Exam-style Questions: Environmental Hazards
a) Define the terms Greenhouse Effect, Ozone Layer, Acid rain.
b) The evidence to support the arguments for global warming is inconclusive. Discuss.
(Marks available: 24)
Answer outline and marking scheme for question: 1
a) Make sure your definitions are in-depth enough to gain full marks. 3 marks per definition is generous.
'The Greenhouse effect is a gradual increase in the temperature of the lower atmosphere. Up to 30 gases produced by human activity have been identified as contributing to the effect. They include carbon dioxide, methane, and nitrous oxide. The name for the process is given because the gases act as the glass in a greenhouse helping to trap the suns energy.'
A fully labelled diagram would also be sufficient to gain 3 marks.
b) You need to clearly outline the arguments for and against global warming and at the end of your answer reach a conclusion based on the evidence you have used. You can either deal with all the arguments for global warming first, followed by those, which are against it, or directly compare the evidence. The majority of marks will be given for presenting evidence, but credit will be awarded for arriving at a logical conclusion based fully on the information you have related to. The more evidence you present the higher the mark. Remember you do not have to agree with the statement.
Evidence you need to include:
- Greenhouse gases occur naturally in the atmosphere.
- There is evidence to suggest that the earth has experienced cooler and warmer periods in the past. (UK little ice age1540 - 1700).
- We have not fully left the last ice age.
- Fossils and rocks - for example, coal are present in the UK yet could not have formed under present climate conditions.
- Other causes of climatic change exist - for example, volcanic activity, plate tectonics, variations in solar energy, and composition of the atmosphere.
- The majority of the warmest years have been in the past 2 decades.
- Hurricanes are increasing in frequency and strength.
- The incidence of flooding in low-lying coastal areas, for example, Bangladesh is increasing.
- Glaciers in the Arctic are melting.
- Mean average sea levels have increased in this century.
- Temperature increases have coincided with industrialisation and the rise in number of Greenhouse gases emitted from industry.
Do include facts and figures to support arguments. It is all very well to say that temperatures have risen but means little unless you give the evidence.
(Marks available: 24)
a) Outline the main sources of Greenhouse Gases.
b) Explain how human and physical factors can affect the atmosphere at a local scale.
(Marks available: 21)
Answer outline and marking scheme for question: 2
a) Although this is a relatively simple question, be careful to acknowledge both natural and man-made sources.
For example: 'Many greenhouses gases exist naturally, such as methane and it is thought to be human actions that are increasing their concentrations within the lower atmosphere.'
You will be awarded marks for mentioning the following sources:
- Water Vapour. A natural source that comes from oceans, lakes, rivers, reservoirs. Humans have little impact upon levels. Water vapour and clouds are responsible for nearly 98% of the natural greenhouse effect.
- Carbon Dioxide. Both a natural and man-made source - for example, burning of fossil fuels, and forests, breathing animals, less produced by southern hemisphere.
- Methane (CH4). Much from break down of organic matter by bacteria (rice Paddy Fields) cows, swamps and marshes.
- Ozone. Comes naturally from some oxygen atoms. Ozone in the troposphere is due to chemical reactions between sunlight and agents of pollution.
- CFC'S. Fridges, polystyrene packaging and aerosols but increasing due to ability to survive within the atmosphere for 100 years.
- Nitrous Oxide. Nitrate fertilisers, transport and power stations (combustion).
b) To gain full marks the examiner will be looking for reference to the following:
- Accurate factual knowledge
- Wide-ranging and accurate use of examples
- Examples to support answers dealing with wind, precipitation and temperature.
- Clear structure
- Atmospheric quality
- Stability and instability
- Seasonal variations
- Locational examples
(Marks available: 21)
a) What are the 2 main ways acid rain is deposited?
b) Describe the damage acid rain causes?
c) ''Acid rain is an international pollutant.'' Explain the statement with reference to examples.
(Marks available: 25)
Answer outline and marking scheme for question: 3
a) 'Acid rain is deposited by both dry and wet deposition. Dry occurs close to the source usually no further away than 5km. It is a result of gas and aerosol emissions. Wet deposition occurs further away from the source after the gases have risen into the atmosphere and mixed with water vapour producing clouds and acid rain.'
The answer above would gain 2 marks as it has no reference to specific sources, and no examples of countries affected.
b) One mark awarded for mentioning any of the following:
- Vegetation/Soil. Much initial concern focused on the death of coniferous trees in Scandinavia. As rain falls to the ground (or snow melts) toxins are released into the soil. Tree roots become damaged, and soil is deficient in nutrients. The ability of vegetation to withstand bacteria and disease is reduced.
- Lakes. Acid rain has led to acid levels in lakes in Scandinavia being exceptionally high. The number of fish in lakes in Norway has fallen since the 1950's.
- Water Supply. Aluminium is washed into lakes and reservoirs from the surrounding land, leading to algae bloom that upsets the ecosystem. Some evidence suggests a link between increased levels of Al in water and Alzheimer's disease.
- Buildings. Acid deposition encourages more rapid weathering of buildings, and their discolouration via carbonation.
The explanation for each will gain you up to 2 marks per point that you have made.
c) This examiner is expecting an answer that relates to wet deposition. It is most likely that the example you use will be that of the UK exporting its acid rain to Scandinavia. The way the answer should be structured and its content is outlined beneath.
- Introduction: What is acid rain, how is it formed.
- Exemplifications to show you understand the question: The UK an industrial country 'exports' its acid rain to Sweden and Norway.
- Explanation of why and how acid rain is exported: The dominant wind direction, depressions passing over the UK to Norway / Sweden, way pollutants mix in the atmosphere.
- An example of the way acid rain has damaged the recipient country (the more you give the more credit you will receive)
- Possible solutions to acid rain.
(Marks available: 25)
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