Water PollutionMiller Chapter 21

Water ResourcesWater is a “renewable” but finite

resourceClean water is essential to

human/animal health – humans can only live about 3 days without water

“Water Planet”About 70% of Earth’s surface is

water97.5% of that is ocean water2.5% is fresh water

1.5% is frozen in ice caps & glaciers0.5% is inaccessible/brackish

Only about 0.02% of the Earth’s water supply is available as liquid freshwater

Who is using Earth’s water resources?

What 2 conclusions

can you draw from this data?

Hydrological Cycle

Hydrological CycleTranspiration – from plantsEvaporation – from rivers, lakes,

ponds, oceansPrecipitation – rainRunoff – to rivers, lakes, etcInfiltration/Seepage – to aquifers,

groundwater, to rivers & oceans, to plants

Surface WaterSurface water is

water that is above ground in lakes, rivers, ponds, and streams

A watershed is the entire area of land that is drained by a river

Fig. 14-3, p. 308

Unconfined Aquifer Recharge Area

Precipitation Evaporation and transpirationEvaporation

Confined Recharge Area

Runoff

Flowing artesian well

Recharge Unconfined Aquifer

Stream Well requiring a pump

Infiltration Water table Lak

eInfiltrationUnconfined aquiferConfined aquiferConfining impermeable rock layer

Less permeable material such as clay

Groundwater and Aquifers

Groundwater – water that seeps down into the soil and is stored underground

Aquifers – large amounts of water in underground rock formationsEx. Edward’s Aquifer (TX)

AquifersAquifers are running low – people are

pumping too much out!It can take millions of years to formRecharge zone: area of land from

which groundwater originates

Freshwater Pollutionthe introduction of chemical,

physical, or biological material into water that degrades the quality of the water and affects the organisms that drink it and live in it.

Major Water Pollutants and Their Sources

Common Diseases Transmitted to Humans through Contaminated

Drinking Water

Point Pollutionpollution that is

discharged from a single source, such as a factory, a wastewater treatment plant, or an oil tanker

                                     

Point Pollution Fairly easy to

identify, regulate, and control

Ex: septic tanks, storage lagoons for polluted waste, landfills, underground gasoline storage tanks, wastewater treatment plants, industrial plants

Nonpoint PollutionPollution that comes from many

sourcesReaches bodies of water via

streets and sewersAccumulation of small amounts

of pollution adds up to huge problems

Hard to regulate and control – mostly public awareness is only help

Nonpoint PollutionEx: highway

construction and maintenance; oil, gasoline, dog feces, litter from storm drain runoff; pesticides and fertilizer; dry salt (for snow and ice on roads)

Major kinds of water pollution

Pathogens – disease causing organisms such as bacteria; caused by untreated human sewage entering water

Organic matter – biodegradable remains of animals and plants, including feces; mainly nonpoint sources

Water PollutionOrganic

chemicals – pesticides, fertilizers, plastics, detergents, gasoline and oil, and other fossil fuel materials (hydrocarbons); nonpoint pollution

Water PollutionInorganic

chemicals – acids, salts, toxic metals; point and nonpoint

Toxic chemicals – poisonous chemicals, incl. heavy metals (lead, mercury, cadmium); industrial and household chemicals

Water PollutionPhysical

agents – heat and suspended solids such as soil

Radioactive waste – from power plants or nuclear processing and defense facilities

Wastewater Treatment Plants

Pipes lead from residential and industrial areas to wastewater treatment plants for treatment before being returned to lakes and rivers

Not 100% effective, especially with industrial wastewater

Sludge – product of treatment – can be used as fertilizer or bricks

Primary Sewage Treatment

One settling tank

Secondary Sewage Treatment

Two settling tanks

Other Treatment Uses

Solutions: Primary and Secondary Sewage

Treatment

Solutions: Septic Tank System

PathogensDisease-causing

microorganismsEnter water

through untreated wastewater/animal feces

Cholera, hepatitis, typhoid

E. coli checked using “fecal coliform test”

BioaccumulationOr biomagnificationBuild up of toxic pesticides in

animals through the food chain

EutrophicationEutrophication – build-up of

abundance of nutrients in lakes and streams over time

uses up large amounts of oxygen dissolved in water

Artificial eutrophicationEutrophication caused by

humansNormal process which has been

acceleratedInorganic plant nutrients

(phosphorous and nitrogen) enter water through sewage and fertilizer runoff

EutrophicationPhosphorous –

contained in detergents, animal wastes

- causes excessive algal growth

Algae BloomsLarge mats of

algae which float on the water

As algae die and decompose, large amts of dissolved oxygen are used

Fish suffocate

Water Quality as Measured by Dissolved Oxygen Content in Parts per Million

Dilution and Decay of Degradable, Oxygen-Demanding Wastes in a Stream

Thermal PollutionExcessive amounts of heat

added to a body of waterFrom power plants and other

industries -use water as a cooling

system -hot water returned to

stream/river -can cause massive fish kills

(suffocate) -hot water does not hold as

much dissolved oxygen as cold water

Clean Water Act“to restore and maintain the

chemical, physical, and biological integrity of the nation’s waters”

To make all surface water clean enough for fishing and swimming

Groundwater PollutionPesticides, fertilizers, agricultural

chemicals that seep into groundwater

EPA has detected at least 200 hazardous chemicals that can seep through the soil and into groundwater

Porosity vs. Permeability

Principal Sources of Groundwater Contamination in the U.S.

Groundwater Contamination from a Leaking Gasoline Tank

Solutions: Groundwater Pollution, Prevention and Cleanup

Ocean Pollution

RunoffAt least 85% of ocean pollution

comes from the landRiver runoff

Dumped directly in the ocean

Sludge from wastewater treatment

Ships dump directly into ocean

Residential Areas, Factories, and Farms Contribute to Pollution of Coastal Waters

A Large Zone of Oxygen-Depleted Water in the Gulf of Mexico Due to Algal Blooms

Oil SpillsLarge

disasters: ex. Exxon Valdez - 1989 only about 5% of oil pollution

Most oil is from tankers slowly leaking (706 Million Gallons of oil per year!!!)100 Million in

the USOil spilled

when loading and offloading tankers

Offshore oil rigs

Plastic

Plastic fishing lines - strangulation, trapped animals

Clear plastic bags - block digestive systems in turtles

Six-pack rings - around necks

The North Pacific Gyre

The world’s largest “landfill”: 100 Million tons of floating plastic, stretching for 500 nautical miles!

PreventionMARPOL - International

Convention for the Prevention of Pollution From Ships

prohibits discharge of oil and plastics in oceans and coastal waters

Marine Protection, Research, and Sanctuaries Act - double hulls on tankers

Solutions: Coastal Water Pollution, Prevention and Cleanup

Ocean OwnershipJurisdiction problemsLaw of the Sea Treaty - 22 km

(12 nautical miles) = exclusive economic zone