ENVIRONMENTAL CHEMISTRY (Air II) Chem. 3030. Stratospheric chemistry and the ozone layer; principles of photochemistry, light absorption by molecules,

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  • ENVIRONMENTAL CHEMISTRY (Air II) Chem. 3030
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  • Stratospheric chemistry and the ozone layer; principles of photochemistry, light absorption by molecules, noncatalytic and catalytic process of ozone distraction, free radicals, Cl and Br as X catalysts, the ozone hole and its consequences, chlorofluorocarbons (CFCs). Ground-level (tropospheric) air chemistry; ground-level ozone and photochemical smog, oxidation of methane, hydrocarbons and atmospheric SO 2, acid rain, ecological effects of outdoor air pollutants, indoor air pollution: formaldehyde, NO 2, CO, tobacco smoke, asbestos, radioactivity from radon gas. The greenhouse effect and global warming; energy absorption, the major and minor greenhouse gases: CO 2, water vapour, methane, N 2 O, CFCs. Environmental consequences of energy use: CO 2 emissions, solar energy, conventional and alternative fuels, nuclear energy. The chemistry of natural waters; acid-base chemistry, CO2/carbonate system, ion concentations, alkalinity, seawater, redox chemistry in natural waters, oxygen demand, the pE scale, sulphur and nitrogen compounds, ion complexes, stratification, precipitation. Soil chemistry; soil components, weathering process, aerobic, anaerobic soils, water- sediment-soil system.
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  • Photochemical smog oxidation reactions are initiated by the hydroxyl radical (produced in large part due to the presence of NO from combustion emissions). Hydrocarbons and other volatile organic compounds are the oxidisable substrates. The products of the smog-producing reactions include partially oxidised hydrocarbons, CO, aldehydes and ketones, residual nitrogen oxides and ozone
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  • Reducing photochemical smog and ground-level ozone: VOCs (C=C) NOx
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  • ACID RAIN (atmospheric precipitation of substantial acid, more acidic than natural) H 2 SO 4 and HNO 3 from SO 2 and NO x (primary pollutants) Sources: volcanos, e.g. Mount Pinatubo in the Phillipines is known to have contributed a lot of sulphate aerosols to the Arctic volcanos, e.g. Mount Pinatubo in the Phillipines is known to have contributed a lot of sulphate aerosols to the Arctic crude oil petroleum industry crude oil petroleum industry Claus reaction removal of sulphides: 2H 2 S + SO 2 3S + 2H 2 O Claus reaction removal of sulphides: 2H 2 S + SO 2 3S + 2H 2 O petrochemical processes (CH 3 SH, (CH 3 ) 2 S, CH 3 SSCH 3 ) petrochemical processes (CH 3 SH, (CH 3 ) 2 S, CH 3 SSCH 3 ) TRS total reduced sulphur TRS total reduced sulphur smelting metal ores with sulphides smelting metal ores with sulphides
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  • The sulphuric acid in precipitation originates from a number of chemical precursors. Reduced sulphur compounds can be oxidised to SO 2 with hydroxyl radical as the primary oxidising agent. The SO 2 then dissolves in water droplets and is further oxidised to sulphuric acid via several homogeneous and heterogeneous processes
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  • Environmental consequences of photochemical smog and acid rain wet deposition dry deposition acidification depends strongly on the soil composition limestone neutralises acid, granite or quartz are strongly affected acidified lakes growth of water animals and plants DOC decreased higher penetration of UV light to the lower water levels elevated conc. of dissolved Al and Fe deterioration of soils washing out plant nutrients effect on trees agriculture crops ozone reacts with ethylene forming free radicals resulting in slowed photosynthesis
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  • Air particulates Solid or liquid particles suspended in air. They are not visible to the naked eye, but form a haze that reduces visibility. Size: 2nm 100 m Coarse particles > 2.5 m < fine particles Soot or inorganicsoot or sulphate, nitrate aerosols Basic due to a soil contentacidic due to unneutralised acids PM index amount of particulate matter per volume (g/m 3 ) PM 10 = 10 m PM 10 = all fine particles

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