2.12 An Explanation. Self test on structure and language features
Social purpose:
How acid rain is caused
Text structure | Language features | |
Paragraph 1. | Acid 1rain is a major environmental problem in the world, causing fish to die in the earth's 1waters and severely affecting trees and forests, as well as damaging buildings. | 1. |
Paragraph 2. | 3Uncontaminated rain that 4falls from an unpolluted atmosphere is slightly 3acidic. This is 6because carbon dioxide, which is naturally present in the air, 4reacts with water vapour to form 2carbonic acid. The pH 8value of such rain is 5.6. Rainfall with a pH of less than 5.6 is referred to as acid rain. | 2. |
Paragraph 3. | On average the rain in Sydney, similar to many other large cities, has a pH of 4.3. This 7acidity 6is caused by 2emissions of sulphur and nitrogen oxides which 4form 2sulphurous, sulphuric and nitric acids when they come into contact with water in the air. These 2compounds 5then 4fall to the ground as rain or snow. | 3. |
Paragraph 4. | Burning 3fossil fuels such as 1coal is a major source of sulphur dioxide, while 3exhaust emissions from cars and trucks 6result in heavy 7concentrations of 2nitrous oxides in the air. | 4. 5. |
Paragraph 5. | These 2pollutants do not just occur in and around big 1cities. Winds can 4blow them for hundreds of kilometres, so that farmlands and even other countries can 6be affected by acid rain caused by the traffic and 3heavy industry of cities. | 6. 7. |