IB ESS HL 8.3 Urban Air Pollution Question Bank

Practise IB ESS HL 8.3 by analysing pollutant cycles and evaluating photochemical smog, acid deposition and coordinated urban responses.

Exam points

Analyse pollutant graphs to identify primary pollutants and traffic, heating or industry peaks.
Trace sulfur and nitrogen oxides through acid formation to soil, freshwater, vegetation and health impacts.
Evaluate air-pollution management through activity change, emission controls and ecosystem restoration.
Explain photochemical smog using NOx, VOCs, sunlight, inversion, topography and ozone impacts.

Covered syllabus points

8.3.1—Urban air pollutants 8.3.2—Primary pollutant sources 8.3.3—Fossil fuel combustion 8.3.4—Management strategies 8.3.5—Acid rain formation 8.3.6—Acid rain impacts 8.3.7—Acid rain management 8.3.8 (HL)—Photochemical smog 8.3.9 (HL)—Smog intensification factors 8.3.10 (HL)—Tropospheric ozone direct impacts 8.3.11 (HL)—Tropospheric ozone indirect impacts

[Maximum number: 10]

Figure:Atmospheric pollutants associated with photochemical smog

(a)

Identify one primary pollutant from the pollutants shown in the photochemical-smog pollutant chart shown above.

[ 1 ]

(b)

Outline why the pollutant named in Question 3 (a)(i) is referred to as a primary pollutant.

[ 1 ]

(c)

Outline one reason why there is an increase in nitrogen oxides and hydrocarbons early in the day.

[ 1 ]

(d)

Explain the changes in ozone concentration over the period shown in the photochemical-smog pollutant chart shown above.

[ 3 ]

(e)

State one environmental impact of the accumulation of ozone shown in the photochemical-smog pollutant chart shown above.

[ 1 ]

(f)

Outline two local conditions that may increase the severity of photochemical smog.

[ 2 ]

(g)

Outline the role of catalytic converters in reducing photochemical smog.

[ 1 ]

[Maximum number: 9]

Figure Average hourly variation in ozone on wet and dry days in Guarujá, Brazil

Figure Average hourly variation in NOx on wet and dry days in Guarujá, Brazil

Figure Average hourly variation in SO2 on wet and dry days in Guarujá, Brazil

(a)

Identify the time of day that ozone is at its lowest concentration on a wet day in Figure.

[ 1 ]

(b)

Outline two reasons for the trend of hourly ozone concentrations shown in Figure.

[ 2 ]

(c)

Describe one impact of high $\mathrm{SO}_{2}$ concentrations on forest systems.

[ 1 ]

(d)

Outline one possible source of the pollutant shown in Figure.

[ 1 ]

(e)

Outline why $\mathrm{SO}_{2}$ levels are lower on wet days than on dry days, as shown in Figure.

[ 1 ]

$\mathrm{SO}_{2}$ dissolves in water / is removed from the atmosphere when it rains/forms acid rain;

(f)

Evaluate a strategy to manage the effects of one pollutant named in Figureor Figure.

[ 3 ]

Example $\mathrm{NOx} / \mathrm{SO}_{2}$ : replacing use of fossil fuels with alternative energy sources;
Advantage: it eliminates emission of pollutants altogether;
Disadvantage: it would involve major social changes that may be unpopular;
Appraisal: could be successful in a society that has strong ecocentric principles;
Example NOx: use of catalytic converters to trap emissions;
Advantage: would enable continued use of fossil fuels appropriate to popular technology; Disadvantage: allows continued emission of other pollutants e.g. CO2/hydrocarbons;
Appraisal: would be relatively easy to introduce and enforce in a society;
Example $\mathrm{NOx} / \mathrm{SO}_{2}$ : clean-up of acidified aquatic ecosystems using lime;
Advantage: relatively easy to apply / no requirement for popular cooperation;
Disadvantage: expensive and short term solution;
Appraisal: in the long run it would be better to remove root cause
Note: Allow 1 max for each valid e.g./advantage/disadvantage/appraisal up to 3 max.

Marking guidance:

Accept other valid strategies.

[Maximum number: 4]

With reference to named examples, distinguish between a primary and secondary pollutant.

primary pollutant is one which is active on emission / directly impacts the environment;
eg $\mathrm{CO}_{2}$ is released from burning fossil fuels and actively contributes to global warming / CFCs are released from aerosols and actively contribute to ozone depletion;
a secondary pollutant is one formed from a primary pollutant through physical/chemical change;
eg $\mathrm{CO}_{2}$ combines with sea water to form carbonic acid that leads to impacts on calciferous shelled organisms or corals / $\mathrm{NO}_{\mathrm{x}}$ combines with water to form acid precipitation / $\mathrm{NO}_{2}$ forms PAN/ozone (that contributes to photochemical smog);

Marking guidance:

Award [2 max] if no examples are given.
Examples of primary pollutants need to include their direct impact (eg $\mathrm{NO}_{x}$ can be either primary or secondary without such specification) and examples of secondary need to include the process leading to their pollutionary impact).
Award [1 max] for example of primary, and [1 max] for example of secondary.

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Covered syllabus points

8.3 Urban air pollution question 1

Question (a)

Question (b)

Question (c)

Question (d)

Question (e)

Question (f)

Question (g)

8.3 Urban air pollution question 2

Question (a)

Question (b)

Question (c)

Question (d)

Question (e)

Question (f)

8.3 Urban air pollution question 3