Houghton Mifflin Grade 4 Science Unit A Chapter 3 - Trash

An archeologist is a person who digs up buried objects and studies them to learn about the people who left them.

A garbologist is a person who digs up, sorts, and catalogs garbage from old landfills and dumps.

The average American produces 4 pounds of trash each day.

A landfill is like a dump. It is a large hole that is filled with trash over time.

Trash is brought to a landfill by TRUCKS.

Trash is ugly and smelly.

Trash in uncovered dumps attracts birds, rats, mice, flies, and other disease-carrying animals.

Rainwater moving through dumps picks up harmful chemicals. It can make drinking water supplies unsafe to drink.

* Bury it
* Burn it
* Make new things out of it
* Make less of it.

The bottom of the landfill has a liner to keep liquids and rainwater from leaking into the soil.

The trash is spread in layers, and each layer is covered with soil.

Landfills can be covered over and covered with grass. Then the landfill can be used for parks or other public uses.

Landfills are expensive to build and run.

It's hard to find new places to put landfills because people don't want to live near them.

Because the trash is squeezed so tightly, there isn't enough air or water to help the trash decay.

Paper trash takes up the most space in landfills.

Incineration is getting rid of trash by burning it.

Pros:
* Burning trash reduces the amount of material that needs to be disposed of.
* The heat from burning trash can also be used to make electricity.

Cons:
* Burning trash causes smoke that make the air dirty.
* Ash from burning trash can contain harmful materials and must be disposed of carefully.

* Trash dumped at sea washes up on beaches.
* Animals that live in or near the ocean can become ill from trash, or become trapped in it.

Polution is adding unwanted materials to the environment.

Pollutants are unwanted materials.

Hazardous wastes are wastes that can pollute the environment, even in very small amounts.

Examples: oil, paint, pesticides, cleaning supplies, batteries

Hazardous wastes can cause diseases..

Plastic is made from petroleum, a non-renewable resource. Throwing away plastic reduces the amount of petrolem in the world.

Litter is solid waste (trash) that is discarded on the ground or in the water.

Litter is ugly and can be harmful to living things.

Litter wastes available resources.

Cans are made from metals mined from the earth -- aluminum and tin. Mining is expensive and uses energy. Ores are non-renewable resources. Throwing away cans reduces the amount of metals available.

Paper is made from trees. Although trees are a renewable resource, it takes a long time for them to grow. Also, making trees from paper creates many pollutants.

Petroleum is used to produce plastic.

Ore is used to produce cans.

Trees are used to produce paper.

The Greeks recycled stones from old buildings to make new buildings.

Scrap iron was recycled to make steel. Old iron tools, machines, and products (like railroad ties) were melted down and used to make steel.

In World War II, lots of materials were needed to build war ships, tanks, and planes. Americans recycled scrap metal, old tires, tin foil, and tin cans.

Amercians began recycling aluminum cans in 1968.

Recycling is processing items in order to reuse them.

Paper is ground up and mixed with water to form a mushy pulp.

The pulp is treated with chemicals to remove ink and other impurities.

The pulp is process in different ways to make things from egg cartons to greeting cards to blank paper.

Plastic is chopped into small pieces and washed. Dirt and non-plastic items are separated from the plastic. The plastic pieces are dried in a dryer.

The plastic pieces are melted, filtered, and shaped into strands. The strands are chopped into small bead-shaped pieces that are used to make new plastic products.

Glass bottles are sorted by color and checked for metal caps. The bottles are crushed into small pieces.

The small glass pieces are are cleaned and mixed with other materials needed to make glass. The galss pieces and materials are melted into new glass.

Aluminum cans are crushed.

The crushed cans are melted.

The liquid aluminum is molded and cooled.

No. The glass in lightbulbs, windows, and car headlights can't be recycled.

It takes energy resources to collect the materials and run the machines used in recycling.

Each person produces about 87 pounds of glass waste per year.

Packaging is the wrappings and containers of items for sale.

Packaging keeps products fresh, safe, and unbroken.

Packaging makes up about 1/3 of the trash in landfills.

Paper makes up most of the trash in landfills.

It is difficult because packaging:

* protects things from breaking

* keeps things fresh

* makes things more convenient

* gives product information

* provides safety (think of child-proof caps for medicine)

* displays and advertises

The burning of trash is incineration.

Processing items and reusing them is recycling.

Wrappings and containers of items for sale is packaging.

Trash discarded on the ground or in the water is litter.

Wastes that can pollute even in small amounts are hazardous wastes.

A large hole filled with trash over time is a landfill.

The addition of unwanted materials to the environment is called
pollution.

Trash discarded along a roadside is litter.

Keeping an item fresh is one purpose of packaging.

Each layer of trash in a landfill is covered with soil.