Transcript Air Pollution & Air Quality Monitoring

Air Pollution & Air Quality
Monitoring
Chapter 1
Assessment
•
•
•
•
Written Tests (2)
50
Practical Reports (min 5)
40
Assignment
10
In order to pass this subject you will be required
to obtain a minimum of 60% for both tests and
hand in 5 practical reports.
• Assessment will be competency based with
grades of A, B, C, and NC (not competent).
Introduction
• functions of the atmosphere include:
– protection from harmful radiation
– moderating the surface temperature
– providing a medium (air) that allows
organisms to exchange gases in order to
survive (breathing).
Introduction
• Any substantial change in the nature or
contents of the atmosphere has a direct
consequence on how well the atmosphere
performs these tasks
• Are there any current scenarios that this
relates to?
Introduction
• Historically air pollutants of greatest
concern have been TSP, and oxides of
sulfur,
• More sophisticated processing industries =
longer list of significant pollutants NOx and
photochemical oxidants as routine
pollutants, and often include Pb, asbestos,
Hg, H2SO4 and many others that require
careful monitoring.
Introduction
• Non-pollutants e.g. CO2 also a problem
• Wastes released into the atmosphere are
diluted and dispersed in the air, and are
processed and recycled through a variety
of natural physical, chemical and biological
mechanisms.
• the atmosphere is continually cleaned of
pollutants
Introduction
• Atmospheric problems are made worse by
weather conditions
• The residence time determines
significance of pollution problem
• compared to natural sources, man’s
activities produce a much smaller amount
of global pollution.
Introduction
Global Emissions form Natural & Man Made Sources
120
100
80
% Emissions from Natural
Sources
60
% Emissions from man made
sources
40
20
0
SOx
CO
NOx
NH3
Pollutant
H/C
Dust
Introduction
• Dispersal of pollutants is a very important
consideration – as the atmosphere is not
homogeneous - pollutants tend to concentrate
in specific areas – most of which are near where
large human populations reside
• means that pollutant levels around residential
areas are often much greater than would be
expected in ambient air
Introduction
• Natural sources are in general more evenly
spread, but there are exceptions such as
extremely high levels of dust and acidic gases
associated with volcanic activity.
• Man's activities (anthropogenic) release heat,
gases, aerosols and other wastes into the
atmosphere in high conc's overloading the
natural dispersal, dilution and recycling systems
Introduction
• Very little is known about the dispersal
processes and the passage through
ecological systems of pollutants. Many are
resistant to degradation, some are
cumulative and harmful.
Introduction
• Air pollution definition
• WHO
• “Air is polluted when one or several pollutants
are present in the atmosphere at such a conc.
and for so long a time that they are harmful to
man, animals, plants or material property, cause
harm or reduce well-being or disturb appreciably
its application”.
Introduction
• NSW Protection of the Environment
Operations Act as “any deviation from the
natural combination of gases in our
atmosphere”.
Introduction
• Definition fails to mention is that the
natural combination of gases in our
atmosphere must be taken as dry air at
sea level.
• Neither completely cover other factors that
we might also call pollution such as the
release of energy, radiation, odour or
noise.
Introduction
• Most air pollution concerns are associated
with ambient air (outdoors and free
flowing) – hence most control programs
focus on ambient air pollution,
• significant pollution now occurs in
occupational environments which are
indoors.
The Atmosphere
• Earth’s atmosphere 160 kilometers deep, 95% of
air mass lies within 20 kilometers of the surface.
• atmosphere is neither uniform, nor static in
nature. Its characteristics vary widely with
altitude, season, location and solar flare activity.
• Air within a few kilometers of the earth’s surface
will typically contain the components
Element
% (by volume) in the
atmosphere
Total Mass in the
Atmosphere (x1012
tonnes)
nitrogen
78.08
3900
oxygen
20.95
1200
argon
0.934
67
carbon dioxide
0.035
2.5
Neon
0.0018
0.065
Helium
0.00052
0.004
Methane
0.00015
0.005
Krypton
0.0001
0.017
Carbon Monoxide
0.00001
0.0006
Ozone
0.000002
0.0003
Nitrogen Dioxide
0.0000001
0.000013
Sulfur Dioxide
0.0000001
0.000018
0.1 – 5 (normal range 1-3)
Varies according to location
water
The Atmosphere
• The pollutants with which we have the most
problems make up an extremely small part of the
atmosphere.
• In polluted city areas these % conc's will change
markedly for some pollutants.
• The conc's of N, O, Ar, Ne, He, Kr, H and Xe
remain essentially constant (most are inert and
play little or no role in atmospheric chemistry).
The Atmosphere
• N is a precursor for other species such as NO3-,
as well as amino acids and nucleic acids
(amongst others) which are essential for life, and
reacts with O.
• O2 important for the nurturing of life, and forming
ozone (O3), acts as a heat and radiation shield
for the planet – maintaining fairly constant
temperatures that allow life to exist.
The Atmosphere
• At 0.035%, CO2 in the atmosphere is very low enormous significance as the raw material used
by plants for carbon fixation to produce the
compounds used for energy by almost all forms
of life.
• also a significant greenhouse gas – which
serves to keep the planet warm.
• Water vapour is the most variable (from 0.1 –
30,000ppm).
• allows the transport of energy around the planet.
The Atmosphere
• Forms clouds that are responsible for the
Earth’s albedo – the ability of the Earth to
radiate sunlight back into space –
controlling the Earth’s surface temperature
• trace gases produced from biological or
geological processes, NH4, CH4, H2S, CO
and SO2
The Atmosphere
• The avg. person breathes 20,000L of air
per day
• 995 of which is N or O.
• 1% is a mixture of gases and particulates,
many of which are pollutants.
• we breathe as much as 200L of pollutants
per day!
Stratification of the Atmosphere
• stratification – or layering of the atmosphere
• 95% of the atmosphere’s air mass is found in the
troposphere. The upper troposphere has a temperature
of -56ºC.
• At the top of the troposphere is the tropopause layer - a
barrier to prevent water vapour rising much higher as it
causes ice formation.
• Water vapour cannot pass through it.
• stratosphere, - The ozone layer is within the
stratosphere, and reaches levels of up to 10ppm in the
middle of the stratosphere – gets hotter due to this.
The Atmosphere
The history of air pollution
• Air pollution was probably as much a problem to
cave men as it is today.
• Reports of air pollution and decimation of forests
have been recorded since the 14th C.
• mostly linked with the burning of soft coal with a
high sulfur content. This activity produces
smoke, sulfur dioxide and particulate matter
containing HCs.
The history of air pollution
• London "pea souper" fogs.
• type of smog is grey in colour and is generally
referred to as London type smog.
• Meuse Valley of Belgium 60 deaths. 21 people
were killed in Donora, Pennsylvania,
• Most victims died of lung and breathing
disorders. Of the survivors, 7000 of the total
population of 14000 became seriously ill.
The history of air pollution
• Los Angeles type smogs conditions
different to those in London
• Large amounts of NO2 and unburnt HC’s,
which then react in the atmosphere in the
presence of UV light and oxidants to form
a brown photochemical smog.
Haze or smog?
• Haze, but how is it different to smog?
• Both typified by a reduction in visibility, but the
intensity varies.
• Haze is a condition where the reduction in
visibility is not great, and is generally applied to
describe the atmospheric conditions over a very
large area
• Smog is significant reductions in visibility,
generally in metropolitan areas
Factors that make things worse
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•
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calm conditions
low level emission sources
temperature inversions
high buildings and narrow streets
The POEO Act
• This act specifies all legal requirements for
the control of air pollution in NSW.
• The current regulation pertaining to air
pollution control (in NSW) is called the;
Protection of the Environment Operations
(Clean Air) Regulation 2002