Atmospheric Issues

1
Atmospheric Issues

• Pollutants

2
Air composition

• Oxygen and nitrogen make 99 of dry air
• remaining 1 consists of argon, carbon dioxide,
  helium and other trace gases

3
water vapor

• inhomogeneous distribution in the atmosphere.
• Depending on climatic conditions and temperature
  may range between 0.1 and 4
• Cold air can take up less water vapour than warm
  air.

4
Pollutants
5
Natural Sources

• occurring for centuries
• atmosphere can adjust with minimal complications.

6
Natural Sources

• Volcanoes
• Forest fires
• Sea salt from the ocean
• Dust from space
• Pollen from trees and plants

7
inorganic pollution

• Dusts and gases from volcanic eruptions
• Salt particles brought by the wind from the sea
• Dust delivered into the air during the dust
  storms
• Gases originating from the lighting during the
  thunderstorms
• Dust coming to the atmosphere from the space

8
organic pollution

• smoke and dust from vegetation fires
• small plants' parts (e.g. pollen, fungi)
• live organisms (e.g. bacteria)
• phytoncides, i.e. volatile substances emitted by
  trees and flowers
• mixture of organic substances produced by the
  plants
• forest regions, savannahs and oceans, where
  natural emissions dominate.

9
Terpenes released from plants

• Monoterpenes - smell of many plants, (needles
  fruity smell) 
• Monoterpenes are organic compounds consisting of
  carbon, hydrogen and sometimes oxygen atoms. 
• Produced by trees and other plants
• React with oxidants (OH or ozone).
• Produce other compounds that can condense in the
  air and form particles or enlarge already
  existing particles
• Aerosols float in the air and are necessary to
  form clouds.

10
Other Natural Sources

• Methane
• Natural nitrous oxide
• Bacteria decompose nitrate and form nitrous
  oxide,
• has increased recently due to use of nitrogen
  fertilizers.

11
Dimethylsulfide (DMS)

•  emitted from marine algae that need special
  sulfur compounds that degrade to the sulfur
  organic compound dimethyl sulfide, a gas, emitted
  to the air.
• oxidized forming sulfur dioxide and finally
  sulfuric acid, which is necessary for cloud
  formation.

12
The tree as source of organic compounds
(following N.C. Hewitt image Elmar Uherek)
Isoprene  and monoterpenes  are important organic
compounds, that are released in high amounts by
trees and other plants. But there are many more
chemicals plants produce.
13
Anthropogenic

• Human activities that occur during our daily
  lives 
• Industrial chimneys and stacks
• Vehicle exhaust
• Agriculture
• Power stations that burn coal, oil or gas
• Mining activity
• Waste dumps

14
Anthropogenic

• Often, it is difficult for the atmosphere to
  adjust to these extra pollutants
• thus high concentrations can occur on a regional
  or local scale.

15
Anthropogenic air pollution

• controlled
• takes place according to well established rules,
  under the supervision of specialists
• accidental
• occurs during demolition of old buildings,
  quarrying, leakiness in industrial installations

• . Anthropogenic air pollution.Smoke from a
  factory chimney Source www.freefoto.com

16
Release of Pollutants by Country
Values in the table are expressed in thousands of
tons.
17
Limit values

• For every pollutant, there are established limit
  values of concentration which should not be
  exceeded.
• Otherwise, the air pollution may be harmful and
  dangerous for our health or even life.

18
Alarm values

• For NO2, SO2 and O3, apart from limit values,
  there are also alarm values
• mean 1-hour concentrations
• If exceeded, local authorities inform the public
  
• undertake actions that would decrease the
  pollutants' concentration in the air,
• limit the traffic in a city, decrease for some
  time industrial production etc.

19
Primary pollutants

• come from sources at the earths surface
• harmful substances emitted directly to the
  atmosphere,

20
secondary pollution

• substances that become harmful after being
  emitted into the atmosphere
• or originating due to the chemical reactions with
  the air.

21
Nitrogen oxides (NOx)

• natural sources include
• Volcanoes
• lightning strikes
• biological decay.

22
Nitrogen oxides (NOx)

• Road transport, shipping and aircraft are
  significant sources
• Humans have doubled the natural rate of nitrogen
  (N) fixation
• atmospheric N deposition rates have increased 3
  10X, compared to pre-industrial times

23
Carbon monoxide (CO)

• main source of anthropogenic CO in the air was
  transportation (60), and industry (36) of the
  total emission
• Waste management and agriculture were of marginal
  importance.

24
Sulfur dioxide (SO2)

• main source of SO2 emissions was industry (93)
• All other sectors delivered the remaining 7.
• emissions of sulfur (S) into the atmosphere have
  more than doubled

25
Sulfur dioxide (SO2)

• Natural sources of SO2
• Volcanoes
• oceans (dimethyl sulfide)
• biological decay
• forest fires.

26
Particulates

• Aerosols are smallest category of particulates
• health hazards
• Larger particulates (soot) are less of a health
  hazard, but do foul surfaces and may block light

27
Particulates

• Particles are something important in our climate
  system
• They are necessary to form clouds and can also
  hold back solar radiation from the Earth's
  surface.