生物炭—铁锰氧化物复合材料调控稻田土壤砷有效性的机制研究

发布时间：2018-05-01 05:41

  本文选题：生物炭-铁锰氧化物 + 砷　； 参考：《沈阳农业大学》2017年硕士论文

【摘要】：我国南方,尤其是湘江流域地区,土壤砷污染问题已经越来越严重,治理农田土壤砷污染、保障稻米质量安全已成为近几年研究热点。本研究以生物炭(BC)为原料,通过浸渍法制备生物炭-铁锰氧化物复合材料(FMBC),探讨其对水环境中砷的吸附机制,在此基础上,通过吸附试验和水稻盆栽试验,研究了生物炭-铁锰氧化物复合材料对砷有效性的影响,探究生物炭-铁锰氧化物复合材料对稻田土壤调控的机制。主要研究成果如下:(1)筛选出吸附效果较好的生物炭-铁锰氧化物复合材料,初步阐明其对砷的吸附机制生物炭-铁锰氧化物复合材料具有非常大的比表面积,较大的pH和相对粗糙不规整的表面,其生物炭与铁、锰氧化物复合材料质量之比25:1:3,对砷的最大吸附量为6.25 mg ·g-1,是生物炭最大吸附量的2.2倍;其对砷的吸附机理是表面的官能团(烷基、羰基、羟基和羧基等),通过表面的络合以及离子之间的化学作用来吸附溶液中的砷;生物炭-铁锰氧化物复合材料的表面铁锰氧化物可以提供一个氧化还原体系,将砷(Ⅲ)氧化成砷(V)再进一步吸附。(2)生物炭-铁锰氧化物复合材料提高了红壤对砷的吸附性添加生物炭-铁锰氧化物复合材料,提高了红壤对砷的吸附性能。添加生物炭-铁锰氧化物的吸附效果好于生物炭,添加F1M3BC25的吸附量为0.687 g· kg-1,是添加BC最大吸附量(0.423 g · kg-1)的1.6倍。XPS结果表明,加入F1M3BC25后,土壤颗粒表面出现明显的Fe2p3/2峰与Mn2p3/2峰,增强了砷(Ⅲ)氧化作用,使其转化为更易被吸附的砷(V),进而增大土壤对砷的吸附性能。(3)生物炭-铁锰氧化物复合材料降低了砷对水稻毒害作用,并提高水稻产量与质量添加生物炭-铁锰氧化物复合材料(F1M3BC25)促进了水稻的生长,降低了水稻各部分的砷的含量,提高了籽粒的产量,必需氨基酸比例有增加的趋势。高、中和低三种污染水平土壤中,最佳的生物炭-铁锰氧化物复合材料添加量为土壤质量的2%,能最大程度的降低水稻各部分的砷含量。与空白对照相比,在高、中和低三种污染土壤中,2%F1MBC25使水稻籽粒的干物重分别增加了 60.3%、80.7%和46.0%,使籽粒中的砷含量分别降低了 54.7%、49.6%和34.4%,籽粒中必需氨基酸所占比例提高了 3.51%、2.54%和1.58%。F1M3BC25对高度污染的土壤砷的有效性产生的影响更大,生物炭-铁锰氧化物复合材料能够氧化土壤中的砷(Ⅲ),使砷的形态发生转化,土壤溶液中主要存在形态是砷(Ⅴ),且与空白对照相比显著降低,进而增大土壤对砷的吸附能力。水稻根表铁锰膜含量增加,减少根系对砷的吸收,降低了水稻地上部分砷的含量,对水稻籽粒吸收砷产生抑制作用。
[Abstract]:In southern China, especially in Xiangjiang River Basin, the problem of arsenic pollution in soil has become more and more serious. In recent years, it has become a hot research point to control arsenic pollution in farmland soil and ensure rice quality and safety. In this study, biological carbon and iron manganese oxide composites were prepared by impregnation method, and the adsorption mechanism of arsenic in water environment was discussed. On the basis of this, adsorption experiments and pot experiments of rice were carried out. The effect of biocarbonion-iron-manganese oxide composite on arsenic availability was studied, and the mechanism of biological carbon-iron manganese oxide composite on soil regulation in paddy field was investigated. The main research results are as follows: (1) A biological carbon-ferromanganese oxide composite with good adsorption effect was selected, and its adsorption mechanism for arsenic was preliminarily explained, the biological carbon-ferromanganese oxide composite has a very large specific surface area. The ratio of biochar to iron and manganese oxide composite material is 25: 1: 3, and the maximum adsorption amount of arsenic is 6.25 mg / g ~ (-1), 2.2 times as much as that of biochar. The adsorption mechanism of arsenic is that the functional groups (alkyl, carbonyl, hydroxyl and carboxyl) adsorb arsenic in the solution through the complexation of the surface and the chemical interaction between ions. The surface iron and manganese oxides of biocarbonion-ferromanganese oxide composites can provide a redox system. The further adsorption of arsenic (鈪，

本文编号：1828010