【正文】 soil used ratio and motor vehicles density. In recent years, sewage irrigation has bee part of the agriculture irrigation. Sewage irrigation be used in China since 1960s, especially in north of China, account for nearly 90% in our country [4]. It’s inevitable to increase heavy metal concentration in soil by using sewage irrigation, especially those toxic metals (Hg、Cd、Cr、As、Cu、Zn、Pb), take Huaiyang and Taiyuan for example, the heavy metal concentration in the soil has exceeded to local background much, and the concentration are increasing yearly [5]. The rejectamenta that contains heavy metals has plenty of types, differential types has differential harm effect. According to the evaluation on rejectamenta [6] and life waste [7], the heavy metal content (Cd、Hg、Cr、Cu、Zn、Ni、Pb、As、Sb、V、Co、Mn) exceeded the local background at a high degree. The exploration, smelt of metal mine can course much acid mine waste solutions, if do not take good measures for the waste solutions, some heavy metal pollutants can be easily released into soil directly or indirectly. In 1989, 56t Hg, 88t Cd, 173t As and 226t Pb [8] were released to the environment by coloured metal industry in our country. Heavy metal means those 60 element that density exceed to or those 45 element that density exceed to , As and Se are not metal element, but because of their toxicity and other characteristics are much nearly to heavy metals, so we put As and Se as heavy metal pollutant. Because of the biotoxicity of Hg, Cd, Cr, Pb, and As, they have been taken the most important heavy pollutants in the environment, also Zn, Cu, Co, Ni，Se and some other pollutant were regarded very toxic. Heavy metal toxicity arises when a number of certain heavy metal species, such as mercury, lead, arsenic and cadmium for example, occur as cations. The behavior of heavy metals in fluids and their relative mobility in the environment varies strongly according to oxidationreduction conditions, to the pH of the surrounding environment, and whether there are organic plexing pounds present [9]. When in solution the ionic strength of the solution or saturation levels of cations in the solution, also influences the behavior of heavy environmentally hazardous metals are too insoluble to move freely in the vascular system of the plant. Many form sulfate, carbonate or phosphate precipitates immobilizing these metals in apoplastic and symplastic partments. Apoplastic transport of these metals is further limited by the high cationexchange capacity of cell walls, unless the metal ion is transported as a noncationic metal chelate. The strong affinity for these cations to form plexes with sulphur interferes with normal enzymatic functions within humans. Numerous enzymes which function as metabolic regulators contain sulphur within ‘sulfhydryl’ groups, and it is these groups which attract, or are attracted to, the metal cations. This consequently alters the capacity of the enzyme to function properly and thus causes often lethal sideeffects. Whilst toxicity may differ according to the metal species, the most potent forms are those which can be absorbed into the tissues of。 目 錄摘 要 IAbstract III1 Introduction 7 Chromium and plants 3 Cadmium and plants 5 Mercury and plants 8 Zinc and plants 10 Lead and plants 11 Research objectives 142 Material and Methods 15 Plant species 15 Heavy metals in study 15 Study method 16 Germination and seedling growth test 16 Chlorophyll and carotenoid estimation 16 Content of the heavy metals test 17 Statistical analyses of data 173 Result and Analyses 18 Toxic effect of chromium on Radish 18 The effect of chromium on seed germination and growth of radish 18 The effect of chromium on Physiological traits of radish 19 Chromium accumulation in shoot and root of radish seedling 20 Toxic effect of cadmium on radish 21 Toxic effect of cadmium on seed germination and growth of radish 21 Toxic effect of cadmium on Physiological traits of radish 22 Cadmium accumulation in shoot and root of radish seedling 23 Toxic effect of zinc on radish 25 Toxic effect of zinc on seed germination and growth of radish 25 Toxic effect of zinc on Physiological traits of radish 26 Zinc accumulation in shoot and root of radish seedling 27 Toxic effect of Lead on radish 28 Toxic effect of Lead on seed germination and growth of radish 28 Toxic effect of Lead on Physiological traits of radish 30 Lead accumulation in shoot and root of radish seedling 30 Toxic effect of chromium and cobalt on radish 32 Toxic effect of chromium and cobalt on seed germination of radish 32 Toxic effect of chromium and cobalt on seed growth of radish 33 Toxic effect of cadmium and zinc on radish 36 Toxic effect of cadmium and zinc on seed germination of radish 36 Toxic effect of cadmium and zinc on seed growth of radish 36 Toxic effect of lead and mercury on radish 39 Toxic effect of lead and mercury on seed germination of radish 39 Toxic effect of lead and mercury on seed growth of radish 39 Effect of heavy metals on chlorophyll and carotenoid production in radish seedling 42 The study of heavy metals on accumulation in radish seedling 424 Discussion 44 effect of chromium and cobalt on radish 44 Toxic effect of cadmium and zinc on radish 46 Toxic effect of lead and mercury on radish 50Conclusion 53References 561 Introduction With the development of global economy, the heavy metal pollutants enter soil by many ways too, and then the soil was polluted by heavy metals seriously. Polluted soil not only effects the plant growth and degrade the quality of food, but also threaten people’s health through the Food Chain, lead to air and water environment polluted too. Heavy metals occur naturally at low concentrations in soils. However, they are considered as soil contaminants due to their widespread occurrence, acute and chron