土壤中多环芳烃的迁移转化规律及其对植物生长的影响

发布时间：2017-12-27 15:23

本文关键词：土壤中多环芳烃的迁移转化规律及其对植物生长的影响　出处：《西安建筑科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：多环芳烃是一类普遍存在于环境中的、难降解的危险性有机污染物,由于其“三致”效应受到各国政府和科学研究领域的广泛关注。不论是大气、水体还是土壤环境中都普遍存在着多环芳烃并且其含量有着日益上升的趋势。多环芳烃能够通过多种途径对环境和人类的健康构成严重威胁,因此研究土壤中多环芳烃的迁移转化规律及其对植物生长的影响,对进一步了解植物对土壤的修复机制与农产品的安全生产具有理论与实际意义。本文以小白菜和小麦为农作物的代表,以萘、菲、芘三种典型的多环芳烃为代表污染物,系统探讨了多环芳烃在土壤中的迁移行为和植物与土壤中PAHs之间的相互作用,主要研究结果如下:1.以萘、菲、芘为代表污染物,分析研究了其在土壤中随时间推移而不断变化的行为,对比分析了三种污染物在土壤中随时间变化的特征。结果表明,随着时间的推移,三种污染物在土壤中的残留浓度均不断降低,且随着PAHs苯环数的增加,其残留浓度最终呈现出萘菲芘的趋势。土壤中多环芳烃的去除途径主要有挥发、光解、微生物降解和其他流失,其中微生物降解和其他流失占主导作用,能达到50%左右;挥发和光解造成的流失不到10%,萘和菲的挥发、光解和微生物降解都较芘容易。2.以小麦为供试植物,研究了植物对土壤中萘、菲、芘残留行为的影响。结果表明,小麦的种植对土壤中低环PAHs的减少具有促进作用,30 d后,种植小麦的土壤中萘、菲、芘的平均残留浓度比无植物对照组低9.75%、8.77%、9.96%,比无植物灭菌对照低8.88%、16.1%、16.14%。以小白菜为供试植物,研究了土壤中多环芳烃在植物体内的积累方式。结果表明,小白菜对土壤中低环PAHs具有一定的富集能力,且地下部分对萘、菲、芘的积累量远远大于地上部分。3.以小白菜和小麦为供试植物,研究了土壤中不同起始浓度的PAHs对植物生长的影响。结果表明,萘、菲、芘对小白菜种子的萌发和幼苗的生长都具有明显的抑制作用,受污染的土壤中小白菜的发芽率和生物量显著低于无污染对照组,且随着起始污染浓度的增大其发芽率明显降低,生物量明显减少。但对于小麦却有所不同,当污染物平均浓度为0~100 mg/kg时,对小麦的萌发具有一定的促进作用,当污染物平均浓度超过100 mg/kg时,则表现为抑制作用。小白菜根部和茎叶部分的PPO和POD活性均随菲和芘处理浓度的升高而呈现出先升高后降低的趋势,菲或芘处理的土壤中,小白菜根部PPO和POD活性都大于茎叶部分。
[Abstract]:Polycyclic aromatic hydrocarbons (PAHs) are a class of hazardous organic pollutants which are ubiquitous in the environment and are difficult to degrade. Due to their "three effects", they are widely concerned by governments and scientific research fields. Polycyclic aromatic hydrocarbons are common in the atmosphere, water and soil environment, and the content of polycyclic aromatic hydrocarbons is increasing. PAHs can pose a serious threat to the environment and human health through a variety of ways, so the study of migration and transformation of polycyclic aromatic hydrocarbons in soil and its effects on plant growth, to further understand the safety of plant to soil remediation mechanism and agricultural products is of great theoretical and practical significance. In this paper, Chinese cabbage and wheat crops, naphthalene, phenanthrene and pyrene in three typical PAHs as representative pollutants, discusses the interaction between PAHs polycyclic aromatic hydrocarbons in soils and migration behavior in plants and soil, the main results are as follows: 1. using naphthalene, phenanthrene and pyrene as representative pollutants, are studied in the soil with time changing behavior, comparative analysis of the characteristics of three kinds of pollutants in the soil varies with time. The results showed that the residual concentrations of the three pollutants in the soil decreased with time, and the residual concentration finally showed a trend of naphthalene phenanthrene pyrene with the increase of PAHs benzene ring number. The removal pathways of polycyclic aromatic hydrocarbons in soil are mainly volatilization, photolysis, biodegradation and other losses, including microbial degradation and other loss is dominant, can reach about 50%; and the loss caused by volatilization photolysis of less than 10%, naphthalene and phenanthrene volatilization, photolysis and microbial degradation of pyrene is easy. 2. the effects of plants on the residue of naphthalene, phenanthrene and pyrene in soil were studied with wheat as the tested plants. The results showed that the cultivation of wheat promoted the reduction of low cyclic PAHs in soil. After 30 d, the residual concentration of naphthalene, phenanthrene and pyrene in wheat soil was 9.75%, 8.77% and 9.96% lower than that in the control group without plant, which was 8.88%, 16.1% and 16.14% lower than those without plant sterilization. The accumulation of polycyclic aromatic hydrocarbons (PAHs) in the soil was studied with Chinese cabbage as a test plant. The results showed that Chinese cabbage has a certain enrichment ability to low ring PAHs in soil, and the accumulation of naphthalene, phenanthrene and pyrene in the underground part is far greater than that in the upper part of the ground. 3. the effects of different initial concentrations of PAHs on plant growth were studied with Chinese cabbage and wheat as the tested plants. The results show that it has obvious inhibitory effect of naphthalene, phenanthrene and pyrene on Cabbage Seed Germination and seedling growth, germination rate and biomass of Chinese cabbage and soil contaminated by pollution was significantly lower than that of control group, and with the increasing of initial concentration of pollution in the germination rate decreased significantly, biomass decreased significantly. But for wheat, it is different. When the average concentration of pollutants is 0~100 mg/kg, it has a certain effect on the germination of wheat. When the average concentration of pollutants is more than 100 mg/kg, it shows inhibition. The activities of PPO and POD in roots and stems and leaves increased with the increase of the concentration of phenanthrene and pyrene. The activities of PPO and POD in the roots of Chinese cabbage were greater than those in stems and leaves.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

【相似文献】