【作者】 王晨；

【导师】 王海燕；

【作者基本信息】 北京林业大学 ， 植物营养学， 2010， 硕士

【摘要】 随着工农业的迅速发展,生态系统中化学污染物质含量急剧增加,工农业生产和人类健康面临着严重挑战。尤其是土壤中重金属污染物的大量聚集导致的土壤重金属污染,对人类生活产生了严重影响。如何治理这些污染土壤、降低重金属在土壤-植物系统中的迁移等已成为人们关注的焦点。该论文综述了土壤-植物系统中重金属污染的研究进展,概述了Si元素对植物生长及其抑制植物吸收重金属的重要作用。结合Si对缓解植物重金属毒害的作用机制,本研究选取多年生黑麦草（Lolium perenne L.）、高羊茅（Festuca arundinacea Schreb）进行盆栽试验,采用正交试验设计的方法,研究了Cd、Zn和Pb复合污染条件下Si对草坪草生理生化特性以及土壤-草坪草系统中重金属元素迁移的影响。研究结果表明:（1）在Cd、Zn、Pb复合污染条件下,随着Cd浓度的提高,黑麦草生物量受到显著抑制,50 mg·kg^-1Zn和Pb有利于黑麦草生物量的积累,但当Zn、Pb的添加量分别达到300 mg·kg^-1和350 mg·kg^-1时,黑麦草地上部分、地下部分生物量都会受到显著抑制:相同浓度下,Cd、Zn、Pb对高羊茅和黑麦草叶绿素a、叶绿素b以及叶绿素总量的影响存在差异,但当Cd添加量超过1 mg·kg^-1、Zn和Pb超过50 mg·kg^-1时,黑麦草和高羊茅叶绿素含量均会降低;两种草坪草叶绿素对Cd、Zn和Pb的敏感程度不同,黑麦草叶绿素含量对Zn的浓度较为敏感,50 mg·kg^-1Zn对其有一定的促进作用;1 mg·kg^-1Cd对高羊茅叶绿素含量存在刺激作用,能提高其叶绿素含量。Cd、Zn、Pb会影响黑麦草和高羊茅CAT和POD活性,黑麦草CAT和POD对1mg·kg^-1Cd有积极的响应,Zn的添加量高于50 mg·kg^-1时会降低其CAT活性,而Pb高于50 mg·kg^-1时可以提高两种酶的活性,黑麦草两种酶对Zn浓度的响应时间有所不同,POD相对滞后;随着Cd、Pb浓度的提高,高羊茅CAT活性会受到显著抑制,但CAT活性对Zn浓度有着积极响应,而POD活性则随着重金属浓度的增加有所提高。此外,Cd、Zn和Pb对高羊茅叶片相对含水量的影响作用不显著且整体上没有规律;土壤中Cd、Zn和Pb添加量的提高会导致高羊茅叶片中MDA含量的大量积累,其中Pb的影响最为显著。（2）Si对黑麦草生物量的影响作用极显著。Si可以通过提高黑麦草叶绿素含量以及降低叶绿素a/b值而改善光合能力、缓解叶片衰老,但在黑麦草生长初期要控制Si的浓度;Si虽然也能够缓解高羊茅叶片老化程度,但Si对高羊茅叶绿素含量的影响并没有表现出良好的规律性。Si能够显著激发黑麦草和高羊茅CAT的活性,并在加强POD活性的同时将其保持在一个适当的水平。同时,Si可以显著提高高羊茅叶片相对含水量,并且对高羊茅叶片MDA含量有极显著的降低作用。（3）黑麦草和高羊茅对Cd、Zn和Pb的吸收都表现出明显的剂量-效应关系;随着Si浓度的增加,黑麦草和高羊茅Cd、Pb、Zn含量均呈现逐渐降低的趋势,两种草坪草Cd、Zn、Pb含量与Si的添加量都分别呈现强的负线性关系;此外,随Si浓度的上升,黑麦草土壤Zn、Cd、Pb的交换态和碳酸盐结合态均呈现下降趋势,而铁锰氧化物结合态和残余态逐渐增加,从而降低了重金属的生物有效性,抑制了重金属在土壤-植物系统中的迁移。从变化幅度而言,Cd的交换态下降最大,其次是Zn和Pb;相比之下,高羊茅对不同形态的Cd、Zn、Pb吸收能力要高于黑麦草。该论文研究表明,Si元素在土壤重金属污染防治方面具有良好的前景,它与具有较强生态适应性和竞争能力的水土保持型草坪草联合使用,能为土壤重金属污染治理提供新的途径和方法。更多还原

【Abstract】 With the rapid development of industry and agriculture, there is a significant increase of chemical pollutants in ecosystems, which becomes a big challenge for global development and human health, especially for soil heavy metal contamination. How to control polluted soil and reduce the mobility of heavy metals in soil-plant system has become the focus.The research progress on heavy metal pollution in soil-plant system and the effects of silicon on plant growth and heavy metal uptake are reviewed in the paper. Ryegrass and tall fescue were selected for pot experiments with orthogonal experiment design L₉（3⁴） and L₁₆（4⁵） in the greenhouse to study the effects of silicon addition on physiological-biochemical properties and heavy metal uptake in soil-turfgrass system under the soil compound pollution of Cd, Zn and Pb.The results showed that:（1） Under the compound pollution, the biomass of ryegrass was significantly inhibted by increasing Cd application, 50 mg·kg^-1 Zn and Pb can facilitate the biomass accumulation, but both shoots and roots biomass were inhibited at 300 mg·kg^-1 Zn and 350 mg·kg^-1 Pb. Cadmium, Zn and Pb of the same concentration differently affected chlorophyll a, b and total content of chlorophyll for tall fescue and ryegrass. However, chlorophyll content of both turfgrass decreased when Cd application was higher than 1 mg·kg^-1, and Zn and Pb application higher than 50 mg·kg^-1. The sensitivity of these two kinds of turfgrass’ chlorophyll to Cd, Zn and Pb were different: ryegrass was sensitive to Zn and 50 mg·kg^-1 Zn increased its chlorophyll content; 1 mg·kg^-1 Cd stimulated and increased chlorophyll content of tall fescue. Cadmium, Zn and Pb affected the CAT and POD activities of the turfgrass as well: ryegrass showed a positive response of CAT and POD at 1 mg·kg^-1 Cd; CAT activity was reduced if Zn application was higher than 50 mg·kg^-1, while both CAT and POD activities were increased if Pb application was higer than 50 mg·kg^-1. Compare with CAT, there was lag of POD to Zn concentration for ryegrass. The CAT activity of tall fescue was significantly inhibited with increasing Cd and Pb concentration but it had positive response to Zn. The POD activity increased with increasing Cd, Zn and Pb concentration. In addition, there was no significant effect of Cd, Zn and Pb on relative water content of tall fescue without regular rules in general. MDA accumulated significantly in tall fescue with increasing Cd, Zn and Pb in soil especially for Pb.（2） Effects of Si on biomass accumulation of ryegrass were very significant. By increasing chlorophyll content and reducing chlorophyll a/b in ryegrass, Si helped to improve capability of photosynthesis and slow down lamina senescence, but its concentration should be under control in the initial growth period of ryegrass. Although Si can slow down lamina senescence of tall fescue, there was no regulation to show its effect on chlorophyll content. Silicon stimulated CAT activity for both ryegrass and tall fescue, and kept POD activity at an appropriate level. Meanwhile Si increased lamina’s relative water content and reduced MDA content of tall fescue significantly.（3） Obvious dose-effect was found for Cd, Zn and Pb uptake by the turfgrass. With increasing Si concentration, Cd, Zn and Pb uptake by ryegrass and tall fescue decreased gradually. There was a significant negative linear correlation between Si addition and Cd, Zn and Pb concentration in the turfgrass. With increasing Si addition, soil exchangeable and carbonate-bound Zn, Cd and Pb decreased, while Fe-Mn oxides and residual fraction increased gradually, and thus reduced heavy metal bioavailability and inhibited the mobility of heavy metals from soil to ryegrass. As for the variation, exchangeable Cd decreased most, followed by Zn and Pb. Tall fescue had stronger ability to take up Cd, Zn and Pb than ryegrass.In a word, Si has a good potential to control soil heavy metal pollution. Silicon addition to some kinds of turfgrass with strong ecological adaptability could be a new option to control heavy metal pollution in soil-plant system.更多还原