teaching pack for key stages 3 & 4, and a-levelfor example, the h+ ion content of rainwater with...

ACE is supported by the Department for Environment, Food & Rural Affairs

Atmosphere, Climate & Environment

Information Programme, aric Manchester Metropolitan University

Chester Street, Manchester M1 5GD Tel: 0161 247 1590

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Teaching Pack for

Key Stages 3 & 4, and A-Level

Sue Hare

1999 (updated 2002)

mailto:[email protected]

http://www.doc.mmu.ac.uk/aric/

http://www.ace.mmu.ac.uk/

ACE Information Programme aric

Acid Rain Teaching Pack: KS3/4 & A 2

Lesson 1. Introduction to Acid Rain Lesson 2. Acid Rain Data Interpretation Lesson 3. Acid Deposition Case Studies

Czech Republic Finland UK Canada

Lesson 4. Freshwater Acidification Lesson 5. Acid Rain Cartoon Analysis Lesson 6. Effects of Acidification on Buildings Lesson 7. Controlling Acid Emissions from Vehicles Lesson 8. Controlling Acid Emissions from Industry References & Sources of Further Information

Glossary



Aim: To highlight and investigate acid deposition as an international environmental issue. Objective: To increase awareness and understanding of the sources and effects of acidifying pollutants and to identify possible responses to improve air quality. Target Audience: Teachers of students aged 12-18 years studying geography, science and environmental studies / science in the National Curriculum at GCSE and A level. Skills Enhancement: Students will develop an awareness and understanding of the continuing environmental problem of acid deposition. Students will gain an appreciation of the problem through the use of real acid deposition data collected in the UK. Students will also gain an appreciation of the major sources of acidifying pollutants in the UK and through the case studies will be able to identify how different parts of the world are affected. Students will also increase their knowledge and understanding of the responses that can be taken by the major polluting sources, vehicles and industry to reduce emissions and hence improve air quality.



The Use of this Pack: • = Teachers are strongly encouraged to read this pack thoroughly

before embarking upon its use • = Maximum benefit will be gained by students if all of the sections

are covered in the order set out in this pack • = The optional exercises at the end of each section are designed to

aid students in understanding the topic covered in each section. Usually the exercise requires the student to draw on information supplied in each section. These exercises may be most useful for GCSE level students.

It is hoped that you will find this resource pack both useful and informative. If you have any criticisms, comments or ideas on how to improve the pack we would be very interested to hear them. You can contact us at the address below: Atmosphere, Climate & Environment Information Programme Atmospheric Research and Information Centre Manchester Metropolitan University Chester Street, Manchester, M1 5GD Tel: 0161 247 1593 Fax: 0161 247 6332 e-mail: [email protected] Internet: http://www.ace.mmu.ac.uk/ © ARIC 1999

mailto:[email protected]

http://www.doc.mmu.ac.uk/aric/arichome.html

http://www.ace.mmu.ac.uk/



Acid Rain or Acid Deposition? Acid rain is a widespread term used to describe all forms of acid precipitation (rain, snow, hail, fog, etc.). Atmospheric pollutants, particularly oxides of sulphur and nitrogen, can cause precipitation to become more acidic when converted to sulphuric and nitric acids, hence the term acid rain. Acid deposition, acid rain and acid precipitation all relate to the chemistry of air pollution and moisture in the atmosphere. UK scientists generally use the term acid deposition but all three terms relate to the same issue. Acid Rain: A New Problem? The term acid rain was first used by Robert Angus Smith, a scientist working in Manchester in the 1870s. The problem of acid rain is hence not a new one but the nature of the problem has changed from being a local problem for towns and cities to being an international problem. In Smith’s time, acid rain fell both in towns and cities whilst today pollutants can be transported thousands of kilometres due to the introduction of tall chimneys dispersing pollutants high into the atmosphere. Sources of Acidic Pollutants Precipitation is naturally acidic because of carbon dioxide in the atmosphere. The burning of fossil fuels (coal, oil and gas) produces sulphur dioxide and nitrogen oxides which can increase the acidity



of rain or other precipitation. Sources of sulphur dioxide and oxides of nitrogen may be natural such as volcanoes, oceans, biological decay and forest fires, or may arise from combustion sources. The increasing demand for electricity and the rise in the number of motor vehicles in recent decades has meant that emissions of acidifying pollutants have increased dramatically from human sources, particularly since the 1950s. Emissions of such pollutants are heavily concentrated in the northern hemisphere, especially in Europe and North America. As a result, precipitation is generally acidic in these countries. In the 1970s and 1980s, Scandinavian countries began to notice the effects of acid deposition on trees and freshwaters. Much of the pollution causing this damage was identified as being transported from other more polluting countries. Acid rain became an international concern. Measuring Acidity The pH (not PH) scale is used to measure the acidity or alkalinity of an aqueous solution and is determined by the hydrogen ion content (H+). This scale was invented by a Danish scientist called Sorenson in 1909. The pH scale ranges from 0, which is strongly acid, to 14 which is strongly alkaline, the scale point 7 being neutral.

ACID NEUTRAL ALKALINE 1 2 3 4 5 6 7 8 9 10 11 12 13 14



Examples of solutions with differing pH values are as follows: ♦ = pH 1 car battery acid ♦ pH 6 milk ♦ = pH 2 lemon juice ♦ pH 7 washing up liquid ♦ = pH 3 apple ♦ pH 8 sea water ♦ = pH 4 beer ♦ pH 10 milk of magnesia ♦ pH 5-6 natural rain ♦ pH 12 ammonia The pH scale is logarithmic rather than linear (see graph 1), and so there is a ten fold increase in acidity with each pH unit, such that rainfall with pH 5 is ten times more acidic than pH 6, rainfall with pH 4 is 100 times more acidic than pH 6 and rainfall with pH 3 is 1000 times more acidic than pH 6.

Graph 1: The logarithmic pH scale for range pH 6.0 - pH 3.0

Rainfall acidity is measured in pH units. The individual pH readings may be converted to hydrogen ions to give a linear rather than a logarithmic representation of acidity. To convert the pH values to hydrogen ions, the following formula applies: H+ µeql-1 = antilog (6.0 - pH) where H+ µeql-1 is the hydrogen ion content in micro equivalents per litre (a unit which measures the concentration of hydrogen ions in a litre of water)



For example, the H+ ion content of rainwater with pH 4.54 is: H+ µeql-1 = antilog (6.0 - 4.54) = 29 The hydrogen ion content of a number of pH values are given in the following table and are illustrated on Graph 1.

pH value H+ µeql-1 pH value H+ µeql-1

6.0 <1 4.0 100 5.5 3 3.5 316 5.0 10 3.0 1000 4.5 32

‘Normal’ or ‘unpolluted’ rainfall has a pH of 5.6 (3 µeql-1 H+). This is slightly acidic due to the presence of carbon dioxide in the atmosphere which forms weak carbonic acid in water. The rainwater pH for the example given above (pH 4.54) is almost 10 times more acidic than ‘unpolluted’ rain. Acid Rain: The Environmental Issue Acid rain became particularly prominent as a media issue during the 1980s. However, during the 1970s many countries started to notice changes in fish populations in lakes and damage to certain trees. By the late 1970s concern led to international efforts to identify the causes and effects of long-range transport of air pollutants and thus during the 1980s much research was conducted in Europe and North America. International legislation during the 1980s and 1990s has led to reductions in sulphur dioxide emissions in many countries but reductions in emissions of nitrogen oxides have been much less. Although media attention has shifted towards other environmental issues such as global warming, acid deposition continues to be a problem during the 1990s.



Late 1970s Some signs of air pollution damage noticed,

particularly in Scandinavia. Long Range Transport of Air Pollutants Programme set up to investigate international issues.

1980s Much international research on acidification causes and effects. Many European and North American countries agree to reduce emissions of sulphur dioxide and nitrogen oxides.

1980s/1990s Reductions of emissions of acidifying pollutants sought by many countries through legislation.



Acid Rain Data The data used in this section is real data collected for the Greater Manchester Acid Deposition Survey (GMADS), for the year 1989. Grid References and Site Descriptions Site 1 Hall i’ th’ Wood, Bolton. Grid reference SD 725 115 . Altitude: 100m. Ground cover 1km2 - 70% urban industry and housing, 20% grassland, 5% water, 5% mixed woodland. Collector situated in parkland in urban Bolton. Site 2 Horwich, Bolton. Grid reference SD 637 126. Altitude: 200m. Ground cover 1km2 - 75% moorland, 10% housing, 10% parkland, 5% water. Collector situated in allotments in Horwich. Site 3 Affetside, Bury. Grid reference SD 758 136. Altitude: 273m. Ground cover 1km2 - 90% pasture, 10% housing. Collector situated on plateau to the north of Bury, surrounded by pasture and adjacent to Affetside Primary School. Site 4 Thurston Hall Farm, Bury. Grid reference SD 828 075. Altitude: 90m. Ground cover 1km2 - 95% pasture, 5% housing. Collector situated on farmland, 10km north of the city centre, 1km from motorway to east and west.



Site 5 Hey Bottom, Littleborough, Rochdale. Grid reference SD 943 163. Altitude: 180m. Ground cover 1km2 - 80% pasture, 16% housing, 4% water. Collector sited in garden in the foothills of the southern Pennines. Site 6 Ashworth Reservoir, Rochdale. Grid reference SD 831 151. Altitude: 275m. Ground cover 1km2 - 70% moorland, 30% water. Collector sited beside Ashworth reservoir, north west of Rochdale town centre. Site 7 Castleshaw, Oldham. Grid reference SD 997 098. Altitude: 300m. Ground cover 1km2 - 60% pasture / moorland, 40% water. Collector sited north east of Oldham on a sluice gate between two reservoirs. Site 8 Strinesdale, Oldham. Grid reference SD 956 065. Altitude: 250m. Ground cover 1km2 - 70% pasture / moorland, 20% water, 10% housing. Collector sited near to reservoir, north east of Oldham. Site 9 Heyrod, Tameside. Grid reference SJ 969 999. Altitude: 200m. Ground cover 1km2 - 80% pasture, 20% woodland. Collector sited in garden on an east facing slope. Site 10 Werneth Low Country Park, Tameside. Grid reference SJ 961 936. Altitude: 250m. Ground cover 1km2 - 60% meadow, 40% housing. Collector sited near the top of Werneth Low, overlooking Ashton-Under-Lyne. Site 11 Lyme Park, Stockport. Grid reference SJ 966 828. Altitude: 250m. Ground cover 1km2 - 60% grassland, 40% mixed woodland. Collector sited south east of Stockport in the western foothills of the Peak District.



Site 12 Town Hall, Manchester. Grid reference SJ 839 980. Altitude: 30m + 30m. Ground cover 1km2 - 100% commercial. Collector sited on flat roof on a 5 storey building in the commercial business district of Manchester. Site 13 Styal, Manchester. Grid reference SJ 842 828. Altitude: 80m. Ground cover 1km2 - 80% farmland, 18% woodland, 2% housing. Collector sited in school grounds, close to Manchester Airport. Site 14 Denzell Hospital, Altrincham, Trafford. Grid reference SJ 767 877. Altitude: 70m. Ground cover 1km2 - 50% pasture, 17% mixed woodland, 33% housing. Collector sited in hospital grounds, surrounded by farmland and a golf course. Site 15 Partington, Trafford. Grid reference SJ 728 914. Altitude: 20m. Ground cover 1km2 - 60% grassland, 40% industry. Collector sited in industrial park, edge of conurbation of Greater Manchester. Site 16 Agecroft Cemetery, Salford. Grid reference SD 806 017. Altitude: 30m. Ground cover 1km2 - 38% lawn, 20% water, 24% industry, 18% other. Collector sited in grounds of cemetery, near to a river valley. Site 17 Douglas Bank, Wigan. Grid reference SD 584 074. Altitude: 50m. Ground cover 1km2 - 53% housing, 25% grassland, 22% mixed woodland. Collector sited in grounds of retirement home, north east of Wigan town centre. Site 18 Crowdon, Glossop, High Peak. Grid reference SK 069 996. Altitude: 250m. Ground cover 1km2 - 80% moorland, 15% pasture, 5% water. Collector sited in bowl of hills, rising to 500m, north east of Glossop.



Acid rain collectors in and around Greater Manchester

Description of Rain Collectors Each collector stands 1.5 metres above the ground on a green aluminium stand, which is painted with polyurethane to resist corrosion. The funnel and filter are made from polyethylene and the collecting bottle from polypropylene. The collecting bottle is surrounded by a double layer of stainless steel, the outside of which is highly polished, the inside being black to discourage algal contamination. Above the funnel, black polypropylene line is strung loosely to deter birds from landing on the collector.



Siting of Collectors The collectors have been sited in Greater Manchester following strict criteria. A summary of the siting specifications are as follows: • = must be 100m away from small point sources (such as domestic

chimneys) • = 100m from small mobile sources (road traffic) • = 1km from major roads • = 5km from large surface works • = 10km from large point sources (such as power stations) Acid Rain Data 1989 The following data are the pH values of weekly rainwater samples collected at each of the 18 sites in the Greater Manchester area. A blank space denotes no rain or missing data.



Table 2.1: Acid Deposition Data, Sites 1 to 9: January - June

SITE/WEEK ENDING

1 2 3 4 5 6 7 8 9

03.01 4.65 4.72 4.54 4.45 4.55 4.50 6.99 4.38

10.01 4.37 4.44 4.47 4.36 4.61 4.48 4.48 4.17

17.01 4.58 4.61 4.49 4.32 4.66 4.60 4.55 6.08 4.43

24.01 6.19 4.32 4.37 4.25 4.42 4.62 4.71 6.18 4.30

31.01 5.90 4.80 4.22 4.44 4.72 6.37 5.09

07.02 5.87 4.37 4.77 4.34 4.97 5.28 6.52 4.47

14.02 6.09 4.37 4.89 4.66 5.29 4.64 5.44 6.63 4.68

21.02 4.78 4.51 4.48 4.63 4.62 5.69

28.02 4.35 4.66 4.39 4.30 4.48 4.36 4.39 6.45 4.42

07.03 4.46 4.35 4.16 4.28 4.43 4.44 4.48 4.47 4.34

14.03 4.41 4.59 6.00 4.18 4.50 4.26 4.36 4.48 4.28

21.03 4.36 4.29 4.28 4.78 4.39 4.10 4.27 4.53 4.31

28.03 4.40 4.28 4.37 4.35

04.04 4.40 4.23 4.19 4.23 4.47 4.93 4.23 4.31 4.27

11.04 4.24 4.24 4.45 4.10 4.34 4.30 4.21 4.03 3.97

18.04 3.84 4.24 4.08 3.96 4.04 4.02 4.10 6.04 4.11

25.04 4.35 4.32 4.55 4.02 4.04 6.16 4.16 5.56 3.94

02.05 4.04 4.06 4.73 5.44 6.31 4.84 4.26

09.05

16.05 6.07 5.77 6.38 5.78 7.34 7.36 5.42 5.18

23.05 4.09 4.12 5.90 8.05 4.55

30.05 3.65 3.97 5.33 4.10 4.32 6.93 3.69 3.72 3.80

06.06 4.50 5.20 7.08 4.74 5.02 4.19

13.06 5.77 4.18 6.70 4.59 4.38 5.80 4.52 4.06 4.00

20.06 6.37 4.06 4.21 3.87 3.86

27.06 6.06 4.90 6.04 4.91 6.85 7.06 5.95 5.73



Table 2.2: Acid Deposition Data, Sites 1 to 9: July - December

SITE/WEEK ENDING

1 2 3 4 5 6 7 8 9

04.07 4.37 4.15

11.07 5.00 4.14 5.58 4.37

18.07

25.07 4.35 4.24 4.43 3.95 4.21

01.08 5.83 5.27 6.93 5.82 7.14 7.05 6.76 4.73

08.08

15.08 4.70 4.32 6.48 5.50 6.92 4.51

22.08 5.33 4.28 6.40 4.45 6.16 4.51 7.50

29.08 4.38 4.25 5.25 4.52 6.06 4.20

05.09 4.71 4.92 4.0 5.52

12.09 3.89 4.47 4.25 4.29 4.04

19.09 4.25 4.06 5.01 4.49 5.39 5.26 7.15 4.00

26.09 4.55 4.12 6.00 4.17 4.53 4.05

03.10 4.08 4.22 3.91

10.10 5.01 4.33 4.74 4.30 6.40 4.53 4.53 4.34

17.10 4.48 4.61 5.88 4.31 4.36 4.71 4.16

24.10 4.48 4.56 6.31 4.29 4.57 4.49 4.46 4.55

31.10 4.35 4.27 4.23 4.20 4.71 4.14

07.11 4.23 4.25 4.97 4.14 4.23 4.24 4.09

14.11 4.04 4.06 3.95 4.16 4.11 4.15 4.18 4.13

21.11 4.19 4.44 3.77

28.11

05.12

12.12 4.01 3.91

19.12 4.29 4.23 4.92 4.33 4.23 4.21

27.12



Table 2.3: Acid Deposition Data, Sites 10 to 18: January - June

SITE/WEEK ENDING

10 11 12 13 14 15 16 17 18

03.01 4.51 4.49 4.74 4.46 4.14 4.37 4.73 4.95 4.35

10.01 4.31 4.26 4.66 4.21 4.58 4.42 4.52 4.72 4.27

17.01 4.62 4.67 5.84 5.10 5.45 4.27 4.94 5.17 4.63

24.01 4.88 4.56 6.13 4.41 4.55 4.35 4.82 4.91 4.35

31.01 5.67 5.95 6.34 6.13 5.93 5.07 5.46 5.55 4.29

07.02 4.65 4.52 6.38 4.57 6.32 4.70 5.03 5.31 4.64

14.02 4.95 4.61 6.75 4.85 6.28 4.44 4.80 5.03 5.69

21.02 5.15 5.88 5.51 5.87 4.37 4.53 5.47 4.63

28.02 4.55 4.52 4.76 4.45 5.63 4.39 4.46 4.60 4.34

07.03 4.31 4.41 6.73 4.27 4.45 4.37 4.47 4.62 4.32

14.03 4.33 4.20 6.53 4.39 4.57 3.95 4.50 5.02 4.28

21.03 4.62 4.77 5.93 4.65 4.68 4.18 4.38 4.34 4.27

28.03 4.60 4.82

04.04 4.46 5.42 4.55 4.85 4.26 4.66 4.34

11.04 3.97 4.14 4.15 4.04 4.10 4.03 3.98 4.56 3.95

18.04 4.01 4.04 4.04 3.90 4.04 3.90 3.91 4.56 4.07

25.04 3.92 3.95 4.65 4.25 4.32 4.14 4.27 4.80 4.01

02.05 4.37 4.44 6.01 4.35 4.85 4.20 4.39 4.77 4.13

09.05

16.05 4.38 6.87 4.58 6.14 4.38 7.47 6.69 4.20

23.05 4.95 4.25 4.68 4.17 4.59 5.27

30.05 3.78 3.93 3.96 3.73 4.10 4.28 3.82

06.06 4.27 4.72 6.66 4.42 6.13 4.59 4.45 6.93 4.36

13.06 4.62 4.31 4.43 4.35 4.18 4.11 4.37 5.12 3.93

20.06 4.02 4.20 4.86 5.02 5.44 3.77

27.06 6.17 6.39 6.85 6.05 6.38 4.90 6.44 6.28 4.91



Table 2.4: Acid Deposition Data, Sites 10 to 18: July - December

SITE/WEEK ENDING

10 11 12 13 14 15 16 17 18

04.07 4.41 4.55 4.56 4.71 4.21 4.64 4.31

11.07 4.33 6.47 4.14 4.36 5.22 3.97

18.07

25.07 4.45

01.08 5.38 5.55 6.54 5.52 5.03 4.21 6.79 6.70 4.60

08.08 5.46

15.08 6.47 6.16 6.39 5.29 5.53 4.61 5.69 5.32 4.49

22.08 5.36 5.02 5.91 4.74 4.38

29.08 4.25 4.27 3.21 4.09 4.62 3.82 6.80 5.75 4.04

05.09 4.95 5.15 4.59 5.01 4.27 4.24 5.74 5.37

12.09 4.43 5.29 4.08 4.26 3.59

19.09 4.04 4.20 5.15 4.18 4.25 3.95 4.18 4.11 3.91

26.09 4.55 4.32 6.40 3.89 4.46 3.96 4.57 6.95 4.05

03.10

10.10 4.60 4.43 6.42 4.23 4.17 4.30 4.56 4.21

17.10 4.67 4.17 5.85 4.00 3.96 6.62 4.32 5.68 4.00

24.10 4.52 4.69 5.62 4.68 4.59 6.00 4.47 4.59 4.54

31.10 4.26 4.09 4.50 4.02 4.09 4.56 4.21 4.34 4.06

07.11 4.12 4.27 4.26 4.24 4.05 4.15 4.13 5.08 5.65

14.11 4.13 4.04 4.12 4.13 4.03 4.18 4.01 4.00 4.19

21.11 4.46

28.11

05.12

12.12 4.02 3.97 5.70 4.10 4.00 3.67 3.95 3.71

19.12 4.04 3.98 4.55 4.01 4.04 4.22 3.97

27.12 4.17



Table 2.5: Meteorological Data, Manchester: January - June

Week Ending

Prevailing wind direction

Prevailing wind direction bringing rain

Wind speed (knots)

Total rainfall (mm)

03.01 S W 8.0 8.1

10.01 S S 8.6 9.8

17.01 WSW WSW 11.2 14.8

24.01 S NW 8.0 10.4

31.01 S W 10.0 3.6

07.02 SSW W 10.4 5.6

14.02 SSE SSW 10.5 6.2

21.02 W SW 12.7 29.0

28.02 S E 8.7 36.2

07.03 SW W 10.3 14.0

14.03 S SW 11.6 10.2

21.03 S S 9.6 21.28

28.03 W SSW 12.2 26.6

04.04 E E 8.7 19.0

11.04 NE SSW 8.7 21.4

18.04 SSW NNE 9.2 2.6

25.04 NNE SSE 5.5 14.8

02.05 S SSE 6.9 5.6

09.05 S no rain 4.7 0.0

16.05 W SSW 7.2 9.6

23.05 SSW WSW 6.9 3.2

30.05 NE NNW 5.7 13.6

06.06 ENE W 6.0 12.8

13.06 S SW 6.2 13.8

20.06 NW S 5.1 0.4

27.06 NW no rain 6.8 0.0



Table 2.6: Meteorological Data, Manchester: July - December

Week Ending

Prevailing wind direction

Prevailing wind direction bringing rain

Wind speed (knots)

Total rainfall (mm)

04.07 NW SSE 7.3 66.8

11.07 NNE NNE 6.2 12.4

18.07 NW W 6.4 1.6

25.07 NW no rain 4.9 0.0

01.08 S WSW 6.9 17.2

08.08 NW WNW 5.0 1.8

15.08 SSW SW 10.0 6.0

22.08 SSW S 9.1 7.8

29.08 W W 6.8 15.4

05.09 SSW W 6.3 11.0

12.09 NE WSW 7.1 0.2

19.09 WSW NE 6.2 5.8

26.09 S NE 8.7 12.2

03.10 NW W 4.1 0.4

10.10 NW W 6.8 13.6

17.10 WSW WSW 7.0 15.4

24.10 S SSE 9.1 28.6

31.10 SSW WSW 9.3 20.8

07.11 S S 8.5 23.6

14.11 S NNW 7.4 39.2

21.11 ESE E 6.4 1.8

28.11 NE SE 4.8 0.4

05.12 NE NE 2.9 0.4

12.12 NNE SSE 2.3 0.8

19.12 NE NE 9.7 39.4

26.12 S S 11.1 32.8



Group Exercises 1. Using OS map sheets 109 and 110, scale 1:50,000, of

Manchester, locate the 18 sites on the maps with map pins or sticky labels.

2. By studying the OS maps, try and identify point sources of

pollution from industry, power stations and highly trafficked areas. Locate the potential sources of air pollution with map pins or labels.

3. Choose three sites which roughly fall along a transect of the

Greater Manchester conurbation. Using tracing paper, mark contour heights along the transect line and plot a graph of the topography of the transect. Which of the sites along your transect would you expect to receive the most rainfall per annum? Give reasons for your choice.

4. The following table gives the mean hydrogen ion value for

each of the 18 sites in Greater Manchester. (Remember that the higher the H+ ion content, the more acid the rainwater.)

Locate the mean H+ µeql-1 for the appropriate site onto your transect. Annotate your transect with details of possible point sources of pollutants. Does there appear to be any relationship between altitude and rainwater acidity or between possible pollutant sources and rainwater acidity?



Site Mean H+ ion µeql-1

Jan-Dec 1989 Number of observations

1 40 40 2 48 43 3 32 31 4 50 28 5 32 39 6 34 38 7 39 37 8 32 23 9 64 37 10 48 37 11 45 40 12 33* 38 13 50 41 14 35 37 15 62 35 16 40 46 17 19 39 18 71 41

* Site 12, Manchester City Centre may appear to have less acid rainfall than may be expected for a city centre location. This is likely to be due to the extensive building work being carried out near the collector site during 1989. Building dust has a neutralising effect on acidifying gases and particles.

5. There are many factors which affect the acidity of rainfall. Discuss within your group how the following conditions may affect the acidity of rain. Use the corresponding meteorological data with the rainfall acidity data as this may help you to identify possible relationships between rainfall acidity and climatic conditions.

• = local sources of pollution • = long range transport of air pollutants • = wind direction • = wind direction bringing precipitation • = temperature



• = wind speed • = atmospheric pressure • = amount of precipitation.

Individual Exercises 1. Plot a graph of the weekly pH readings for any one of the 18

sites, for the January to December period. Give reasons why the rainfall pH might differ from week to week.

2. Convert the weekly pH readings to hydrogen ion readings for

the same site as in 1) above. Plot a graph of this data and compare this graph with your graph from 1) above. Which graph makes it easier to identify acid rain events? Give reasons for this. Does there appear to be any seasonal variation? Comment on whether you would or would not expect to identify seasonal variation.

3. Identify the weeks with the most acidic rainfall and the least

acidic rainfall for each of the 18 sites. Did each site experience its most acidic or least acidic event during the same week? Give reasons to support your conclusions.



Site Most acidic week,

week ending (pH) Least acidic week, week ending (pH)

1 30th May (3.65) 24th Jan (6.19) 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

4. Identify the weeks where there was obviously little or no

rainfall. Do the pH readings for the week following each dry period suggest a particularly acid or alkaline collection of rainfall?

During the week ending 30th May, the prevailing wind direction was north easterly and wind speeds were low. How might these conditions have contributed to the acidic results recorded?

5. Identify the most acidic reading during the year for one of the

18 sites. Convert the pH reading to the equivalent hydrogen ion value using the formula:

H+ µeql-1 = antilog (6.0 - pH)



How many times more acid is this reading than ‘unpolluted’ rain with pH 5.6 which has a H+ µeql-1 of 3?

6. Choose one of the 18 Greater Manchester sites. How many

times did the pH fall below pH 4.00 during the year 1989? Which season had the highest number of events with pH <4.00 for the site chosen? (Take Jan, Feb, Mar as winter; Apr, May, Jun as spring; Jul, Aug, Sep as summer and Oct, Nov, Dec as autumn). Try and explain your findings. How does this compare with your answers to question 2?

7. Refer to the description of the acid rain collector and the siting

requirements of the collector. Why do you think the collector has to be so specifically designed? Why would it be important for the collector to be sited away from buildings, roads, trees and other sources of pollution?

8. In the environment there are many contaminants that could

affect the acidity of precipitation collected in the rain collector. List as many of these as you can think of and explain how these contaminants may get into the funnel of the collector. For each contaminant, state whether you would expect it to make the rainwater more acid or more alkaline.



THE CZECH REPUBLIC Background Information Since 1st January 1993, the Czech Republic has become a separate state along with Slovakia, both states being previously known as Czechoslovakia. Key Facts on the Czech Republic Population: 10.3 million (2001) Size: 78 866km2 Capital: Prague (1.2m population) Neighbours: Germany, Austria, Slovakia, Poland Climate: Four seasons, coldest January (-2°C), warmest July (20°C) Average altitude: 450m above sea level Air Quality: Generally poor, particularly during winter months Acid Deposition: One of the highest acid deposition levels in Europe



Source: The Perry-Castañeda Library Map Collection, The General Libraries, The University of Texas at Austin, Austin, TX 78713-8916, USA

Acidic Pollutant Emissions The main acidic pollutants are sulphur dioxide and oxides of nitrogen and during 1998, the Czech Republic emitted 0.44 million tonnes of sulphur dioxide and 0.41 million tonnes of nitrogen oxides. This is a sizeable output considering the relatively small population of 10.3 million, although sulphur dioxide emissions have fallen by 76% since 1990. Emissions of nitrogen oxides have also been falling in the Czech Republic, by nearly half between 1990 and 1998. Nevertheless, air quality in Czech Republic is still considered to be a problem.



The Czech Republic is an important industrial nation in Europe with its main economic sector being industry, employing more than 2 million and generating 62% of national income. There are several heavily polluted areas within the Czech Republic, such that a large percentage of the population live in severely polluted air. In Prague, winter concentrations of sulphur dioxide and particulates can be more than twice the World Health Organisation (WHO) Air Quality Guidelines (AQG). At these times the long term guidelines set by WHO for exposure to these pollutants are exceeded. The most polluted area of the Czech Republic is in northern Bohemia which stretches for 60km from Chutomov to Literomice (see map). Here, power stations are fuelled by lignite, otherwise known as brown coal, which has a high sulphur content and when burnt produces large quantities of sulphur dioxide. Additionally, because the coal has a low calorific value, large quantities are required to obtain the power. The low energy value of the coal also means that it has to be burnt near the mines. Hence the industrial areas are situated in the valley of the Ore Mountains where mining takes up almost 10 000 hectares of land. The towns in the valleys of northern Bohemia are further troubled by temperature inversions which trap the pollutants in the cold air of the valley bottom. This prevents normal air currents from dispersing the pollutants. The towns become enveloped in a cold and smelly smog, whereas up on the hill tops the air is warm and clear. The valley is thus known as the Bohemian basin. Acidic Pollutant Depositions The Czech Republic also receives acidic pollutants from other countries, as shown in Table 3.1.



Table 3.1: Originating countries of sulphur deposition on Czech Republic

Country Sulphur Deposition, 000 tonnes 1998 (weight of sulphur)

Czech Republic 45.3 Slovakia 3.3 Germany 31.3 Poland 28.9 France 3.0 UK 2.0 Hungary 6.9 Others 22.5 Total sulphur deposition 143.2

Total deposition of sulphur on the Czech Republic during 1998 was around 0.14 million tonnes (by weight of sulphur). When this is compared to the amount that is emitted in the Czech Republic (0.44 million tonnes of sulphur dioxide or 0.22 million tonnes of sulphur, 1998) it becomes apparent that much of the sulphur produced within the Republic is transported to other countries. Most of this pollution is exported to Poland, Germany, and the Russian Federation, as shown in Table 3.2.

Table 3.2. Selected countries receiving sulphur from the Czech Republic (1998)

Country receiving sulphur pollution from Czech Republic

Sulphur deposition, ‘000 tonnes, originating from Czech Republic (weight of sulphur)

Poland 39.2 Germany 20.6 Russian Federation 15.1 Ukraine 10.4 Austria 4.9 Slovakia 5.6



The Czech Republic, along with other countries in the industrialised zone from Poland through to Germany, the Benelux countries to the UK, receive the highest levels of acid deposition in Europe. In the Czech Republic industrial sources of sulphur and nitrogen oxides account for the major emission sources, whilst in the UK for example vehicles are a more important source of nitrogen oxides due to much higher car ownership. Effects of Acid Deposition on Forests Around one third of the Czech Republic is covered in forest and so timber is a major economic resource. The high levels of acid deposition experienced over recent decades have had serious damaging effects on both broadleaf and coniferous trees in the Czech Republic. The European Forest Damage Survey results for 2000 show that 52% of all trees in the Czech Republic are classified as moderately to severely damaged (trees with more than 25% loss of leaves or needles). The trees most affected are Norway spruce (Picea abies) in the mountainous area of the country where soil acidification and acidic deposition have resulted in the loss of 100,000 hectares of forest. Trees aged over sixty years are particularly vulnerable and all trees on the forested areas of the Ore mountains and other land over 800m altitude have been affected by sulphur dioxide. The trees are additionally stressed on occasion with extreme climatic conditions. The problem of acidification was first observed by foresters in the 1960s and 1970s when individual spruces died and crown thinning of older trees became apparent. The damage is now spreading to the valleys and is also affecting deciduous trees. More resistant species of spruce such as Picea pungens are being planted where trees have died and other areas are being replaced by grassy meadows.



Effects of Acid Deposition on Water Water supplies in many parts of the Czech Republic are already severely polluted as a result of poor sewage treatment, industrial effluent and artificial fertilisers. The severe soil acidification problems often lead to higher pH levels in groundwaters in the Czech Republic. Surface water acidification can be expected when acid deposition levels are high and the bedrock is sensitive to acid deposition (i.e. there is little buffering capacity). Lakes and rivers in the mountainous Erzgebirge forested areas have been identified as acidic as a result of high acid deposition levels and sandy soils with low buffering capacity. Effects of Acid Deposition on Buildings Many of the buildings in the Czech Republic have become blackened by air pollutants and corrosion is occurring at faster rates than through normal weathering. In the capital city of Prague, there are more than 200 large emission sources in addition to small sources and motor vehicles which contribute to the pollution. The highest concentrations of pollutants are recorded in the historical core of the city in the ‘Old Town’ due to a combination of factors including topography and emission source locations. This air pollution causes high economic losses through accelerated corrosion on buildings in Prague and other buildings in the Czech Republic. Effects of Acid Deposition on Health The human health effects from air pollution and acidification are evident in the Czech Republic. Since the 1960s, air pollution has become an increasing problem affecting health. During smog



conditions, hospital admissions increase, most relating to respiratory diseases. Those most at risk are the young, the elderly and asthmatics. Life expectancy and infant mortality appear to be affected in areas associated with high levels of air pollutants. In northern Bohemia high levels of air pollutants are associated with high numbers of bronchial diseases. During February 1993, winter smog conditions occurred in northern Bohemia and daily mean concentrations of 825µgm-3 sulphur dioxide and 480µgm-3 particulates were recorded. These levels exceed World Health Organisation AQGs by around 4 times indicating the severity of the air quality in this region. Control and Policy The Czech Republic are committed to reducing sulphur emissions through the 1994 UNECE Protocol ‘Further Reduction of Sulphur Emissions’. This Protocol requires the Czech Republic to reduce sulphur emissions by 50% by the year 2000, 60% by 2005 and 72% by 2010 (all based on 1980 levels). To date, the country is on target to achieve this level of emissions reduction. The Government has also introduced counter measures to reduce air pollution during smog conditions. These include limiting car use and the use of high quality coal in power stations at such times.



FINLAND Key facts on Finland Population: 5.2 million (1999) Size: 304 529km2 Capital: Helsinki (0.55 million population) Neighbours: Norway, Sweden, Russian Federation Climate: Temperate January (-10°C), July (15°C) Land use: Forest 65%, agriculture 8%, water 10%, other 17% Altitude: 152m (average) Air Quality: Generally good, but potential conditions for winter smogs in cities where vehicles contribute large amounts of nitrogen oxides to the atmosphere Acid Deposition: Amongst the lowest acid deposition levels in Europe. Surface water acidification is a serious problem.



Source: The Perry-Castañeda Library Map Collection, The General Libraries, The

University of Texas at Austin, Austin, TX 78713-8916, USA Acidic Pollutant Emissions The main acidic pollutants are sulphur dioxide and oxides of nitrogen, and during 1998 Finland emitted 0.09 million tonnes of sulphur dioxide and 0.25 million tonnes of nitrogen oxides (as NO2). Nitrogen oxides are hence the major acidifying pollutants in Finland and these emissions mainly arise from road transport. The air quality



in Finland can be poor in the cities due to the number of vehicles although in the more rural areas there are few large industrial sources of air pollution. Emissions of both sulphurous and nitrous pollutants are falling in Finland but the reduction in nitrogen oxides is very slight as shown in Table 3.3.

Table 3.3: Emissions of Acidifying Air Pollutants in Finland

Pollutant Emissions 1990

Emissions 1998

% reduction

Sulphur dioxide (‘000 tonnes)

260 90 65

Nitrogen oxides (‘000 tonnes)

300 252 16

Around one third of total electricity in Finland is used in the paper and pulp industry which is an important industry within Finland. Acidic Pollutant Depositions Air pollutants deposited on Finland originate from other countries as well, as shown in Table 3.4. Table 3.4: The Originating Countries of Sulphur and Nitrogen Deposition

on Finland

Country Sulphur Deposition, ‘000 tonnes 1998 (weight of sulphur)

Nitrogen deposition ‘000 tonnes 1998 (weight of nitrogen)

Finland 20.5 19.1 Russian Federation 34.8 6.1 Poland 11.0 2.8 Germany 6.3 3.6 Others 48.3 34.0 Total deposition 120.9 65.6



Total deposition of sulphur on Finland during 1998 was around 0.12 million tonnes whereas the amount emitted in Finland was less (0.09 million tonnes sulphur dioxide or 0.045 million tonnes sulphur, 1998). This highlights that Finland receives more sulphur pollution than originates there. However, Finland exports a significant proportion of sulphurous and nitrous pollutants to other countries, mainly the Russian Federation and Sweden and to the Baltic Sea and Atlantic Ocean. Finland does not generally experience high levels of acid deposition although when south westerly winds occur deposition levels increase as pollutants are transported from central Europe. Effects of Acid Deposition on Forests Although the level of acid deposition is less in Finland than in many other European countries, the areas of rocky and barren land with thin soils, plus the climate, make Finland particularly susceptible to damage from air pollution. With the economy of Finland being dependent upon forestry, air pollution is considered to be a serious problem. Forests cover 2.6 million hectares of Finland, of which 2 million hectares are productive forest. Acid deposition is known to wash essential nutrients such as calcium, potassium and magnesium from soils, and aluminium which is normally bound in the soil may be released into ground water. Soil acidification may affect the health of trees. In the 2000 Forest Damage Survey, 12% of all trees were classified as moderately to severely damaged (more than 25% loss of needles or leaves). Annual surveys have shown a decrease in trees in the moderate to severely damaged category since 1989 when 18% were recorded in this category.



The problem of acidification appears to be affecting older trees in northern Finland where the climate is also harsher. Norway spruce (Picea abies) trees in southern Finland have shown discolouration which significantly correlates with modelled air pollution depositions. Pollution sensitive beard lichens have also become sparser in the southern region which indicates the effects of air pollution. Effects of Acid Deposition on Water Water covers 10% of Finland and, relative to its size, Finland has more lakes than any other country. Acidification studies in Finland have shown that freshwater acidification is a serious problem in this country. Lake pH values have fallen in three out of four lakes studied and approximately 10% of 1000 lakes studied were seriously affected. Acidification has been shown to gradually increase from 1915 to 1950, to rapidly increase between 1950 and 1980 and generally to have since remained unchanged, possibly due to reductions of pollutants in most European countries. Some smaller forest lakes have become more acidic through acid deposition. No lakes in Finland have been found to be fishless but several have lost gastropods, lamellibranches and many crustacean species. Spring snow melts, flushing acid waters into lakes and streams, have led to low stocks of fish in the acid lakes in southern Finland. Effects of Acid Deposition on Buildings Many of the buildings in the capital city of Helsinki and other towns and cities in the country are likely to experience accelerated



corrosion due to the high levels of vehicle pollutants emitted from transport in urban areas. Effects of Acid Deposition on Health The human health effects from air pollution and acidification are not serious in Finland. However, in large urban areas such as Helsinki, concentrations of air pollutants may be sufficient, particularly during winter months, to cause aggravation to those most vulnerable to air pollution, such as asthmatics. Groundwater quality may also be reduced by the leaching of metals such as aluminium from soils. Control and Policy Finland is committed to reducing sulphur emissions through the 1994 UNECE Protocol ‘Further Reduction of Sulphur Emissions’. This protocol requires Finland to reduce sulphur emissions by 80% by year 2000 (on 1980 levels). Emissions of sulphur dioxide in Finland have fallen dramatically in the last 20 years and this commitment has been met. Finland is also a Party to the Gothenburg Protocol, designed to Abate Acidification, Eutrophication and Ground-level Ozone. Finalnd is committed to reducing 1990 emissions of sulphur dioxide by 75% by 2010 and nitrogen oxides by 50% over the same period.



UNITED KINGDOM Key facts on United Kingdom Population: 59.7 million (2000) Size: 244 014 km2 Capital: London (7.2 million population in Greater London) Neighbours: Ireland Climate: Marine West Coast, January (2-7°C), July (13-18°C) Land use: Agriculture 77%, forest 10%, urban 10% Altitude: 0-800m above sea level Air Quality: Generally good in rural areas but ozone levels may be high during summer months. High emissions of acidic pollutants in large urban areas from industry and transport lead to potentially poor air quality. Acid Deposition: Amongst the highest acid deposition levels in Europe, particularly in eastern England.



Acidic Pollutant Emissions In the 1980s, the UK was described by Scandinavian countries as ‘the dirty old man of Europe’ due to high emissions of sulphur dioxide from industrial sources. Emissions of sulphur dioxide and oxides of nitrogen have since been reduced, resulting in emissions of 1.2 million tonnes of sulphur dioxide and 1.6 million tonnes of nitrogen oxides (as NO2) in the UK during 1999. However, these amounts are still considerable compared to other European countries. Most of the UK sulphur dioxide comes from power stations (65% in 1999) and other industries (22% in 1999) whilst the largest source of nitrogen oxides is road transport (44% in 1999) and power stations (21% in 1999). Total emissions of sulphurous and nitrogen oxides in 1990 and 1999 and their reductions over this time are shown in Table 3.5.

Table 3.5: Emissions of Acidifying Air Pollutants in UK

Pollutant Emissions 1990 Emissions 1999 % reduction Sulphur ‘000 tonnes

3754 1187 68

Nitrogen oxides ‘000 tonnes

2761 1605 42

Reductions in UK sulphur dioxide have occurred largely through the reduction in use of coal by power stations and the installation of control technologies such as flue gas desulphurisation at Drax power station. Emissions of nitrogen oxides have also reduced from power stations as a result of increasing generation from Combined Cycle Gas Turbine and decreasing use of coal. Emissions from vehicles have slowly been falling since 1989 through increasing use of diesel fuel and the introduction of catalytic converters to all petrol engined cars sold since 1993. Increasing car ownership.has meant



that the reduction in nitrogen oxides emissions has not been as rapid as that fo sulphur dioxide. Acidic Pollutant Depositions Air pollutants deposited on the UK originate not only from the UK but from other countries as well, as shown in Table 3.6. Table 3.6: The Originating Countries of Sulphur and Nitrogen Deposition

on UK

Country of pollution origin

Sulphur deposition on UK, ‘000 tonnes 1998 (weight of sulphur)

Nitrogen deposition on UK, ‘000 tonnes 1998 (weight of nitrogen)

UK 248.6 100.9 France 7.2 8.5 Germany 5.2 5.1 Italy 0.4 0.4 Others 66.7 55.0 Total deposition 328.1 169.9

Total deposition of sulphur on UK during 1998 was around 0.33 million tonnes whereas the amount emitted in UK was more (1.19 million tonnes sulphur dioxide or 0.59 million tonnes sulphur, 1999). This highlights that the UK emits more sulphur pollution than is deposited in the UK. A significant proportion of sulphurous and nitrous pollutants are hence exported to other countries, mainly Germany, France, Norway, Sweden, the Netherlands and the Russian Federation in addition to the North Sea and Atlantic Ocean. The wind direction is the main factor affecting where UK pollutants are deposited. The UK generally experiences high levels of acid deposition due to the large quantities of acidic pollutants emitted into the atmosphere each year.



Effects of Acid Deposition on Forests In 2000, the United Nations Economic Commission for Europe (UNECE) Forest Survey revealed that 22% of UK trees were damaged (with 25% or more leaf or needle loss). Both coniferous and broadleaf trees showed the same degree of damage. Damage cannot be attributed to air pollution alone as many other factors such as climatic conditions, pests, age of tree, and exposure need to be considered. However, air pollution may cause an additional stress to trees and therefore may be a direct or indirect factor affecting tree health. The commercial forest areas in the UK are mainly located in northern and western Britain where acid deposition is high due to higher levels of precipitation, mist and cloud. These areas of the UK are also particularly sensitive to acid deposition due to their granite-based bedrock offering low buffering capacity. Trees in these areas are more vulnerable to the effects of acid precipitation and air pollution Effects of Acid Deposition on Water Acidification studies in UK have shown that freshwater acidification is a serious problem in susceptible parts of the UK. These include central and south west Scotland, the Pennines, parts of Cumbria, central and North Wales and parts of Northern Ireland. Some lakes within these areas are acidified to the extent that they can no longer support many fish species. Diatom analysis from lake sediments has shown that lake acidification has occurred in some UK freshwaters, with most rapid pH changes occurring since the 1950s. Freshwaters that have been intensively studied include Lyn Brianne in Wales and Loch Fleet in south west Scotland. The sensitivity of freshwaters in the UK has been studied and critical loads have been determined for areas of



the UK. Critical loads are the amounts of acidic pollutants that an area can tolerate before damage occurs. Many areas of the UK already exceed such levels, although since the 1970s there is evidence that a recovery has taken place in response to significant reductions in emissions of sulphur dioxide. Effects of Acid Deposition on Buildings Acid deposition is known to accelerate normal weathering effects on buildings. Certain stone such as limestone, calcareous sandstone and marble have been shown to deteriorate faster through exposure to acid precipitation. Individual pollutants such as sulphur dioxide have effects on building materials, but pollutants can also act synergistically; nitrogen oxides and ozone may increase the effects of sulphur dioxide attack on certain materials. On limestone, a black crust may form as pollutants react with the stone. This can accelerate damage as frost and other weather conditions cause this crust to blister and peel. Many historic monuments and buildings are affected by air pollution in the UK and studies of cathedrals such as Lincoln and St. Paul’s highlight that aspect and position are important factors in determining corrosion rates on historical buildings. The cost of damage to buildings is very difficult to estimate but includes costs of restoration to historic buildings which amounts to millions of pounds per year. Effects of Acid Deposition on Health The human health effects from acid deposition are not serious in the UK. Indirect effects may occur if ground or surface waters are contaminated by heavy metals leached from soils as a result of



acidification. Health effects may occur as a result of the acidic pollutants in acid precipitation. Back in the 1950s, the famous London smogs highlighted the serious nature of the effects of acidic pollutants on human health. 4,000 excess deaths were attributed to the effects of sulphur dioxide and particulate pollution during the December 1952 smog. Since then, smoke and sulphur dioxide levels have fallen considerably and such smogs are now history. However, the UK does experience poor air quality episodes under certain climatic conditions which are sometimes classified by the UK Department of the Environment as “poor” air quality. Often such conditions occur during the summer months when photochemical reactions cause nitrogen oxides and hydrocarbons (mainly from traffic sources) to produce ozone. This can cause breathing difficulties amongst, for example, asthmatics. During different meteorological conditions such as temperature inversions, “poor” air quality may also occur when sulphurous and nitrous oxides build up in the atmosphere. Control and Policy The UK is committed to reducing sulphur emissions through the 1994 UNECE Protocol ‘Further Reduction of Sulphur Emissions’. This protocol requires UK to reduce sulphur emissions by 50% by year 2000, 70% by 2005 and 80% by 2010 (all on 1980 levels). Emissions of sulphur dioxide in the UK have fallen dramatically in the last 20 years and this commitment has been met. The UK is also a Party to the Gothenburg Protocol, designed to Abate Acidification, Eutrophication and Ground-level Ozone. The UK is committed to reducing 1990 emissions of sulphur dioxide by 75% by 2010 and nitrogen oxides by 50% over the same period.



A 1988 Directive for European Union countries has also been introduced; it require all member countries to reduce emissions of sulphur dioxide and nitrogen oxides from Large Combustion Plants (over 50MW in size) by varying percentages. The UK is required to reduce sulphur dioxide by 60% by 2003 and nitrogen oxides by 30% by 1998 (on 1980 levels). The UK has met or is well on course to achieve both of these targets, through new gas-fired power stations which produce smaller quantities of acidic pollutants than conventional coal fired stations, and flue gas desulphurisation equipment fitted to Drax and Ratcliffe on Soar power stations. All petrol engined vehicles sold in EU countries since January 1993 have to be fitted with a catalytic converter. Catalytic converters reduce nitrogen oxide emissions from vehicles considerably compared with non-catalyst cars. However, there are still many non-catalyst cars in the UK and the increasing number of vehicles registered each year is likely to ensure that vehicular pollutants remain a major source of acidic pollution in the UK. The introduction of the UK National Air Quality Strategy in March 1997 (and updated in 2000) is intended to achieve new air quality objectives throughout the UK by 2005, and hence improve air quality. The proposed standards and objectives of acid deposition pollutants under this new Strategy are shown in Table 3.7.



Table 3.7: The Proposed Standards and Objectives for Acid Deposition Pollutants in the UK National Air Quality Strategy

Pollutant Standard

concentration (parts per billion)

Measured as Objective - to be

achieved by:

nitrogen dioxide

105 ppb not to be exceeded more than

18 times per year 21 ppb

1 hour mean

annual mean

31.12.05

31.12.05

sulphur dioxide

132 ppb 47 ppb

100 ppb

1 hour mean 24 hour mean

15 minute mean

31.12.04 31.12.04 31.12.05

The National Air Quality Strategy standards and objectives will require reductions in emissions from sources throughout the UK if the objectives are to be met. This should form the basis for less acidic pollution in the UK over the coming years.



CANADA Key facts on Canada Population: 30.0 million (2001) Size: 9 970 610 km2 Capital: Ottawa Neighbours: United States of America, Alaska Climate: Cool temperate, polar in far north; January (-30 to -5°C), July (10-20°C) Altitude: 0-3000+m above sea level Air Quality: Generally good in rural areas but ozone levels may be high during summer months. High emissions of acidic pollutants in large urban areas from industry and transport can lead to poor air quality. Acid Deposition: Eastern Canada is most sensitive to the effects of acid deposition because of its thin granitic soil. The sensitive area covers 43% of Canada, over 4 million km2. Most of the emission sources are also located in the east of the country.



Source: The Perry-Castañeda Library Map Collection, The General Libraries, The

University of Texas at Austin, Austin, TX 78713-8916, USA Acidic Pollutant Emissions The major sources of acidifying pollutants in Canada arise from human activities. The largest source of sulphur dioxide in Canada is from metal ore smelting and fossil fuel power generation whilst most of the nitrogen oxides arise from transport and industry. Emissions of sulphur dioxide have been falling over recent years, resulting in emissions of 2.7 million tonnes of sulphur dioxide in 1995, a 41% reduction from 1980. Emissions of nitrogen oxides remained fairly static at around 2 million tonnes between 1980 and 1995. Canadian emissions of sulphurous and nitrogen oxides are considerable but are less than the emissions from countries such as Germany, the



UK, the Russian Federation and the United States of America. Emissions of sulphur dioxide from the neighbouring USA totalled approximately 16 million tonnes in 1995. Most of the sulphur dioxide in Canada comes from metal ore smelting and other industrial sources (61% in 1995) and power generation (21% in 1995). The major source of nitrogen oxides in Canada is transport (59% in 1995). Total emissions of sulphurous and nitrogen oxides in 1980 and 1994 and their reductions over this time are shown in Table 3.8.

Table 3.8: Emissions of Acidifying Air Pollutants in Canada

Pollutant Emissions 1980 Emissions 1995 % reduction Sulphur dioxide ‘000 tonnes

4600 2700 41

Nitrogen oxides ‘000 tonnes

2000 2000 0

Reductions in Canadian sulphur dioxide have occurred largely as a result of industrial process changes, installation of scrubbers, and fuel switching in the 1990s. Emission reductions of nitrogen oxides are being sought by the introduction of more stringent performance standards on exhaust emissions from new vehicles. Acidic Pollutant Depositions Fifty per cent of acid deposition in eastern Canada is estimated to originate from sources in the USA. Because of prevailing southerly winds during summer months, much of the pollution from the USA is exported to Canada. Some pollutants from Canada are transported to the US but on balance, Canada receives much more pollution than it exports. The import / export of pollutants across the border has therefore made acid rain a serious diplomatic issue between the



US and Canada. The problem is compounded by the fact that the states in the US that are most heavily populated and have high air pollution emissions are located south of the sensitive eastern regions of Canada. In a country as large as Canada, long range transport of pollutants means that pollutants emitted in one part of the country may be deposited hundreds or thousands of kilometres away in another part of Canada. With the continents of Europe and Asia being great distances away and separated from North America by the Pacific and Atlantic Oceans, acid pollutants from Canada are unlikely to be transported to countries other than neighbouring countries. Eastern Canada generally experiences high levels of acid deposition due to the large quantities of acidic pollutants emitted into the atmosphere each year in the heavily populated areas (the southern border and the lakes) of Canada and from pollution imported from the US. Acid deposition is less serious in western Canada due to a less acid-sensitive environment and lower levels of acid deposition. Effects of Acid Deposition on Forests In 1995, the Acid Rain National Early Warning System indicated an absence of large scale decline in Canadian forests caused by atmospheric pollution. In certain areas however, a decline in health of one or more particular species was identified. A decline in the health of white birch (Betula papyrifera and B. cordifolia) in eastern Canada around the Bay of Fundy in New Brunswick and Nova Scotia was apparent as leaf browning and premature leaf fall. The area of concern experiences frequent acid fogs during summertime with pH 3.0 or less. The Canadian sugar maple (Acer saccharum) has also been identified as having sustained reduction in growth with increasing levels of acid deposition. Maples on soils with low buffering capacity



also show higher levels of dieback compared to those on well-buffered soils. Effects of Acid Deposition on Water Acidification studies in Canada have shown that freshwater acidification is a serious problem in Canada. Between 1986 and 1990 studies of 1 253 lakes in Quebec revealed that 19% had a pH level of less than 5.5, and 52% had a pH of less than 6.0. Acid deposition (mainly sulphuric acid) is thought to be largely responsible for the acidity of lakes in southwestern Quebec and natural organic acids the cause in northeastern Quebec. Studies of lakes in Ontario, Quebec and the Atlantic Region between 1981 and 1994 have shown that lake acidity has improved in 33% of the 202 lakes studied, 56% remained stable and 11% have worsened. Lakes were noticeably less acidic in the Sudbury region of Ontario and this has been attributed to large reductions in sulphur dioxide emissions from Sudbury’s nickel smelters. However, large reductions in sulphur dioxide in eastern Canada over recent years have not generally led to improvements in lake acidity in southern and eastern Canada. This is likely to be a result of the large quantities of pollutants being deposited which have originated in the United States. Effects of Acid Deposition on Buildings Acid deposition is known to accelerate normal weathering effects on buildings. The harsh climatic conditions in Canada cause degradation of materials because of the many freeze-thaw cycles that occur in winter and the high humidity in the summer. Acid deposition adds to this and effects can be seen for example on bronze statues in Montreal. The bronze becomes streaked with



brown, black and blue-green surfaces which result from a combination of acid deposition, de-icing salts and corrosive dust. Many historic monuments and buildings are slowly being eroded by acid rain, including the Parliament Buildings. Effects of Acid Deposition on Health There is concern in North America that human health is affected by acid deposition. The 1994 Canada - United States Air Quality Agreement have reported that long-term ambient exposures to acid aerosols have been linked to decrease in lung function in children. Acid aerosols are very tiny particles (less than 2.5 micrometres in size) which can enter the respiratory system and because of their size may filter through natural bodily defences. The basis of concern arises from a study of more than 10 000 children aged between 8 and 12 years in 24 North American cities. Most air pollution studies have been carried out on sensitive persons, such as asthmatics but this study identifies that acid aerosols have a detrimental effect on normal lung function. Short-term exposure to poor air quality episodes may also cause breathing difficulties amongst for example asthmatics. These conditions may occur during summer months, particularly in cities where car pollution is the main source of nitrogen oxides. Control and Policy The long range transport of air pollutants is a problem which has long faced Canada. For many years Canada has been receiving much larger amounts of pollution from the United States than vice versa. After many research programmes were carried out during the 1980s, international agreements were set up between Canada and the US in 1991 for mutual reductions in sulphur dioxide and nitrogen



oxide emissions. The history of control of acid rain in Canada and the US is outlined in Table 3.9.

Table 3.9: Canadian Acid Rain Control Chronology

Late 1970s

Long-Range Transport of Air Pollutants Programme established to investigate air pollution within and into Canada.

1979 Canada signed the United Nations Economic Commission for Europe (UNECE) agreement to reduce and prevent long-range transboundary air pollution.

1980s

Extensive research conducted in US and Canada on acid deposition.

1985 Canada signed the UNECE Helsinki Protocol, agreeing to reduce national annual sulphur dioxide emissions by at least 30% below 1980 levels by 1993.

1988 Canada signed the UNECE Sofia Protocol to freeze nitrogen oxide emissions in 1994 at 1987 levels (approx. 2 million tonnes).

1990 US Clean Air Act amended to include SO2 and NOx emissions controls.

1991 Canada / US Air Quality Agreement signed. Mutual obligations for reducing SO2 and NOx.

1994 Canada signed the UNECE Oslo Protocol. An emissions cap of 1.75 million tonnes of SO2 established for the main source region in eastern Canada.



Introduction The pH of water of lakes and streams is predominantly determined by the soil and rock types of the area, since 90% of the water entering these water courses has passed through the ground. Only 10% of water in lakes and streams comes directly from precipitation. Sweden has over 85,000 lakes that are greater than one hectare in size. Of these, 14,000 are acidified by air pollution, 4,000 being severely acidified. The number of acidified lakes would be in the order of 17,500 if liming had not been carried out to restore the pH of many of Sweden’s waters over recent years. Acid sensitive species are absent from around 40% of Sweden’s rivers and streams. Acidification of a lake occurs over time. At first the natural buffering capacity of the lake neutralises the additional acidity entering the lake but at some point, the lake buffering capacity runs out and the acidity of the water increases rapidly. In time, the lake water stabilises at a certain acidity, maintaining a small number of species of plants and animals but often cannot support any fish. An example of a Swedish lake which has experienced these stages of acidification is lake Gårdsjön, near Gothenburg in the south west of the country; a lake of 31 hectares.



Lake Gårdsjön In the late 1940s, Gårdsjön had a pH of 6.25. By the early 1960s the pH level had fallen to less than 6.0, with pH levels of 4.3-5.5 during snowmelt. By 1970, the pH had fallen to 4.5-5.2 for the whole year. Scientists have helped to identify the causes of acidification of this lake by diatom stratification. A slow natural decline in pH from 7.0 to 6.0 is thought to have occurred over many centuries before the 1950s. After 1950 rapid acidification began to occur. This coincided with a rapid increase in the number of soot particles from coal and oil burning, which were identified in the lake sediment analysis for the post 1950 period. It is also during these recent decades that pH measurements have rapidly fallen and that many species of fish have declined. These species include perch (Perca fluviatilis), roach (Leuciscus rutilus), Northern pike (Esox lucius) and European eel (Anguilla anguilla). An acid lake is usually very clear, deceptively looking very beautiful but is in fact clear due to the absence of floating plankton. The light which reaches the bottom of the clear, acidified Swedish lakes enables Sphagnum moss to thrive to the extent that it often carpets the lake floor. Water lilies can also survive because their long roots can reach into sediment areas. However, species adversely affected include lobelia, quillwort and shore weeds. Aquatic life first to be affected by lake acidification are crayfish, shrimps, snails, mussels and some species of mayfly. The fish most sensitive to a fall in pH are minnows, salmon, roach and trout, as shown in Table 4.1. Once a lake pH falls to 4.5-5.0, all that usually remains are bog moss, certain plankton species and the hardiest insects.


Table 4.1: Sensitivities of freshwater life to pH pH 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 The leaching of nutrients from soil, released often as a result of acidification causes additional problems in lakes and water courses. Aluminium is absorbed by fish and can be stored in various organs. It can also form aluminium hydroxide on the gills, reducing blood oxygenation and causing the fish, as a result, to suffocate. Other metals such as mercury, lead, zinc and cadmium can be taken up by plants and animals causing toxicity problems. Heavy metal contamination may be passed through the food chain causing high

Crustaceans, snails, molluscs

Salmon, char, roach

Sensitive insects & plant and animal plankton

Whitefish, greyling, rainbow trout

Perch, pike, brown trout

Eel & brook trout

Insensitive insects survive

Water lily survives, white moss increases


levels of metals to be found, for example in fish, fish-eating birds and humans eating contaminated fish. Hence, an acid lake is not a dead lake but one that maintains a poorer range of plant and animal life. This may then lead to changes in the food chain. Insect species increase as fish species are lost



and this, in turn, leads to a loss of fish-eating birds and other predators. Acidified lakes in Sweden may be restored in the short term by liming. This raises the pH of the water through the addition of powdered limestone. Each year thousands of tonnes of limestone are sprayed on Swedish lakes and watercourses, by means of trucks, boats or helicopters. The cost of liming in Sweden in 1992 was 210 million kronor. Liming causes aluminium and other metals to precipitate and fall to the bottom of the lake which may cause toxicity problems for organisms living on the lake bed. Liming provides only a temporary solution, hence it is far better to attack the source of the problem by reducing emissions of acidifying pollutants at the source. Exercise 1. What causes the acidity of water entering lakes and

watercourses? 2. How much of the water added to a lake enters directly as a

result of rain or other precipitation? 3. What percentage of Swedish lakes are acidified? 4. What percentage of lakes in Sweden are severely acidified? 5. In your own words describe what the buffering capacity of a

lake is. 6. When did the buffering capacity of Lake Gårdsjön run out? 7. What is a diatom? (Use a dictionary if necessary.)



8. What causes did the diatom analysis suggest for the rapid acidification process after the 1950s?

9. For what reason does an acid lake look clear? 10. Which aquatic life is affected first by lake acidification? 11. Give examples of aquatic life that are very sensitive to a fall in

pH. 12. What species of aquatic life can survive in water more acid

than pH 5? 13. How does soil acidification affect lake life? 14. How can an acid lake indirectly affect humans? 15. What good does liming do to acidified lakes? 16. What percentage of Swedish lakes have been limed? 17. How much would it cost to lime 14 000 lakes if it costs 210

million kronor to lime 4,000 lakes? 18. What is the best way to prevent lake acidification?



Acid Rain Cartoons



Exercise 1. Classify each of the 18 cartoons into the following categories.

List the numbers of the cartoons under their appropriate headings (they may fit into more than one category). For example, Cartoon 4 can be listed under tree damage and vehicle pollution.

CATEGORY CARTOON NUMBER Emissions of Air Pollutants Tree damage Freshwater Acidification Soil Acidification Vehicle Pollution Politics of Acidification

2. Choose any three cartoons. Taking each in turn, write a few

sentences on what you believe the artist is trying to portray. 3. Write down all the information that you can obtain about the

acid rain issue from the 18 cartoons. 4. The artist Burki lives in Switzerland, the artist Albrechtsen lives

in Denmark and the artists Forshed and Good live in Sweden. What does this tell you about the artists’ concern about acidification?

5. Draw your own cartoon illustrating any of the effects of acid

deposition that you choose.

Printing permission of the cartoons was kindly given for ©Burki, 24 Heures by Professor P. Goeldlin, Director, Musee Zoologique, Lausanne and from Klaus

Albrechtsen, Nils Forshed and Bengt Good respectively.



Buildings and Acidification

In 1856, Robert Angus Smith - the scientist who first used the term acid rain - wrote: “it has often been observed that the stones and bricks of buildings crumble more readily in large towns where much coal is burnt.... I was led to attribute this effect to the slow but constant action of acid rain.” Buildings have always been subject to attack by weathering; the effects of rain, wind, sun, frost etc. Air pollution accelerates the rate of this damage . During the Industrial Revolution, soiling of buildings was particularly evident due to high concentrations of particulate pollution in towns and cities. Since then, Clean Air Acts have resulted in much lower levels of smoke and sulphur dioxide but levels today are still sufficient to cause blackening of buildings and increased degradation. Throughout the world, emissions of sulphur dioxide and nitrogen oxides contribute to the international problem of acidification. Acid deposition affects most materials to some degree. Limestone, marble and sandstone are particularly vulnerable, whilst granitic-based rocks are more resistant to acidity. Other vulnerable materials include carbon-steel, nickel, zinc, copper, paint, some plastics, paper, leather and textiles. Stainless steel and aluminium are more resistant metals. Structural damage to underground pipes, cables and foundations submerged in acid waters can also occur, in addition to damage to buildings, bridges, vehicles, etc. above ground.



Building stone can be damaged when calcium carbonate in stone dissolves in acid rain to form a crust of calcium sulphate (gypsum). This accelerates the damage during frost and other weather conditions and results in more stone being exposed. Many countries have noticed an acceleration of damage to their cultural heritage. Cathedrals such as York Minster and Westminster Abbey have been severely eroded in recent years. Similarly, the Taj Mahal in India, the Collosseum in Rome and monuments in Krakow, Poland are continuing to deteriorate. In Sweden, medieval stained glass windows are thought to have been affected by acid rain. Words underlined on the previous page can be found in the word search on the next page.



Word Search Exercise B I L Y E R E D E X N LS L E N L I L U I C U A RI E W S R O O B N K D D C H Z K A S HA W A T Y T I A R B C T S O A M O I Y TS T N J N S O U Y A E I S M W G O U S T I SR P I D D B Z E I M O N U M E N T S N O T LD S T A I N E D L S A I F H H T A N F P H R N E L AR C N S A V E A E T A R O I R E T E D C A I T S I RG Y P S U M R K E A D M R J Y A H A X Q A I R L V DL J E G A T I R E H S C Y A L P E I T R Y O N A D EA O N S G O I A I L A R U T C U R T S I R B J T N HS D G N M A H A L S M S E W V C I H T C O P P E R TS B U I L D I N G E Z I N C O M N A S O R I N M D AU N I S Y C U L T U R A L H L E G A M A D L D I E C The following words are all hidden in a straight line (vertically, horizontally or diagonally).

TAJ DAMAGE PAINT STRUCTURAL MAHAL GYPSUM BUILDING SANDSTONE ACID COPPER CULTURAL CATHEDRALS RAIN NICKEL HERITAGE WEATHERING GLASS METALS STAINED MONUMENTS ZINC MARBLE MATERIALS DETERIORATE



Vehicle Emission Control In 2000 there were 24.8 million passenger cars and light goods vehicles licensed in the UK. In 1950 there were 2.4 million, over a ten fold increase in licensed UK cars and light goods vehicles in just 50 years. World car populations have increased at a similar rate from around 50 million in 1950 to an estimated 630 million in the early 1990s and predicted escalation to 1,000 million by the 2020s. UK consumption of energy during 2000 accounted for 160.1 million tonnes of oil equivalent. Motor vehicles accounted for over a third of this, and are consequently a major contributor to gaseous air pollution, in particular from nitrogen oxides, hydrocarbons and carbon monoxide. In 1999, road transport contributed the following:

Contribution to UK

emissions from road transport

Total UK emissions 1999 million tonnes

Nitrogen Oxides (NOx)

44% 1.6

Carbon Monoxide (CO)

69% 4.8

Hydrocarbons (VOCs)

27% 1.7

Black Smoke 48% 0.3

A motor vehicle produces air pollutants when fuel is burnt to give mechanical power. In a totally efficient combustion process,



hydrocarbons and oxygen will react to form carbon dioxide and water. However, the combustion process is never perfect; some of the hydrocarbon fuel is only partially burnt forming carbon monoxide and water, whilst some of the hydrocarbons are not combusted at all. These can, and often are, emitted from the exhaust as unburned hydrocarbons. During the combustion process the temperature can reach 2500°C. At these temperatures nitrogen and oxygen from the air in the combustion chamber react to form nitrogen oxides. Vehicle pollution can be significantly reduced by fitting a catalytic converter to the exhaust system. This is a relatively low cost method of pollution control (around £350) which has little effect on vehicle performance and fuel consumption. All new cars sold in Britain from January 1993 onwards have catalytic converters but most cars bought before 1993 will not have one fitted.

The most widely used catalytic converter consists of a cylindrical ceramic body with a honeycomb structure, chemically treated and coated with platinum group metals. The honeycomb structure enables a high surface area (equivalent to three football pitches) to be incorporated within a relatively small space. This is critical to the durability and reliability of performance. The catalyst is usually incorporated into the car exhaust system.



There are three basic types of catalyst, an oxidation catalyst which controls the emission of hydrocarbons and carbon monoxide by oxidising the pollutants to water and carbon dioxide, a three way catalyst which provides efficient removal of nitrogen oxides, carbon monoxide and hydrocarbons, and a diesel catalyst which controls the emissions of hydrocarbons (the characteristic diesel smell) and carbon monoxide. The catalyst will also substantially reduce smoke emissions. The United States of America and Japan first introduced tough standards for controlling emissions from motor vehicles in the early 1970s. The US standards can only be met by the use of catalytic converters. Many European countries including Switzerland, Austria, Sweden and Norway also adopted US standards during the 1980s. In 1990, a European Community Directive stated that all petrol engined cars sold in EC countries from January 1993 must be fitted with a three way catalytic converter. Europe has been slow to act on the link between vehicle emissions and acid rain and air quality. Directly and indirectly vehicle emissions make a significant contribution to the cause of acid deposition, the formation of photochemical smog and are a potential risk to human health. The major gases leading to the formation of acid deposition are sulphur dioxide (SO2) and nitrogen oxides NOx. Vehicles do not produce much sulphur dioxide as petroleum contains very little sulphur. In 1999, vehicles contributed only 1% of the UK SO2 emissions whilst power stations being the major source of the total UK SO2 emissions contributed 65%. Nitrogen oxides from vehicles are however, a major contributor to acid deposition in the UK. In 1999, road transport accounted for 44% of NOx emissions. The atmospheric chemistry of nitrogen oxides is complex but generally speaking, the nitrogen oxides arising from motor vehicles may either be oxidised to nitric acid or react with hydrocarbons to form ozone.



Photochemical smog, sometimes called summertime smog is the result of the sunlight-stimulated reaction between hydrocarbons and nitrogen oxides leading to the formation of low level atmospheric ozone and other chemical oxidants. Such smogs and hazes are typical of warmer cities, a particularly well-known example being Los Angeles. However, many instances of photochemical smogs have occurred in the UK in recent years which may be due to the growth of vehicle ownership. Wintertime smogs also occur when atmospheric pollutants, mainly those found in car exhausts, are trapped at ground level by a layer of colder air above towns and cities. During high pressure conditions, warm air rises during the daytime but if this is followed by a cloudless night, ground level temperatures fall and cold air rises but is trapped by warmer air above. The cold air forms a lid if conditions are calm, trapping pollutants from vehicles and other sources.

Lars-Erik Håkansson. Health risks associated with car exhaust emissions are usually connected with carbon monoxide which reduces the oxygen carrying capacity of the blood. However, nitrogen oxides can cause breathing problems at high concentrations and therefore sufferers from emphysema and chronic bronchitis are likely to be most at risk. Some of the hydrocarbons found in vehicle exhaust fumes are



known to be carcinogenic. Indirect effects of vehicle emissions on health may arise when air pollution episodes occur such as summertime or wintertime smogs. At such times, those suffering from heart or lung diseases may find that their symptoms worsen. The increase in use of catalytic converters on vehicles should in the long term help to reduce emissions of pollutants from vehicles although the continued growth in car ownership may impede this improvement.



Crossword

1 2 3 4

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ACROSS 1. The type of fuel burnt by most cars (6) 3. Benzene is a known one to humans (10) 5. Type of precipitation which may be acidic (4) 6. See 4 down 8. Required by an engine to make it run (4) 9. Cars, vans and lorries are all these (8) 11. Type of converter added to vehicles to reduce exhaust emissions (9) 13. Pollutants from vehicles react in this (3) 14. Major type of vehicles (4) 16. Nitric and sulphuric are these (5) 18. Motor vehicles are the major source of nitrogen oxide ............... (9) 19. All member states in this continent must have catalysts on all new petrol cars sold (6) 20. This group of pollutants are found in vehicle exhaust and some species are carcinogenic (12)

DOWN 1. Emissions of gases and particles from vehicles may cause this (9) 2. May cause a jam at rush hour (7) 3. A catalytic one of these reduces vehicle exhaust emissions (9) 4. & 6 across. The major acidifying gases of vehicle exhaust (8) + (6) 7. Fuel type used by some vehicles, particularly buses, taxis and lorries (6) 10. Cars driven at high .. emit more pollution (5) 12. & 17 down. Type of catalyst (5) + (3) 15. These, and particles, form exhaust (5) 17. See 12 down.


Acid Rain Teaching Pack 75

Answers to Crossword

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Industrial Emission Control Acidic emissions of sulphur dioxide (SO2) and nitrogen oxides (NOx) arise from many industrial sources as a result of combustion processes. In the UK in 1999, power stations contributed 65% of all SO2 emitted in the UK. Other industries were responsible for 21%. Industries also emit nitrogen oxides which can also cause rainfall to become more acidic. While road transport is the major source of NOx in the UK (44% in 1999), power stations accounted for 21% and other industries 13% in 1999 There are many technologies which can be used in industry to reduce the emissions of pollutants to the atmosphere and these can be applied before, during or after combustion. Pre-combustion & during combustion technology Examples of pre-combustion technology include coal scrubbing and oil desulphurisation. Another removal process is to change the design of the boiler and to install pressurised fluidised bed combusters (FBC) which removes sulphur from coal during combustion. Another process which removes sulphur dioxide from coal during combustion is the Integrated Gasification Combined Cycle. Coal is gassified under pressure with a mixture of air and steam which results in the formation of gas which can then be burned to produce electricity.



Post-combustion technology One of the post-combustion controls is Flue Gas Desulphurisation (FGD). In FGD processes, waste gases are scrubbed with a chemical absorbent such as limestone to remove sulphur dioxide. There are many different FGD processes, the main ones being the limestone-gypsum process and the Wellman-Lord regenerative process. The limestone-gypsum FGD is installed at Drax in Yorkshire, the largest UK power station. This technology involves mixing limestone and water with the flue gases to produce a slurry which absorbs the sulphur dioxide. The slurry is then oxidised to calcium sulphate (gypsum) which can then be used in the building trade. However, whilst the benefits of FGD are known, the costs of installing FGD are very high. To install a 2GW power station with FGD costs around £300 million. Fuel efficiency Some fuels are naturally less polluting in terms of acidic emissions (e.g. gas), whilst the traditional coal power generation in the UK is more polluting, depending on the amount of sulphur there is in the coal being burnt. To help reduce atmospheric emissions of SO2 and NOx in the UK, many of the more recent power stations have been built to operate on gas rather than coal. Table 8.1 compares the relative efficiencies and emissions of different fuel types from UK power stations.



Table 8.1: Relative efficiencies and emissions from UK power stations

Fuel type + control technology

Efficiency Relative emissions (coal =1) SO2 NOx CO2

Coal 39% 1 1 1

Oil 40% 1.2 0.75 0.85

Coal + FGD + Low NOx burners

38%

0.1 0.6 1.05

Gas (Combined Cycle Gas Turbine)

50%

Negligible 0.25 0.5

Coal + Pressurised Fluidised Bed Combustion

42%

0.1 0.3 0.95

Coal + Integrated Gasification Combined Cycle

43%

0.05 0.3 0.9

The current trend in the UK is a move from gas to coal due to the low levels of sulphur dioxide, nitrogen oxides, dust and carbon dioxide emitted when gas is burned. However, whilst gas is currently plentiful, availability in the long term is unknown. Hence, research is being carried out into techniques for reducing sulphur dioxide emissions from coal such as FBC and IGCC . Such techniques are unlikely to be used on a commercial scale until well after the year 2000. Legislative controls The UK, as a member country of the European Union, is under obligation to comply with the Large Combustion Plant Directive of 1988 which concerns reductions in emissions of SO2 and NOx from plants over 50MW in size



The UK is, under this Directive, required to reduce SO2 by 60% by 2003 and NOx by 30% by 1998 (from 1980 levels). The UK is also a Party to the Gothenburg Protocol, designed to Abate Acidification, Eutrophication and Ground-level Ozone. The UK is committed to reducing 1990 emissions of sulphur dioxide by 75% by 2010 and nitrogen oxides by 50% over the same period. In addition, the UK National Air Quality Strategy sets out standards and objectives for reducing key air pollutants to be achieved by year 2005. To meet the objectives for the acid deposition pollutants (largely SO2 and NOx), industry will have a significant part to play in reducing emissions. As most of the SO2 emitted in the UK is from industry and power generation, reductions in annual emissions will be necessary from industrial sources. The use of cleaner fuels and the use of control technologies will be required at all new industrial plants if SO2 levels are to continue in a downward trend.



Exercise 1. The following table shows the emissions of sulphur dioxide

from various sectors in the UK during 1995.

Source SO2 (thousand tonnes) 1999

Power stations 776 (65%)

Domestic 53 (4%)

Commercial/ public sector 22 (2%)

Other industry 249 (21%)

Road transport 12 (1%)

Shipping 22 (2%)

Others 53 (4%)

Draw a pie chart to show the proportion of SO2 emitted in the UK in 1999. The use of a computer will help with this exercise.

2. If sulphur dioxide emissions from Large Combustion Plants in

the UK were 3 007 000 tonnes in 1980, and nitrogen oxides emissions were 861 000 tonnes, what are the target totals for year 1998 (NOx) and 2003 (SO2)?

LCP SO2 emissions 1980 (tonnes)

LCP NOx emissions 1980 (tonnes)

Target 60% reduction SO2

year 2003

Target 30% reduction NOx 1998

3 007 000

861 000

?

?

Look at the answer you have found for NOx. In 1998, Large Combustion Plants emitted 365 000 tonnes of NOx. Would this have met the reduction target of 30% from 1980 levels?

3. Under the Gothenburg Protocol, what will be the UK targets for

total sulphur dioxide and nitrogen oxides emissions?



1990 Total SO2 emissions in UK = 3 754 000 tonnes 1990 Total NOx emissions in UK = 2 585 000 tonnes 2010 SO2 emissions target: 75% reduction = 2010 NOx emissions target: 50% reduction =



Acidification Becoming acidic. An acid is any substance which dissociates with water to give a sour corrosive solution containing hydrogen ions. Buffer A compound which can be added to stabilise the pH of a solution. Carbon monoxide A colourless, odourless, poisonous gas which is produced when fossil fuels are burned and there is a lack of air available. Catalytic converter A device used to clean the exhaust gases from a vehicle. A catalyst increases the rate of a chemical reaction without itself suffering any permanent chemical change. Combustion The process of burning. Desulphurisation The removal of sulphur. Diatom A microscopic algae made up of one cell. Found in fresh or sea water. Emissions The release of something, for example emissions of pollutants (gases and particles) from a chimney into the atmosphere. Flue A chimney or pipe used to carry off gases.



Fossil fuel Any naturally occurring fuel, such as coal, oil, petroleum, peat and natural gas, formed by the decomposition of prehistoric organisms. Heritage Evidence of the past, such as buildings and monuments. Hydrocarbons Any organic compound made up of only carbon and hydrogen. Produced as unburnt particles of fuel. Leaching The washing out of a substance by a liquid. Meteorological The weather conditions. Neutralising Becoming neither acidic nor alkaline. Nitrogen oxides A term referring to all the oxides of nitrogen which are mainly nitrogen dioxide and nitric oxide. Waste gases of fossil fuel combustion. Nutrients Minerals absorbed by the roots of plants for growth. pH A scale from 0 to 14 measuring acidity or alkalinity of a solution. Photochemical oxidants Substances formed under the influence of sunlight, through the uptake of oxygen, e.g. ozone.



Pollutant An impure substance, usually a chemical substance that is produced from an industrial process. Precipitation A term which includes rain, snow, sleet, hail, fog and mist. Stratification Layers of sediment deposited over a specific period of time. Sulphur dioxide A colourless, soluble, pungent gas produced when sulphur is burnt.



References Department for Environment, Food & Rural Affairs. 2001. Digest of Environmental Statistics. http://www.defra.gov.uk/environment/statistics/des/intro.htm Electricity Association (2000) Controlling Atmospheric Emissions from Fossil Fuel Power Stations. Environmental Briefing Number 10, EA, London. Environment Canada (1996) Acid Rain, State of the Environment Bulletin No. 96-2, Ontario. European Environment Agency (1995) Europe’s Environment, The Dobris Assessment, EEA, Copenhagen. Facts About Finland (1996), Otava Publishing, Helsinki. Finnish Environment Agency (1995) International Cooperative Programme on Integrated Monitoring of Air Pollution Effects on Ecosystems, Helsinki. Greater Manchester Acid Deposition Survey, 1989 data, ARIC. International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (1996) Forest Condition in Europe. International Joint Commission (1994) Canada - United States Air Quality Agreement Progress Report 1994, Ontario / Washington.

http://www.defra.gov.uk/environment/statistics/des/intro.htm



Ministry of Economy of the Czech Republic (1996) Tourism in the Czech Republic, 1995, Min. of Economy, Prague. Ministry of International Relations of the Czech Republic (1992) The Lands of the Czech Crown, Orbis, Prague. Murley, L. (1995) Clean Air Around the World, 3rd Edition, IUAPPA, Brighton. National Expert Group on Transboundary Air Pollution (NEGTAP). 2001. Transboundry Air Pollution: Acidification, Eutrophication and Ground-Level Ozone in the UK. NEGTAP, DEFRA Contract EPG 1/3/153. http://www.nbu.ac.uk/negtap/ Swedish NGO Secretariat on Acid Rain (1996) Acid News, No. 5, December 1996. Swedish NGO Secretariat on Acid Rain (2001) Acid News, No. 4, December 2001. UK Buildings Effects Review Group (1989) The Effects of Acid Deposition on Buildings and Building Materials, HMSO, London. UK Review Group on Acid Rain (1997) Acid Deposition in the UK 1992-1994, Fourth Report, AEA Technology, Oxford.

http://www.nbu.ac.uk/negtap/



Sources of Further Information Atmospheric Research & Information Centre Manchester Metropolitan University Chester Street Manchester M1 5GD Tel: 0161 247 1590 Email: [email protected] Internet: http://www.doc.mmu.ac.uk/aric/ Department for Environment, Food & Rural Affairs Air Quality Division Ashdown House 123 Victoria Street London SW1E 6DE Internet: http://www.defra.gov.uk/ Environment Canada State of the Environment Directive Environment Conservation Service Environment Canada Ottawa, Ontario K1A 0H3 CANADA Internet: http://www.ec.gc.ca/

Finnish Embassy 38 Chesham Place London SW1X 8HW Tel: 0207 838 6200 National Society for Clean Air & Environmental Protection 136 North Street Brighton BN1 1RG Tel: 01273 326313 Swedish NGO on Acid Rain Int. Forsurningssekretariatet Box 7005 S-402 31 Goteborg Sweden Internet: http://www.acidrain.org/ US Environmental Protection Agency Acid Rain Division Mail Code: 6204J 401 M Street, SW Washington, DC 20460 Internet: http://www.epa.gov/

http://www.doc.mmu.ac.uk/aric/

http://www.defra.gov.uk/

http://www.ec.gc.ca/

http://www.acidrain.org/

http://www.epa.gov/

teaching pack for key stages 3 & 4, and a-levelfor example, the h+ ion content of rainwater with...

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