Mechanisms of bioavailability regulation in soil

土壤生物利用度调节机制

• 批准号: 6577218
• 负责人: FREDERIC PFAENDER
• 金额: $ 17.52万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2003-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6577218
• 关键词: biotransformation; carbopolycyclic compound; chlorohydrocarbon; environmental contamination; environmental exposure; environmental toxicology; environmental transport; hazardous substances; insecticides; microorganism metabolism; organic chemicals; oxidation reduction reaction; soil microbiology; soil pollution; soil sampling

A significant part of the assessment of risk is based on the exposure of sensitive populations to environmental contaminants. It has become clear over the last several years that assessments of environmental concentrations of many hydrophobic organic contaminants (HOC) based on total amount extractable may vastly over-estimate the exposure concentration. A large fraction of HOC may be sequestered in forms that are not readily bioavailable. The amount so sequestered appear to increase over time or during aging in the soil or sediment. There have been several proposed mechanisms to account for this loss of bioavailability, including sorption onto or partitioning into the soil organic carbon, physical entrapment within the organic matter or soil pores, organic binding of the HOC or their microbial degradation products within the soil organic carbon matrix or an absence of factors, such as adequate electron acceptors that will make the sequestered materials degradable. We have also discovered that the presence of active microbes promotes sequestration. Understanding the mechanism is critical if we are to adequately describe the health risk of these chemicals. The current state of knowledge does not permit the sequestration mechanisms to be identified and therefore the risk of the HOC reappearing is unknown. The specific aims of the proposed research are to: 1. Investigate the factors that control the mechanisms of sequestration including properties of the mineral and organic fractions of soil. This includes examination of the role of microbes both in changing the soil organic matter and the HOC. 2. Examine the role of redox changes and added electron acceptors on the transformations and sequestration of HOC in soil. 3. Expand the soils and chemicals studies to include soils that have been aged for nearly 50 years with a variety of chlorinated hydrocarbon insecticides to determine whether mechanisms identified in Aim 1 for PAH are also operative for other soils and chemicals. 4. Investigate how manipulation of mechanism regulating factors can impact bioavailability and serve as the basis for Bioremediation strategies.

风险评估的很大一部分是基于敏感人群接触环境污染物的情况。在过去几年中，很明显，基于可提取总量的许多疏水性有机污染物（HOC）的环境浓度评估可能大大高估了暴露浓度。很大一部分的HOC可能以不易生物利用的形式被隔离。在土壤或沉积物中，这种隔离的量似乎随着时间的推移或老化而增加。已经提出了几种机制来解释这种生物有效性的损失，包括土壤有机碳的吸附或分配，有机质或土壤孔隙内的物理夹带，土壤有机碳基质内HOC或其微生物降解产物的有机结合或缺乏因素，例如足够的电子受体，将使隔离的材料可降解。我们还发现，活跃微生物的存在促进了封存。如果我们要充分描述这些化学品的健康风险，了解其机制是至关重要的。目前的知识状况不允许确定封存机制，因此HOC再次出现的风险是未知的。提出的研究的具体目的是：1。研究控制固碳机制的因素，包括土壤的矿物和有机组分的性质。这包括检查微生物在改变土壤有机质和HOC中的作用。2. 考察氧化还原变化和添加的电子受体对土壤中HOC的转化和封存的作用。3. 扩大土壤和化学物质的研究，包括使用各种氯化烃杀虫剂陈化近50年的土壤，以确定Aim 1中确定的多环芳烃机制是否也适用于其他土壤和化学物质。4. 研究调控因子如何影响生物利用度，并为生物修复策略提供依据。