【作者】 张丽娜；

【导师】 宗良纲；

【作者基本信息】 南京农业大学 ， 环境科学， 2007， 硕士

【摘要】 本文采用生物盆栽土培和水培试验从三个方面研究了不同调控措施对土壤-水稻系统中Cd行为的影响：(1)不同改良剂作用效果的比较。在研究不同改良剂的影响时，采集了pH值分别为酸性、中性和碱性的江西红壤性水稻土、苏南的黄泥土以及苏北的潮黄土三种典型水稻土，改良剂分别选择了石灰、钙镁磷肥和硅肥。在对改良剂的研究中，除了选择一些无机改良剂外，还对有机肥和生物肥等有机生物改良剂进行了一些比较研究。(2)不同栽培管理方式的影响，主要研究了不同的水稻水分管理方式，包括全生育期淹水、不同生育期烤田和水稻旱作等。(3)在低Cd污染水平下硅素对水稻生长及吸收Cd的影响，本方面研究是以水稻幼苗期水培试验进行的。施用改良剂的生物盆栽试验结果显示，在中度Cd污染土壤上施用石灰、钙镁磷肥和硅肥这三种改良剂对水稻生长，水稻吸收Cd以及Cd在土壤中的赋存形态和改善糙米品质安全性都产生影响。虽然三种改良剂都有一定的改良效果，但由于各种改良剂的性质和改良机理上存在差异，改良效果各不相同，其中硅肥的改良效果最好，其次是钙镁磷肥，然后是石灰。虽然3种改良剂均能降低土壤中有效态Cd以及糙米和秸秆中Cd的含量，使稻米质量符合国家食品卫生安全标准，但土壤性质的不同会影响改良剂的效果。同一改良剂施用在红壤上的效果最为明显，其次是黄泥土，而呈碱性的潮黄土由于土壤有效态Cd的含量明显低于前两种土壤，施用改良剂后糙米和秸秆中的Cd含量虽有所降低，但改善效果不太明显。在对生态肥和有机肥的比较研究中发现：和有机肥相比，生态肥不仅在促进水稻生长、提高水稻产量方面的作用更加显著，而且在降低土壤中有效态Cd以及糙米、茎叶和水稻根中镉含量的作用效果更好。施用生态肥和有机肥使水稻体内镉含量和土壤中有效态Cd含量的降低，主要是由于施用不同肥料导致的土壤中Cd形态的变化。通过水稻盆栽试验，研究了Cd污染土壤上旱作、不同生育期烤田和全生育期淹水等不同水分管理方式对水稻生长及其吸收Cd的影响。结果表明，旱作栽培对水稻生长发育影响较大，水稻产量较低，与全生育期淹水栽培相比，产量下降了28.74％。全生育期淹水栽培具有一定的产量水平，但不是最高，分蘖期和灌浆期烤田比其产量提高14.58％和10.27％。在全生育期淹水栽培方式下，水稻糙米中Cd含量最低，旱作和不同生育期烤田，水稻籽粒中Cd的含量会增加，其中水稻旱作的增加最多，达166.31％，而灌浆乳熟期增加较少。研究表明，被Cd在一定程度上污染的土壤上种植水稻，采用旱作方式应慎重，以避免水稻旱作所带来的粮食品质的安全风险。在对不同改良剂的研究中发现，硅的改良效果最好，但对硅的不同浓度的影响没有详细研究。同时虽然土壤镉污染的控制标准较低，但镉在土壤中活性较强，容易被作物吸收，而我国低浓度镉污染的土壤面积也较大。因此通过水稻幼苗水培试验，研究了低镉污染水平以及不同的硅处理浓度对水稻幼苗生长和吸收镉的影响。结果表明，低浓度的镉污染虽然对水稻幼苗的生长有一定的促进作用，但幼苗体内的镉含量较高，且镉的富集系数在低浓度下也较大。因此，低浓度镉污染所引起的食品安全风险不容忽视。在镉污染条件下施加硅处理，能增加水稻幼苗蛋白质和叶绿素的含量，提高根系活力以及抗氧化酶SOD、POD的活性，但要选择适宜的浓度，硅处理浓度过高或过低时效果较差。一定浓度范围内的硅处理对于抑制水稻幼苗对镉的吸收效果非常明显，但随着硅浓度的增加，幼苗体内镉含量降低的幅度趋缓。因而从经济因素考虑，只要施加适量的硅就可以达到较好的降镉效果。更多还原

【Abstract】 By rice pot experiments and solution culture, the effects of different controlling measures and principles on behaviors of cadmium in soil-rice system were investigated. This study included three sections. (1) We compared the improvement effects of various amendments. This experiment used three different pH typical paddy soil, including paddy soil derived from red soil, yellow paddy soil, fluro-aquic yellow paddy soil, and three amendments, i.e. lime, calcium magnesium phosphate and silica fertilizer. In addition to inorganic amendments, we also studied the improvent effects of organic fertilizer and ecological fertilizer. (2) We studied the effects of different different ways of water control on rice yields, including continuous flooding, dry cultivation and mid-way drainage in different growing stages. (3) Effects of Si on rice seedlings growth and uptake of Cd in the solution culture at the low concentrations of Cd pollution were investigated.The results of rice pot experiments of amendments showed that lime, calcium magnesium and silica fertilizer could cause the effects on rice growth , yield formation, uptake of Cd by brown rice and stalk, the contents of effective Cd in soil and forms of soil Cd in some types of paddy soils. The improvement effects of various amendments were different, as the character and mechanism of amendments were different. Of these amendments, silica fertilizer was the most efficient in suppressing Cd uptake by the plants, and the effect of calcium magnesium phosphate was better than that of lime. In addition, all three amendments could decrease the content of Cd in brown rice, stalk and effective Cd content in soil, and make rice accord with the National Food Safety Standards. However, different properties of soils influenced the improvement effects of amendments. The effects in paddy soil derived from red soil were the best, followed by yellow paddy soil. Effective Cd content of alkali and fluro-aquic yellow paddy soil was lower than that of other soils obviously. When three amendments were applied in alkali and fluro-aquic yellow paddy soil, Cd content of brown rice and stalk was decreased, but the effects were not obvious.The pot experiment of comparing improvement effects of ecologica fertilizer with organic fertilizer showed that, although organic fertilizer and ecological fertilizer both promoted rice growth, increased grain yield and decreased the content of Cd in rice and effective Cd content in soil, ecological fertilizer induced these effects more remarkably, comparing with organic fertilizer. The main reason that two fertilizers decreased the content of Cd in paddy and effective Cd content in soil was that they changed Cd fractions in soil.The study is aimed at reporting the authors’ pot rice -growing experiments in hoping to investigate the effects of different ways of water control on rice yields and its intake of Cd, that is, continuous flooding, dry cultivation and mid-way drainage in different growing stages. The results of our experiments indicate that dry cultivation brings about remarkable effects on the rice growth and brings about the lowest yields. Compared with the continuous flooding, dry cultivation tends to decrease the rice yields by 28.74%. On the other hand, continuous flooding tends to bring about relatively higher yields, but not the highest. Drainage at tillering and filling periods could increase the rice yields more remarkably than continuous flooding, that is, by 14.58% vs 10.27%. The content of Cd in brown rice proves the least with the continuous flooding, while the dry cultivation and midseason drainage in different growing stages tend to increase its content in brown rice, which appears most obviously with dry cultivation. In our experiments, dry cultivation has brought about an increase of Cd content as high as by 166.31%. On the other hand, the influence on Cd content in brown rice with the mid-way drainage proves weakest. Thus, it can be concluded that continuous flooding is most favorable to be chosen as a cultivation method on Cd contaminated soil, with the drainage cultivation following. In addition, dry cultivation is also likely to affect rice growth with an obvious increase of the Cd content, for which it is unfavorable to be chosen on Cd contaminated soil.The study of different amendments showed that the improvement effects of silica fertilizer were best, but the effects of different concentrations of silica were not investigated detailedly. The control standard of Cd pollution is lower but the activity of Cd in soil is high, plants absorb Cd easily. And the soil areas of low concentration of Cd pollution are large in China. So effects of Cd and Si on rice seedlings growth and uptake of Cd in the solution culture at the low concentrations of Cd pollution were investigated. Results indicated that the low concentrations of Cd could promote rice seedlings growth, but the content of Cd in rice seedlings was relatively higher, and the accumulation coefficient of Cd were also higher. So the food security risk caused by low concentrations of Cd pollution should not be overlooked. Si could improve rice seedling’s biomass, increase the content of protein and chlorophyll, enhance the vitality of rice root system and the activities of antioxidant enzyme SOD and POD in the condition of Cd pollution, but the suitable concentrations of Si should be chosen, the effects were weak when the silicon concentrations were too high or too low. Effect of Si on suppressing Cd uptake by the rice seedlings was very obvious in the range of silicon concentrations. But with the increasing concentrations of Si, the effect was weaker gradually. Thus considering the economic factor, the effect on decreasing the content Cd of the rice seedlings might be good as long as chosen the suitable concentrations of Si.更多还原