Project 6: Geochemical Controls on the Sorption, Bioavailability, Formation

项目 6：吸附、生物利用度、形成的地球化学控制

• 批准号: 9257389
• 负责人: Stephen A. Boyd
• 金额: $ 37.44万
• 依托单位: MICHIGAN STATE UNIVERSITY
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/9257389
• 关键词: Affect; Amendment; Animal Feed; Attenuated; Bacteria; Biological Availability; Characteristics; Charge; Chemistry; Chlorophenols; Collaborations; Dioxins; Economics; Elements; Exposure to; Funding; Furans; Generic Drugs; Goals; Health; Human; Immune response; Immunosuppression; In Situ; In Vitro; Individual; Instruction; Knowledge; Liquid substance; Measures; Methods; Minerals; Modeling; Movement; Mus; Phase; Physiological; Prevalence; Process; Reaction; Research; Resistance; Risk; Risk Assessment; Role; Salvelinus; Site; Soil; Source; Surface; Technology; Testing; Tissues; Toxic effect; Water; Work; aryl hydrocarbon receptor ligand; base; clay; experimental study; functional genomics; in vivo; microbial; particle; remediation; response; water solubility

PROJECT SUMMARY (See instructions): Due to their exceptionally low water solubilities polychlorinated dibenzodioxins and furans (PCDD/Fs) are strongly and extensively bound to soil and sediment particles. Sorbed PCDD/Fs are distributed among the primary component geosorbents, namely char-like carbonaceous materials, amorphous organic matter, and clays, and the fractional distribution among these geosorbents is hypothesized to change with the total PCDD/F load. Since PCDD/Fs are also highly resistant to decomposition, sorption is a primary determinant of their environmental fates and impacts. Importantly, sorption to soil/sediment particles may modify the bioavailabilities and toxicities of PCDD/Fs in unknown ways, and bioavailability is expected to be geosorbent-specific. The major goals are: (1) to advance fundamental understanding of PCDD/F sorption by these dominant geosorbents comprising soils/sediments, especially at very low environmentally relevant (pptppb) concentrations where carbonaceous materials (e.g. chars) are hypothesized to control soil-water distribution, (2) to determine the differential bioaccessibilities/bioavailabilities of PCDD/Fs sorbed to each key geosorbent type using physiologically based extraction fluid, and mammalian models, (3) to test the hypothesis that mechanistic knowledge of sorption/desorption reactions for PCDD/Fs with individual component geosorbents can be extrapolated to predict site-specific bioaccessibilites and bioavailabilities for contaminated whole soils/sediments, and (4) to evaluate the clay-facilitated formation of PCDD/Fs, and corresponding predioxins/furans, from precursor chlorophenols, and elucidate the underlying mechanistic basis for these reactions. Estimates of PCDD/F bioavailability in soils/sediments are few and inconsistent, hence most risk assessment models for exposure to environmental PCDD/Fs make generic assumptions of 100% bioavailability, irrespective of soil/sediment characteristics. The results of the proposed research will provide the basis for (1) a more mechanistic understanding of the relationship between soil/sediment composition and the human and ecological risks posed by a given total PCDD/F load in soil/sediment, and (2) understanding the prevalence of clay-facilitated PCDD/F formation as an on-going in-situ process leading to unexpected PCDD/F accumulations that threaten human health. Further, it would be of great economic and environmental benefit if certain chars, such as those produced as intentional by-products of biofuels/Csequestration technologies, were shown to be effective as soil/sediment amendments to diminish bioavailability of PCDD/Fs.

项目摘要（参见说明）： 由于其水溶性极低，多氯二苯并二恶英和呋喃 (PCDD/F) 与土壤和沉积物颗粒牢固而广泛地结合。吸附的 PCDD/F 分布在主要成分地质吸附剂中，即炭状碳质材料、无定形有机物和粘土，并且假设这些地质吸附剂之间的分数分布随着 PCDD/F 总负荷的变化而变化。由于 PCDD/F 也具有很强的耐分解性，因此吸附是其环境命运和影响的主要决定因素。重要的是，土壤/沉积物颗粒的吸附可能会以未知的方式改变 PCDD/F 的生物利用率和毒性，并且生物利用率预计与地质吸附剂有关。主要目标是：(1) 增进对这些由土壤/沉积物组成的主要地质吸附剂吸附 PCDD/F 的基本了解，特别是在环境相关 (pptppb) 浓度非常低的情况下，其中假设碳质材料（例如炭）可以控制土壤水分布，(2) 使用基于生理学的提取液和哺乳动物模型确定吸附到每种关键地质吸附剂类型上的 PCDD/F 的差异生物可及性/生物利用度， (3) 检验以下假设：可以推断 PCDD/F 与各个组分地质吸附剂的吸附/解吸反应的机械知识，以预测受污染的整个土壤/沉积物的特定地点的生物可及性和生物利用度，以及 (4) 评估粘土-促进了前体氯酚形成 PCDD/F 和相应的前二恶英/呋喃，并阐明了这些反应的潜在机制基础。对土壤/沉积物中 PCDD/F 生物有效性的估计很少且不一致，因此大多数环境 PCDD/F 暴露风险评估模型都做出 100% 生物有效性的一般假设，而与土壤/沉积物特性无关。拟议研究的结果将为以下方面提供基础：（1）更机械地理解土壤/沉积物成分与土壤/沉积物中给定总 PCDD/F 负荷所造成的人类和生态风险之间的关系，以及（2）了解粘土促进 PCDD/F 形成的普遍性，这是一个持续的原位过程，导致 PCDD/F 意外积累，威胁人类健康。此外，如果某些炭，例如作为生物燃料/碳封存技术的有意副产品产生的那些，被证明可以有效地作为土壤/沉积物改良剂来降低PCDD/F的生物利用度，那么将具有巨大的经济和环境效益。