EDTA强化盐生植物修复Pb、Cd与次生盐渍化复合污染土壤

发布时间：2018-01-17 03:04

本文关键词：EDTA强化盐生植物修复Pb、Cd与次生盐渍化复合污染土壤　出处：《西南大学》2017年硕士论文　论文类型：学位论文

【摘要】：设施农业是随农业现代化和种植结构调整发展起来的新型产业。目前,我国设施农业面积约为400万hm2,其中设施菜地占设施农业总面积的95%以上。2010年我国设施蔬菜总产量超过1.7亿吨,占蔬菜总产量的25%。在设施农业生产中,盲目施肥与过度灌溉会引起土壤板结、次生盐渍化等问题,特别是土壤酸化会提高重金属在土壤中的迁移性,进而加剧重金属在土壤中的积累,其中设施土壤重金属污染以Pb、Cd较为突出。设施土壤次生盐渍化和重金属积累会降低农产品品质,甚至危害人体健康,阻碍设施农业可持续发展,修复重金属与次生盐渍化复合污染土壤是设施农业生产中亟待解决的问题。目前,盐渍土的修复主要有工程措施、化学措施、生物措施和农业措施,虽取得一定成效,但还存在修复时间长、成本高或效率低等问题;重金属污染土壤的修复技术主要有客土法、热处理法、电动修复法、植物修复法、化学固定法和淋洗法等,这些方法投资大、运行成本高或容易造成二次污染。盐生植物的脱盐能力强,一些盐生植物还对重金属表现出一定的富集能力,对于修复重金属污染的土壤表现出一定潜力。另一方面,螯合剂可以提高土壤中重金属的生物有效性,结合植物修复能够提高重金属的去除率,其中EDTA被广泛用于强化植物修复重金属污染土壤,并取得较好的修复效果。因此,应用EDTA强化盐生植物修复重金属与盐渍化复合污染土壤值得进一步探讨。目前,修复重金属与次生盐渍化复合污染土壤的研究较少,采用EDTA强化盐生植物的修复研究更少见报道。为此,本文采用盆栽试验,考察景天三七、翅碱蓬和紫花苜蓿对模拟盐渍土中阴离子(NO3-、Cl-、SO42-)的去除效果,筛选出可有效去除盐分阴离子的盐生植物;考察添加和不添加EDTA时3种植物对模拟Pb、Cd污染土壤的修复效果,筛选出可有效去除Pb、Cd的盐生植物和EDTA添加水平;在此基础之上,采用EDTA强化盐生植物修复Pb、Cd污染盐渍土,并应用于实际污染土壤的修复研究。取得如下主要研究结果:1.移栽盐生植物70 d,对模拟盐渍土中盐分阴离子(NO3-、SO42-、Cl-)的去除实验表明:在土壤盐度为0.15%时,3种植物的生物量都高于对照,景天三七对NO3-的去除率达到68.56%,紫花苜蓿对SO42-和Cl-的去除率分别达到53.46%和66.42%。在土壤盐度为0.45%时,翅碱蓬的生物量高于对照,而另两种盐生植物的生物量都低于对照,景天三七对NO3-、SO42-和Cl-的去除率分别为68.36%、47.36%和57.38%。在土壤盐度盐度为0.75%时,紫花苜蓿不能存活,景天三七的生长受到抑制,而翅碱蓬的生物量高于对照;景天三七对NO3-的去除率为35.68%,翅碱蓬对SO42-和Cl-的去除率分别为31.83%和31.25%。说明中低盐度水平下景天三七对盐分阴离子的去除效果最好,而在高盐度时翅碱蓬对盐分阴离子的去除效果更好。2.移栽盐生植物70 d,对模拟重金属污染土壤中Pb、Cd的去除实验表明:在考察的Pb、Cd含量水平下,土壤中的Pb、Cd几乎不影响3种盐生植物的生长。景天三七对轻度、中度和重度污染土壤中的Pb、Cd均表现出较高的去除效率,且对Cd的去除率略高于Pb;添加EDTA有利于提高土壤中Pb、Cd的去除率和植物对Pb、Cd的积累量,当EDTA的添加水平为4 mmol/kg土时,轻度、中度和重度污染土壤中Pb的去除率分别达到30.84%、32.59%和28.78%,Cd的去除率分别达到34.22%、36.47%和35.83%。添加EDTA后,3种盐生植物对Pb、Cd的富集系数和转运系数都有不同程度的增加,进一步说明添加EDTA可以提高土壤中Pb、Cd的去除效率,以添加4 mmol/kg EDTA的效果最好,又以景天三七对Pb、Cd的富集积累能力最强。3.移栽翅碱蓬和景天三七70 d,对模拟重金属与次生盐渍化复合污染土壤的修复实验表明:在土壤盐度为0.15%时,两种植物的生物量均高于对照;在土壤盐度为0.45%和0.75%时,翅碱蓬的生物量高于对照,而景天三七的生物量低于对照。景天三七对低盐度土壤中NO3-、SO42-、Cl-的去除率分别达到71.23%、51.67%和58.27%;对于高盐度土壤,景天三七对NO3-的去除率为37.42%,翅碱蓬对SO42-和Cl-的去除率分别为31.83%和31.68%。景天三七对对轻度、中度和重度污染土壤中Pb的去除率分别为41.37%、41.21%和38.56%,对Cd的去除率分别为47.25%、45.67%和45.39%。景天三七对Pb、Cd的富集系数和转运系数较大,高盐度时会出现下降。土壤盐度越大,翅碱蓬和景天三七对Pb、Cd去除效果越好。分析植物生理生化指标(叶绿素、脯氨酸、丙二醛、SOD活性)发现:随着土壤盐度增大,景天三七受胁迫反映更加强烈,而翅碱蓬则没有表现出受胁迫症状;同一盐度水平下,Pb、Cd浓度变化对植物的生长影响不明显。4.用EDTA强化景天三七修复实际污染土壤,获得土壤中NO3-、SO42-和Cl-的去除率分别为59.22%、42.11%和51.65%,Pb、Cd的去除率分别为37.87%和41.61%,景天三七地上部Pb、Cd含量分别为486和5.16 mg/kg干重,对土壤中Pb、Cd和盐分阴离子都有较好的去除效果,可以有效修复重金属与盐渍化复合污染土壤。
[Abstract]:Facility agriculture is a new industry with agricultural modernization and the adjustment of planting structure development. At present, our country agriculture area is about 4 million Hm2, which accounted for more than the total area of greenhouse facility agriculture in China.2010 95% vegetable total output of more than 1.7 tons, accounting for the total amount of 25%. in the vegetable production facilities in agricultural production. Blind fertilization and excessive irrigation will cause soil compaction, secondary salinization problems, especially soil acidification will increase the mobility of heavy metals in the soil, thereby increasing the accumulation of heavy metals in the soil, the soil heavy metal pollution facilities in Pb, Cd is more prominent. The soil salinization and accumulation of heavy metals will reduce the quality of agricultural products, and even harm to human health, hinder the sustainable development of agriculture facilities, remediation of heavy metal contaminated soil and salinization is an urgent problem in agricultural production. Before the repair of saline soil are the main engineering measures, chemical measures, biological measures and agricultural measures, although achieved some success, but there are still a long time to repair, high cost or low efficiency; remediation of heavy metal contaminated soil are the main soil method, heat treatment method, electric repair method, phytoremediation, chemical fixation and leaching method, the method of large investment, high operation cost and easy to cause two pollution. Halophyte desalting ability, some halophytes of heavy metals showed enrichment ability, for the remediation of soil heavy metal pollution showed some potential. On the other hand, chelating agent can improve the biological the effectiveness of heavy metals in soil, combined with phytoremediation can improve the removal rate of heavy metal, which EDTA is widely used to strengthen phytoremediation of heavy metal contaminated soil, and achieve better repair effect. Therefore, the application of ED TA enhanced salt plant remediation of heavy metals contaminated soil salinization and composite is worthy of further study. At present, research on remediation of heavy metal contaminated soil secondary salinization and less, strengthened by EDTA repair of halophytes more rarely reported. Therefore, the pot experiment, effects of Sedum 37, Suaeda Heteroptera and alfalfa on saline anion simulation the soil (NO3-, Cl-, SO42-) removal, screening can effectively remove salt anionic halophytes; study with and without EDTA on the simulation of Pb 3 plants, Cd contaminated soil repair effect, screening can effectively remove Pb, Cd and EDTA levels of halophytes; on this basis, using EDTA to strengthen the halophytes repair Pb, Cd pollution remediation of saline soil, and applied to the actual contaminated soil. Obtains main results as follows: 1. transplanting halophytes 70 D, to simulate the salt Saline soil salt anionic (NO3-, SO42-, Cl-) showed that the removal experiment in soil salinity was 0.15%, the biomass of 3 species of Sedum were higher than the control, 37 removal rate of NO3- reached 68.56%, alfalfa on the SO42- and Cl- removal rate reached 53.46% and 66.42%. in the soil salinity is 0.45% the biomass, S.heteroptera was higher than that in the control, and the other two species of halophyte biomass were lower than the control, Sedum 37 pairs of NO3-, SO42- and Cl- removal rates were 68.36%, 47.36% and 57.38%. in the soil salinity at a salinity of 0.75%, alfalfa cannot survive, Sedum 37 inhibited the growth of biological the amount of suaedasalsa is higher than that of control; Sedum 37 the removal rate of NO3- was 35.68%, SO42- of Suaeda salsa and Cl- removal rates were 31.83% and 31.25%. showed low salinity levels of salinity 37 Sedum anion removal effect is best, while in high salinity When suaedasalsa to salt anion removal effect of.2. is better transplanting of halophytes is 70 D, the simulation of heavy metal pollution in soil Pb, showed that the Cd removal experiment: in the study of Pb, Cd content, soil Pb, Cd almost does not affect the 3 halophytes growth. 37 of Sedum mild. Moderate and severe pollution in soil Pb, Cd showed higher removal efficiency, and the removal rate of Cd was slightly higher than that of Pb; adding EDTA can improve the soil Pb, the removal rate of Cd and Pb in plants, the accumulation of Cd, when the addition level of EDTA was 4 mmol/kg soil, mild. Moderate and severe pollution in soil Pb removal rate reached 30.84%, 32.59% and 28.78%, the removal rate of Cd reached 34.22%, 36.47% and 35.83%. after the addition of EDTA, 3 species of halophytes on Pb, the coefficient of enrichment coefficient and translocation of Cd have varying degrees of increase, further addition of EDTA can improve the soil Pb in soil, the removal efficiency of Cd, with the addition of 4 mmol/kg EDTA had the best effect, and in 37 Sedum on Pb, Cd accumulation capacity of the strongest.3. transplanting of Suaeda salsa and Sedum 37 70 D, showed that the repair of experimental simulation of heavy metals and the secondary salinization of soil contaminated by soil salinity in 0.15%, biomass the two plants were higher than that of the control; in the soil salinity of 0.45% and 0.75%, the biomass of suaedasalsa is higher than that of control, while the biomass of Sedum 37 lower than that of the control. 37 Sedum on NO3-, low salinity in soil SO42-, Cl- removal rate reached 71.23%, 51.67% and 58.27%; for the high salinity soil, Sedum 37 the removal rate of NO3- was 37.42%, SO42- of Suaeda salsa and Cl- removal rates were 31.83% and 31.68%. of 37 Sedum of mild, moderate and severe pollution in soil and the removal rate of Pb was 41.37%, 41.21% and 38.56%, the removal rate of Cd points For 47.25%, 45.67% and 37 45.39%. Pb Cd of Sedum, enrichment coefficient and transfer coefficient is larger, will decline at high salinity. Soil salinity increasing, and 37 Pb of Sedum suaedasalsa Cd, better removal efficiency. The analysis of plant physiological and biochemical indexes (chlorophyll, proline, C two aldehyde, SOD activity found) with the increase of soil salinity, Sedum 37 stress reflect more strongly, while suaedasalsa showed no symptoms of stress; the same level of salinity, Pb, effect of Cd concentration on the growth of plants was improved by EDTA.4. 37 repair Sedum actual contaminated soil, soil NO3-, SO42- and Cl- the removal rates were 59.22%, 42.11% and 51.65% Pb, the removal rate of Cd were 37.87% and 41.61%, 37 Sedum shoot Pb, Cd content were 486 and 5.16 mg/kg dry weight of soil, Pb, Cd and salt Yin has better removal effect from the child, can Effective remediation of heavy metal and salinization compound contaminated soil.

【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53;X173

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