【作者】 俞协治；

【导师】 成杰民； 黄铭洪；

【作者基本信息】 南京农业大学 ， 环境工程， 2003， 硕士

【摘要】 植物修复（phytoremediation）这种新兴的绿色生物技术应用于治理重金属污染土壤时，超积累植物生物量小、土壤中重金属生物有效性低是该项技术成功应用的主要限制因素。近年来提出的螯合诱导—植物修复技术虽能提高修复效率，但缺点是环境风险大，成本高。因此，寻求安全、经济的技术途径已成为当前急需研究的课题。 本文以红黏土红壤、长江冲积物形成的高砂土和香港灰化土为供试土壤，分别加入Cu（0，100，200，400 mg／kg）或Cd（0，5，10，20 mg／kg）模拟土壤污染，设置接种蚯蚓（Pheretima sp．）与不接种蚯蚓处理，通过培养试验、盆栽黑麦草（Lolium multiflorum）试验、接种菌根（Glomus mosseae+Glomus intraradices）实验等，研究蚯蚓对植物生物量和土壤中重金属生物有效性的影响，揭示蚯蚓对土壤—植物系统中重金属化学行为作用机理，为蚯蚓在植物修复技术中的应用与发展提供理论依据。 供试蚯蚓是对重金属的忍耐品种，但土壤重金属的污染明显抑制蚯蚓的生长。在高砂土和红壤中，蚯蚓对Cd的富集系数分别为2.78～3.41和3.08～3.84，说明蚯蚓对Cd具有明显的富集作用；Cu的富集系数分别为0.13～0.16和0.18～0.28，蚯蚓对Cu则是部分吸收。蚯蚓活动增加了高砂土Cu、Cd各处理中黑麦草地上部分的产量，增产幅度为33％～96％，且随重金属浓度的升高而降低。蚯蚓活动增加红壤Cu处理中黑麦草地上部分的产量，增产幅度为0～40％，对Cd处理中的产量无显著影响。蚯蚓活动显著提高了红壤和高砂土中速效N的含量，增加幅度分别为11％～56％、24％～94％，而对两种土壤上速效P和K的含量以及黑麦草中P、K含量没有明显影响。增加土壤速效N含量，提高植物对N的吸收，进而促进植物生长，是蚯蚓活动增加生物量的机理之一。 酸性红壤接种蚯蚓后pH显著降低，降低幅度为0.03～0.18个pH单位，而高砂土的pH则略有升高。蚯蚓活动增加了红壤中DTPA-Cu、CaCl₂-Cu和H₂O-Cd的含量；但对高砂土中Cu和Cd的各形态含量没有明显影响。土壤中三种形态的Cd含量与土壤pH均呈负相关，其中CaCl₂-Cd达到极显著水平（-0.950^¨）。蚯蚓通过影响土壤pH，进而影响土壤中重金属的生物有效性，或通过影响土壤pH值，进而影响蚓粪中重金属的生物有效性。蚯蚓活动没有增加黑麦草地上部分重金属含量，但由于生物量的显著增加，增加了黑麦草对Cu的吸收总量。这对提高植物修复效率具有重要意义。 在灰化土上和设定的Cd浓度范围内，菌根侵染率不受添加Cd浓度的影响，平均虹蝴在植物修复重金属污染土壤中的应用可行性研究侵染率为22%，加入蛆川能使菌根的侵染率提高9%.但接种菌根，对蛆川的生长率影响没有呈现明显的规律性.仅接种菌根能显著增加土壤中速效N、P和可溶性有机碳的含量以及黑麦草对N、P的吸收，但没有提高黑麦草地上部的产量，原因是菌根侵染促进了黑麦草对Cd的吸收，抑制了植物生长。接种菌根不仅能促进黑麦草对Cd的吸收，而且还能促进Cd从植物的根部向地上部分转移，这对提高植物修复效率有重要意义. 蛆州与菌根的相互作用，除了增加黑麦草对N的吸收外，在增加土壤速效养分、植物对养分的吸收、提高植物产量、降低土壤PH、提高土壤重金属活性和植物对重金属的吸收方面没有显著的协同作用。当添加cd的浓度大于10mg/kg时，接种菌根可部分地抑制蛆川对植物的增产作用。 洲粪中H20一Cd和DTPA一cd含量均显著高于相应处理的土壤中的含量，Cacl厂Cd含量则显著低于土壤中的含量.蛆川通过摄取含重金属的土壤，经体内研磨消化排泄等作用，以及分泌大量粘液蛋白对重金属的络合作用，增加了HZO一Cd和DTPA一Cd的含量，这是蛆川提高土壤中重金属活性的主要机理之一同时接种菌根后，川粪中三种形态的含量均低于仅接种蛆川的处理，可见接种菌根后部分抑制了蛆洲对土壤中cd的活化作用.由于川类中三种形态的cd含量与黑麦草吸收呈极显著的正相关，而圳粪中HZO一Cd和DTPA一cd含量均高于土壤中的含量。因此，川粪中有效态Cd是植物吸收Cd的重要供源。 上述研究表明，蛆州在重金属污染土壤上仍能提高土壤速效养分含量，促进植物生长;蛆州能通过多种机理活化土壤中重金属，提高其植物有效性，但其作用大小因土壤性质而异;菌根真菌与蛆洲虽没有表现出更好的协同作用，但其能促进植物对重金属的吸收和转移.因此，蛆圳和菌根有很大潜力提高植物修复的效率，进一步的研究需要在超积累植物上进行.更多还原

【Abstract】 Phytoremediation of heavy metals in contaminated soil has been widely accepted as a cost-effective, environmental-friendly technology. Metal-accumulating plants are usually planted to remove metals from soils by concentrating them in the harvestable parts, while the efficiency depends on the amount of aboveground biomass and the bioavailabililty of metals. Though addition of chelating agents has been shown to increase metal bioavailabililty and phytoremediation efficiency, it costs too much and shows environmental risk.Three soils, Red soil from Jiangxi Province, Orthic aquisols from Jiangsu Province and Podzol from Hongkong, were used in the experiments. Soils were amended respectively to contain 0, 100, 200, 400 mg Cu kg-1 and 0, 5, 10 and 20 mg Cd kg-1 by adding appropriate concentrations of CuSO4 and CdCl2. By comparing with treatments with and without earthworm (Pheretima sp.) in earthworm culture experiment ryegrass (Lolium multiflorum) planting experiment and mycorrhiza {Glomus mosseae + Glomus intraradices) inoculation experiment, the objective of this study was to investigate the effects of earthworm on the plant biomass and bioavailability of heavy metal in soils, to show the mechanisms of earthworm effect on chemical behavior of heavy metal in soil-plant system, and to provide theoretic base for the application of earthworm in phytoremediaton.The used earthworms can tolerate heavy metals, but their growth was negatively affected by heavy metal pollution in soil. Earthworm enriched Cd significantly but not for Cu, and the Cd enrichment coefficients in Orthic aquisols and Red soil were 2.78~3.41 and 3.08~3.84 respectively, while the Cu enrichment coefficients were only 0.13~0.16 and 0.18~0.28 respectively. In Orthic aquisols with Cu or Cd addition, earthworm activity increased ryegrass aboveground biomass by 33%~96%, but the increment decreased with the increasing heavy metal application in soil. And in Red soil with Cu addition, earthworm activity also increased ryegrass aboveground biomass by about 0~40%, but had little effect in Red soil with Cd addition. Earthworm activity markedly enhanced concentration of available N in Red soil and Orthic aquisols by 11%~56% and 24%~94% respectively, but had little effect on available P and K contents in two soils and P and K content in ryegrass.One of the mechanisms that earthworm activity enhanced plant biomass is by increasing soil available N and plant absorbing N, consequently improving plant growth.The pH of Red soil decreased by 0.03-0.18 units in the presence of earthworm, but pH of Orthic aquisols increased slightly. Earthworm activity increased concentrations of DTPA-Cu, CaCl2-Cu and H2O-Cd in Red soil, but had little effect on fractions of Cu and Cd in Orthic aquisols. Soil pH was negatively correlated with each fraction of Cd in soil, and the correlation between soil pH and CaCl2-extractable Cd content was the most significant, the coefficient was -0.950**. So by affecting soil pH, earthworm activity affects bioavailability of heavy metal in soil or in earthworm cast. Though concentration of heavy metal in plant tissue did not increased, total uptake of Cu by ryegrass was enhanced by earthworm activity for the biomass increment. This is important for enhancing efficiency of phytoremediation.The mean mycorrhiza infection rate of root was about 22%, and it was not affected by Cd addition in Podzol, but it increased by 9% in the presence of earthworm. But mycorrhiza inoculation had no regular effect on earthworm growth rate. Mycorrhiza inoculation enhanced concentration of available N P and dissoluble organic carbon in soil and increased uptake of N and P by ryegrass, but did not increased ryegrass aboveground biomass. The reason is that mycorrhiza infection improved uptake of Cd by ryegrass, consequently restrained ryegrass growth. Mycorrhiza inoculation improved not only uptake of Cd by ryegrass but also transfer of Cd from root to shoot. This is beneficial to phytoremediation efficiency.Except in enhancing uptake of N by ryegrass,更多还原