top 14 photochemical smog (part 2) (1)
TRANSCRIPT
![Page 1: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/1.jpg)
CHEM115 Envrionmental Chemistry 1
TOPIC 14(part 2)
SMOG & OZONE DEPLETION
![Page 2: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/2.jpg)
CHEM115 Envrionmental Chemistry 2
SMOG
![Page 3: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/3.jpg)
CHEM115 Envrionmental Chemistry 3
Introduction
It is a general term first used in 1905 for a mixture of smoke and fog.
A kind of urban air pollution.
2 major types:Photochemical smogSulfurous smog (Classical smog)
![Page 4: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/4.jpg)
CHEM115 Envrionmental Chemistry 4
Photochemical Smog
Solar radiation is important for formation of photochemical smog.
The reactions that occur is complex and involve nitrogen oxides (NOx) and hydrocarbons.
It is directly related to automobile use.
![Page 5: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/5.jpg)
CHEM115 Envrionmental Chemistry 5
Formation of Photochemical Smog
Sun
Nitrogen oxides (NOx) + Hydrocarbons
Photochemical Smog
Solar radiation
Pollutants are trapped in an inversion layer.
Source: Botkin&Keller.2003. Environmental Science, 4th ed.
![Page 6: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/6.jpg)
CHEM115 Envrionmental Chemistry 6
Example: Photochemical Fog Formation over Los Angeles Area
Source: Botkin&Keller, 2003. Environmental Science. 4 th ed. Chapter 23.
![Page 7: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/7.jpg)
CHEM115 Envrionmental Chemistry 7Source: Botkin&Keller, 2003. Environmental Science. 4 th ed. Chapter 23.
The city of Los Angeles, on a clear day (left) and a smoggy day (right)
![Page 8: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/8.jpg)
CHEM115 Envrionmental Chemistry 8
Sulfurous Smog (Classical Smog)
It is mainly due to burning of coal or oil at large power plants.
Sulfur oxides and particulates combine to produce sulfurous smog.
![Page 9: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/9.jpg)
CHEM115 Envrionmental Chemistry 9
Formation of Sulfurous SmogBurning of coal or oil
Sulfur oxides + particulates
releases
Concentrated sulfurous smog
•stagnant and stable air•sufficient relative humidity•cloud cover •formation of inversion layer
![Page 10: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/10.jpg)
CHEM115 Envrionmental Chemistry 10
What are the consequences?
• Reduce visual range and atmospheric clarity• Damage plant tissues• Increase lung disease and respiratory system
disease such as bronchitis• Aggravate chronic disease such as asthma and
emphysema
![Page 11: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/11.jpg)
CHEM115 Envrionmental Chemistry 11
Control of Smog
• Stricter emission control for automobiles• Requirement for more making fuel cleaner• Improvement in public transportation and
incentives for people to use it• Enforcing mandatory carpooling• Increase control on industrial and household
activities
![Page 12: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/12.jpg)
CHEM115 Envrionmental Chemistry 12
Relevant Regulations and Guidelines
Clean Air ActNational Ambient Air Quality Standards (NAAQS)Air Quality IndexClean Air RegulationsAir Pollution Index
![Page 13: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/13.jpg)
CHEM115 Envrionmental Chemistry 13
OZONE DEPLETION
![Page 14: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/14.jpg)
CHEM115 Envrionmental Chemistry 14
Introduction
Ozone is a triatomic form of oxygen.
In the lower atmosphere, ozone is a pollutant produced by photochemical reactions which involve sunlight, nitrogen oxides, hydrocarbons, and oxygen.
In the upper atmosphere, ozone acts as a sunscreen against UV radiation.
![Page 15: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/15.jpg)
CHEM115 Envrionmental Chemistry 15
Formation of Stratospheric Ozone
Source: Botkin&Keller, 2003. Environmental Science. 4 th ed. Chapter 25.
![Page 16: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/16.jpg)
CHEM115 Envrionmental Chemistry 16
Ozone Depletion
CFCs are considered responsible for most of the ozone depletion.
CFCs, unlike other pollutants cannot be broken down by sunlight, rain-out and oxidation. CFCs are transparent to sunlight, insoluble in water, and non-reactive in oxygen-rich at lower atmosphere.
![Page 17: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/17.jpg)
CHEM115 Envrionmental Chemistry 17
When CFCs wander to the upper atmosphere, the highly energetic UV splits up the CFCs, releasing chlorine. Then, ozone depletion occurs.
Cl + O3 -> ClO + O2
ClO + O -> Cl + O2
The series of reactions is known as catalytic chain reaction.
![Page 18: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/18.jpg)
CHEM115 Envrionmental Chemistry 18
Formation and Destruction of Ozone
Source: Botkin&Keller, 2003. Environmental Science. 4 th ed. Chapter 25.
![Page 19: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/19.jpg)
CHEM115 Envrionmental Chemistry 19
What are the consequences?
• Damage on food chain• Increase in skin cancer, cataracts and
suppression of immune system
![Page 20: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/20.jpg)
CHEM115 Envrionmental Chemistry 20
Control
• Montreal Protocol, 1987• Substitutes for CFC.
![Page 21: Top 14 Photochemical Smog (Part 2) (1)](https://reader035.vdocuments.mx/reader035/viewer/2022081512/55320ba24a7959a2318b4afd/html5/thumbnails/21.jpg)
CHEM115 Envrionmental Chemistry 21