球囊霉素相关土壤蛋白在土壤中的分布及与PAHs的结合作用

发布时间：2018-09-05 11:13

【摘要】：当前,我国土壤污染问题严重。多环芳烃(PAHs)已成为我国土壤中常见的一类高风险有机污染物,土壤污染后,PAHs可通过土壤一植物系统进入食物链,严重威胁人群健康和生态安全。如何修复PAHs污染土壤、减低植物污染风险?这是当前国内外环境领域迫切需要着力解决的重大科技问题之一。已往研究表明,接种从枝菌根真菌(AMF)可减低植物地上部PAHs含量、提高PAHs污染土壤的根际修复效率,但对于其内在机制,国内外仍缺乏了解。球囊霉素相关土壤蛋白(GRSP)是由AMF菌丝产生并脱落进入土壤中的一类糖蛋白,可改善土壤通透性、提高土壤团聚体的稳定性、利于植物生长。但迄今,GRSP在土壤中的分布及与PAHs的作用关系国内外仍了解甚少,阐明这一问题,对于揭示AMF影响植物吸收PAHs和促进土壤中PAHs降解的本质有重要意义。本文研究了不同土地利用方式下土壤中GRSP的含量差异及垂直分布特征;采用温室盆栽实验方法,分析了接种AMF对PAHs污染土壤中植物生长和GRSP含量的影响;初步探讨了 GRSP与菲的结合作用。取得的主要成果如下:(1)研究了不同土地利用方式下土壤中GRSP含量及剖面分布特征。以南京市黄棕壤为例,采集了 5种土地利用方式(林地、草地、水稻田、茶园土和菜园土)下土壤样品,测得供试土壤中总球囊霉素相关土壤蛋白(T-GRSP)含量为1.96～3.12 mg·g-1,占土壤有机碳量的12.5%～29.0%,所占比例随土壤有机碳含量的增加而降低。相对于人为扰动较少的林地和草地,3种耕作土壤中T-GRSP和易提取球囊霉素相关土壤蛋白(EE-GRSP)含量低,0～40cm土层中T-GRSP含量随着土层深度增加而降低,EE-GRSP未表现出显著的垂直分布规律;土壤中T-GRSP含量与土壤有机碳含量极显著正相关,与土壤pH值显著负相关,EE-GRSP与土壤有机碳含量呈极显著负相关。(2)分析了 AMF对PAHs污染土壤中植物生长和GRSP含量的影响。供试AMF为密色无梗囊霉(A.s)、摩西球囊霉(G.m)、根内球囊霉(G.i)、幼套球囊霉(Ge)、缩球囊霉(Gc),供试植物为紫花苜蓿。接种AMF促进了植物茎叶和根的生长,但不同AMF对植物生物量的促进程度存在差异。其中G.i组促进效果最佳,A.s组效果最弱。随着培养时间延长,不接种AMF对照组(CK)和接种Gi组的土壤中EE-GRSP和T-GRSP含量增大,G.i组EE-GRSP和T-GRSP含量为4.13和2.13 mg·g-1,分别是30d时二者含量的3.93和4.65倍。90d时,各处理土壤中T-GRSP和EE-GRSP含量大小有相同的趋势,均表现为G.iG.eG.mG.cA.sCK,G.i组EE-GRSP含量为1.33 mg·g-1,是对照组含量(0.79mg-g-1)的1.7倍,A.s组含量最低,为0.87mg-g-1。Gi、G.e、G.m、G.c 和 A.s 组产生的 T-GRSP 含量分别为 4.61、4.07、3.27、3.46 和 2.90 mg·g-1,对照组含量为2.30 mg·g-1,其中G.i组是对照组含量的2倍,A.s组含量略高于对照组。接种AMF能增加植物对土壤中菲的积累,其中G.i组植物体内菲含量高于另外4种AMF处理。接种AMF提高了土壤中PAHs的去除效率,其中,G.i组和G.c组处理的土壤中菲的降解率均在97%以上,A.s组的菲降解效果最差。侵染率、T-GRSP和植物体内菲含量均与土壤中菲残留含量显著负相关,T-GRSP分别与侵染率正相关、与植物中菲含量显著正相关。(3)初步探讨了水中GRSP与菲的结合规律。GRSP对菲的结合等温线能用Langmuir方程较好地拟合,结合属于单分子层结合模式。水溶液中GRSP对菲的结合量随时间的延长而逐渐增加,24 h后结合基本达到平衡,结合过程符合准二级动力学模型,平衡结合量为44.26 μ·mg-1。溶液pH值对GRSP结合菲有较大影响,当溶液pH=4时,菲的平衡结合量最小;随着溶液酸性减弱,菲的结合逐渐增强,当pH=6时,GRSP对菲的结合量达到最大54.19μg·mg-1,当pH超过7后,随着溶液碱性的增强,结合量逐渐减小。溶液中Ca~(2+)浓度越大,菲的结合量越小。
[Abstract]:At present, the problem of soil pollution is serious in China. Polycyclic aromatic hydrocarbons (PAHs) have become a common high-risk organic pollutant in China's soil. After soil pollution, PAHs can enter the food chain through soil-plant system, which seriously threatens the health and ecological safety of the population. Previous studies have shown that inoculation with mycorrhizal fungi (AMF) can reduce PAHs content in aerial parts of plants and improve the rhizosphere remediation efficiency of PAHs-contaminated soils. However, there is still a lack of understanding of the underlying mechanism. Ballomycin-related soil protein (GRSP) is produced by AMF mycelia. A group of glycoproteins that grow and fall into the soil can improve soil permeability, improve the stability of soil aggregates and facilitate plant growth. However, the distribution of GRSP in the soil and the relationship between GRSP and PAHs are still poorly understood at home and abroad. The difference of GRSP content and its vertical distribution in soil under different land use patterns were studied. The effects of AMF inoculation on plant growth and GRSP content in PAHs contaminated soil were analyzed by pot experiment in greenhouse. The combined effects of GRSP and phenanthrene were preliminarily discussed. GRSP content and profile distribution characteristics in soils under different land use patterns were studied. Soil samples under five land use patterns (forest land, grassland, paddy field, tea garden soil and vegetable garden soil) were collected. The total content of T-GRSP in tested soils was 1.96-3.12 mg g-1, accounting for soil organic matter. The content of T-GRSP and EE-GRSP in three tillage soils were lower than that in forests and grasslands with less disturbance, and the content of T-GRSP in 0-40 cm soil layer decreased with the increase of soil depth, but EE-GRSP did not show significant difference. (2) The effects of AMF on plant growth and GRSP content in PAHs-contaminated soil were analyzed. AMF was A.s., G.m. The growth of alfalfa was promoted by inoculating AMF, but the promotion degree of AMF on plant biomass was different. The effect of G. I was the best, A. s was the weakest. With the extension of culture time, no AMF control group (CK) and inoculation were used. The contents of EE-GRSP and T-GRSP in the soil of G I group increased. The contents of EE-GRSP and T-GRSP in G.i group were 4.13 and 2.13 mg.g-1, respectively, which were 3.93 and 4.65 times as high as those in 30 days. The contents of T-GRSP and EE-GRSP in the soil of all treatments had the same trend. The contents of EE-GRSP in G.eG.mG.cA.sCK and EE-GRSP in G.i group were 1.33 mg.g-1 and 0.30 mg. The content of T-GRSP in A.s, G.e, G.m, G.c and A.s groups were 4.61, 4.07, 3.27, 3.46 and 2.90 m g.g-1, respectively, and that in control group was 2.30 m g.g-1. Among them, the content in G.i group was twice that in control group, and that in A.s group was slightly higher than that in control group. Among them, the content of phenanthrene in plants of G.i group was higher than that of other four AMF treatments. AMF inoculation improved the removal efficiency of PAHs in soil. The degradation rates of phenanthrene in soil of G.i group and G.c group were all above 97%, and that of phenanthrene in A.s group was the worst. The binding isotherms of GRSP to phenanthrene can be well fitted by Langmuir equation. The binding amount of GRSP to phenanthrene in aqueous solution increases with time, and then increases after 24 hours. The binding process accorded with quasi-second-order kinetic model, and the equilibrium binding amount was 44.26u mg-1. The pH value of the solution had a great influence on the equilibrium binding amount of phenanthrene to GRSP. When the pH value of the solution was 4, the equilibrium binding amount of phenanthrene was the smallest; with the decrease of the acidity of the solution, the binding amount of phenanthrene gradually increased, and when the pH value was 6, the binding amount of GRSP to phenanthrene reached 54.19 UG When the concentration of Ca~ (2+) in the solution increases, the amount of phenanthrene binding decreases.
【学位授予单位】：南京农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

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