8.2 3.1.3 environment  (Page 4/8)

Chemical control: use of insecticides to kill insects that damage food crops. This also harms the environment and gets washed into rivers, dams and seas, negatively impacting onfood chains.

Biological control: use natural predators to eradicate (get rid of) of pests that feed and damage on food crops. This ensures that the useful plants and animals as well as the soilas a natural resource is not damaged.

Deforestation: removal of natural forests. This destroys biodiversity, and also removes plants which help to decrease the carbon dioxide burden.

Acid Rain : Burning fossil fuels may also produce sulphur dioxide and nitrogen oxide gases. These gases rise up in the atmosphere from factories, power stations andvehicles and dissolve in the water in clouds forming acid rain. Acid rain can damage trees directly.If the water in rivers and lakes becomes too acidic,plants and animals cannot survive. Acid rain also damages buildings

Eutrophication: Pollution of water by fertilisers may cause eutrophication. The fertiliser causes rapid growth of aquatic plants such as algae. The increased amount ofalgae on the surface of the water blocks out sunlight, preventing plants at the bottom of river from photosynthesising. These plants die and begin todecompose. Micro-organisms feed and decompose dead plants using up oxygen in the water. Fish and other aquatic organisms die due to oxygen shortage.

Sewage pollutes the sea and fresh water, unless it is treated properly.This is a health hazard, but it also upsets the balance of organisms living in the water.Untreated sewage provides food for micro-organisms and causes eutrophication.

Toxic chemicals are released from industrial plants and by farmers. These can pollute the land and water.Some toxins e.g. DDT can accumulate along food chains until the toppredator has very high, often lethal, amounts in its body.DDT is carcinogenic (cancer causing)

Definitions and terms

Pollution: an undesirable change in the natural resources due to negative influences of human activities.

Thermal pollution: hot waste water released by industries and mining into rivers and lakes increases temperature of water ‘driving’ out oxygen killing fishand other aquatic life.

Contamination: not fit for human consumption as it contains bacteria

Sewage: waste water containing faeces

Flora: refers to all plant life

Fauna: refers to all animal life

Activities

The greenhouse effect

To see how greenhouse gases affect the climate try this simulation from PhET. Explore the atmosphere during the ice age and today. What happens when you addclouds? Change the greenhouse gas concentration and see how the temperature changes. Then compare to the effect of glass panes. Zoom in and see how lightinteracts with molecules. Do all atmospheric gases contribute to the greenhouse effect?

Phet: The Greenhouse Effect: http://phet.colorado.edu/en/simulation/greenhouse

Human’s influence on greenhouse gas concentrations

Take a look at http://www.breathingearth.net/ to see how much CO2 is currently been released into the atmosphere.