【作者】 李红霞；

【导师】 伍钧；

【作者基本信息】 四川农业大学 ， 环境科学， 2010， 硕士

【摘要】 重金属复合污染是土壤污染的主要存在形式,植物修复现已被普遍认为是治理重金属复合污染土壤的有效技术之一。本文以鱼腥草为试验材料,采用盆栽实验技术,探讨了不同浓度Pb、As及其复合处理对鱼腥草生长发育的影响,及鱼腥草对Pb、As的富集特征,结果表明：1.单一Pb (0～2 000mg/kg)处理下,鱼腥草株高及产量均随Pb处理浓度的增加而降低,根长呈先上升,后下降的趋势,受害症状明显；单一As(0～120 mg/kg)处理下,鱼腥草生长状况良好,无明显毒害症状,株高、根长、产量随As处理浓度的增加呈先升后降趋势,且均不低于对照,在供试As浓度范围对鱼腥草生长的毒性效应表现为毒物的低剂量兴奋效应。Pb、As复合处理下,就株高而言,As和Pb对彼此的毒性效应没有显著影响；就根长和产量而言,As对Pb的毒性效应影响不显著,高浓度Pb(=1000mg/kg)促进了As对根长的毒物兴奋效应,而低浓度Pb(=500mg/kg)促进了As对产量的毒物兴奋效应。2.在不同浓度的Pb、As处理土壤中,Pb、As的加入均可影响鱼腥草根、茎、叶对Pb、As的吸收能力。就As对Pb的影响而言：Pb处理浓度=1000mg/kg时,As可抑制鱼腥草根和茎对Pb的吸收,而Pb浓度为2000mg/kg时,As可促进鱼腥草根和茎对Pb的吸收,当Pb处理浓度=500mg/kg时,As可抑制鱼腥草叶部对Pb的吸收；就Pb对As的影响而言,Pb可抑制鱼腥草根和茎对As的吸收,而Pb对鱼腥草叶部吸收累积As的影响表现为先促进后抑制的趋势,随As处理浓度的增加,对鱼腥草叶部吸收累积As产生抑制作用时的Pb浓度逐渐降低。3.鱼腥草对Pb的富集系数为0.21～0.46,对As的富集系数为0.01-0.3；鱼腥草对Pb的转移系数为0.24～2.51,对As的转移系数为0.09～2.09,随Pb、As处理浓度的增加,鱼腥草对Pb、As的富集系数逐渐增加,转移系数则逐渐下降。鉴于鱼腥草对Pb、As较高的富集系数,可以考虑作为修复Pb、As污染土壤的植物修复物种。4.单—Pb处理浓度为2000mg/kg及Pb、As复合处理浓度分别为1000、60mg/kg时,鱼腥草从土壤中提取最多的铅,分别为1244.4ug/盆和3132.4ug/盆。单—As处理浓度为120mg/kg及Pb、As处理浓度分别为500、120mg/kg对,鱼腥草从土壤中提取最多的砷,分别为27.3ug/盆和254.1ug／盆。Pb、As复合处理下,鱼腥草从土壤中提取Pb、As的量较各自对照均有显著的增加。5.Pb、As在鱼腥草器官水平的分布规律是：根>茎>叶,且随着Pb、As处理浓度的增加,根部重金属含量所占比例也逐渐增加,表明在Pb、As胁迫下,鱼腥草将大部分的重金属固定在根部,限制其向地上部转移,降低重金属对鱼腥草的毒害作用。Pb在鱼腥草细胞水平分布规律为：细胞壁>可溶性成分>细胞器,细胞壁具有重金属的束缚作用和解毒能力,将大部分的Pb固定在细胞壁中,可降低Pb对鱼腥草的毒害。As在鱼腥草体内细胞内分布规律是：可溶性成分>细胞壁>细胞器。细胞器作为细胞进行各种生理活动的部位,其中的Pb和As含量均保持在相对较低的水平,对于保证鱼腥草正常的生理活动具有重要意义。6.单一Pb处理下,土壤中各形态Pb含量的大小顺序是：交换态>有机结合态>残渣态>碳酸盐结合态>铁锰氧化物结合态,交换态含量随Pb处理浓度的增加而增加；As加入后,残渣态Pb含量降至最低,表明As对Pb有一定活化作用。交换态和有机结合态Pb含量与植物中Pb含量相关性均是最大,为鱼腥草吸收Pb的主要形态。As在土壤中各形态含量的顺序为：有机结合态>铁锰氧化物态>硫化物态>碳酸盐结合态>交换态。交换态作为植物最易吸收的形态,其所占比例仅在1%左右,但其与鱼腥草体内的As含量的相关性却是最高的,为鱼腥草累积As的主要形态。交换态As含量极低,表明As在土壤中的生物有效性较低,对鱼腥草的毒害作用较小更多还原

【Abstract】 Combination contamination of heavy metals is a common but important form of soil contamination. Phytoremediation has become an effective approach for remediation of heavy metal contaminated soils. Taking Houttuynia cordata Thunb. as test material, this paper studied the effects of different concentrations of Pb, As and their combination treatment on the growth and development of H. cordata. and its accumulation of Pb and As by adopting pot culture experiments. The results showed that:1. Plant height and yield of H. cordata. were increased as the concentration of Pb decreased, the root length was first increased and then decreased to suffer symptoms under the single treatment of Pb; Because of the low-dose stimulating effect of As on H. cordata., the plant height, root length, yield increased with the concentration of As and no less than the control. H. cordata. growth was in good condition and there were no obvious toxicity symptoms under the single treatment of As; Under the combined treatments of Pb and As, in terms of plant height, there were no significant interactive influence on the toxic effects. In terms of the root length, the toxic effects of high concentration of Pb (=1000mg/kg) on As showed inhibition while the toxic effects of As on Pb was not significant; In terms of the yield, the toxic effect of low concentrations of Pb (= 500mg/kg) on As showed inhibition while the toxic effect of As on Pb was not significant.2. In the soil of different concentrations of combined treatments of Pb and As, the accession of Pb and As affected the roots, stems, and leaves of H. cordata.on the absorptive capacity of Pb and As, respectively. In terms of the impact of As on Pb:When the concentration of Pb= 1000mg/kg, As inhibited Pb absorption of root and stem, respectively. When the concentration of Pb reached 2000mg/kg, As promoted Pb absorption of root and stem, respectively. What’s more, when the concentration of Pb=500mg/kg, As inhibited Pb absorption of leaves; In terms of the impact of Pb on As, Pb inhibited As absorption of root and stem, respectively, while the impact of Pb on As absorption and accumulation of leaves showed the trend of first promotion and then inhibition. The restraining concentration of Pb on As absorption and accumulation of leaves decreased with the increase of the concentration of As.3. The Enrichment Coefficient of Pb and As were 0.21～0.46 and 0.01～0.3, respectively, while the translocation factor of Pb and As were 0.24～2.51 and 0.09～2.09, respectively, in terms of H. cordata. With the concentrations of Pb and As increased, the Enrichment Coefficient of Pb and As increased while the translocation factor of Pb and As decreased gradually, respectively. In view of its high Enrichment Coefficient, H. cordata. can be considered as phytoremediation species to repair Pb and As contaminated soil.4. When the concentration was 2000mg/kg under the single treatment of Pb and the concentration of Pb and As were 1000 mg/kg and 60 mg/kg under the combined treatments, H. cordata. extracted the most lead from the soil, which was 1 244.4 ug/pot and 3 132.4 ug/pot, respectively. When the concentration was 120mg/kg under the single treatment of As and concentration were 500 mg/kg and 120mg/kg under the combined treatments of Pb and As, H. cordata. extracted the most arsenic from the soil, which was 27.3ug/pot and 254. 1ug/pot respectively. The amounts of Pb and As that H. cordata.extracted from soil were higher than the control significantly, respectively.5. The distribution of Pb and As in vivo organ-level of H. cordata. was:root> stem> leaf. The proportion of heavy metals in roots increased gradually with the concentration of Pb and As, respectively, indicating that under the stress of Pb and As, most of the heavy metals are fixed in root of H. cordata., limiting them to transfer to the shoot to reduce the toxicity of heavy metals on H. cordata.. The distribution of Pb in the body cells- level of H. cordata. was:cell wall> soluble components> organelles, cell wall plays an important role in binding with heavy metals and detoxification, which can reduce Pb poisoning on H. cordata. The distribution of As in the body cells- level of H. cordata. was:soluble components> cell wall> Cell device. Cell organelle is the location for various physiological activities, the contents of Pb and As are maintained at a relatively low level, which is significant to guarantee the normal physiological activities of H. cordata..6. The order of content in various forms of Pb in soil under the single treatment of Pb was: exchangeable> organic bound> residual> carbonate bound> Fe-Mn oxides. The content of exchangeable Pb increased with the concentration of Pb in the treatment, the content of residual Pb reduced to minimum when As was added, indicating that As shows a certain activation on Pb. The correlations of Pb content in exchangeable and organically bound with Pb content in plants were the highest, which were the main form of absorption Pb in H. cordata.. The order of content in. various forms of As in soil was:organic bound> Fe-Mn oxide phase> sulfide> carbonate> exchangeable. The proportion of exchangeable, which is the most easily absorbed form of plants, is only about 1%, but it’s the main form of H. cordata. that accumulated As as its highest relevance to the content of As in H. cordata. The content of exchangeable As was extremely low, indicating that As bioavailability in soil is very low and it’s less harmful to H. cordata..更多还原