Secondary Air Pollution.pptx

Envi

1. Secondary Air Pollution

2. Secondary pollutants Formed by the interaction of primary air pollutants with each other or with other components of the atmosphere.

3. What is Smog A combination of smoke and fog Found in heavily polluted air in urban and industrialized areas What we typically call "smog" today is a mixture of pollutants but is primarily made up of ground-level ozone.  

4. Where does smog come from? Smog usually is produced through a complex set of photochemical reactions involving volatile organic compounds (VOC's ), PANs( peroxy acetyl nitrates) and nitrogen oxides in the presence of sunlight that result in the production of ozone. 

5. Photochemical smog Photochemical smog  is produced when pollutants from the combustion of fossil fuels react with sunlight. The energy in the sunlight converts the pollutants into other toxic chemicals. In order for photochemical smog to form, there must be other  pollutants  in the air, specifically nitrous oxides and other volatile organic compounds (VOCs).

6. Creation of Smog NO 2 + sunlight  O + NO CH 4 + 2O 2 + 2NO  H 2 O + HCHO + 2NO 2 O + O 2  O 3

7. Do Caribbean cities suffer from Smog? Why?

8. Industrial or Grey Air smog Formed from the mixing of Sulphur dioxide, sulphuric acid and suspended particulate matter (from fossil fuels) Reaction takes place in troposphere. Sulphur dioxide + Oxygen  Sulphur trioxide Sulphur trioxide + ammonia  solid ammonium sulphate

9. Severity of smog depends on: Climate Topography population density level amount of industry fuel types used in industry and transport

10. Impacts of Smog suspended particulate matter leads to increase in cardio-respiratory ailments Ozone affects vegetation by decreasing productivity Damages synthetic materials Visually unappealing (can affect tourism and business)

11. Acid Deposition

12. Acid Deposition Acid deposition , is a broad term that includes any form of   precipitation  with  acidic   components, such as sulfuric or nitric  acid  that fall to the ground from the atmosphere in wet or dry forms. This can include  rain , snow, fog, hail or even dust that is  acidic

13. Sources of Primary Pollutants Naturally: volcanoes, forest fires decaying vegetation Human: SO 2 and NO x from fossil fuels etc Conversion to secondary pollutants due to interaction with gases from high in the atmosphere.

14. Wet deposition Pollutants descend to the surface as acid rain, snow or fog usually within 2-3 days near to source of emissions. Reacts with receptors directly (vegetation and aquatic organisms or in soil.

15. Dry deposition Pollutants descend as acidic particles within 4- 14 days downwind of source . May become incorporated into dust or smoke or stick to ground, buildings, trees etc. May be washed from these surfaces causing acidic runoff.

16. Acid Rain i s a mild solution of sulphuric acid and nitric acid formed when the oxides react with water vapour to form an acidic solution. The pH of acid rain is less than 5.6

17. Effects of acid rain Extent of effect depends on acidity of water, chemistry and buffering capacity of soils and species relying on/utilizing the water.

18. Causes or exacerbates human respiratory diseases such as asthma and bronchitis Leaches toxic metals from pipes (lead and copper) Acidifies lakes and streams Damages trees at high elevations by affecting sensitive soils. Weak trees are susceptible to other issues Speeds up decay of building materials and paints Impacts agriculture by damaging crops, soil and water. Leaches fertile elements of soil (K, Mg, Ca ions)