Modeling Fate of Toxic Organic Compounds and Nitrogen in Soils.

在为期一年的时间里，三个实验室的联合研究工作主要集中在两个方面，即(1)分析土壤中有毒有机化合物（VOCs）的运动和延缓；(2)模拟和测量颗粒内孔隙空间和不动水对土壤化学运动的影响。针对(1)，提出了一种改进的微柱气相色谱法测定土壤中挥发性有机化合物（VOCs）滞留率的方法。试验表明，该方法可以快速、直接、准确地测定多种挥发性有机化合物的阻滞因子。利用土壤微柱，研究了孔隙水流速、温度、土壤粒度和有机质含量对VOCs的阻滞作用。对于土壤中挥发性有机化合物的多组分，通过稳态模型模拟及其相关的实验测量，证实了土壤中存在多组分通量密度。此外，利用菲克扩散定律和多组分非线性吸附等温线建立的瞬态输运模型能够准确预测VOCs浓度。关于（II），进行了微孔介质柱中示踪溶质（氯化物）输运的长期实验，结果与我们开发的新输运模型密切一致。该模型将水分为流动水、膜水和微孔水。这项研究于1993年11月在美国辛辛那提举行的美国土壤科学学会会议上提出。并建立了18种VOCs对环境影响的筛选模型（CRIOCATS）。因此，在这两个研究领域（一和二）内，取得了适合在国际期刊上发表的重要新发现。

During the one-year period, the joint research effort in all of the three laboratories has mainly focused one two areas, namely (I) analysis of the movement and retardation of toxic organic compounds (VOCs) in soils and (II) modeling and measuring the effects of intra particle pore space and of immobile water on chemical movement in soils. With respect to (I), an improved micro-column gas-cromatograph-based method for measuring the retardation of VOCs in soils was developed. Tests showed the method to be promising for rapid, direct and accurate determination of the retardation factor for a number of VOCs. By using the soil micro-column, the effect of pore-water velocity, temperature, soil grain size, and organic matter content on retardation of VOCs was studied. Concerning the multicomponent of VOCs in soil, the presence of multicomponent flux densities was confirmed by the steady-state model simulation and its related experimental measurements. Furtheremore, a transient transport model using Fick's law for diffusion and multicomponent non-linear adsorption isotherm predicted measured VOCs concentrations accurately. With respect to(II), long-term experiments for transport of a tracer solute (chloride) in micro-porous media columns were carried out and results were in close agreement with a new transport model that we developed. The model partitions the water into mobile, film, and micro-pore water. The research was presented at the Soil Science Society of America meetings in Cincinnati, USA in November, 1993. Also, a screening model (CRIOCATS) to evaluate the effect of 18 kinds of VOCs to the environment was proposed. Thus, within both research areas (I and II), important new findings appropriate for publication in international journals were achieved.