Powerpoint TemplatesPage 1Powerpoint Templates Chapter 5: Water “All is born of water, all is sustained by water.” Johann Wolfgang von Goethe German Poet

Powerpoint Templates Page 1Powerpoint Templates

Chapter 5: Water

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

Johann Wolfgang von GoetheGerman Poet and Dramatist

Powerpoint Templates Page 2

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

since water first formed on Earth billions 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

• Two kinds of water are found on Earth…Fresh water (water people can drink, contains little salt) and Salt water (water in the oceans, contain higher concentrations of dissolved salts)

• 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)


The Water Cycle

• Earth is called the water planet because of the abundance of water (solid, liquid and gas)

• Water is renewable; endlessly circulated through the water cycle

• In the water cycle, water molecules travel between Earth’s surface and the atmosphere. (water evaporates, leaves behind salts and other impurities; water vapor rises into the air; gas cools and condenses into drops of liquid water that form clouds; water falls back to Earth and replenishes Earth’s fresh water supply)


Global Water Distribution• About 71% of Earth’s surface is covered by

water• 97% of that water is salt water, in oceans

and seas• 3% is fresh water; 77% of that is frozen in

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

• The water we require for our everyday needs (agriculture and drinking) comes mainly from lakes and rivers and from a relatively narrow zone beneath the Earth’s surface.


Surface Water• Surface water is fresh water on Earth’s land

surface (lakes, rivers, streams, wetlands); however, that distribution has played a vital role in the development of human societies.

• Surface water makes up a small fraction of Earth’s fresh water

• Most large cities depend on surface water (fresh water that is above ground in lakes, ponds, rivers and streams) for drinking water, water to grow crops, food such as fish and shellfish, power for industry, transportation by boat


River systems• All rivers are a result of precipitation; rain falls,

snow melts (from mountains, hills, plateaus and plains)

• The more streams that run into a river, the larger the river becomes

• As streams and rivers move across the land, they form a flowing network of water called a river system; viewed from above, it would look like the roots of a tree feeding into the truck

• The Mississippi, the Amazon and the Nile are enormous river systems; The Amazon River systems is the largest in the world (drains an area nearly the size of Europe!)

•


Watersheds• 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

• Pollution anywhere in a watershed may end up polluting a river

• Lakes provide a more stable water source; rapidly melting snow and spring and summer rains can dramatically increase amount of water in a watershed

• Communities that depend on rivers for water can be severely affected by changes in river systems

•


Groundwater• Most of the fresh water that is available for human

use cannot be seen---it exists underground• Not all rain flows into lakes and streams; plants use

some the water, most seeps underground• Water percolates through the soil and down into the

rocks beneath; water stored beneath Earth’s surface in sediment and rock formations is called groundwater.

• The water table is where the rocks and soil are saturated with water; in wet regions, the water table may be at the Earth’s surface and a spring of fresh water may flow out onto the ground; in deserts, the water table may be hundreds of meters beneath Earth’s surface


Aquifers• 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)

• Holds water in the same way a sponge holds water

• Groundwater can dissolve rock formations (limestone) and fill vast caves with water, forming underground lakes

• Important sources of water for many cities and for agriculture


Porosity and Permeability• Most rock appears to be solid; however, many kinds

of rocks contain small holes, or pore spaces• Porosity is the amount of space between the

particles that make up a rock• Water in aquifers is stored in the pore spaces and

flow from one pore to the next; the more porous the rock, the more water it holds

• Permeability is the ability of rock or soil to allow water to flow through it (ex: gravel)

• Impermeable - stops the flow of water (clay, granite)• Most productive aquifers form in permeable materials

(sandstone, limestone, layers of sand, gravel)

•


The Recharge Zone• Area of land from which groundwater

percolates down into the aquifer is called the recharge zone (through soil and rocks); takes an extremely long time to refill an aquifer (tens of thousands of years)

• Recharge zones are environmentally sensitive areas because pollution can enter the aquifer; buildings, parking lots (impermeable layers) can reduce the amount of water entering an aquifer

• Communities need to carefully manage recharge zones


Wells• If you dig deep enough, you will find water

• Dig deep into the ground to reach water: wells; may be a more reliable source of water because it is filtered and purified as it travels through all the layers

• Height of water tables changes seasonally, so wells are dug to extend below the water table

• If water table falls too low or is removed faster than it can be recharged, the well must be dug deeper

• 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


5.2: Water Use and Management

• “We all live downstream.” What does it mean?? When a water supply is polluted or overused, everyone living downstream is affected.

• Number of people relying on freshwater is increasing daily

• One of Earth’s most pressing environmental problems is a shortage of clean, fresh water

• According to the World Health Organization, more than 1 billion people lack access to a clean source of fresh water


Global Water Use• Three major uses for water: residential,

agricultural, and industrial

• Most fresh water worldwide is used to irrigate crops

• Availability of fresh water, population size and economic conditions affect how people use water; patterns of water use are not the same everywhere (Asia 80%, Europe 38%)

• Industrial use accounts for 19%; highest percentage of use in Europe and North America

• About 8% is used by households for drinking and washing


Residential Water Use• Major differences in water use

throughout the world; average person in US uses about 300 L (80 gal) of water per day, half used for inside the home for drinking, washing, cooking and personal needs, the other half is used outdoors for watering lawns and washing cars; India uses about 41 L per day


Water Treatment• Most water needs to be treated to make it

potable (safe to drink); removes elements (mercury, arsenic, lead) which are poisonous to humans in low concentrations (found in polluted water but can also be found naturally in groundwater)

• Also removes pathogens (organisms that cause illness or disease: bacteria, viruses, protozoa, parasitic worms); found in water contaminated by sewage and animal feces

• Several methods of treating water (both physical and chemical treatment)


Industrial Water Use• Industry accounts for 19% of water used in the

world; manufacturing goods, disposal of waste, generating power

• Nearly 1000 L of water is needed to produce 1 kg of aluminum; 500,000 L of water is needed to manufacture a car; vast amounts of water is used to produce computer chips and semiconductors

• Mostly used to cool power plants (pump water from a surface water source, a river or lake, carry that water through pipes in a cooling tower, and then pump the warmer, generally clean water back into the original source)


Agricultural Water Use• Agricultural use accounts for 67% of

the water used in the world; nearly 300 L (80 gal) of water to produce 1 ear of corn

• Plants require a lot of water; 80% of the water used to water plants never reaches the plant roots, it evaporates


Irrigation• Fertile soil oftentimes found in areas with little

rainfall so extra water must be supplied by irrigation

• Irrigation is a method used to provide plants with water from sources other than direct precipitation (earliest forms of irrigation involved flooding the fields)

• Many forms of irrigation are used today, ex: shallow, water-filled ditches (cotton), high pressure overhead sprinklers (inefficient because nearly ½ evaporates and never reaches roots

• Newer, more efficient methods are becoming more common


Waste Management Projects• For thousands of years, humans have altered

streams and rivers to make them more useful• Nearly 2000 years ago, Romans built aqueducts

(huge canals from mountains to dry areas); some are still used today; today, modern engineering has allowed water projects to become more complex

• Water management projects (dams and water diversion canals) allow people to live in desirable areas where surface water is inadequate, or to create reservoirs for recreation or drinking water, and to generate electric power

• Piped in water allows people to live and grow crops in Southwest US (desert areas)

•


Water Diversion Projects• All or parts of rivers can be diverted into canals to provide

water to dry regions, ex: Owens River in California provides drinking water to Los Angeles; Colorado River provides water to 7 states

• Colorado River (flows 1450 miles) begins as a glacial stream in the Rocky Mountains, grows larger as of the streams feed into it; then divided to meet the needs of the states; so much of the water is diverted for irrigation and drinking water that it runs dry before it ever reaches Mexico and the Gulf of California (only makes it there in the wettest years)

• River water is in high demand; disputes over who have rights to it occur often (ex: Colorado River)

• 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 and Reservoirs• Structures built across a river to restrict the flow of water

downstream and form a reservoir (artificial lake formed behind the dam)

• Water is used for drinking, irrigation, manufacturing, flood control, electricity and recreation

• Hydroelectric dams use the power of flowing water to turn a turbine that generates electrical energy; about 20% of the world’s electricity is generated by hydroelectric energy

• Mixed blessing: artificial lake destroys existing ecosystems when they are formed and disrupts ecosystems downstream when they get less water; people are displaced from their homes (close to 50 million people worldwide); farmland below a dam is affected as a result of nutrient rich sediment being blocked behind the dam rather than flowing downstream

• Dams can malfunction and burst, killing many people below the dam

• No additional dams being built in US but will probably continue in developing countries (Brazil, India and China)


Water Conservation

• As water sources become depleted, water becomes more expensive;

• Water conservation is one way people will have enough water at reasonable prices


Water Conservation in Agriculture

• Most water loss in agriculture comes from evaporation, seepage and runoff

• Drip irrigation systems offer an initial step toward conservation (deliver small amounts of water directly to plant roots by using perforated tubing, released as needed at a controlled rate); managed by computer programs; very little loss of water to evaporation, seepage or runoff


Water Conservation in Industry• Industries have developed water conservation

plans due to the rising cost for water• Most conservation practices involve recycling of

cooling water and wastewater; instead of returning water to rivers, businesses recycle the water and reuse it (ex: production of paper uses less than 30% of the water required to produce the same amount of paper as 50 years ago)

• In Denver, Colorado, the city pays small businesses to introduce water conservation methods; saves money for the city and the businesses and makes more water available for agriculture and residential use.


Water Conservation at Home• Households use much less water than

agriculture and industry, however, people can make a difference by changing a few everyday habits (using low flow toilets and shower heads, water lawns at night, take shorter showers don't run water while brushing your teeth, wash only full loads of laundry and dishes)

• Xeriscaping - designing landscapes that require minimal water use

•


Solutions for the Future• Conservation alone is not enough

to prevent water shortages, other sources of fresh water needs to be developed

• Two possible solutions: Desalination and transporting fresh water


Desalination• Desalination is the process of

removing salt from saltwater; desalination plants heat salt water and collect the fresh water that evaporates

• Some coastal communities rely on the oceans to provide fresh water and have built desalination plants (Middle East)

• Desalination consumes a lot of energy, the process is too expensive for many nations to consider


Transporting Water• In areas where freshwater resources are not

adequate, water can be transported from other regions (ex: Greece, high tourist area, not enough fresh water to handle residents and tourists so large ships towing enormous plastic bags of water travel regularly to the Greek Islands to pump fresh water)

• This is a solution the US is considering, too. (Alaska has 1/2 the available fresh water; tow Alaskan water down the Californian coast)

• With 76% of Earth's fresh water in frozen icecaps, people have considered towing icebergs to communities needing fresh water; however, efficient ways to tow the icebergs is yet to be discovered


5.3: Water Pollution• You cannot always determine if water is polluted by the way it looks

or smells; there are different forms of water pollution (chemical, physical or biological agents)

• The introduction of these agents can adversely affect the water quality and the organisms that depend on the water

• There are two underlying causes of water pollution: industrialization and rapid human population growth

• In the past 30 years, developed countries are making provisions to clean up polluted water supplies; however, many sources continue to be dangerously polluted

• Water pollution continues to be a big problem in developing countries; industry is NOT the major cause of pollution in those countries

• Available drinking water in these countries is polluted with sewage and agricultural runoff (spreading waterborne diseases)

• People must understand where pollutants come from in order to prevent water pollution; comes from two main sources: point and non-point


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 • Water that goes down a drain ends up in a

wastewater treatment plant• Wastewater is water that contains waste

from homes and industry• At a wastewater treatment plant, the water

is filtered and treated; then it is returned to a river or lake

•


Treating Wastewater• Home wastewater is biodegradable

and can be broken down by living organisms (ex: toilet and kitchen wastewater contains animal and plant waste, paper and soap – all are biodegradable)

• However, some home, industrial and storm runoff may contain toxic substances that interfere with treatment and cannot be removed by the standard treatment


Sewage Sludge

• By-product of wastewater treatment is sewage sludge (solid materials that remains after treatment); 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.


Artificial Eutrophication • Most nutrients in water come from organic matter (leaves,

animal waste); it is broken down into mineral nutrients by decomposers (bacteria, fungi)

• An overabundance of nutrients can disrupt the ecosystem (eutrophic)

• Eutrophication is a natural process; however, the addition of inorganic plant nutrients from fertilizer runoff and sewage (phosphorous and nitrogen, ex: laundry detergents, dishwashing soap, lawn fertilizers) 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 (artificial eutrophication)

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


Section 5.4: Thermal, Groundwater and Ocean Pollution

• 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


Groundwater Pollution• Pollutants usually enter groundwater when polluted surface

water percolates down from Earth’s surface.• Likely to plague us for centuries to come (petroleum products,

pesticides, herbicides, fertilizers, and agricultural chemicals are common pollutants)

• Leaking underground storage tanks also contribute and are a major source of groundwater pollution (located beneath gas stations, farms and homes; hold products like gasoline and heating fuel; as they age, they develop leaks which seep into groundwater)

• EPA has detected at least 200 hazardous chemicals that can seep through the soil and into groundwater; location of many tanks is unknown so they cannot be repaired or replaced until they have leaked enough pollutants to be located; modern underground storage tanks are contained in concrete

• Other sources of groundwater pollution include: septic tanks, unlined landfills, industrial wastewater lagoons


Cleaning Up Groundwater Pollution• One of the most challenging environmental

problems that the world faces today.• Even if we were to stop polluting the

groundwater today, the water would remain polluted for generations to come; groundwater recharges very slowly (hundreds or thousands of years)

• Very difficult to decontaminate, water is dispersed throughout large areas of rock and sand, pollutants cling to materials that make up an aquifer

•


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 Pollutants Get Into Oceans• At least 85% of ocean pollution (oil, toxic

wastes and medical wastes) 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)

•


Oil Spills• Accidental oil spills, account for only 5%

(Exxon Valdez, 1989, in Prince William Sound, Alaska; 2001 a fuel-oil spill occurred off the coast of the Galapagos Islands)

• Every year, about 37 million gallons of oil spills into the ocean

• Most oil that pollutes oceans comes from cities and towns (200 to 300 million gallons enter from nonpoint sources)


Water Pollution and 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)


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)


Cleaning Up Water Pollution• Congress has passed several laws designed to improve water quality in

the US; • In 1969, Cuyahoga River in Cleveland, OH was so polluted the river

caught on fire and burned for several days; this event was the major factor in the passage of the1972 – Clean Water Act – “restore and maintain the chemical, physical and biological integrity of the nation’s waters.” Goal was to make all surface water clean enough for fishing and swimming by 1983 (not achieved, but increased by 30%)

• 1972 - Marine Protection, Research and Sanctuaries Act (strengthened laws against ocean dumping)

• 1975 – Safe Drinking Water Act• 1980 Comprehensive Environmental Response Compensation and

Liability Act• 1987 Water Quality Act• 1990 Oil Pollution Act (requires oil tankers traveling in US waters to have

double hulls by 2015)• They were able to succeed in curbing point pollution, but non-point

pollution continues to be a problem•


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

Documents

Powerpoint TemplatesPage 1Powerpoint Templates Chapter 5: Water “All is born of water, all is sustained by water.” Johann Wolfgang von Goethe German Poet