【作者】 安玲瑶；

【导师】 朱诚；

【作者基本信息】 浙江大学 ， 植物学， 2012， 博士

【摘要】 随着工业化的发展,大量的重金属被排入环境中,对土壤特别是耕地造成严重的污染。由于重金属可随食物链移动,最终积累在人体内,对人类健康造成危害,因此对重金属污染土壤的修复迫在眉睫。与传统的物理、化学修复手段相比,新型的植物修复方式具有成本低、对土壤扰动性小、不造成二次污染等优点,被誉为土壤重金属污染修复的最佳方法。但是由于常用于植物修复的高积累植物,往往生物量小、生长缓慢,修复效果并不理想。因此迫切需要寻找新方法来提高重金属污染土壤的修复效率,或者降低重金属在农作物中的积累,从而获得在污染土壤中也可实现安全食用的农产品的生产。1.本研究选择了四种Cd吸收能力显著差异的作物(Cd相对高积累青菜(杭州油冬儿)和番茄(中蔬4号)；Cd相对低积累甘篮(京丰一号)和玉米(金珠蜜甜玉米)),在Cd污染土壤中进行间作试验。实验结果如下：1)在Cd 2.62 mg kg-1的污染水平下,青菜和甘蓝间作条件与单作相比,Cd在青菜中的积累浓度提高(地上部分从6.55 mg kg-1升高至9.29 mg kg-1,地下部分从4.45 mg kg-1升高至7.65 mg kg-1),而在甘蓝中的积累浓度下降(地上部分从3.70 mg kg-1降低至0.54 mg kg-1,地下部分从3.32 mg kg-1降低至1.99 mg kg-1)。在Cd 3.70 mg kg-1的污染水平下,番茄和玉米间作和限制性间作条件与单作相比,Cd在番茄中的积累浓度提高(叶部从13.52 mg kg-1分别升高至24.94 mg kg-1和27.30 mg kg-1)。表明采用间作方式可以同时实现提重金属污染的植物修复效率和污染土壤中产出可安全食用农产品的目的。2)与未种植作物的对照组相比,种植青菜和甘蓝后,土壤pH值有小量下降,酸性磷酸酶活性上升,脲酶活性下降,并且青菜单作组土壤pH值下降幅度最大,脲酶活性下降幅度最小；种植番茄和玉米后,番茄根围土壤pH值有所下降,酸性磷酸酶活性上升,脲酶活性下降,并且间作组土壤pH值下降幅度最大,酸性磷酸酶活性升高幅度最大,脲酶活性下降幅度最小。这些变化进一步影响到土壤中Cd的存在形式,最终导致作物对Cd的吸收能力发生变化。间作还能提高Cd高积累番茄根围土壤中,对重金属吸收有促进作用的微生物种群的丰度,而降低对重金属吸收有抑制作用的微生物种群的丰度,最终实现Cd高积累番茄对Cd的吸收能力提高。因此,不同作物间作影响其对重金属的吸收能力可能是通过改变土壤pH值、土壤酶活性、根围土中微生物种群分布而实现的。2.本研究选用青菜、甘蓝、番茄、玉米和重金属高积累植物鸡眼草,在多种重金属(Cd、Pb、Cr、Cu和Fe)低浓度复合污染的大田中进行单作、间作试验,研究不同植物种类、不同种植方式下对不同重金属的吸收特性。结果表明,番茄对土壤中重金属尤其是Cd的吸收能力较高,当番茄和其他作物间作时,番茄对重金属的吸收能力还会提高,因此番茄是一种适合修复土壤重金属污染的植物；玉米对Cr、Cu和Fe的积累较高,当玉米和其他植物间作时,玉米对重金属的吸收能力还会降低,因此玉米适合在重金属污染土壤中间作种植来产出可安全食用的产品；鸡眼草的地下部分易吸收土壤中的Cd和Pb,当鸡眼草和其他作物间作时,鸡眼草对重金属的吸收能力下降；青菜和甘蓝既不适用于修复土壤的重金属污染,也不适用于作为食品产出而种植在重金属污染土壤中。本研究为同时实现高效率的土壤重金属污染修复和在污染土壤中产出可安全食用的农产品提供了线索。更多还原

【Abstract】 Along with the development of the industry, a great deal of heavy metal was released into the environment, causing serious pollution to soils especially the farmland soil. Heavy metal can transport through the food chain, and finally accumulate in the human body, resulting in serious human health concerns. So the remediation of heavy metal contamination is imminent. Compared with the traditional physical or chemical remediation methods, the new method, phytoremediation with advantages of inexpensive, causing fewer disturbances to the soil, and not lead to secondary pollution, is known as the best method for remediation of soil heavy metal contamination. Due to the hyperaccumulators which are often used in the phytoremediation are always of small biomass and grow slowly, the remediation efficiency is not ideal. Thus, it is urgent to develop new methods of enhancing the efficiency of remediation of contaminated soil, or decrease heavy metal extraction by crops for safe food production in contaminated soil.1. In this study, four plant species with significantly different Cd absorption ability were chosen (relatively Cd high-accumulator: greengrocery and tomato; relatively Cd low-accumulator:cabbage and maize) to intercropping in the soil of Cd contamination. The results indicated as follow:1) Compared with monoculture, intercropping of greengrocery and cabbage increased the Cd extraction by greengrocry (increased from 6.55 mg kg-1 to 9.29 mg kg-1 in shoot and from 4.45 mg kg-1 to 7.65 mg kg-1 in root), and decreased the Cd extraction by cabbage (decreased from 3.70 mg kg-1 to 0.54 mg kg-1 in shoot and from 3.32 mg kg-1 to 1.99 mg kg-1 in root), when cultured in soil with 2.62 mg kg-1 Cd. Compared with monoculture, intercropping and restricted intercropping of tomato and maize increased the Cd extraction by tomato (increased from 13.52 mg kg-1 to 24.94 mg kg-1 and 27.30 mg kg-1 in leaves). Thus, the remediation efficiency of Cd contamination was advanced while output from contaminated soil is safe to eat through intercropping. 2) Compared with non-planted soil, after culture of greengrocery and cabbage, soil pH decreased a little, activities of acid phosphatase increased and activities of urease decreased. The most decrease of soil pH and the least decrease of urease activities were determined in monoculture of greengrocery. After culture of tomato and maize, soil pH decreased, activities of acid phosphatase increased and activities of urease decreased. The most alteration of soil pH and acid phosphatase activities, and the least decrease of urease activities were determined in intercropping of tomato and maize. All the alteration influenced the Cd form in soil, eventually leading to the alteration of Cd absorption ability by plants. At the same time, intercropping increased the microorganism species abundance which are beneficial to heavy metal extraction, and decreased the microorganism species abundance which will block the heavy metal extraction in the rhizosphere soil of tomato, finally achieved the enhancing of Cd absorption capability by tomato. Therefore, intercropping influenced the heavy metal absorption ability through the alteration of soil pH, soil enzyme activity, and microorganism species abundance in the rhizosphere soil.2. In this study, greengrocery, cabbage, tomato, maize, and Japan Clover Herb which is reported as a heavy metal high accumulator, were cultured in monoculture and intercropping, in field which is contaminated by a variety of heavy metal (Cd、Pb、Cr、Cu和Fe) in low concentrations. The study evaluated the heavy metal absorption status between different plant species, different heavy metals, and different planting patterns. The results showed that tomato absorbed a great amount of heavy metals (especially Cd). Furthermore, accumulation of heavy metals increased when tomato was intercropped with other plant species. Thus, tomato planted in intercropping is suitable for remediation of soil heavy metal contamination. Maize absorbed much Cr, Cu and Fe. The heavy metal concentrations were reduced when maize was intercropped with other plant species. Thus, maize planted in intercropping is suitable for producing safe products from heavy metal contaminated soil. The roots of Japan Clover Herb were easy to accumulate Cd and Pb. The heavy metal concentrations were reduced when Japan Clover Herb was intercropped with other plant species. Greengrocery and cabbage are neither suitable for repair the soil heavy metal contamination, nor for output of safe production from the heavy metal contaminated soil.This research provided clues for simultaneous efficient remediation of heavy metal contamination and output of safe production from contaminated soil.更多还原