8.3 Urban air pollutionIB Environmental Systems and Societies SL: Subtopic test

1. 1
   Delhi, India, regularly records some of the highest concentrations of fine particulate matter (PM2.5) of any capital city; annual averages are many times the World Health Organization guideline. Pollution is worst in winter. Sources include exhaust from millions of vehicles, coal-fired power stations and industry, burning of rubbish, and, in autumn, burning of crop stubble on farmland in nearby states. Dust blown from the surrounding arid land also contributes.

   (a)

   Which of the following is a primary pollutant released directly by burning fossil fuels in vehicle engines?

   [1 mark]

   • ANitrogen oxides (NOx)
   • BSulfuric acid
   • CNitric acid
   • DDust blown from arid land

   (b)

   Which statement about the sources of primary pollutants is correct?

   [1 mark]

   • AAll primary pollutants come from human activities
   • BNatural sources are always more important than human sources in cities
   • CMost urban pollutants are derived from nuclear energy
   • DPrimary pollutants have both natural and anthropogenic sources

   (c)

   Identify one natural and one anthropogenic source of particulate matter shown in the scenario, and explain why most pollutants in urban air come from combustion of fossil fuels.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   In the 1970s and 1980s thousands of lakes in southern Sweden became acidic. Fish such as roach and perch disappeared from many of them. Much of the acidity came from sulfur dioxide and nitrogen oxides released by power stations and industry elsewhere in Europe and carried north by the prevailing winds. Over the same decades, stone statues and historic buildings in European cities eroded faster than in the past. Sweden has since added lime to thousands of its lakes.

   (a)

   Which reaction sequence leads to the formation of sulfuric acid in acid rain?

   [1 mark]

   • ANitrogen oxides react with sunlight
   • BCarbon monoxide dissolves in rain
   • CSulfur dioxide reacts with water and oxygen in the air
   • DParticulate matter reacts with limestone

   (b)

   Which is an ecological impact of acid deposition on lakes?

   [1 mark]

   • AAn increase in pH, which kills fish eggs
   • BMobilised aluminium ions, which can harm fish
   • CGreater oxygen production by aquatic plants
   • DFaster growth of fish populations

   (c)

   Explain why acid deposition causes damage to stonework on buildings.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A city introduced a low-emission zone in 2019, charging older, more polluting vehicles to enter. The mean annual concentration of nitrogen dioxide (NO2) measured at roadside monitors was 64 µg/m³ in 2018, 48 µg/m³ in 2020 and 41 µg/m³ in 2022. Daily traffic on the main road fell from 62,000 vehicles in 2018 to 51,000 in 2022. The World Health Organization annual guideline for NO2 is 10 µg/m³.

   (a)

   Calculate the percentage change in NO2 concentration between 2018 and 2022, and compare the 2022 value with the World Health Organization guideline.

   [3 marks]

   (b)

   Evaluate the effectiveness of the low-emission zone as a strategy for reducing urban air pollution.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   The 'Black Triangle' is a region where the borders of the Czech Republic, Poland and Germany meet. In the 1970s and 1980s, power stations there burned large amounts of brown coal (lignite) with a high sulfur content and had no emission controls. Spruce forests in the Ore Mountains (Krušné hory) died on a large scale, lakes became acidic, and stonework on historic buildings was badly eroded. Since the 1990s, power stations have been fitted with flue-gas desulfurisation equipment, and sulfur dioxide emissions in the region have fallen sharply.

   (a)

   Evaluate strategies used to reduce the impact of sulfur dioxide emissions on ecosystems such as those in the Ore Mountains.

   [6 marks]

   (b)

   Discuss the ecological, human and building impacts of acid rain, with reference to the Black Triangle.

   [6 marks]

   Total for question 4: 12 marks

End of questions