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 LAND-

BASED 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

Urban streets

Suburban development

Wastewater treatment plant

Rural homes

Cropland

Factory

Animal feedlot

POINT SOURCES

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.

MississippiRiver Basin

MissouriRiver

OhioRiver

MississippiRiver

LOUISIANAMississippi

River

Depleted

Oxygen

Gulf of Mexico

Drainagebasin

No oxygen Low concentrationsof oxygen

PENNSYLVANIA

NEW YORK

WESTVIRGINIA

MARYLAND

DELAWARE

NEWJERSEY

ATLANTICOCEAN

VIRGINIA

Cooperstown

Harrisburg

Baltimore

Washington

Richmond

Norfolk Chesapeake Bay

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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 treatedmunicipal sewage

(primary and secondary treatment: nitrates and phosphates)

Dissolving ofnitrogen oxides

(from internal combustion engines and furnaces)

Lake ecosystemnutrient overload

and breakdown of chemical cycling

Discharge of detergents

(phosphates)

Natural runoff(nitrates and phosphates) Inorganic fertilizer runoff

(nitrates and phosphates)

Manure runoff from feedlots

(nitrates, phosphates, ammonia)

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

Reduce input of toxic pollutants

Separate sewage and storm lines

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

Cleanup

Improve oil-spill cleanup capabilities

Require at least secondary treatment of coastal sewage or use wetlands, solar-aquatic, or other sewage treatment methods

Require improved air pollution cleanup to reduce input from the atmosphere

• 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

Solutions: methods for preventing and reducing water pollution.

• 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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