Industrial waste and greenhouse gases

Materials thrown away after factory production processes that cannot be used again are called industrial waste. Their release into the environment has created harmful conditions.

Hydrocarbons

Compounds formed by carbon (C) and hydrogen (H) alone, combined in various proportions, are hydrocarbons — the compounds of chapter 14. They reach the environment in these ways:

• Bacteria acting on dead plants, animal parts and organic waste in rubbish heaps, farmland and marshes produce large amounts of methane (CH₄), the simplest hydrocarbon.
• Using the products of the fractional distillation of crude oil — LP gas, petrol, diesel, kerosene — as fuels adds hydrocarbons to the environment.
• Using lubricating oil and grease from crude oil adds hydrocarbons to the environment.

Greenhouse gases

There is a balance between the energy received from the Sun and the energy radiated back from the Earth. Gases in the air — carbon dioxide, water vapour, methane, ozone and chlorofluorocarbons — absorb much of the radiation leaving the Earth and radiate part of it back to the surface. This keeps the Earth warm and keeps a climate fit for life. It is called the greenhouse effect, and the gases that cause it are greenhouse gases. A rise in their concentration causes global warming to rise harmfully.

The textbook lists sulphur dioxide among the greenhouse gases. It is best known as a cause of acid rain; scientists do not usually count it as a greenhouse gas.