黄土高原土壤钙积过程的定量研究

The mechanisms of CaCO3 eluviation and deposition process in soils of the Loess Plateau was quantitatively explored by means of the mathematical modeling method based on long term experiment and leaching column. A coupled model called CAEDP (A model for CaCO3 eluviation and deposition process in soils of the Loess Plateau) was developed. CAEDP is composed of physically-based components for simulating soil water balance in layers, soil organic matter turnover, soil erosion, soil CaCO3 eluviation and deposition, and related processes such as weather factors. An algorithm of successive approximation was presented for computing Ca2+ concentrations and pH values in soil solutions at arid area, with known CO2 partial pressures in soil air and soil temperatures only. The algorithm provides a significant supporting technology for computer to simulate the process of soil calcium carbonate formation. The model had been applied and verified in the Zhuanyaogou experiment area, in Hequ county, the north west of Sharnxi province, China. The results demonstrated that the yearly change of CaCO3 contents in soil profile was correlated with annual precipitation and not with mean annual temperature. The change was a relatively slow process, so that the significant change caused by human activity in soil profile distribution in short time, for example in 30 years, could not present. The model system structure was clearly and the characteristics of the model were the practicability and the process mechanism. Verification results generally indicated that CAEDP model was capable of representing the process of CaCO3 eluviation and deposition in soils of the Loess Plateau quantitatively.

采用点和面结合、田间和实验结合、物理模型和数学模型结合的方法，基于多年定位试验和面上调查数据，定量研究黄土高原土壤钙积过程机理，建立土壤水、气、热与化学平衡过程耦合的碳酸钙淋溶淀积数学模型，并用于黄土高原土壤环境变化的分析，探讨人类活动对土壤发育的影响。为黄土高原土壤资源的持续利用提供科学理论依据。