环境生态学---第二十三章 空气、水和土壤污染物.pptVIP

2001年和2002年的臭氧空洞 W1 空气、水和土壤污染物 要 点 空气污染 空气污染是由人类活动引起的天然与合成的有害物质向大气中的排放。污染物可直接进入大气（初级污染物），或在太阳辐射的影响下于大气中产生（次级污染物）。已表明会给环境和健康带来威胁的主要空气污染物包括氧化氮类、二氧化硫、臭氧和固体颗粒。空气污染也能改变气候以及土壤、湖泊和河流的化学性质。 笼罩着空气污染的城市 Water bodies in northern temperate regions of Europe and North America have suffered form acidification due to ‘acid rain is a result of fossil fuel burning, which produces sulfur oxides (SOx) and nitric oxide (NO) which may combine with atmospheric water to form sulfuric acid (H2SO4) and nitric acid (HCO3), respectively, The term ‘acid deposition’ is more accurate as acid may also be deposited from the air in the form of snow, sleet and fog. Acid rain reduces the pH of soil and lakes, while acidification can also cause the death of trees and allow toxic metals (e.g. aluminium and mercury) to be leached from soils and sediments. Acid rain 酸 雨 欧洲和北美的北温带地区的水体已经遭受到酸雨带来的酸化。酸雨是化石燃烧的结果。化石燃料的燃烧会产生氧化硫类物质（SOx）和一氧化氮（NO），它们能分别和大气中的水分结合而形成硫酸（H2SO4）和硝酸（HNO3）。这种现象称为“酸降”更恰当，因为酸也会以雪、雨和雾的形式从空气中沉降下来。酸雨降低土壤和湖泊的pH，同时酸化也能导致树木的死亡，并使得有毒金属（如铝和汞）从土壤和沉积物中释放出来。 酸雨形成 因酸雨致死的树木 Water pollution can be divided into one of four categories: (i) biological agents, (ii) dissolved chemicals, (iii) nondissolved chemicals, and (iv) heat. The eutrophication of aquatic ecosystems occurs due to an excess of inorganic nutrients. Organic matter in the water is broken down by microorganisms that deplete the oxygen levels, which may be quantified by the ‘biochemical oxygen demand’ (BOD). A particularly important class of organic water pollutants is the family of polychlorinated biphenyls (PCBs), a group of stable chlorinated compounds, that are highly toxic to vertebrates. Water pollutants 水体污染物 水污染分为四类：（i）生物试剂，（ii）溶解的化学物质，（iii）不溶的化学物质和（iv）热。水生态富营养化是无机营养物过剩造成的。水中的有机物质被微生物分解，降低了溶氧水平。溶氧水平可以由“生化需氧量”（biochemical oxygen demand, BOD）来定量。有机水体污染物中非常重要的一类是多氯联苯族化合物PCBs，这是一组稳定的含氯化合物，对脊椎动物有剧毒。 水污染 A range of chemical cause soil pollution problems, of which halogens (primarily solvents and pesticides) constitute the larg