Geochemical Controls on the Adsorption, Bioavailability, and Environment

我们的目标是表征知之甚少的控制Ahreceptor吸附的机械过程 配体（AhRL）的矿物表面，然后使用这些定义明确的系统来探测 吸附的AhRL对细菌和哺乳动物的生物利用度。由于AhRL往往具有异常低的水分 由于溶解度低，这些高毒性化合物主要作为吸附物质存在于环境中。我们 认为粘土矿物是一个主要的，在很大程度上未被认识到的AhRL在环境中的汇。我们 初步研究和文献表明，粘土可能发挥几乎相等的作用，甚至占主导地位， 有机质对土壤中二恶英的固定作用。我们的建议有四个具体目标： 测量关键AhRL对粘土矿物的吸附和螯合，并表征地球化学特征 2）通过积分确定这种吸附的分子机制 批量结果与光谱和分子模拟研究，从而促进更合理的长期 超级基金现场管理，3）确定微生物对矿物质本身的遗传和功能反应 和矿物吸附AhRL，以阐明微生物与这些相互作用的关键机制， 吸附的化合物，和4）量化微生物功能，使生物利用度和 通过使用与关键微生物表达的荧光标记物来生物降解矿物吸附的AhRL 应答因此，我们的建议支持超级基金基础研究和培训计划的使命 因为在目标1中，我们将致力于“识别和量化污染物的化学形式”， 目标1-2：我们将评估“影响环境中化学品的物理、化学和生物过程， 在目标3-4中，我们将把这项工作直接与超级基金的生物利用度联系起来 细菌和哺乳动物的化学物质。这项研究与公共卫生的相关性：许多有毒有机污染物在水中不溶，人类接触的主要途径是通过摄入吸附的污染物。我们建议表征吸附二恶英和相关化合物的粘土矿物，然后使用散装和 分子方法来了解吸附对化合物（对小鼠）毒性的影响， （通过土壤细菌）对化合物进行生物降解，这是补救和风险评估所需要的。

Our objectives are to characterize poorly understood mechanistic processes that control sorption of Ahreceptor ligands (AhRLs) to mineral surfaces, and then use these well-defined systems to probe the bioavailability of sorbed AhRLs to bacteria and mammals. Since AhRLs tend to have exceptionally low water solubilities, these highly toxic compounds exist in the environment predominantly as sorbed species. We argue that clay minerals are a major, largely unrecognized sink for AhRLs in the environment. Our preliminary studies and the literature suggest that clays may play a nearly equal or even dominant role to that of organic matter in the immobilization of dioxins in soils. Our proposal has four specific aims: 1) To measure sorption and sequestration of key AhRLs to clay minerals and to characterize the geochemical controls on that sorption, 2) To determine the molecular mechanisms of such sorption through integrating bulk results with spectroscopy and molecular simulation studies, thereby promoting more rational long-term Superfund site stewardship, 3) To identify microbial genetic and functional responses to minerals themselves and to mineral-adsorbed AhRLs in order to elucidate key mechanisms of microbial interaction with these adsorbed compounds, and 4) To quantify the microbial functionality enabling bioavailability and biodegradation of mineral-sorbed AhRLs by using fluorescent markers that are expressed with key microbial responses. Thus our proposal supports the mission of the Superfund Basic Research and Training Program because in Objective 1 we will work to "identify and quantify chemical forms of the contaminants," in Objectives 1-2 we will assess "the physical, chemical and biological processes affecting chemicals in environmental media," and in Objectives 3-4 we will link this work directly to bioavailability of Superfund chemicals to bacteria and to mammals. Relevance of this research to public health: Many toxic organic contaminants are so insoluble in water that the main route of human exposure is through ingestion of adsorbed contaminants. We propose to characterize adsorption of dioxins and related compounds to clay minerals, and then use both bulk and molecular methods to understand the effects of adsorption on the toxicity of the compound (to mice) and the biodegradation of the compound (by soil bacteria), which is needed in remediation and risk assessment.