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CHAPTER # 3. E nvironmental consequences of combustion processes – Part I (Smog, Acid Rain, and ozone depletion). Dr. Hassan Arafat Department of Chem. Eng. An-Najah University. (these slides were adopted, with modification, from Ms. Paulina Bohdanowicz , KTH Institute, Sweden). Combustion.
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Environmental consequences of combustion processes – Part I(Smog, Acid Rain, and ozone depletion)
Dr. Hassan Arafat
Department of Chem. Eng.
(these slides were adopted, with modification, from Ms. Paulina Bohdanowicz , KTH Institute, Sweden)
Source: WCI 2005
Source: Liss R., Saunders A., Power generation and the Environment, Oxford 1990; Turns S.R., An introduction to combustion, concepts and application, Singapore 2000
Source: Siemiński M., Środowiskowe zagrożenia zdrowia, Warszawa 2001
Occurs mainly in urban areas but not exclusively
Smoke + fog = smogSmog
dates back to the 14th century
the "Killer Smog" reported in 1952, claimed 4000 fatalities in London - by far the most devastating event of this type in recorded history.
Inefficient combustion of high-sulphur coal => high concentration of unburned carbon soot and other particulates, acidic sulfate aerosols (such as sulfuric acid, H2SO4) as well as elevated levels of sulphur dioxide.
SO2 and soot, => sulphuric acid, sulfate aerosols
Characteristic brownish haze - formed usually under conditions of high humidity and relatively low temperatures, characterised by reducing and acidic properties.
In case of humid atmospheres carbon particulates serve as condensation nuclei for water droplets resulting in formation of fog, highly irritant.
Classical smog can persist for days when atmospheric conditions allow.Sulphur smog / London smog
Batter Sea power station, London, UK
encountered in automobile rich cities – with specific climatic conditions
mid-1940s - repeated occurrence of heavy injury to vegetable crops in the Los Angeles area - traced to high concentrations of ozone that appeared to be created at low altitudesPhotochemical smog / LA smog
First studies on rain chemistry were conducted in late 1800s, but modern investigations date back to 1960s.
Nowadays the chemistry of atmospheric precipitation is fairly well known.
The phenomenon of acid rain has been known and studied from 1950s.
1960 – lowered fish production in Scandinavian lakes
In 1972 it became an international public policy issue at the first United Nations Conference on the Environment held in Stockholm.
The transboundary effect of atmospheric pollution has been officially accepted, based on the fact that sulphur and nitrogen oxides are commonly emitted in one location while the acid deposition occurs in distant area.
In Sweden and Norway around 90% of the acid deposition comes from other countries, primarily UK, Germany, Poland and other Central Europe countries. Canada receives major acid contribution form the US.Acid Rain
Source: Van Loon G.W., Duffy S.J., 2000.
Natural surface waters - pH of 6-8, acidified waters pH 3 (conditions unbearable for many aquatic species, which eventually die, and lakes become lifeless)
Today some 14000 lakes in Sweden are affected by acidification. Similar situation is in Canada
Nitrogen can induce eutrophication, which results in depletion of oxygen in water, further affecting the aquatic flora and faunaImpacts of acid rain
A record size of ozone hole was 10.5 million square miles on Sept 19, 1998
Red color would denote high ozone levels; blue denotes lowAntartic/Arctic ozone hole
Humans (a 10% drop in stratospheric ozone levels is likely to lead globally to
300000 more skin cancers,
1.6 million more eye damage – cataracts) per year
Reptiles (damage to eggs)
Plants (reduced photosynthesis, increased sensitivity to stress)
Damage to marine ecosystems (direct and indirect)Ozone layer depletion