砷和锑在土壤中的有效性及其对土壤酶的影响

发布时间：2018-03-22 19:12

本文选题：锑　切入点：砷　出处：《西北农林科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：砷和锑都是自然界中有毒的非金属元素。锑常与砷共存,它们进入土壤后将严重影响土壤质量。土壤酶参与土壤中各种生物化学过程,其活性大小可以作为评价土壤肥力高低、土壤生态环境质量优劣的一个重要生物指标。由于重金属直接影响土壤酶活性变化,因此土壤酶同时也可用于表征重金属的污染程度。现阶段已有不少关于砷对于土壤酶影响的研究,但对于砷的研究大多只考虑砷浓度的变化,而忽略了土壤含水量这一重要的土壤性质参数对于砷含量的调控进而对土壤酶造成的影响;对锑的研究目前主要集中在锑在土壤中的存在形式、锑的有效性、锑对植物的影响等,但关于土壤酶是否能表征锑的污染程度,目前还鲜有报道。因此对于开展不同浓度锑对土壤酶的影响及不同水分条件下砷对土壤酶活性影响的研究是非常有必要的。本文采用室内模拟的方法,开展了以下两个方面的研究:(1)不同浓度锑污染对18个省典型土壤中脱氢酶活性的影响及水溶态锑在土壤中的变化规律。(2)研究了35%、65%以及110%最大饱和持水量条件下,不同浓度砷污染后土壤中有效砷变化及砷对土壤碱性磷酸酶、芳基硫酸酯酶、脱氢酶的影响。主要结果如下:1.水溶态锑含量随锑添加量增大而升高,土壤对锑的吸附能力随锑浓度增大而降低,锑在土壤中的吸附规律符合Langmuir和Freundich方程,锑的最大饱和吸附量为5747.13mg kg-1。锑污染可显著抑制脱氢酶活性。土壤pH、有机质、CEC是影响锑在土壤中毒性大小的主要因素,在有机质与CEC含量高及pH低的土壤中,锑表现出越小的毒性。2.砷急性污染条件下,磷酸酶、脱氢酶、芳基硫酸酯酶的酶活均受到砷的抑制。有机质含量高的土壤中,砷对酶活性抑制率低,甚至有激活作用。3.砷的老化污染试验中,在三种含水量条件下,土壤有效砷浓度均随培养时间的延长而减小,土壤碱性磷酸酶、芳基硫酸酯酶、脱氢酶的活性受到砷的抑制且随时间的延长,其抑制作用减小。砷对土壤脱氢酶的抑制程度较低,在培养中期出现激活作用,表明脱氢酶活性对供试砷浓度有一定抗性。相同培养时间下,相比于干旱胁迫(35%)与65%含水量条件,110%水分含量条件下,土壤中有效砷含量最低且三种酶活性均受到最大抑制。进一步计算生态剂量值,发现在淹水(110%)及干旱胁迫(35%)条件下,砷在土壤中的生物毒性较强。综合全文,可以得出以下结论:锑可显著抑制脱氢酶活性,水溶态锑含量受锑添加浓度和土壤性质影响;砷对土壤碱性磷酸酶、芳基硫酸酯酶及脱氢酶活性有抑制作用,有效砷含量受砷添加量、土壤水分及土壤性质影响。
[Abstract]:Both arsenic and antimony are toxic nonmetallic elements in nature. Antimony often coexists with arsenic, which will seriously affect soil quality when they enter the soil. Soil enzymes participate in various biochemical processes in soil, and their activity can be used to evaluate soil fertility. It is an important biological index of soil ecological environment quality. Because heavy metals directly affect the change of soil enzyme activity, Therefore, soil enzymes can also be used to characterize the pollution degree of heavy metals. At present, there have been many studies on the effects of arsenic on soil enzymes, but most of the studies on arsenic only consider the variation of arsenic concentration. However, the influence of soil moisture content, an important soil property parameter, on arsenic content and soil enzymes was neglected. At present, the research on antimony is mainly focused on the existence form of antimony in soil and the availability of antimony. Effects of antimony on plants, but whether soil enzymes can characterize the degree of antimony contamination, Therefore, it is necessary to study the effects of different concentrations of antimony on soil enzymes and the effects of arsenic on soil enzyme activities under different water conditions. The effects of different concentrations of antimony pollution on dehydrogenase activity in typical soils of 18 provinces and the variation of water-soluble antimony in soil were studied in the following two aspects. The changes of available arsenic in soil and the effect of arsenic on alkaline phosphatase, aryl sulfate enzyme and dehydrogenase in soil after different concentrations of arsenic pollution. The main results are as follows: 1. The content of water-soluble antimony increases with the increase of antimony content. The adsorption ability of soil to antimony decreases with the increase of antimony concentration. The adsorption law of antimony in soil accords with Langmuir and Freundich equations. The maximum saturated adsorption capacity of antimony is 5747.13mg kg-1.The activity of dehydrogenase can be significantly inhibited by antimony pollution. Soil pH and organic matter are the main factors affecting the toxicity of antimony in soil, especially in the soil with high organic matter and CEC content and low pH. The lower the toxicity of antimony is, the less the enzyme activity of phosphatase, dehydrogenase and aryl sulfate is inhibited by arsenic. In the soil with high organic matter content, the inhibition rate of arsenic on enzyme activity is low. Under three water content conditions, the concentration of available arsenic in soil decreased with the prolongation of culture time, and soil alkaline phosphatase, aryl sulfate enzyme, alkaline phosphatase, aryl sulfate enzyme, alkalic phosphatase, aryl sulfate enzyme, aryl sulfate enzyme, alkaline phosphatase, aryl sulfate enzyme, alkaline phosphatase, aryl sulfate enzyme, The activity of dehydrogenase was inhibited by arsenic and decreased with the prolongation of time. The inhibition of arsenic on soil dehydrogenase was low and activated in the middle stage of culture. The results showed that dehydrogenase activity was resistant to arsenic concentration in the test. Under the same culture time, compared with drought stress and water content of 65% water content, the dehydrogenase activity was higher than that under drought stress. The content of available arsenic in soil was the lowest and the activity of three enzymes was restrained to the maximum. Further calculation of ecological dose showed that arsenic had strong biotoxicity in soil under the conditions of water flooding (11010g) and drought stress (35%). The following conclusions can be drawn: antimony can significantly inhibit dehydrogenase activity, the content of water-soluble antimony is affected by the concentration of antimony and soil properties, and arsenic can inhibit the activities of alkaline phosphatase, aryl sulfate enzyme and dehydrogenase in soil. The available arsenic content is affected by arsenic addition, soil moisture and soil properties.
【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】：X131.3;S153;S154.2

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