRY
NUTRIENTS INTO BODIES OF
WATER.
THERMAL POLLUTION:
HEATED WATER DISCHARGES
MAY EXCEED THE
TEMPERATURE TOLERANCE
LIMITS OF MANY AQUATIC
ORGANISMS AND THE
WITHDRAWAL OF WATER FOR
COOLING PURPOSES MAY TRAP
AND KILL FISH.
Alaska
Hawaii
Arsenic level
(micrograms per liter)
> 50
10 - 50
Prevention
Cleanup
Reduce input of
toxic pollutants
Improve oil-spill
cleanup capabilities
Separate sewage
and storm lines
Require at least
secondary
treatment of coastal
sewage or use
wetlands, solaraquatic, or other
sewage treatment
methods
Ban ocean
dumping of sludge
and hazardous
dredged material
Protect sensitive
areas from
development, oil
drilling, and oil
shipping
Regulate coastal
development
Recycle used oil
Require double
hulls for oil tankers
Require improved
air pollution
cleanup to reduce
input from the
atmosphere
Solutions: methods for preventing and reducing
water pollution.
• Prevent groundwater contamination
• Greatly reduce nonpoint runoff
• Reuse treated wastewater for irrigation
• Find substitutes for toxic pollutants
• Work with nature to treat sewage
• Practice four R's of resource use (Refuse, Reduce,
Reuse, Recycle)
• Reduce resource waste
• Reduce air pollution
• Reduce poverty
• Reduce birth rates
• Not depleting aquifers
• Preserving ecological health of
aquatic systems
• Preserving water quality
• Integrated watershed management
• Agreements among regions and
countries sharing surface water
resources
• Outside party mediation of water
disputes between nations
• Marketing of water rights
• Wasting less water
• Decreasing government subsides
for supplying water
• Increasing government subsides
for reducing water waste
• Slowing population growth
WATER
TREATMENT
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