Many toxic industrial chemicals (TICs) such as chlorine and ammonia are very reactive with commonly encountered materials in the environment. The amount of TIC material reacted in the environment is an important factor in determining the impact of a release. Typically characterized with a dry deposition rate in atmospheric dispersion models, the reaction rate has predominately been studied in field scale experiments at concentration levels typical for air pollution (ppm levels). When considering the removal of chlorine by (dry) deposition in an episodic release, gas phase concentrations will be much higher than those associated with air pollution, and near-field reaction of chlorine with local vegetation will be strongly influenced by the response of leaves and other elements of the surface “canopy” to those high concentrations. In this work, standard engineering methods characterizing the rate of mass transfer from a fluid to a surface in conjunction with reaction at that surface are applied. Previous experimental programs that studied the removal of chlorine under conditions relevant to this study show that deposition of chlorine to plant material can reach a limiting maximum so that the plant material can no longer react with gaseous chlorine despite continued exposure. In the analysis presented here, it is shown that the effect of the maximum deposition can be treated using the same approach as has been used to model catalyst poisoning. This study developed a model to account for boundary layer resistance and the impact of maximum deposition in a framework that could be incorporated in atmospheric dispersion models. To test the efficacy of this model, the Controlled Environment Reactivity Test (CERT) apparatus was designed to expose selected environmental materials (substrates including soil, rye grass, white clover, maple leaves, and spruce branches) to chlorine with initial concentration of (nominally) 1000 ppm where the gas phase chlorine concentration can be measured as a function of time to determine relevant modeling parameters. The apparatus was built to control the flow velocity of the chlorine/air mixture over the experimental substrates with turbulence levels that are comparable to the atmosphere. Model parameters were found for the environmental materials tested.

许多有毒的工业化学品（TIC）（例如氯和氨）与环境中常见的材料具有极强的反应性。在环境中反应的TIC物质的量是确定释放影响的重要因素。通常在大气扩散模型中以干沉降速率为特征，反应速率主要在田间规模实验中以典型的空气污染浓度水平（ppm级）进行研究。当考虑通过偶发释放中的（干）沉积去除氯气时，气相浓度将大大高于与空气污染相关的浓度，并且氯气与当地植被的近场反应将受到叶片和叶片的强烈影响。表面的其他元素“冠层”到那些高浓度。在这项工作中，运用表征从流体到表面的质量转移速率以及该表面的反应的标准工程方法。先前在与本研究相关的条件下研究了除氯的实验程序表明，氯在植物材料上的沉积可以达到极限最大值，因此，尽管持续暴露，植物材料仍无法与气态氯发生反应。在此处介绍的分析中，表明可以使用与模拟催化剂中毒相同的方法来处理最大沉积物的影响。这项研究开发了一个模型，该模型考虑了边界层电阻和最大沉积在框架中的影响，该框架可以纳入大气弥散模型。为了测试此模型的功效，设计了受控环境反应性测试（CERT）装置，以使选定的环境材料（包括土壤，黑麦草，白三叶草，枫叶和云杉分枝的基质）暴露于初始浓度为（标称）1000 ppm的氯气中，其中氯气为可以将浓度作为时间的函数进行测量，以确定相关的建模参数。该设备被构造成以与大气相当的湍流水平来控制氯/空气混合物在实验基板上的流速。找到了用于测试的环境材料的模型参数。或云杉分支）为初始浓度（标称）为1000 ppm的氯，其中气相氯浓度可以作为时间的函数进行测量，以确定相关的建模参数。该设备被构造成以与大气相当的湍流水平来控制氯/空气混合物在实验基板上的流速。找到了用于测试的环境材料的模型参数。或云杉分支）为初始浓度（标称）为1000 ppm的氯，其中气相氯浓度可以作为时间的函数进行测量，以确定相关的建模参数。该设备被构造成以与大气相当的湍流水平来控制氯/空气混合物在实验基板上的流速。找到了用于测试的环境材料的模型参数。