RPG: Nonionic Organic Pollutant Sorption Mechanisms in Natural Clay-Rich Aquitards

RPG：天然富含粘土的弱透水层中非离子有机污染物的吸附机制

• 批准号: 9506403
• 负责人: Richelle Allen-King
• 金额: --
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-09-01 至 1997-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9506403&HistoricalAwards=false
• 关键词: RPG; Nonionic; Organic; Pollutant; Sorption

ABSTRACT EAR-9506403 Allen-King Clay-rich aquitards and constructed clay-liners provide low permeability barriers to contaminant migration and are used for hazardous waste disposal because of the margin of protection provided to underlying groundwater resources. Sorption in the aquitard matrix retards transport and provides a sink for uptake and release of organic contaminant mass over time. However, the mechanisms of sorption in clay-rich aquitards are not well understood. Recent observations, for example, have shown that perchloroethene (PCE) sorption in several natural clay-rich and relatively low carbon aquitards is significantly under-predicted by existing methods. It is hypothesized that in natural, low-fraction organic content (foc) and clay-rich aquitards, organic matter is the primary sorbing medium for nonionic organic compounds (NIOCs) such as PCE. The objectives of the proposed research are: (1) to determine the relative importance of organic carbon and/or direct sorption to clay minerals; (2) to determine the effects of differences in oxidation and distribution of organic matter on the magnitude and form of sorptionO and (3) to test for competitive sorption between similar solutes. Using the Planning Grant, the hypothesis will be tested using two contrasting natural aquitard samples with similar clay mineralogy and foc, but markedly different PCE sorption behavior. The results will provide insights into sorption mechanisms and bases for establishing the best methodologies for a more comprehensive study. The objective is to improve mechanistic understanding of NIOC sorption in natural low-carbon geologic samples, thereby allowing more accurate assessments of contaminant transport for groundwater resource protection and remediation.

Allen-King富粘土弱透水层和建造的粘土衬层为污染物迁移提供了低渗透性屏障，并用于危险废物处置，因为它们为下层地下水资源提供了保护边际。弱透水层基质中的吸附延缓了运输，并为有机污染物的吸收和释放提供了一个汇。然而，在富含粘土的弱透水层的吸附机制还没有得到很好的理解。例如，最近的观察表明，现有方法对几种天然富粘土和相对低碳的弱透水层中的全氯乙烯吸附量预测严重不足。据推测，在自然，低馏分有机含量（FOC）和粘土丰富的弱透水层，有机质是主要的非离子有机化合物（NIOC），如PCE的吸附介质。拟议的研究的目标是：（1）确定有机碳和/或直接吸附到粘土矿物的相对重要性;（2）确定不同的氧化和分布的有机物质的吸附的大小和形式的影响和（3）测试之间的竞争吸附相似的溶质。利用规划补助金，将使用两个对比的天然弱透水层样品进行测试，这些样品具有相似的粘土矿物学和foc，但具有明显不同的PCE吸附行为。研究结果将为更全面的研究提供更深入的了解吸附机制和建立最佳方法的基础。其目的是提高对NIOC在天然低碳地质样品中吸附作用的机械理解，从而能够更准确地评估污染物迁移，以保护和补救地下水资源。