Environmental Science

Chapter 11

Section 1

2 Types of Water on Earth Fresh water

Contains little to no salt

Used for drinking and agriculture

Salt water

Contains a higher concentration of dissolved salts

Found in the oceans

The Water Cycle Remember the steps of

the water cycle & the processes that occur with each step!

Evaporation

Condensation

Precipitation

Transpiration

Global Water Distribution Water is a limited

resource because most of the water on our planet is not fresh.

Most of the fresh water on our planet is trapped in ice caps and glaciers.

The fresh water we have available to use comes from lakes, rivers, and groundwater.

Surface Water Surface water is fresh water found on Earth’s surface

Composed of:

River systems

Watersheds

Surface water provides drinking water, water for crops, power for industry, transportation by boat, and food in the form of fish and shellfish

Surface Water (cont.)River System – a flowing network of water composed of streams & rivers

Watershed – the area of land that is drained by a river

The Amazon River System is the largest in the world. It drains an area the size of

Europe!

Groundwater Most of the freshwater available for human use is

found underground

Water beneath the Earth’s surface in sediment and rock formations is called groundwater

As water travels beneath the Earth’s surface, it eventually reaches a level where the rocks and soil are saturated with water

Known as the water table

Can be very close to the surface or hundreds of meters deep

Groundwater (cont.) Aquifers is rock or

sediment that stores water

Most aquifers are an important water source for cities and agriculture

Groundwater (cont.) A hole that is dug or

drilled to reach groundwater is called a well

Wells should extend below the water table to stay filled Wells dry up if Groundwater is removed

faster than it is recharged

The water table falls below the bottom of the well

Porosity & PermeabilityPorosity – the % of the total volume of rock that has spaces/pores

Permeability – the ability of rock or soil to allow water to flow through it

The Recharge Zone To reach an aquifer, water has to travel through layers

of permeable rock and soil

An area of the Earth’s surface that allows water to percolate into an aquifer is called a recharge zone

Recharge zones are environmentally sensitive because pollution in this area will also enter the aquifer

The size of the recharge zone is affected by the sediment above the aquifer

Buildings and parking lots can prevent water from entering an aquifer

The Recharge Zone

Section 2

Global Water Use There are 3 major uses of

water:

Residential use

Agricultural use

Industrial use

Residential Water Use In the U.S., the average

person uses about 300 L (80 gallons) per day.

In India, a person uses only 41 L per day…

This water use goes toward drinking, cooking, washing, using the toilet, lawn watering, cleaning, etc.

Water Treatment for Residential Use Water must be treated to make it potable, or safe to

drink.

Water treatment removes harmful toxins and elements that are poisonous to humans even in low levels.

These things can be found occurring naturally in groundwater or in polluted water.

Arsenic, mercury, and lead

Water treatment also removes pathogens that might cause disease

Pathogens are found in water contaminated by sewage or animal feces

Bacteria, protozoa, parasitic worms, etc.

Industrial Water Use Water is used to

manufacture goods, dispose of waste, and to generate power.

Most water used in industries is used to cool the power plants.

Agricultural Water Use Water is critical to the

growing of crops. It can take nearly 300L to

grow 1 ear of corn! We use that in a day!

However, fertile soil isn’t always found near water sources. So, extra water is supplied via irrigation. Irrigation is a method of

providing plants with water from sources other than precipitation.

Water Management Water management projects, such as dams and canals,

are designed to meet the needs of the people living in a particular area.

Water management projects may have various goals such as:

Making a dry area habitable (the American Southwest).

Creating a reservoir for recreation, drinking water, or generating electric power.

Types of Water ManagementWater Diversion Projects – diverting a river into a canal (the Owens River gets diverted to provide water to L.A.)

Dams & Reservoirs – dams are structures built to control a river’s flow while reservoirs form behind dams

Pros & Cons of Dams Pros

Dams make reservoirs that can be utilized for residential water use.

Dams can be used for hydroelectric power…a clean, renewable energy source.

Cons When the land behind a dam is flooded, people can be displaced

and ecosystems can be destroyed.

Since water builds up behind a dam, the fertile sediment it carries downstream never reaches the land further down. As such, farmland below a dam may be less productive.

Water Conservation As water sources become

depleted, water becomes more expensive.

As such, we must find a way to conserve that water that we have…

Water Conservation in Agriculture Most of the water loss in

agriculture comes from evaporation, seepage, and runoff.

New technologies are being developed to reduce these

problems. Drip irrigation systems deliver

small amounts of water directly to plant roots by using small, perforated tubes. Water is released to the plants as needed at a controlled rate and there is little water loss from the irrigation system.

Water Conservation in Industry Many industries now

have water conservation plans.

Most of these plans revolve around the recycling of cooling water and wastewater in the plant.

Water Conservation at Home Even though homes use much

less water than agriculture or industry, we can still have an impact.

Ways we can conserve:

Low-flow toilets and shower heads

Water lawns at night and sparingly

Turn water off while brushing your teeth

Only wash full loads in dishwasher and washing machine

Solutions for the Future In some places, water conservation alone is not enough

to prevent water shortages.

2 possible solutions are:

Desalination - This process removes salt from salt water to make it usable. Some countries in the Middle East have built desalination plants to provide fresh water. However, desalination requires a lot of energy and is too expensive for many nations to utilize.

Transporting water – In some areas of the world, freshwater resources are not adequate and countries pay to have fresh water shipped in. This is occurring on the Greek Islands due to an increase in tourism.

Section 3

Water Pollution Water pollution is the introduction of chemical, physical,

or biological agents into the water. Because of this, the water quality degrades and adversely affects

organisms that depend on the water.

Almost everything we use water for contributes to water pollution, but industry and rapid human growth are the primary factors.

Water pollution comes from 2 types of sources: Point-source pollution – water pollution from a single source

Nonpoint-source pollution – water pollution from many different sources

2 Sources of PollutionPoint-source Pollution – comes from a single source, such as a leaking oil tanker

Nonpoint-source Pollution – comes from many different sources and is difficult to identify, such as runoff into a river

Common Water Pollutants

Wastewater Wastewater is water that contains waste from homes

or industry.

A wastewater treatment plant will filter and treat the water to make it clean enough to return to a river or lake.

One of the products of wastewater treatment is sewage sludge. This is the solid material that remains after treatment.

It usually must be disposed of as hazardous waste due to the large concentrations of toxic chemicals. Many communities are looking to reduce toxicity levels to make the sewage sludge safe to use.

How a Wastewater Treatment Plant Works

Artificial Eutrophication Most of the nutrients in water come from organic

matter, such as leaves, that is broken down into mineral nutrients by decomposers.

Eutrophication is a natural process where the nutrients in water build up into higher levels.

The problem occurs when humans accelerate this process by using fertilizers. Runoff from farms and yards brings nitrogen and phosphorus into water sources and artificial eutrophication.

Algal blooms often result from this process. As the algae die, the oxygen gets used up and fish and other organisms will suffocate.

Artificial Eutrophication

Thermal Pollution Thermal pollution

results when the temperature of a body of water increases.

This usually occurs near industries where they discharge the water used from cooling back into the source it came from.

Can cause massive fish kills…

Groundwater Pollution Pollutants will enter the groundwater when polluted

surface water percolates down from the Earth’s surface.

Any surface water pollution can affect the groundwater.

The most common groundwater pollutants are:

Pesticides

Herbicides

Chemical fertilizers

Petroleum products

Groundwater Pollution

Cleaning Up Groundwater Pollution Groundwater pollution is one of the most challenging

environmental problems in the world.

Even if we could stop all groundwater pollution today, the groundwater would remain polluted for many generations yet to come. Remember that it can take hundreds or thousands of years for an

aquifer to recharge!

Groundwater is also difficult to decontaminate since water is dispersed throughout large areas of sediment in an aquifer. Even if the water was clean, the pollutants that cling to the

sediment could still pollute the clean water.

Ocean Pollution Pollutants are often dumped directly into the world’s

oceans.

Many ships can legally dump wastewater and garbage overboard in some parts of the ocean.

Despite this, most of the pollution in our oceans come from human activities on land.

Not only does this harm ocean ecosystems, but coastal ecosystems such as coral reefs, estuaries, and marshes are affected as well.

Oil Spills Oil spills have dramatic

effects on oceans, but they only account for about 5% of oil pollution in the ocean.

Most oil comes from cities and towns and as runoff from nonpoint sources on land.

The BP oil spill in the Gulf of Mexico will have far reaching consequences…

Water Pollution & Ecosystems Many pollutants cause damage to ecosystems because

they do not decompose quickly and accumulate in the bodies of organisms.

This can occur due to biomagnification. This occurs when pollutants build up in more toxic quantities at higher levels in the food chain.

DDT almost caused the bald eagle populations in North America to go extinct…

Biomagnification

Cleaning Up Water Pollution New legislation has paved the way to try to improve

water quality and water conservation…

Clean Water Act of 1972 – set a national goal to make all natural surface water fit for washing & swimming by 1983

Marine Protection, Research, and Sanctuaries Act of 1972 – empowered the EPA to control the dumping of sewage and toxic chemicals in U.S. waters

Water Quality Act of 1987 – supported state and local efforts to clean polluted runoff

Oil Pollution Act of 1990 – requires all oil tankers in U.S. waters be double-hulled by 2015