Water PollutionWater Pollution

WATER POLLUTION: SOURCES, WATER POLLUTION: SOURCES, TYPES, AND EFFECTSTYPES, AND EFFECTS

Water pollutionWater pollution is any chemical, biological, is any chemical, biological, or physical change in water quality that has a or physical change in water quality that has a harmful effect on living organisms or makes harmful effect on living organisms or makes water unsuitable for desired uses.water unsuitable for desired uses. Point sourcePoint source: specific location (drain pipes, : specific location (drain pipes,

ditches, sewer lines).ditches, sewer lines). Nonpoint sourceNonpoint source: cannot be traced to a single : cannot be traced to a single

site of discharge (#1:agricultural / #2: industrial / site of discharge (#1:agricultural / #2: industrial / #3: residential runoff) #3: residential runoff)

Effects of PollutantsEffects of Pollutants

Water Pollutants can:Water Pollutants can: Cause disease (Cause disease (Biological Pollutants)Biological Pollutants) Deplete oxygen needed by aquatic organism, Deplete oxygen needed by aquatic organism,

(Animal Waste)(Animal Waste) Cause excessive algae growth Cause excessive algae growth (Plant Nutrients)(Plant Nutrients) Add toxins to aquatic systems Add toxins to aquatic systems (Chemical (Chemical

Pollution) Pollution) Disrupt photosynthesis Disrupt photosynthesis (Sediments)(Sediments)

POLLUTION OF FRESHWATER POLLUTION OF FRESHWATER STREAMS AND LAKESSTREAMS AND LAKES

Most developed countries have sharply Most developed countries have sharply reduced point-source pollution but toxic reduced point-source pollution but toxic chemicals and pollution from nonpoint chemicals and pollution from nonpoint sources are still a problem.sources are still a problem.

Stream pollution from discharges of Stream pollution from discharges of untreated sewage and industrial wastes is a untreated sewage and industrial wastes is a major problem in developing countries.major problem in developing countries.

Global Outlook: Stream Pollution in Global Outlook: Stream Pollution in Developing CountriesDeveloping Countries

Water in many of Water in many of central China's rivers central China's rivers are greenish black are greenish black from uncontrolled from uncontrolled pollution by pollution by thousands of thousands of factories.factories.

Figure 21-5Figure 21-5

Case Study: India’s Ganges River: Case Study: India’s Ganges River: Religion, Poverty, and HealthReligion, Poverty, and Health

Religious beliefs, cultural traditions, poverty, Religious beliefs, cultural traditions, poverty, and a large population interact to cause severe and a large population interact to cause severe pollution of the Ganges River in India.pollution of the Ganges River in India. Very little of the sewage is treated.Very little of the sewage is treated. Hindu believe in cremating the dead to free the Hindu believe in cremating the dead to free the

soul and throwing the ashes in the holy Ganges.soul and throwing the ashes in the holy Ganges.• Some are too poor to afford the wood to fully cremate.Some are too poor to afford the wood to fully cremate.• Decomposing bodies promote disease and depletes DO.Decomposing bodies promote disease and depletes DO.

Case Study: India’s Ganges River: Case Study: India’s Ganges River: Religion, Poverty, and HealthReligion, Poverty, and Health

Daily, more than 1 Daily, more than 1 million Hindus in million Hindus in India bathe, drink India bathe, drink from, or carry out from, or carry out religious religious ceremonies in the ceremonies in the highly polluted highly polluted Ganges River.Ganges River.

Figure 21-6Figure 21-6

POLLUTION OF FRESHWATER POLLUTION OF FRESHWATER STREAMSSTREAMS

Flowing streams can recover from a Flowing streams can recover from a moderate level of degradable water moderate level of degradable water pollutants if they are not overloaded and their pollutants if they are not overloaded and their flows are not reduced.flows are not reduced. The amount of oxygen required by organisms is The amount of oxygen required by organisms is

known as Biological oxygen demand.(BOD)known as Biological oxygen demand.(BOD) In a flowing stream, the breakdown of degradable In a flowing stream, the breakdown of degradable

wastes by bacteria depletes DO and creates and wastes by bacteria depletes DO and creates and oxygen sag curveoxygen sag curve..• This reduces or eliminates populations of organisms This reduces or eliminates populations of organisms

with high oxygen requirements.with high oxygen requirements.

Water Pollution Problems in StreamsWater Pollution Problems in Streams

Dilution and decay of degradable, oxygen-Dilution and decay of degradable, oxygen-demanding wastes and heat in a stream.demanding wastes and heat in a stream.

Figure 21-4Figure 21-4

POLLUTION OF POLLUTION OF FRESHWATER LAKESFRESHWATER LAKES

Dilution of pollutants in lakes is less effective Dilution of pollutants in lakes is less effective than in most streams because most lake than in most streams because most lake water is not mixed well and has little flow.water is not mixed well and has little flow. Lakes and reservoirs are often stratified and Lakes and reservoirs are often stratified and

undergo little mixing.undergo little mixing. Low flow makes them susceptible to runoff.Low flow makes them susceptible to runoff.

Cultural EutrophicationCultural Eutrophication Cultural eutrophicationCultural eutrophication: human activities : human activities

accelerate the input of plant nutrients (mostly accelerate the input of plant nutrients (mostly nitrate- and phosphate-containing effluents) nitrate- and phosphate-containing effluents) to a lake.to a lake. 85% of large lakes85% of large lakes

near major near major population centerspopulation centers in the U.S. have in the U.S. have some degree of some degree of cultural eutrophication.cultural eutrophication.

OCEAN POLLUTIONOCEAN POLLUTION Oceans, if they are not overloaded, can Oceans, if they are not overloaded, can

disperse and break down large quantities of disperse and break down large quantities of degradable pollutants.degradable pollutants.

OCEAN POLLUTIONOCEAN POLLUTION Pollution of coastal waters near heavily Pollution of coastal waters near heavily

populated areas is a serious problem.populated areas is a serious problem. About 40% of the world’s population lives near on or About 40% of the world’s population lives near on or

near the coast.near the coast. The EPA has classified 4 of 5 estuaries as The EPA has classified 4 of 5 estuaries as

threatened or impaired.threatened or impaired. Oceans are impacted by:Oceans are impacted by:

Sewage DumpingSewage Dumping Agricultural RunnoffAgricultural Runnoff Garbage DumpingGarbage Dumping Toxic WasteToxic Waste Oil Oil

http://www.ted.com/talks/capt_charles_moore_on_the_seas_of_plastic.html

OCEAN POLLUTIONOCEAN POLLUTION

Harmful algal blooms (HAB) are caused by Harmful algal blooms (HAB) are caused by explosive growth of harmful algae from explosive growth of harmful algae from sewage and agricultural runoff.sewage and agricultural runoff.

Figure 21-11Figure 21-11

Oxygen Depletion in the Northern Oxygen Depletion in the Northern Gulf of MexicoGulf of Mexico

A large zone of A large zone of oxygen-oxygen-depleted water depleted water forms for half of forms for half of the year in the the year in the Gulf of Mexico Gulf of Mexico as a result of as a result of HAB.HAB.

Figure 21-AFigure 21-A

OCEAN OIL POLLUTIONOCEAN OIL POLLUTION While Oil Spills have devastating effects, While Oil Spills have devastating effects,

most ocean oil pollution comes from human most ocean oil pollution comes from human activities on activities on landland..

Studies have shown it takes about 3 years for many forms of marine life to recover from large amounts of crude oil (oil directly from ground).

Recovery from exposure to refined oil (fuel oil, gasoline, etc…) can take 10-20 years for marine life to recover.

POLLUTION OF GROUNDWATERPOLLUTION OF GROUNDWATER Groundwater can become contaminated with Groundwater can become contaminated with

a variety of chemicals because it cannot a variety of chemicals because it cannot effectively cleanse itself and dilute and effectively cleanse itself and dilute and disperse pollutants.disperse pollutants.

It can take hundreds to thousand of years for It can take hundreds to thousand of years for contaminated groundwater to cleanse itself of contaminated groundwater to cleanse itself of degradable wastesdegradable wastes.. Nondegradable wastesNondegradable wastes (toxic lead, arsenic, (toxic lead, arsenic,

flouride) are there permanently.flouride) are there permanently.

POLLUTION OF GROUNDWATERPOLLUTION OF GROUNDWATER Leaky landfills, waste lagoons, and Leaky landfills, waste lagoons, and

underground storage tanks can introduce underground storage tanks can introduce contaminants into aquiferscontaminants into aquifers According the the EPA, one or more organic According the the EPA, one or more organic

chemicals contaminate about 45% of chemicals contaminate about 45% of municipalmunicipal groundwater supplies.groundwater supplies.

Most groundwater contamination occurs in Most groundwater contamination occurs in shallow unconfined aquifers located near a shallow unconfined aquifers located near a contaminant sourcecontaminant source

Groundwater PollutionGroundwater Pollution

Groundwater pollution may go un-noticed for Groundwater pollution may go un-noticed for a long time because ground water moves so a long time because ground water moves so slowly.slowly.

The cloud of contaminated ground water that The cloud of contaminated ground water that moves away from the source is called a moves away from the source is called a contaminant plume.contaminant plume.

Fig. 21-8, p. 502

Aquifer

Water well

Migrating vapor phase

Contaminant plume moveswith the groundwater

Free gasolinedissolves ingroundwater(dissolved phase)

Groundwaterflow

Watertable

Gasolineleakage plume(liquid phase)

Leakingtank

Bedrock

El Toro Marine Base: CaliforniaEl Toro Marine Base: California

Raytheon Raytheon Chemical Chemical Plant St. Plant St.

Petersburg Petersburg FloridaFlorida

PREVENTING AND REDUCING PREVENTING AND REDUCING WATER POLLUTIONWATER POLLUTION

The key to reducing pollution is to prevent it The key to reducing pollution is to prevent it from reaching bodies of water.from reaching bodies of water. Farmers can reduce runoff by planting buffers Farmers can reduce runoff by planting buffers

and locating feedlots away from steeply sloped and locating feedlots away from steeply sloped land, flood zones, and surface water.land, flood zones, and surface water.

Use substitute chemicalsUse substitute chemicals Monitor Landfills and underground tanksMonitor Landfills and underground tanks Store harmful chemicals above groundStore harmful chemicals above ground

PREVENTING AND REDUCING PREVENTING AND REDUCING WATER POLLUTIONWATER POLLUTION

Most developed countries use laws to set Most developed countries use laws to set water pollution standards, but such laws water pollution standards, but such laws rarely exist in developing countries.rarely exist in developing countries. The U.S. Clean Water Act sets standards fro The U.S. Clean Water Act sets standards fro

allowed levels of key water pollutants and allowed levels of key water pollutants and requires polluters to get permits.requires polluters to get permits.

EPA is experimenting with a EPA is experimenting with a discharge trading discharge trading policypolicy similar to that for air pollution control. similar to that for air pollution control.