Hành động độc hại của chất gây ô nhiễm Khi có mặt tại một nồng độ đủ cao, chất gây ô nhiễm có thể gợi ra những ảnh hưởng xấu đến các quá trình sống của một sinh vật. Để gây thiệt hại cho sinh vật tiếp xúc, một chất gây ô nhiễm đầu tiên phải nhập máy chủ và tiếp cận trang web mục tiêu của nó. Một con đường phức tạp tồn tại giữa thời gian tiếp xúc với độc tố ban đầu và biểu hiện của thiệt hại do sinh vật. Chương này thảo luận về cách chung,. | Chapter 4 Toxic Action of Pollutants INTRODUCTION When present at a sufficiently high concentration a pollutant can elicit adverse effects on the living processes of an organism. To exert damage to an exposed organism a pollutant must first enter the host and reach its target site. A complex pathway exists between the time of initial toxicant exposure and the manifestation of damage by the organism. This chapter discusses general ways in which environmental pollutants exert their actions on plants animals and humans. PLANTS Sources of Pollution For the most part environmental pollution is an anthropogenic human-made problem. As mentioned previously the most important source of atmospheric pollution in the . is motor vehicles. Other major sources include industrial activities power generation space heating and refuse burning. The composition of pollutants from different sources differs markedly with industry emitting the most diverse range of pollutants. While carbon monoxide CO is the major component of pollution by motor vehicles sulfur oxides SOx are primary pollutants of industry power generation and space heating. In some large cities such as Los Angeles accumulation of ozone O3 peroxyacyl nitrate PAN and other photochemical oxidants constitute the major atmospheric pollution problem. Pollutant Uptake Terrestrial plants may be exposed to environmental pollutants in two main ways. One is exposure of forage to air pollutants another is uptake of toxicants by roots growing in contaminated soils. Vegetation growing near industrial facilities such as smelters aluminum refineries and coal-burning power plants may absorb airborne pollutants through the leaves and become injured. The pollutants may be in gaseous form such as sulfur dioxide SO2 nitrogen dioxide NO2 and hydrofluoric acid HF or in particulate form such as the oxides or salts of metals contained in fly ash Figure . 2005 by CRC Press LLC Atmospheric pollutants Acid deposition so2
