铅在铁路岩石边坡创面人工土壤中的迁移特性研究

发布时间：2018-10-24 06:21

【摘要】：山区大规模的铁路建设产生了大量的岩石边坡,前期研究表明边坡创面人工土壤受Pb污染,且有中等程度的富集。土壤类型、植被搭配类型是影响Pb迁移特性的重要因素,而目前却未见人工土壤及植被搭配类型对Pb迁移特性影响的相关报道。该研究以铁路岩石边坡创面人工土壤为对象,利用原子吸收分光光度法、红外光谱法分析了人工土壤对Pb的吸附-解吸特性及机制;运用野外人工模拟降雨实验,进一步考察在暴雨径流作用下,Pb在不同植被搭配类型的边坡人工土壤中的迁移过程。结果表明人工土壤对Pb的吸附量随着溶液平衡浓度的增加而急速增加,等温曲线呈"S"型,Freundlich方程能较好地描述人工土壤对Pb的吸附行为,R2为0.91。二次幂函数方程能较好描述NH_4AC对铅的解吸过程,R2为0.96。人工土壤有高岭石红外光谱特征吸收峰,属于高岭石型图谱。高岭石表面—OH、腐殖质表面—OH和—COOH参与吸附作用,置换出H+。人工土壤易将交通运输产生的Pb固定,但又容易再次释放。不同植被搭配类型边坡Pb流失量表现为草本草本+灌木草本+灌木+乔木。暴雨径流作用下Pb随沉积物相流失是边坡创面人工土壤Pb流失的主体,边坡土壤的侵蚀是导致Pb迁移扩散的主要原因,因此促进边坡植被的恢复,减小边坡人工土壤的侵蚀作用是防止Pb迁移扩散的关键。
[Abstract]:A large number of rock slopes have been produced by the large-scale railway construction in mountainous areas. Previous studies show that the artificial soil on the slope surface is polluted by Pb and has a moderate enrichment. Soil type, vegetation collocation type is an important factor affecting the characteristics of Pb migration, but there is no report on the effect of artificial soil and vegetation collocation type on Pb migration characteristics. In this study, the characteristics and mechanism of Pb adsorption and desorption in artificial soil were analyzed by atomic absorption spectrophotometry and infrared spectroscopy, and the artificial soil was used to simulate rainfall in the field. The migration process of Pb in slope artificial soil with different vegetation collocation types was further investigated under the action of rainstorm runoff. The results showed that the amount of Pb adsorbed by artificial soil increased rapidly with the increase of equilibrium concentration of solution, and the isothermal curve was of "S" type. Freundlich equation could describe the adsorption behavior of Pb on artificial soil with R2 = 0.91. The quadratic power function equation can better describe the desorption process of lead by NH_4AC, R2 is 0.96. The artificial soil has the characteristic absorption peak of kaolinite infrared spectrum, which belongs to the kaolinite type map. The surface of kaolinite-OH, humus surface-OH and-COOH participated in the adsorption and replaced H. The Pb produced by transportation is easily fixed by artificial soil, but easily released again. The Pb loss of slope with different vegetation collocation type was herbaceous shrub tree. Under the action of rainstorm runoff, Pb loss with sediment phase is the main body of Pb loss in artificial soil of slope wound, and the soil erosion of slope is the main cause of Pb migration and diffusion, so it promotes the restoration of slope vegetation. Reducing soil erosion is the key to prevent Pb migration and diffusion.
【作者单位】：成都医学院公共卫生系;
【基金】：国家自然科学基金项目(41501112) 四川省教育厅重点项目(16ZA0279)资助
【分类号】：X131.3

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