摘要
用(32)P标记扩散池法测定了不同时间下土壤磷的扩散量，并用5种动力学模型对其拟合，结果表明土壤磷扩散过程最符合抛物线扩散方程。20％含水量下，磷扩散速率温度商Q(10)。为1．20左右，与扩散是一个物理过程相吻合。由阿尼乌斯公式求得的磷扩散活化能（E）随土壤水分增加而降低；在土壤水低吸力范围内（＜105Pa水吸力）为12—34kJ／mol，平均为25kJ／mol左右，与溶液中离子扩散活化能较接近，说明低吸力下磷扩散主要在液相进行。将绝对反应速率理论移植用于磷扩散，所求出的磷扩散净活化能、活化熵变、活化焓变和活化自由能变在供试土壤中相同含水量下均呈规律性变化，且与E变化趋势基本一致，证明这些参数可用于表征磷扩散的能量特征。
The diffusion amounts of phosphate in soils at varying time were determined byhalf-cell technique using 32P. Five kinetic equations were used to fit the dynamicprocess of phosphate diffusion in the soils. It was found that parabolic diffusionequation was the best model to describe the process. The temperature quotient (Q10) ofPhosphate diffusion in the soils at 20% water content was 1.2 or so, which was inagreement with that diffusion is a physical process. The activation energy (EDa) ofphosphate diffusion in soils, calculated by Arrhenius equation, decreased withincreasing soil moisture and varied from 12 to 34 kJ / mol with an average value of25kJ / mol under low water tension range (< 105 Pa), which was close to theactivation energy of nutrient ion diffusion in solution. Therefore, it was suggested thatthe phosphate diffusion in soils at low water tension condition occurred mainly in theliquid Phase. Moreover, the absolute reaction-rate theory was transplanted and used toinvestigate the diffusion process in soils. The parameters, net activation energy,activation entroPy, activation enthalpy and activation free energy of phosphate diffusionin soils, were derived from the theory. The results showed that these parameters inthe four soils at the same water content changed in the similar to EDa, which indicatedthat the parameters could be used to describe the energy characteristics of Phosphatediffusion in soils.
出处
《土壤学报》
CAS
CSCD
北大核心
1998年第2期202-209,共8页
Acta Pedologica Sinica
关键词
磷
扩散
动力学
活化能
活化熵
土壤
Phosphate, Diffusion, Kinetic, Activation energy, Activation entropy
