powerpoint templatespage 1powerpoint templates chapter 5: water all is born of water, all is...

Powerpoint Templates Powerpoint Templates

Chapter 5: Water

“All is born of water, all is sustained by water.”

Johann Wolfgang von GoetheGerman Poet and Dramatist

Powerpoint Templates

5.1: Our Water Resources• Much of our water we drink today has been around

since water first formed on Earth millions of years ago• Clean, fresh water is essential to life and is critical to

human health • People can survive for more than a month without

food; can only life for a few days without water• People live longer today because we have clean

water (to drink, to bathe in, to wash with, to irrigate crops and to flush away sewage)

• Water is renewable; endlessly circulated through the water cycle


Water, Water Everywhere, but…

• Earth is called the water planet• About 70% of Earth’s surface is covered by

water• 97% of that water is salt water• 3% is fresh water; 77% of that is frozen in

the polar icecaps; leaving only a fraction of the freshwater for human use

• The water we require for our everyday needs (agriculture and drinking) comes from two sources: surface water and groundwater


Surface Water

• Most large cities depend on surface water (fresh water that is above ground in lakes, ponds, rivers and steams)

• All rivers are a result of precipitation; rain falls, snow melts; it all drains into rivers (ex: Mississippi)

• Area of land that is drained by a river is its watershed; amount of water that falls on a watershed varies from year to year

• Lakes provide a more stable water source


Rivers of Controversy• River water is in high demand; disputes over who

have rights to it occur (ex: Colorado River) often• Colorado River flows 1450 miles; passes through

the Grand Canyon to Gulf of California; by the time it reaches the Gulf there is very little water left because so much has been removed along the way

• 40% of world’s people rely on water that originates in another country; conflicts over water rights, especially when dams are built restricting flow to other countries downstream are common

• Disputes over water rights is likely to become more common as populations increase and demand for fresh water increases


Dams• Structures built across a river to restrict the

flow of water downstream and form a reservoir (artificial lake)

• Water is used drinking, irrigation, manufacturing, flood control, electricity

• Mixed blessing: artificial lake destroys existing ecosystems when they are formed and disrupts ecosystems downstream when they get less water

• No additional dams being built in US but other countries will probably continue to build


Groundwater• Not all rain flows into rivers and streams, some

soaks into the ground• Plants use some of the water, most seeps

underground• Large amounts of water is found underground in

rock formations called aquifers (consist of rocks, sand, gravel with lots of air space where water can accumulate)

• Aquifers continuously receive water that percolates down from the surface (very slow process)

• Area of land from which groundwater originates is called it recharge zone

• Deep: wells; close to surface: springs


Aquifers Are Running Low• Problem: People are pumping out

water faster than it can be replaced naturally; consequently, water levels are dropping rapidly

• Ogallala Aquifer (western US) is being depleted rapidly

• Some communities who once depended on aquifers are now using other sources of fresh water


Solutions to Water Shortages• Many potential solutions to water

shortages:

– Develop new sources of fresh water

– Use less by practicing conservation

– Minimize pollution


Desalting the Sea• Some coastal countries and

communities are trying to resolve water shortages by removing salt from salt water (desalinization)

• Two main methods of desalinization are distillation and reverse osmosis (pressure is used to push the water through a semi-permeable membrane that does not allow salt to pass through)

• Very expensive


Towing Water• Considered towing water from one

place to another• Ex: towing icebergs; problem with this?

They melt, hard to tow

• Alaska considered sending fresh water in huge plastic bags and selling it!


Water Conservation• Fresh water is a precious and limited

resource

• It takes time for water to move through the water cycle, so people need to do whatever they can to use water wisely

- install low flow faucets and showerheads

- turn off tap while brushing teeth or shaving

- water lawns at night

- put filled water bottles in toilet tanks


5.2: Freshwater Pollution

• Over the past 20 years, developed countries have been working to clean up polluted waters.

• Less developed countries continue to have polluted water from industrial and agricultural waste. (Soviet bloc countries and Poland are among the worst)

• In poor countries, industry is NOT the problem but population has outgrown the water supply; only supply of drinking water is polluted with sewage and agriculture runoff, causing sickness and death from waterborne diseases.


Freshwater Pollution…continued

• Water pollution – chemical, physical or biological agents introduced into the water supply degrading the quality and affecting the organisms depending on it.

• Two underlying causes: industrialization and human population explosions


Point Pollution• Pollution that is discharged from a

single source (ex: factory, waste treatment plant, oil tanker)

• Relatively easy to regulate and control because it is easily identified and traced

• Hard to enforce clean-up


Nonpoint Pollution• Comes from many sources rather than from

a single specific site; reaches bodies of water via streets and storm sewers (ex: homes, lawns, farms, highways, also from pesticides, fertilizers, animal feces)

• Extremely difficult to regulate and control• Small amounts add up to a huge pollution

problem; 96% of polluted bodies of water come from nonpoint pollution contamination

• Public awareness and education will probably be the most effective way of reducing nonpoint pollution


Wastewater Treatment Plants• Water that goes down a drain ends up in a

wastewater treatment plant; then returned to a river or lake

• Cannot always remove all the harmful substances; home wastewater is biodegradable and can be purified; industrial and storm runoff may contain toxic substances that interfere with treatment

• By-product of wastewater treatment is sludge; many contain toxic chemicals; incinerated and then buried

• Non-toxic sludge can be used as fertilizer (contain plant nutrients) if it is free of toxins; can be made into bricks when combined with clay


Pathogens• Disease causing organisms (bacteria,

viruses, parasitic worms)

• Can enter water supplies in untreated wastewater or animal feces

• Cholera, hepatitis, typhoid are diseases people can get from drinking water containing these pathogens

• Public water supplies are constantly monitored for the presence of these pathogens.


How Water Pollution affects Ecosystems

• Biological magnification – starts at the level where a toxin enters the ecosystem; bottom dwelling organisms enter their bodies-> eaten by small fish -> eaten by large fish -> eagle

• The toxin increases in concentration from one tropic level to the next

• Polluted water may also cause an immediate change in the ecosystem; killing nearly all things for miles downstream

• Harmful to humans; harmful to fish (cancers, scale

rot, fin rot) or accumulate in fish tissue making them dangerous for humans to consume (birth defects, reproductive, nervous system, liver, kidney damage)


Artificial Eutrophication• Eutrophication occurs naturally over time;

however, the addition of inorganic plant nutrients (phosphorous and nitrogen) from fertilizer runoff and sewage causes excessive growth of algae (algal blooms)

which die and when they decompose use large amounts of dissolved oxygen in the water; fish suffocate and die

• Some states are now banning phosphate detergents; others have limited the amount of phosphates in the detergents


Thermal Pollution• Excess amount of heat added to the water

creates thermal pollution; from power plants and industries use the cool water to circulate in their engines and then return the warmed water to the lake or river

• Can kill large quantities of fish when it is too warm; warm water holds less oxygen – depriving organisms of oxygen; constant influx of warm water disrupts the ecosystem

• Citizens are usually opposed to new construction of power plants


Cleaning Up Water Pollution• Congress has passed several laws

designed to improve water quality in the US

• 1972 – Clean Water Act

• 1972 - Marine Protection, Research and Sanctuaries Act

• 1975 – Safe Drinking Water Act

• 1980 Comprehensive Environmental Response Compensation and Liability Act

• 1987 Water Quality Act

• They were able to succeed in curbing point pollution, but non-point pollution continues to be a problem


The Special Problem of Groundwater Pollution• Likely to plague us for centuries to

come (pesticides, fertilizers, agricultural chemicals are common pollutants)

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

• Groundwater recharges very slowly so it is very difficult to decontaminate the aquifers


Bottled Water• Many people have opted to drink

more bottled water than tap because they feel it is safer to drink

• Most bottled water comes from the tap that is filtered and treated with various chemicals

• Bottled water is regulated by the government but is NOT tested for pollutants as often as the public water supply is tested


5.3: Ocean Pollution• How much pollution can the oceans

absorb? Sailors have reported a “river of polystyrene” that stretches across the ocean from Bermuda to the African coast.

• How long will it take to decompose?

• Where does it come from?


How Pollution Gets Into Oceans• At least 85% of ocean pollution (mostly oil)

comes from activities on the land (most

occurring near the coastline); harms sensitive coastal ecosystems like coral reefs and estuaries the most

• Pollution entering rivers flows to the ocean• Pollutants are dumped directly into the

oceans (sludge from wastewater treatment and garbage)

• Accidental oil spills, only 5% (Exxon Valdez,

1989); plastic (six pack rings, bags, fishing line)


Preventing Ocean Pollution• MARPOL – prohibits the discharge of oil

and disposal or abandonment of plastic in oceans or coastal water

• 1974 Helsinki Convention – seeks to control land-based sources of ocean pollution (toxic dumping – DDT, cadmium,

mercury); and raw wastewater• US is strengthening its laws: 1990 (Marine

Mammal Protection Act) requiring ships have double hulls

• Problem: It is difficult to monitor every ship in the ocean


Who Owns the Oceans?• Who has jurisdiction over the oceans? In the

past, international law allowed nations to control the water extending out 3 miles from the coast; rest of the ocean was high seas and open to everyone

• Now, Law of Sea Treaty – extends out 12 nautical miles (22 km) or its territorial sea and then another 370 km (200 nautical mi) or its exclusive economic zone (environmental preservation and research); the rest is communal

• US did not sign treaty (didn’t like restrictions on seabed mineral mining)

powerpoint templatespage 1powerpoint templates chapter 5: water all is born of water, all is...

Documents

surface water fresh

water conservation fresh

water people

water shortages

towing water

water rights

flow of water

clean water