镉污染条件下农田土壤微生物活性研究

发布时间：2019-03-12 21:25

【摘要】：重金属易通过大气沉降、肥料施用等途径进入农田土壤系统,长期以往会对土壤结构、微生物、动植物等造成严重的损害。农田环境质量的恶化,会导致农田丧失基本的生产能力。由于农田作物对镉具有较强的蓄积能力,镉通过一定的途径会对人体健康产生危害,因此,农田镉污染受到高度关注。农田土壤中微生物活性一定程度上能表征土壤中镉污染的程度,而国内外学者有通过测定土壤中酶活性来表征土壤中微生物活性,从而预测和评价镉污染的程度。但是不同地区的土壤理化性质的差异会导致酶活性的不同,从而影响农田镉污染程度的判断。本文选择苏州地区的水稻土、山林土和菜园土三种典型农田土壤作为研究对象,测定了水稻土、山林土和菜园土的基本理化性质,分别比较了三种不同农田土壤中过氧化氢酶、脲酶和蔗糖酶的活性。通过外源添加镉对三种农田土壤中过氧化氢酶、蔗糖酶和脲酶活性的影响以及土壤中不同形态镉的分布及变化,进一步探讨镉形态与酶活性之间的关系。最后研究了pH、有机质和盐分的变化对水稻土、菜园土和山林土中过氧化氢酶、脲酶和蔗糖酶活性的影响。主要得到以下结论:(1)由于土地利用方式的不同,在一定程度上会导致土壤理化性质的差异,通过水稻土、山林土和菜园土中酶活性的测定发现,过氧化氢酶活性表现为水稻土菜园土山林土,脲酶活性表现为水稻土菜园土山林土,蔗糖酶活性表现为水稻土山林土菜园土。(2)外源镉对水稻土、山林土和菜园土中过氧化氢酶、蔗糖酶和脲酶活性有抑制作用。随着外源镉浓度的升高,以及培养时间的增加,过氧化氢酶、蔗糖酶和脲酶活性均具有下降趋势。镉对脲酶和蔗糖酶的抑制作用,在山林土中强于水稻土和菜园土;对过氧化氢酶活性的抑制作用则是在水稻土中强于菜园土和山林土。(3)外源镉浓度较低时,初始水稻土中镉主要以可氧化态存在,潜在生物可利用态含量高;初始山林土和菜园土中镉主要以弱酸提取态存在,生物易利用态含量高。随着外源镉浓度的升高,水稻土、山林土和菜园土中镉的弱酸提取态含量增加,生物易利用态含量增加。而随着培养时间的增加,水稻土、山林土和菜园土中镉主要以弱酸提取态存在,但是弱酸提取态含量下降,生物易利用态含量下降,潜在生物可利用态含量增加,生物难利用态含量增加。(4)山林土、菜园土和水稻土中镉形态的分布和变化规律与酶活性呈现一定的相关性。随着镉浓度的升高,土壤中镉的生物易利用态含量增加,土壤中酶活性下降;随培养时间的增加,土壤中镉的生物易利用态含量减少,潜在生物可利用态含量增加,生物难利用态含量增加,酶活性呈下降趋势,但下降趋势幅度减弱。(5)pH、有机质和盐分变化对酶活性均有影响。随土壤pH值的升高,水稻土、山林土和菜园土中过氧化氢酶和脲酶活性呈现上升趋势,蔗糖酶的活性趋势表现为先上升后下降,说明土壤酸浓度的升高能够抑制过氧化氢酶、脲酶和蔗糖酶活性,过氧化氢酶和脲酶活性的升高是由于土壤中碱浓度升高所致,但会抑制蔗糖酶活性;随有机质含量的增加,水稻土、山林土和菜园土中过氧化氢酶和脲酶活性呈现上升趋势,说明土壤中有机质的增加能刺激土壤中酶活性的增加,在葡萄糖添加量为1%时,对土壤中脲酶有强刺激作用;随盐分含量的增加,水稻土、山林土和菜园土中过氧化氢酶活性下降,脲酶活性下降,蔗糖酶活性也下降,说明盐会抑制土壤中酶的正常功能与代谢。
[Abstract]:The heavy metal is easy to enter the farmland soil system through the way of atmospheric sedimentation, fertilizer application and the like, and can cause serious damage to the soil structure, the microorganism, the plant and the plant and the like for a long time. The deterioration of the environmental quality of the farmland can lead to the loss of basic production capacity of the farmland. As a result of the strong accumulation capacity of the farmland crops to the human body, the health of the human body can be caused by a certain way, and therefore, the pollution of the farmland is highly concerned. In that field, the activity of the microorganism in the soil can represent the degree of soil pollution in the soil to a certain extent, and the domestic and foreign scholars have the effect of determining the activity of the microorganism in the soil by measuring the activity of the enzyme in the soil, so as to predict and evaluate the degree of the soil pollution. However, the difference of the physical and chemical properties of the soil in different areas can lead to the difference of the enzyme activity, thus affecting the judgment of the pollution degree of the farmland. In this paper, three typical farmland soils of paddy soil, mountain forest and garden soil in Suzhou area are selected as the research object. The basic physical and chemical properties of paddy soil, mountain forest soil and vegetable garden soil are determined, and the activities of catalase, yeast enzyme and sucrase in the soil of three different fields are compared. The relationship between the enzyme activity and the activity of the catalase, the sucrase and the enzyme in the soil of the three agricultural fields and the distribution and the change of the different morphological characteristics of the soil were further discussed. The effects of changes of pH, organic matter and salt on the activity of catalase, catalase and sucrase in paddy soil, vegetable garden soil and mountain forest were studied. The results are as follows: (1) Because of the different land-use methods, the physical and chemical properties of the soil can be different to some extent, and the activity of the catalase in the soil of the paddy soil, the soil of the mountain and the soil of the garden soil has been found, and the activity of the catalase is shown as the soil of the soil and the soil of the paddy soil, The activity of the enzyme is as the soil of the soil and the soil of the soil of the paddy soil, and the activity of the sucrase is the soil of the soil and vegetable garden of the paddy soil. (2) The effect of exogenous yeast on the activity of catalase, sucrase and enzyme in paddy soil, forest soil and vegetable garden soil was inhibited. With the increase of the concentration of the exogenous enzyme and the increase of the culture time, the activity of the catalase, the sucrase and the enzyme of the enzyme has a downward trend. The inhibitory effect of the enzyme on the activity of the catalase and the sucrase is stronger than that of the paddy soil and the vegetable garden soil in the mountain forest soil, and the inhibition effect on the activity of the catalase is stronger than the garden soil and the mountain forest soil in the paddy soil. (3) When the concentration of the exogenous yeast is low, the initial paddy soil is mainly in the oxidizable state, and the potential bioavailable state content is high; the initial mountain forest soil and the vegetable garden soil are mainly in the weak acid extraction state, and the bioavailability is high. With the increase of the concentration of the exogenous yeast, the content of weak acid in paddy soil, the soil of the mountain and the soil of the vegetable garden is increased, and the content of the bioavailability is increased. However, with the increase of the culture time, the rice soil, the mountain forest soil and the vegetable garden soil are mainly in the weak acid extraction state, but the content of the weak acid extraction state is reduced, the bio-availability state content is reduced, the potential bioavailable state content is increased, and the biorefractory utilization state content is increased. (4) The distribution and the change of the morphology of the soil in the soil, the vegetable garden soil and the paddy soil have a certain correlation with the activity of the enzyme. As the concentration of the soil is increased, the biomass of the soil in the soil is increased, the activity of the enzyme in the soil is reduced, the biomass of the soil in the soil can be reduced with the increase of the culture time, the potential bioavailable state content is increased, and the biorefractory utilization state content is increased, The activity of the enzyme decreased, but the decrease of the decreasing trend. (5) The change of pH, organic matter and salt has an effect on the activity of the enzyme. As the pH value of the soil increases, the activity of the catalase and the enzyme in the paddy soil, the mountain forest soil and the vegetable garden soil shows a rising trend, the activity trend of the sucrose enzyme shows that the increase of the activity trend of the sucrose enzyme is first increased, and the increase of the concentration of the soil acid can inhibit the activity of the catalase, the yeast enzyme and the sucrase, the increase of the activity of the catalase and the enzyme is due to the increase of the concentration of the alkali in the soil, but the activity of the sucrase is inhibited; the activity of the catalase and the enzyme in the paddy soil, the mountain forest soil and the vegetable garden soil is increased with the increase of the content of the organic matter, the increase of the organic matter in the soil can stimulate the increase of the enzyme activity in the soil, and when the addition amount of the glucose is 1%, the enzyme in the soil has strong stimulation effect; the activity of the catalase in the paddy soil, the mountain forest soil and the garden soil is reduced with the increase of the salt content, and the enzyme activity is reduced, Sucrose enzyme activity also decreased, indicating that the salt would inhibit the normal function and metabolism of the enzyme in the soil.
【学位授予单位】：苏州科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53

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