【作者】 丛伟；

【导师】 张兴昌；

【作者基本信息】 西北农林科技大学 ， 环境科学， 2011， 博士

【摘要】 以陕西省神木县六道沟流域黄绵土为供试土壤,研究了植物和丛枝菌根(arbuscular mycorrhizal, AM)真菌对硒在土壤中纵向迁移和横向迁移的影响,讨论了AM真菌及盐胁迫对植物硒和养分吸收的影响机理。并通过室内混合置换实验,运用对流—弥散方程(CDE)对亚硒酸根离子在土壤中的运移进行了模拟,分析比较了不同拟合方法及不同CDE模型的拟合精度。获得以下进展:1.适量施Se能显著促进植物对土壤中N、P、K的吸收,当植物中Se含量较高(约2 mg·kg-1)时,会抑制植物对N、P、K的吸收。水培条件下,植物对Se的适应范围较高(约20 mg·kg-1)。2.接种GC(Glomus constrictum)、GM(Glomus mosseae)显著提高了植物中N、P、K含量。接种GC促进植物吸收土壤Se,降低不同施Se水平对植物吸收养分的影响,保持植物稳定吸收养分;接种GM降低植物吸收土壤Se,提高适量施Se对植物吸收养分的促进作用,降低过量施Se的抑制作用。3.玉米和刺槐的根系均能将Se固定于根际土壤,减弱其在土壤中的垂直迁移。接种GC能提高0～12 cm土壤Se含量,降低Se在土壤中的垂直迁移;玉米接种GM能降低Se在土壤中的垂直迁移,而刺槐接种GM促进Se的垂直迁移。4.接种GC能促进玉米对远端Se的吸收,接种GM则起到抑制作用;接种GC和GM对刺槐吸收远端Se影响较小。玉米接种AM真菌使Se的水平迁移减弱,GM作用优于GC,刺槐接种AM真菌对Se水平迁移影响较小。5.适量钙盐、钠盐和钙钠混合盐可促进玉米和刺槐吸收土壤Se,盐种类的不同对玉米吸收硒的影响较大,表现为钠盐的作用高于钙盐和钙钠混合盐,对刺槐吸收硒有影响但差异较小。当过量盐胁迫时,植物中硒含量随盐量的增加而降低,玉米对盐浓度的变化更为敏感。6.适量钙盐、钠盐或钙钠混合盐能促进玉米对N、P、K的吸收及刺槐对N、P的吸收。施钙盐和钙钠混合抑制刺槐对K的吸收。与施单一盐相比,施混合盐能使植物吸收养分保持相对稳定。7.接种GM和GC均可缓解过量施盐对植物吸收土壤Se及N、P、K的抑制作用;GC更利于提高玉米的耐盐性,GM则更利于提高刺槐的耐盐性。适量施盐时,不同植物接种不同AM真菌对植物养分吸收作用不同。8.混合置换实验可拟合Se在土壤中迁移的行为,其拟合结果精确较高,无示踪剂拟合方法的拟合精确度高于示踪剂拟合。STANMOD软件能有效的近似分析Se在土壤中一维运移问题。初始浓度愈高,CDE方程拟合的弥散系数D值愈大,穿透曲线出现的拐点愈早;随流速的增大,弥散系数D值总体上呈增大趋势;随土壤容重增大,阻滞因子R值也随之增大,弥散系数D值则呈先增大后减小趋势;随土柱高度的增加,弥散系数D值减小,阻滞因子R值则变化不大。用土柱实验通过求解对流-弥散方程逆问题求解阻滞因子R的方法有较高的精确度。9.平衡模型和非平衡两区模型均可较好地模拟亚硒酸根离子在沙质黄绵土中的迁移,非平衡两区模型模拟结果精度较高。穿透曲线能较好的反映亚硒酸根离子在土体中的运移特征,初始穿透时间越早,曲线出现拐点时间越短,对应的弥散系数D值越大;穿透曲线的线形则能较好的反映出阻滞因子的大小,曲线越平缓则阻滞因子R值越大。更多还原

【Abstract】 Loessial soil was used to investigate the effect of plant and Arbuscular Mycorrhizal (AM) fungi on the horizontal and vertical migration of selenium (Se) in soil in Liudaogou watershed Shenmu County, Shaanxi Province, and discussed the effect mechanism of AM fungi and sail stress on Se and nutrient uptake. The transport of Se in loessial soil columns was studied using a miscible displacement technique to analyze the accuracy of fitting results by different fit methods and different convection-dispersion equation (CDE) models. The main results were shown as following:1. Proper Se can significantly promote the uptake the selenium and nutrient of plants from soil. While the plants with high levels of Se about 2 mg·kg-1, it may inhibit the nutrient uptake in plant. In hydroponics, plants can adapt to higher concentration range of Se, which was 20 mg·kg-1.2. Inoculation with Glomus constrictum (GC) and Glomus mosseae (GM) significantly increased the nitrogen, phosphorus and potassium contents of plants. Inoculation with GC increased Se uptake of plants, decreased the effect of different Se levels on nutrient uptake in plant. Inoculation with GC decreased Se uptake of plants,enhanced the effect of an adequate of Se level on nutrient uptake in plant,and reduced the effect of high levels of Se.3. Zea mays and Robinia pseudoacacia Lynn. (RPL) can reduce the vertical migration of Se in soil columns by immobilization of roots. Zea mays and RPL inoculation with GC reduced the vertical migration of Se by increasing Se content in soil of 0~12 cm depths. Zea mays inoculation with GM reduced the vertical migration of Se, RPL inoculation with GM enhanced the vertical migration.4. Zea mays inoculation with GC enhanced the uptake of Se, which lied in the soil 40 cm away from plant, but inoculation with GM reduced the uptake of Se. RPL inoculation with GC and GM had little influence of Se uptake. Zea mays inoculation with AM fungi reduced the horizontal migration, and the influence of GM was higher than GC. RPL inoculation with AM fungi had little influence on Se horizontal migration.5. Proper calcium salt, sodium salt and mixed salt may promote Se uptake of Zea mays and RPL. The types of salt had great influence on Se uptake of Zea mays, as the effect of sodium salt exceeded calcium salt and mixed salt. Types of salt had influence on Se uptake of RPL but a little difference between them. When salt stress in excess, Se content of plant could reduce with the increase of salt content, and Zea mays was more sensitive to salt concentration.6. Proper calcium salt, sodium salt and mixed salt may promote nitrogen, phosphorus, and potassium uptake of Zea mays, or nitrogen and phosphorus uptake of RPL. The mixed salt could restrain potassium uptake of RPL. Compare with single salt, the mixed salt enable plant nutrient uptake remained relatively stable.7. Inoculation with GC and GM decreased the inhibitory action of high salt levels on Se and nutrition uptake of plants. Inoculation with GC had higher effect on improving the salt tolerance of Zea mays, and GM was more conducive to improving the salt tolerance of RPL.8. The method of parameter estimation using CDE accurately defined the dispersion coefficient (D) and retardation factor (R) from the breakthrough curves (BTC) and modeled selenite transport through soil. The method without tracer was more accurate than the method with the tracer. STudio of ANalytical MODels (STANMOD) was a very flexible tool for approximate analysis of one dimensional solute transport problems in soil. D increased with the increase of influent concentration and average pore-water velocity. R increased with the increase of soil bulk density, while D was first increase and then decrease. D decreased with the increase of soil column height.9. Nonequilibrium two-region model was more suited in fitting the transport of selenite ion than equilibrium model. D was larger if the inflection point of the BTCs occurred earlier or the curve was closed to the y-axis, R was larger if the curve was more flat.更多还原