生物炭对淹水土壤中铁还原过程的影响及对减弱土壤盐渍化的贡献

发布时间：2018-06-18 14:28

本文选题：生物炭 + 旱改水　；参考：《西北农林科技大学》2017年硕士论文

【摘要】：中国针对盐碱土改良的研究已积累大量的成果,其措施也表现出多样性,其中“旱改水”措施在一些地区已体现出显著的功效。然而,在“旱改水”过程中,土壤中的盐分依旧存在,如何有效地降低盐分的影响,是该措施推广和扩大利用范围的核心。生物炭(biochar)是有机质在缺氧环境下经热化学转化而形成的多孔含碳固体,具有适于在环境中长时间并安全贮存碳的物理、化学和生物学性质。向土壤中加入生物炭,不仅可改变土壤中的离子平衡、调节盐基离子浓度和pH,而且能够显著提高土壤中微生物的活性及多样性,改善微生物的附着性能,促进土壤微生物的生长,进而可强化生物抗盐和生物净化的能力。在中国各大农业区进行的试验表明,在盐碱瘠薄土壤、环境污染土壤、退化板结土壤上施用生物炭,均表现出快速消除低产因子,规避和控制重金属污染,遏止盐分上升等多种良好作用。在盐碱地施用生物炭,能够降低土壤pH和盐分离子含量,而该研究目前只限于旱地土壤。在“改水”后,土壤形成厌氧环境,在干湿交替变化中,由微生物介导的异化铁还原过程在稻田土壤厌氧环境中占据重要地位,添加生物炭能够改变盐基离子、微生物及有机物的聚集状态,所以伴随的厌氧微生物学过程也会发生改变。此外,脱氢酶活性是也表征环境氧化还原状态的一个重要参数,它与土壤中微生物的活性及种群信息密切相关。因此,研究“旱改水”与生物炭配合使用对盐碱地的改良效果和机理对减弱土壤盐渍化有重要意义。本论文通过淹水模拟“旱改水”过程,添加不同用量和粒径的生物炭,分析该过程中体系pH、铁还原过程、脱氢酶活性以及游离碳酸盐、碳酸氢盐的变化及其之间的相互关系,以探究生物炭对淹水土壤中微生物过程的影响及添加生物炭后淹水土壤中碳酸盐赋存形态的变化特征,为阐述生物炭在淹水土壤中的作用机理提供必要的理论依据,进而阐明生物炭在“旱改水”措施中降低土壤盐碱化的机理。研究主要得到以下结论:(1)“旱改水”措施能够降低盐碱土pH,促进Fe(III)还原过程和脱氢酶活性,有效降低了游离碳酸盐的含量。pH、Fe(II)含量、碳酸盐、碳酸氢盐含量中各因素之间均表现出极显著的相关关系。(2)生物炭能提高吉林(JL)、宁夏(NX)、天津(TJ)土中的脱氢酶活性和铁还原能力,不同生物炭用量处理之间差异显著。不同生物炭用量对脱氢酶活性和铁还原能力的影响,表现为随着生物炭用量的增加脱氢酶活性和铁还原能力增大。JL、NX、TJ土中,添加生物炭的处理最大铁还原潜势分别增加了1.3%-2.6%、1.5%-7.6%、0.3%-6.5%,脱氢酶最大活性分别增加了57.9%-130.0%、53.3%-151.3%、63.8%-136.9%。铁还原最大潜势与达到脱氢酶最大生成速率对应的时间极显著相关,两者在培养过程中相互促进。(3)生物炭能够提高吉林(JL)和天津(TJ)两种土壤中脱氢酶活性和铁还原能力,不同生物炭粒径处理之间差异显著。不同粒径生物炭对脱氢酶活性和铁还原能力的影响,表现为随着生物炭粒径的减小脱氢酶活性和铁还原能力增大。脱氢酶活性的增加加速了脱氢产氢过程,H2作为电子供体促进微生物铁还原过程;Fe(II)含量的增加能够协助脱氢酶加快NAD+的还原速度,提高脱氢酶活性。培养过程中脱氢酶活性和铁还原过程相互促进,两者呈现显著的正相关关系。土壤初始pH影响微生物反应,生物炭对脱氢酶活性和铁还原过程的影响,因两种土样初始pH不同而存在差异。(4)在淹水培养条件下,添加生物炭增加了碳酸氢盐的浓度,即增大碳酸盐的溶出量,不同处理之间表现为随着生物炭用量的增加、粒径的减小,碳酸氢盐浓度增大。土壤初始pH值是制约碳酸盐溶出量的重要因素。生物炭的添加显著增强了微生物还原Fe(III)的能力,生成的Fe(II)理论上能够与CO32-结合形成沉淀态铁化合物,从而降低碳酸盐累积造成的危害。培养过程中碳酸盐、碳酸氢盐浓度与体系pH呈现显著的正相关及负相关关系。生物炭不仅能够吸附体系中的阳离子,同时生物炭对微生物的作用促进了厌氧培养体系的产氢产酸过程,导致盐碱土中阳离子含量降低、碳酸盐向碳酸氢盐及二氧化碳转化,从而有效降低了土壤碳酸盐含量及pH,显示出生物炭在“旱改水”措施中对盐碱土改良的功效。生物炭对盐碱土改良效果因土壤性质不同而存在一定差异,但均表现为随着生物炭添加量的增加及粒径的减小,改良效果越显著。
[Abstract]:A large number of achievements have been accumulated in the study of salt and alkali soil improvement in China, and the measures also show diversity. The measures of "dryland diversion" have shown significant effects in some areas. However, in the process of "dryland diversion", the salt in the soil still exists, and how to effectively reduce the effect of salt is the promotion and expansion of the measures. The core of the scope. Biological carbon (biochar) is a porous carbon containing solid formed by thermochemical transformation of organic matter under anoxic environment. It has physical, chemical and biological properties suitable for long time and safe storage of carbon in the environment. Adding carbon to soil can not only change the ion balance in soil, regulate the concentration of salt ions and pH, Moreover, it can significantly improve the activity and diversity of microorganisms in the soil, improve the adhesion of microbes, promote the growth of soil microbes, and then strengthen the ability of biological salt and biological purification. Carbon has many good effects on fast elimination of low yield factors, avoiding and controlling heavy metal pollution and inhibiting the increase of salt. The application of biological carbon in saline alkali land can reduce the content of pH and salt ions in soil, but the study is limited to dry soil. Biologically mediated dissimilation iron reduction process occupies an important position in the anaerobic environment of paddy soil. Adding biological carbon can change the concentration of salt based ions, microorganism and organic matter, so the accompanying anaerobic microbiological process will also change. In addition, dehydrogenase activity is an important parameter that also characterizes the state of environmental oxidation and reduction. It is closely related to the microbial activity and population information in the soil. Therefore, it is important to study the improvement effect and mechanism of "dry water" and biological charcoal to reduce soil salinization. In this paper, the process of flooding simulation "dry water" is used to add different amount and particle size of biological carbon, and the process of this process is analyzed. System pH, iron reduction process, dehydrogenase activity and changes in free carbonate, bicarbonate and their relationship, in order to explore the effects of biological charcoal on microbial processes in flooded soil and the change characteristics of carbonate occurrence in flooded soils after adding biological charcoal, in order to explain the mechanism of biological charcoal in flooded soil. For the necessary theoretical basis, the mechanism of reducing soil salinization in the process of "dry water diversion" was clarified. The main results were as follows: (1) the measures of "dry water diversion" could reduce the pH of saline alkali soil, promote the reduction process of Fe (III) and dehydrogenase activity, effectively reduce the content of free carbonate,.PH, Fe (II), carbonate, carbonate, and carbonate. There was a very significant correlation between the hydrogen salt content. (2) Biocharcoal could improve the dehydrogenase activity and iron reduction ability of Jilin (JL), Ningxia (NX), Tianjin (TJ) soil, and the difference between different biological charcoal dosage treatments. The increase of dehydrogenase activity and iron reduction capacity increased in.JL, NX, TJ soil. The maximum iron reduction potential of adding bio carbon was increased by 1.3%-2.6%, 1.5%-7.6%, 0.3%-6.5%. The maximum activity of dehydrogenase was increased by 57.9%-130.0%, 53.3%-151.3%, 63.8%-136.9%. iron reduction and maximum dehydrogenase production rate, respectively. The corresponding time was very significant. (3) biological charcoal could improve dehydrogenase activity and iron reduction ability in two soils of Jilin (JL) and Tianjin (TJ). The difference between different biological charcoal particle size treatment was significant. The effect of different particle size carbon on dehydrogenase activity and iron reduction ability was shown with biological carbon. The increase of dehydrogenase activity and iron reduction ability increases the dehydrogenase activity and the increase of dehydrogenase activity. The dehydrogenase activity accelerates the dehydrogenation process. H2 as an electron donor promotes the reduction process of microorganism iron. The increase of Fe (II) can help dehydrogenase accelerate the reduction rate of NAD+ and increase the activity of dehydrogenase. In the process of culture, dehydrogenase activity and iron reduction process The effect of soil initial pH on the microbial reaction, the effect of biological charcoal on dehydrogenase activity and iron reduction process is different from the initial pH of the two soil samples. (4) the addition of biological charcoal increases the concentration of hydrogen carbonate in the submerged culture condition, that is, increasing the dissolution of carbonate and different places. With the increase of the amount of biological carbon, the particle size decreases and the concentration of bicarbonate increases. The initial pH value of the soil is an important factor restricting the dissolution of carbonate. The addition of biological carbon significantly enhances the ability of microorganism to reduce Fe (III). The generated Fe (II) can theoretically combine with CO32- to form a precipitated iron compound, thus reducing it. There is a significant positive correlation and negative correlation between carbonate, bicarbonate concentration and system pH in the process of culture. Biological charcoal not only can adsorb cations in the system, but also promote the process of hydrogen production in the anaerobic culture system and lead to the decrease of cation content in the saline alkali soil. Low, carbonate conversion to bicarbonate and carbon dioxide, thus effectively reducing soil carbonate content and pH, showing the effect of biological charcoal on the improvement of saline alkali soil in the "dry water" measures. The effect of biological carbon on saline alkali soil is different because of the different soil properties, but all show the increase of the amount of biological carbon and the increase of the amount of carbon. The decrease of particle size, the better the improvement effect.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S156.4

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