THERMAL REMEDIATION

热修复可用于处理在超级基金场址发现的危险废物。这些场所可能含有氯化碳氢化合物和重金属。这些材料的热处理会将有害的副产品释放到环境中。本项目旨在确定氯化副产物或金属的释放对人类的风险。最令人感兴趣的氯化化合物是二恶英。将在风洞实验中研究废物和空气混合速率对二恶英形成的影响。将收集副产品样本，以便稍后与毒理学项目一起分析是否存在二恶英。这些金属的焦点将被收集起来，以便以后与毒理学项目一起分析二恶英的存在。金属研究的重点将放在铬上。铬是一种不易挥发的金属，在高温系统中容易形成超细气溶胶。六价形式的铬毒性很大；其他的价态是无毒的。因此，重要的是能够预测铬的排放状态和设计系统，以尽量减少六价形式的形成。这需要在燃烧系统中铬氧化动力学的知识。将建造一个低压燃烧器，在一个简单的层流预混合火焰中进行实验，火焰中加入铬。在线飞行时间质谱仪将提供铬中间体的测量。结果将用于调整动力学模型的铬氧化应用于实际系统的设计。与科罗拉多大学博尔德分校的合作将允许对反应中间体进行激光诱导荧光测量。还将对铬气溶胶的动力学进行建模，以预测气溶胶颗粒的大小。颗粒的毒性可能随着它们在大气中的老化而改变。一个室内的人工老化将被用来模拟大气中粒子的反应，在它们到达人类的途中。老化颗粒的毒性将通过分析化学以及在超级基金项目中可用的各种生物测定来研究。老化颗粒的毒性将在体外以及动物体内暴露于人工条件燃烧产生的气溶胶中进行评估。

Thermal remediation can be used to treat hazardous wastes found at Superfund sites. These sites can incorporate chlorinated hydrocarbons and heavy toxic metals. The thermal treatment of these materials can release hazardous byproducts into the environment. This project seeks to determine the risk to human populations as a result of a release of chlorinated by-products or metals. The chlorinated compounds of most interest are the dioxins. The impact of the rate of mixing of waste and air on the formation of dioxins will be studied in a wind tunnel experiment. Samples of by-products will be collected for later analysis with the toxicology projects for the presence of dioxins. The focus of the metals will be collected for later analysis with the toxicology projects for the presence of dioxins. The focus of the metals research will be on chromium. Chromium is a non volatile metal that tends to form an ultrafine aerosol in high temperature systems. The hexavalent form of chromium is very toxic; the other valence states are not toxic. Hence, it is important to be able to predict the state of chromium emissions and to design systems to minimize the formation of the hexavalent form. This requires knowledge of the kinetics of chromium oxidation in combustion systems. A low pressure burner will be constructed to undertake experiments in a simple, laminar pre-mixed flame that is seeded with chromium. An on-line time of flight mass spectrometer will provide measurement of chromium intermediates. The results will be used to tune a kinetic model of chromium oxidation for application in the design of practical systems. Collaboration with the University of Colorado Boulder will permit laser induced fluorescence measurements of reactive intermediates to be undertaken. Modeling of the dynamics of the chromium aerosol will also be undertaken to predict the size of the aerosol particles. The toxicity of the particles may change as they age in the atmosphere. Artificial aging in a chamber will be used to simulate the reaction of particles in the atmosphere, on their way to human populations. The toxicity of the aged particles will be studied by analytical chemistry as well as by the various bioassays that are available to use throughout the Superfund program. The toxicity of the aged particles will be assessed in vitro, as well as in vivo with animal exposures to artificially condition combustion generated aerosols.