tailieunhanh - Introduction to ENVIRONMENTAL TOXICOLOGY Impacts of Chemicals Upon Ecological Systems - CHAPTER 7

Vô cơ khí các chất ô nhiễm Trong chương này, năm trong số các chất ô nhiễm không khí lớn được coi là, tức là, lưu huỳnh oxit (SOx), các oxit nitơ (NOx), ôzôn (O3), carbon monoxide (CO), và florua (F). Mặc dù nhiều fluoride vào khí quyển phát ra từ các nguồn khác nhau là ở dạng hạt, có chứa chất florua được bao gồm trong cuộc thảo luận của chúng tôi ở đây với các chất ô nhiễm vô cơ khí chủ yếu là bởi vì có chứa chất florua khí gây thiệt hại nhất đối với các sinh. | CHAPTER 7 Inorganic Gaseous Pollutants In this Chapter five of the major gaseous air pollutants are considered . sulfur oxides SOx nitrogen oxides NOx ozone O3 carbon monoxide CO and fluoride F . Although much of the fluoride emitted into the atmosphere from various sources is in the particulate form fluoride is included in our discussion here with other inorganic gaseous pollutants mainly because gaseous fluoride causes the most damage to living organisms especially plants. SULFUR OXIDES Sulfur oxides include both sulfur dioxide SO2 and sulfur trioxide SO3 of which SO2 is more important as an air pollutant. Sulfur trioxide may be formed in the furnace by reaction between sulfur and O2 or SO2 and O2. Sulfur dioxide is probably the most dangerous of all gaseous pollutants on the basis of amounts emitted. Sources of SO2 Sulfur oxide emission results from the combustion of sulfur-containing fossil fuels such as coal and oil. The sulfur content of coal ranges from to 7 and the sulfur is in both organic and inorganic forms while in oil sulfur content ranges from to and its sulfur is in organic form. The most important sulfur compound in coal is iron disulfide FeS2 or pyrite. When heated at high temperatures pyrite undergoes the following reactions FeS2 3 O2 FeSO4 SO2 4 FeS2 11 O2 2 Fe2O3 8 SO2 1999 by CRC Press LLC In the smelting process sulfide ores of copper lead and zinc are oxidized roasted to convert a sulfide compound into an oxide. For example zinc sulfide undergoes the oxidation process in a smelter forming ZnO and SO2 as shown below 2 ZnS 3 O2 2 ZnO 2 SO2 In the . SO2 emission from stationary sources and industry accounts for about 95 of all SO2 emission. Characteristics of SO2 SO2 is highly soluble in water with a solubility of 100 ml. Once emitted into the atmosphere SO2 may undergo oxidation in the gaseous phase forming H2SO4 aerosol. Gaseous SO2 also may become dissolved in water droplets and following oxidation form .