air pollution & air quality monitoring
Post on 30-Dec-2015
60 Views
Preview:
DESCRIPTION
TRANSCRIPT
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
0
20
40
60
80
100
120
SOx CO NOx NH3 H/C Dust
Pollutant
% Emissions from NaturalSources
% Emissions from man madesources
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
water 0.1 – 5 (normal range 1-3) Varies according to location
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
• 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
top related