砷镉超标农田钝化剂的筛选及调控效应研究

发布时间：2018-01-16 21:37

本文关键词：砷镉超标农田钝化剂的筛选及调控效应研究　出处：《中国农业科学院》2015年硕士论文　论文类型：学位论文

【摘要】：近年来,土地重金属污染问题已成为当今土壤污染问题中污染面积较广、危害严重的环境问题之一。化学钝化修复技术作为一项行之有效的土壤重金属污染修复技术,由于简单、快捷和经济高效等特点受到广泛关注,寻找高效的钝化材料及生产性能良好的钝化剂成为该技术的热点和难点。在此方面,以往的研究多集中于针对单一重金属的钝化剂研究,我国土壤重金属污染多表现为复合污染,尤其以砷镉复合超标问题突出,对砷镉超标农田的钝化修复与安全利用,成为当今农业环境学科面临的突出问题。本文以砷镉超标农田为主要研究对象,筛选和制备出了多种对砷镉具有良好的吸附性能的功能性材料,并以土壤培养试验和盆栽试验为手段,探讨各材料对土壤中砷镉的钝化效果,明确不同材料对砷镉超标农田的调控效应,初步建立砷镉高风险农田的安全利用模式,为砷镉超标农田安全生产提供科学依据。全文主要研究结果如下:1.通过比较不同材料对溶液中As(V)和Cd的吸附能力,当溶液中As(V)浓度为10mg?L-1时,研究发现零价铁、铁改性生物炭,酸改赤泥、铁改性炭黑对砷的吸附能力较强,对As(V)的去除率在70%以上,其它材料如赤泥、膨润土、天然沸石等的吸附能力较低;对Cd而言,在p H值为5.5条件下,Cd浓度为5mg?L-1的溶液中,除了浓酸改性赤泥和膨润土吸附能力较弱之外,其余材料如零价铁、生物炭及改性生物炭等对水溶液Cd的去除率也均在70%以上。总体而言,铁改性生物炭、零价铁等对Cd和As(V)均具有良好吸附性能。2.不同类型生物炭及其铁改性材料对砷镉吸附试验的研究表明,其吸附过程能很好地符合吸附动力学准二级方程,决定系数为0.98-1.00,计算求得的理论平衡吸附量与试验中所得最大平衡吸附量结果基本吻合;不同农业废弃物秸秆生物炭及其铁改性材料对As(V)、Cd的等温吸附过程符合Freundlich等温吸附方程,相关系数均在0.71以上,这表明这些材料对于As(V)、Cd的吸附以物理吸附过程为主,化学吸附过程为辅。3.将不同类型秸秆(玉米、稻草、杂草)制备的铁改性生物炭材料按照1%、2%和4%比例添加到土壤中,经过一段时间土壤培养试验,结果表明,各比例铁改性生物炭均可显著降低土壤中Na HCO3提取态砷、EDTA提取态Cd含量,其中,添加量为4%的铁改性草炭对砷镉具有最佳钝化效果,对土壤有效态As、Cd钝化效率分别为13.5%、42.9%,这种固定效应主要与土壤中活性砷、镉向残渣态的转化过程有关。4.盆栽试验的结果表明,铁改性生物炭及其与零价铁的不同组合配比材料施入土壤后,对小白菜生长构成明显影响。与对照比较,随着施入土壤铁改性生物炭量的增加,其生物量也显著增加(P0.05),而1%处理的生物量有所下降;在铁改性生物炭与零价铁联合作用下,作物的生长得到了明显改善,增产效应明显,尤其是1%铁改性生物炭分别与0.1%、0.5%零价铁联合作用下,生物量相比对照分别增加了63.4%和71.8%,比零价铁单独施用时显著增加(P0.05)。5.将不同比例的生物炭、铁改性生物炭及零价铁配合施用入土壤后,小白菜吸收砷镉的状况也发生了明显的变化。单独施用铁改性生物炭可导致小白菜吸收砷镉的量大大降低,其中,1%及4%处理下的对砷降低幅度分别达33.3%、42.9%,相应处理对Cd降低的幅度为27.4%、45.2%。而生物炭处理下,虽然其表现出对Cd钝化修复的良好效果,却导致植物吸收As含量增加,铁改性生物炭与零价铁的配合施用下,以4%铁改性生物炭+0.5%零价铁处理、1%铁改性生物炭+0.1%零价铁处理、1%铁改性生物炭+1%零价铁处理对砷镉超标农田的钝化效果较好,其中,1%铁改性生物炭+1.0%零价铁处理下作物吸收砷镉的量减少了42.9%、74.0%,作物品质大大改善。
[Abstract]:In recent years, the heavy metal pollution of land problem has become a wide area of the pollution problem of soil pollution, one of the serious environmental problems. As a simple and effective remediation of heavy metal contaminated soil remediation technology, chemical technology as fast and efficient features such as attention, looking for an efficient passivation passivation material and produce a good performance the agent has become a hot and difficult point of the technology. In this regard, previous research focused on the study of passivation agent for single heavy metal, heavy metal pollution of soil in China showed the compound pollution, especially arsenic cadmium exceed the standard problem, remediation and safety use of arsenic and cadmium exceed the standard of farmland, which has become a prominent problem facing today agro environmental discipline. The arsenic and cadmium exceed the standard farmland as the main research object, screening and preparation of a variety of good adsorption of arsenic and cadmium The function of material properties, and soil culture experiment and pot experiment as a means of various materials on the passivation effect of arsenic and cadmium in soil, clear different materials on arsenic and cadmium exceed the standard farmland regulation effect, the initial establishment of arsenic and cadmium high risk safety farmland utilization pattern, and provide scientific basis for the safe production of arsenic and cadmium exceeded farmland. The main results are as follows: 1. by comparison of different materials in solution As (V) adsorption capacity and Cd, As (V) when the solution concentration is 10mg? L-1, the study found that zero valent iron, iron modified biochar, acid modified red mud, iron modified carbon black on the adsorption capacity of arsenic strong, on As (V) removal rate is over 70%, other materials such as red mud, bentonite, adsorption capacity of natural zeolite is low; in the case of Cd, P in the H of 5.5, Cd concentration is 5mg? L-1 solution, in addition to acid modified bentonite and the adsorption of red mud bentonite is weak, the More than material such as zero valent iron, charcoal and modified biochar on the aqueous solution of Cd removal rate is above 70%. Overall, iron modified biochar, zero valent iron on Cd and As (V) have good adsorption properties of.2. with different types of biological carbon and iron modified materials inspection the research shows that the arsenic cadmium adsorption test, the adsorption process can be well in line with the quasi two stage adsorption kinetic equation, the coefficient of determination was 0.98-1.00, the theory of equilibrium adsorption test and calculate the maximum adsorption capacity results; different agricultural waste straw biochar and iron modified materials of As (V) Cd, the adsorption isotherm accords with Freundlich isotherm equation, the correlation coefficient was above 0.71, which indicates that these materials for As (V), Cd adsorption by physical adsorption process, the adsorption process of.3. will be supplemented by different types of straw (corn, straw, weed) preparation The iron modified biological carbon materials in accordance with the 1%, 2% and 4% was added to the soil, after a period of soil culture test results show that the ratio of iron modified biochar can significantly reduce arsenic extraction Na HCO3 in soil, extractable Cd content, EDTA content which has the best passivation effect on arsenic cadmium is 4% iron modified peat on soil available As, Cd passivation efficiency were 13.5%, 42.9%, the fixed effects mainly in soil and the activity of arsenic, cadmium results transformation process to the residue on the.4. pot experiment showed that iron modified biochar and the different combinations of materials with zero valent iron fertilizer on Chinese cabbage growth, a significant effect. Compared with the control, with the increase in soil iron modified biochar amount, the biomass was also significantly increased (P0.05), and the 1% processing biomass declined; in iron modified charcoal combined with zero valent iron Under the effect of crop growth has been significantly improved, increasing production effect is obvious, especially the 1% iron modified biochar respectively with 0.1%, 0.5% combined effects of zero valent iron, compared to biomass were increased by 63.4% and 71.8%, significantly higher than the single application of zero valent iron (P0.05).5. different ratio of biological carbon, iron modified biochar and zero valent iron fertilizer in soil, arsenic and cadmium uptake by Chinese cabbage status changed significantly. The separate application of iron modified biochar can lead to arsenic and cadmium uptake by Chinese cabbage is greatly reduced, among them, 1% and 4% under the treatment of arsenic decrease up to 33.3%. 42.9%, respectively, corresponding to the decrease of Cd amplitude is 27.4% 45.2%., and biochar, although it showed good effect on Cd remediation, but cause plants to absorb the increase of As content, with the application of iron modified biochar with zero valent iron, biological change in 4% iron Carbon +0.5% zero valent iron processing zero valent iron modified biochar +0.1% 1% iron, 1% iron modified biochar +1% zero valent iron processing better passivation effect on arsenic and cadmium exceed the standard farmland in which 1% iron modified biochar +1.0% zero valent iron treatment of arsenic and cadmium crop absorption decreased by 42.9%. 74%, crop quality is greatly improved.

【学位授予单位】：中国农业科学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

【参考文献】