中国干旱半干旱草原地区土壤中腐殖质的提取与表征研究
发布时间：2018-12-14 20:32
【摘要】：随着气候异常和人类非理性活动的影响,我国干旱半干旱地域不断扩展,区域生态环境恶化,导致土地荒漠化、草场退化和土地污染等一系列问题加剧。土壤腐殖质作为土壤微生物和植物生长营养物质的主要承担者,其含量和质量直接决定着土壤品质的优劣。研究表明,土壤腐殖质通过与土壤重金属和有机污染物作用,参与其在土壤中的迁移归宿,在土壤界面化学领域具有重要意义。为了解区域生态环境问题,本文选取干旱半干旱地域(内蒙古-甘肃)土壤为研究对象,采用国际腐殖质协会提供的标准方法对土壤有机质进行提取和纯化,采用紫外/可见光谱、傅里叶红外变换光谱和X-射线光电子能谱技术对提取的腐殖质样品进行结构表征,通过酸碱滴定实验对腐殖酸和富里酸表面酸性官能团-COOH和Ar-OH进行定量分析。实验结果表明:土壤腐殖质含量受地域干燥指数的影响,随区域内干燥指数AI(年平均降水量/蒸发量)的增大,土壤中可提取腐殖质的含量增大,当干燥指数低至0.05时,实验所采取的提取方法无法将土壤中少量的腐殖质提取出来。紫外/可见吸收光谱E4/E6和E2/E3比值随干燥指数的变化表明,对于腐殖酸分子,干燥指数对分子量和芳香度的影响存在一个阈值,即干燥指数为0.53,干燥指数在由0.17增至0.53,腐殖酸相对分子质量和芳香性逐进增强,当干燥指数超过0.53时,腐殖质分子芳香度和分子量降低。而对于富里酸分子,分子量和芳香度随干燥指数的变化呈无规律腐殖酸和富里酸表面元素主要为碳、氮、氧(除氢以外),表面氮含量约占3.32-5.79%,碳含量为62.98-71.08%,氧含量为25.68-35.38%。腐殖酸表面含氧量和(O+N)/C值均随干燥指数上升而增加;而富里酸表面含氧量和(O+N)/C随干燥指数的变化存在一临界干燥值(AI=0.32),临界干燥值范围内,样品极性和氧含量随区域干燥指数成正比,干燥指数超过0.32,富里酸样品极性和氧含量随区域干燥指数增加而降低。碳在腐殖质中的7种化学形态和结合能分别为:芳香碳C/C-H(282.5e V)、烷基碳C/C-H(283e V)、C(O)O(283.5e V)、O(284.4e V)、C=O(285.6e V)、C(O)N(286.45e V)、C(O)O(287.1e V);氮在土壤腐殖质中的三种化学形态和结合能为:NH2(397.8 e V)、NR3+(399.1e V)和NO2(400.5e V);氧在土壤中的化学形态和结合能为:C=O(529.5e V)和C-O(530.5e V)。研究区域内,腐殖酸分子中羧基的含量在3.24-4.79mmol/g,酚羟基的含量约在0.16-0.34 mmol/g;富里酸分子中羧基的含量在5.96-10.66mmol/g,酚羟基的含量约为0.12-5.44mmol/g,同一样品中富里酸分子的羧基官能团含量高于腐殖酸物质。腐殖酸和富里酸分子羧基和酚羟基含量的变化与地域干燥指数无关。
[Abstract]:With the influence of abnormal climate and irrational human activities, the arid and semi-arid areas in China are expanding and the regional ecological environment is deteriorating, which leads to a series of problems, such as land desertification, grassland degradation and land pollution, etc. Soil humus, as the main carrier of soil microorganism and plant growth nutrients, its content and quality directly determine the quality of soil. The results showed that soil humus participated in the migration of soil through its interaction with heavy metals and organic pollutants, which was of great significance in the field of soil interface chemistry. In order to understand the problem of regional ecological environment, the soil in arid and semi-arid region (Inner Mongolia and Gansu) was selected as the research object, and the soil organic matter was extracted and purified by the standard method provided by the International Humus Association. The structure of the extracted humus was characterized by UV / vis, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The surface acidic functional groups of humic acid and fulvic acid-COOH and Ar-OH were quantitatively analyzed by acid-base titration. The results showed that the content of soil humus was affected by regional drying index. With the increase of AI (annual average precipitation / evaporation), the content of extractable humus in soil increased, and when the drying index was lower than 0. 05, the content of extractable humus in soil increased. The method used in the experiment could not extract a small amount of humus from the soil. The ratio of E4/E6 and E2/E3 in UV-Vis absorption spectra varies with drying index, which indicates that there is a threshold for the effect of drying index on molecular weight and aromaticity of humic acid molecules, that is, the drying index is 0.53. When the drying index was increased from 0.17 to 0.53, the relative molecular weight and aromaticity of humic acid increased gradually. When the drying index was higher than 0.53, the aromatic degree and molecular weight of humus molecule decreased. For fulvic acid molecules, the surface elements of humic acid and fulvic acid are mainly carbon, nitrogen, oxygen (except hydrogen), and the content of surface nitrogen is about 3.32-5.79g, and the change of molecular weight and aromaticity with drying index is irregular, and the surface elements of humic acid and fulvic acid are mainly carbon, nitrogen and oxygen (except hydrogen). The carbon content was 62.98-71.08 and the oxygen content was 25.68-35.38. The surface oxygen content and (O N) / C value of humic acid increased with the increase of drying index. In the range of critical drying value, the polarity and oxygen content of the sample are proportional to the drying index, and the drying index is more than 0.32, while the oxygen content and oxygen content on the surface of fulvic acid have a critical drying value (AI=0.32). The polarity and oxygen content of fulvic acid samples decreased with the increase of regional drying index. The seven chemical forms and binding energies of carbon in humus are: aromatic carbon C/C-H (282.5e V), alkyl carbon C/C-H (283e V), C (O) O (283.5e V), O (284.4e V), Con O) (285.6e V),) C (O) N (286.45e V), C (O) O (287.1e V); The three chemical forms and binding energies of nitrogen in soil humus are NH2 (397.8 e V), NR3 (399.1 EV) and NO2 (400.5 e V);). The chemical forms and binding energies of oxygen in soil are Cno (529.5e V) and C-O (530.5e V). The contents of carboxyl and phenolic hydroxyl groups in humic acid molecules were 3.24-4.79 mmol / g and 0.16-0.34 mmol/g;, respectively. The content of carboxyl group in fulvic acid molecule is 5.96-10.66 mmol / g, and the content of phenolic hydroxyl is 0.12-5.44 mmol / g. The carboxyl group content of fulvic acid molecule in the same sample is higher than that of humic acid. The changes of carboxyl and phenolic hydroxyl groups of humic acid and fulvic acid were not related to the regional drying index.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S153.622
本文编号：2379273
[Abstract]:With the influence of abnormal climate and irrational human activities, the arid and semi-arid areas in China are expanding and the regional ecological environment is deteriorating, which leads to a series of problems, such as land desertification, grassland degradation and land pollution, etc. Soil humus, as the main carrier of soil microorganism and plant growth nutrients, its content and quality directly determine the quality of soil. The results showed that soil humus participated in the migration of soil through its interaction with heavy metals and organic pollutants, which was of great significance in the field of soil interface chemistry. In order to understand the problem of regional ecological environment, the soil in arid and semi-arid region (Inner Mongolia and Gansu) was selected as the research object, and the soil organic matter was extracted and purified by the standard method provided by the International Humus Association. The structure of the extracted humus was characterized by UV / vis, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The surface acidic functional groups of humic acid and fulvic acid-COOH and Ar-OH were quantitatively analyzed by acid-base titration. The results showed that the content of soil humus was affected by regional drying index. With the increase of AI (annual average precipitation / evaporation), the content of extractable humus in soil increased, and when the drying index was lower than 0. 05, the content of extractable humus in soil increased. The method used in the experiment could not extract a small amount of humus from the soil. The ratio of E4/E6 and E2/E3 in UV-Vis absorption spectra varies with drying index, which indicates that there is a threshold for the effect of drying index on molecular weight and aromaticity of humic acid molecules, that is, the drying index is 0.53. When the drying index was increased from 0.17 to 0.53, the relative molecular weight and aromaticity of humic acid increased gradually. When the drying index was higher than 0.53, the aromatic degree and molecular weight of humus molecule decreased. For fulvic acid molecules, the surface elements of humic acid and fulvic acid are mainly carbon, nitrogen, oxygen (except hydrogen), and the content of surface nitrogen is about 3.32-5.79g, and the change of molecular weight and aromaticity with drying index is irregular, and the surface elements of humic acid and fulvic acid are mainly carbon, nitrogen and oxygen (except hydrogen). The carbon content was 62.98-71.08 and the oxygen content was 25.68-35.38. The surface oxygen content and (O N) / C value of humic acid increased with the increase of drying index. In the range of critical drying value, the polarity and oxygen content of the sample are proportional to the drying index, and the drying index is more than 0.32, while the oxygen content and oxygen content on the surface of fulvic acid have a critical drying value (AI=0.32). The polarity and oxygen content of fulvic acid samples decreased with the increase of regional drying index. The seven chemical forms and binding energies of carbon in humus are: aromatic carbon C/C-H (282.5e V), alkyl carbon C/C-H (283e V), C (O) O (283.5e V), O (284.4e V), Con O) (285.6e V),) C (O) N (286.45e V), C (O) O (287.1e V); The three chemical forms and binding energies of nitrogen in soil humus are NH2 (397.8 e V), NR3 (399.1 EV) and NO2 (400.5 e V);). The chemical forms and binding energies of oxygen in soil are Cno (529.5e V) and C-O (530.5e V). The contents of carboxyl and phenolic hydroxyl groups in humic acid molecules were 3.24-4.79 mmol / g and 0.16-0.34 mmol/g;, respectively. The content of carboxyl group in fulvic acid molecule is 5.96-10.66 mmol / g, and the content of phenolic hydroxyl is 0.12-5.44 mmol / g. The carboxyl group content of fulvic acid molecule in the same sample is higher than that of humic acid. The changes of carboxyl and phenolic hydroxyl groups of humic acid and fulvic acid were not related to the regional drying index.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S153.622
【参考文献】
相关硕士学位论文 前1条
1 曲风臣;土壤腐殖酸分级、表征及其光化学作用研究[D];大连理工大学;2006年
，本文编号：2379273
本文链接：https://www.wllwen.com/kejilunwen/nykj/2379273.html
