Mechanisms of bioavailability regulation in soil

土壤生物利用度调节机制

• 批准号: 6587622
• 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/6587622
• 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.

风险评估的一个重要部分是根据敏感人群暴露在环境污染物中的情况。在过去的几年里，很明显，基于可提取总量对许多疏水性有机污染物(HOC)的环境浓度进行评估可能会大大高估暴露浓度。很大一部分HOC可能以不易生物利用的形式被隔离。这样被隔离的量似乎随着时间的推移或在土壤或沉积物中老化期间而增加。已经提出了几种机制来解释这种生物有效性的丧失，包括吸附或分配到土壤有机碳上，物理捕获在有机质或土壤孔隙中，HOC或其微生物降解产物在土壤有机碳基质中的有机结合，或者缺乏使隔离材料可降解的足够的电子受体等因素。我们还发现，活跃微生物的存在促进了隔离。如果我们要充分描述这些化学品的健康风险，了解其机理是至关重要的。目前的知识状况不允许确定自动减支机制，因此临时重新出现的风险是未知的。研究的具体目的是：1.研究土壤矿质组分和有机质组分的性质等因素对土壤固持机理的影响。这包括研究微生物在改变土壤有机质和HOC中的作用。2.研究氧化还原变化和添加的电子受体对土壤中HOC的转化和截留的影响。3.扩大土壤和化学品研究，包括使用各种氯代烃杀虫剂老化近50年的土壤，以确定目标1中确定的多环芳烃的作用机制是否也适用于其他土壤和化学品。4.研究机制调节因子的操纵如何影响生物利用度，并作为生物修复策略的基础。