气体污染物的来源和类型.ppt

Atmosphere New words & expressions monoxide n.一氧化物 dioxide n.二氧化物 nitrogen n.氮 toxicity n.毒性 volatile adj.挥发性的，不稳定的 evaporate v.（使）蒸发，消失 New words & expressions respiratory adj.呼吸的 airborne adj.空气传播的 pesticide n.杀虫剂 perchloroethylene n.全氯乙烯 thermal inversion 逆温 catalytic converter 催化转化器 Air Pollutants Carbon monoxide Volatile organic compounds Particulate matter Sulfur dioxide Nitrogen dioxide Lead Ground-level ozone and photochemical smog Hazardous air pollutants Primary Air Pollutants Carbon monoxide Volatile organic compounds Particulate matter Sulfur dioxide Oxides of nitrogen Primary standards provide public health protection, including protecting the health of “sensitive“ populations such as asthmatics, children, and the elderly. Secondary standards provide public welfare protection, including protection against decreased visibility and damage to animals, crops, vegetation, and buildings. Units of measure for the standards are parts per million (ppm) by volume, parts per billion (ppb) by volume, and micrograms per cubic meter of air (g/m3). Criteria air pollutants Criteria air pollutants National ambient air quality standards Carbon Monoxide Carbon monoxide is produced when organic materials such as gasoline, coal, wood, and trash are burned with insufficient oxygen. The single largest source of carbon monoxide is the automobile. Volatile organic compounds VOCs are composed primarily of carbon and hydrogen. VOCs are either evaporated from fuel supplies or are remnants of fuel that did not burn completely. Volatile organic compounds The use of internal combustion engines accounts for the majority of VOCs released into the air, although refineries and other industries add to the total atmospheric burden. Consumer products such as oil-based paint, charcoal lighter, and many other chemicals are important. Particulate Matter Particulate matter consists of minute (10 micros and smaller) solid particles and liquid droplets dispersed into the atmosphere. Travel on roads, agricultural activities, construction sites, industrial processes, and smoke particles from fires are the primary sources of coarse particles. (greater than 2.5microns) Particulate Matter Fine particles (2.5microns or less) are most secondary pollutants that form in the atmosphere from interactions of primary pollutants. For example: Sulfates and nitrates formed from sulfur dioxide and nitrogen oxides. Sulfur Dioxide SO2 is a compound of sulfur and oxygen that is produced when sulfur-containing fossil fuels are burned(S+O2SO2). Today ,the major source of sulfur dioxide is from the burning of coal in power plants. Nitrogen Dioxide The burning of fossil fuels produces a mixture of nitrogen-containing compounds commonly known as oxides of nitrogen (NOX). The two common are nitrogen monoxide and nitrogen dioxide. The primary molecule produced is nitrogen monoxide , but nitrogen monoxide can be converted to nitrogen dioxide in the air to produce a mixture of NO and NO2 . Nitrogen Dioxide The primary source of nitrogen oxides is the automobile engine. Lead Lead (Pb) can enter the body through breathing airborne particles or consuming lead that was deposited on surfaces. At one time , the primary source of airborne lead was from additives in gasoline. Another major sources of lead is paints. Lead Today , the major sources of lead are from industrial sources where metals are smelted or batteries are manufactured. Ground-level Ozone and Photochemical Smog Ozone(O3) is molecule that consists of three oxygen atoms bonded to one another. Photochemical smog is a mixture of pollutants including ozone, aldehydes, peroxyacetyl nitrates resulting from the interaction of nitrogen dioxide and volatile organic compounds with sunlight in a warm environment. Ground-level Ozone and Photochemical Smog The two most destructive components of photochemical smog are ozone and peroxyacetyl nitrates. Ground-level Ozone and Photochemical Smog 光化学烟雾形成的示意图 Ground-level Ozone and Photochemical Smog The development of photochemical smog in an area involves the interaction of climate, time of day, and motor vehicle emissions in the following manner. Hazardous Air Pollutants While all criteria air pollutants already discussed cause health concerns, hundreds of oth