SGER: The Effects of Acid Deposition on Soil Physical Properties

本研究的目的是研究酸沉降产生的主要离子成分对土壤结构特性的影响。 酸沉积影响土壤溶液的成分以及成分在土壤中的迁移。 认识到酸沉积会改变土壤的化学和矿物学，因此假设酸化会改变土壤的物理性质，包括胶结剂的行为，甚至在缓冲良好的土壤中也是如此。酸沉积对土壤形态和结构的影响将在两种实验室实验中进行检查。长时间浸出长柱中的不同土壤，以及浸出经过不同处理（包括润湿和干燥）的较浅盘中的土壤。 对于对照实验，将在天然和人造混合土壤中使用两种水泥：碳酸水泥和铁铝氧化物。 在评估所选胶结剂对土壤结构的重要性时，将通过比较不同缓冲条件下的酸处理和对照处理来检查土壤的物理性质，包括导水率、粘聚力和骨料稳定性。 在可能的情况下，将对土壤内部结构进行非破坏性 X 射线、伽马射线或 CT 扫描观察，将内部结构的变化与测量的物理特性联系起来。 由于土壤与土壤化学和水文过程有关，了解它们之间的相互关系应该可以提高我们预测不同环境对酸沉降的反应的能力。

The objective of this research is to examine the effect of major ion constituents arising from acid deposition on soil structural properties. Acid deposition effects the composition of the soil solution and the migration of constituents through the soil. Recognizing that the chemistry and mineralogy of soils are transformed by acid deposition, it is postulated that acidification alters physical properties of soils including the behavior of cementing agents perhaps even in well buffered soils The effects of acid deposition on soil morphology and structure will be examined in two kinds of laboratory experiments. Prolonged leaching of different soils in long columns, and leaching of soils contained in shallower pans subjected to different treatments, including wetting and drying. For controlled experiments, two kinds of cement, carbonated and iron-aluminum oxides will be used in mixed natural and artificial soils. In evaluating the importance of selected cementing agents to soil structure, physical properties of the soil including hydraulic conductivity, cohesion and aggregate stability will be examined by comparing acid and control treatments under different buffering conditions. To the extent possible, non-destructive X-ray, gamma ray or CT-scan observations of the internal structure of the soil will be made to relate changes in internal structure to measured physical properties. Because soil relates to soil chemistry and hydrologic processes, understanding the interrelation among them should improve our ability to predict how different environments respond to acid deposition.