西安建筑科技大学：《环境学 Environmentology》双语课程电子课件_Unit 8 Air Quality Issues

Environmental science A Study of interrelationships Unite 8 Air Quality Issues

Unite 8 Unite 8 Air Quality Issues Air Quality Issues Environmental Science Environmental Science A Study of interrelationships A Study of interrelationships

The Atmosphere Composition -About 99%of the clean, dry air in the troposphere consists of(2) gases: Nitrogen(79%)Oxygen (20%) Water vapor accounts for. 01% to 5% Most of the atmosphere is held close to the earth by the pull of gravitational force, thus it gets thinner with increasing distance from the earth

The Atmosphere • Composition - About 99% of the clean, dry air in the troposphere consists of (2) gases: Nitrogen (79%) Oxygen (20%). – Water vapor accounts for .01% to 5%. – Most of the atmosphere is held close to the earth by the pull of gravitational force, thus it gets thinner with increasing distance from the earth

The Atmosphere As the atmosphere absorbs heat from the earth, it expands and rises When heat is radiated into space Weste Convection currents air cools becomes more dense and flows toward the Trade winds earth

The Atmosphere • As the atmosphere absorbs heat from the earth, it expands and rises. – When heat is radiated into space, air cools, becomes more dense, and flows toward the earth

The Atmosphere Air quality degraded by multiple sources Air pollution includes both aesthetic and human health problems Accumulation uebec of air pollution

The Atmosphere • Air quality degraded by multiple sources. – Air pollution includes both aesthetic and human health problems. Accumulation of air pollution

100 Layers of the Atmosphere 90 80 870 ionosphere 060 850 ------- 40 Stratosphere 30 20 10 0

Primary Air Pollutants Five major materials released directly into the atmosphere in unmodified forms Secondary air pollutants form under reaction of primary pollutants and water or sunlight

Primary Air Pollutants • Five major materials released directly into the atmosphere in unmodified forms. – Secondary air pollutants form under reaction of primary pollutants and water or sunlight

Primary Air Pollutants Carbon Monoxide- Produced when organic materials are incompletely burned Single largest source is the automobile Not a persistent pollutant Hydrocarbons Nitrogen Oxides

Primary Air Pollutants • Carbon Monoxide - Produced when organic materials are incompletely burned. – Single largest source is the automobile. – Not a persistent pollutant. Hydrocarbons Nitrogen Oxides

Primary Air Pollutants Hydrocarbons-Group of organic compounds consisting of carbon and hydrogen Evaporated from automobile fuel or remnants of fuel incompletely burned Catalytic converters used to burn exhaust gases more completely

Primary Air Pollutants • Hydrocarbons - Group of organic compounds consisting of carbon and hydrogen. – Evaporated from automobile fuel or remnants of fuel incompletely burned. ™ Catalytic converters used to burn exhaust gases more completely

Primary Air Pollutants Particulates- Minute pieces of solid materials dispersed into the atmosphere(<10 microns) Smoke. Asbestos. Dust Ash Can accumulate in lungs and interfere with the ability of lungs to exchange gases Sulfur Dioxide(So2)- Sulfur and oxygen compound produced when sulfur-containing fossil fuels are burned Burning coal releases sulfur dioxide

Primary Air Pollutants • Particulates – Minute pieces of solid materials dispersed into the atmosphere (<10 microns). – Smoke, Asbestos, Dust, Ash – Can accumulate in lungs and interfere with the ability of lungs to exchange gases. • Sulfur Dioxide (SO 2 ) – Sulfur and oxygen compound produced when sulfur-containing fossil fuels are burned. – Burning coal releases sulfur dioxide

Primary Air Pollutants Nitrogen Oxides(NO, No2)-Formed when combustion takes place in the e aIr N and o molecules from the air may react with one another

Primary Air Pollutants • Nitrogen Oxides (NO, NO 2 ) - Formed when combustion takes place in the air. – N and O molecules from the air may react with one another