Development of Stable Isotope Based Methods to Predict Bioavailability of Hydroph

项目摘要/摘要 人类暴露在沉积物中的污染物与土壤中的化学物质浓度没有直接关系 而是由生物可利用浓度或生物利用度控制。 补救做法，如疏浚、封沙、吸附剂修正，甚至监测 自然恢复(MNR)对沉积物污染物生物有效性的影响可能都不同于 散装沉积物的化学浓度。特别是，生物利用度是更好地评估人类 接触疏水性有机污染物，如滴滴涕、多氯联苯、多环芳烃和二恶英 食用受污染地区的鱼类。然而，目前测定泥沙的方法 特定的生物利用度受到特定方法的限制。部分提取技术用于估计 生物可及性总是受到所选萃取剂类型和提取条件的影响。 被动取样器，包括固相微萃取(SPME)，必须在平衡状态下使用 可能需要几个月才能达到的条件。 在这个项目中，我们开发了稳定同位素标记化合物和GC-MS的广泛可用性 系统在两个新的应用中旨在极大地提高效率和准确性 生物利用度测量。第一种方法使用同位素交换(或稀释)的概念， 类似于对痕量元素所做的操作，将可交换浓度导出为 接近生物可达浓度。大多数HOC是高度稳定的，这一事实使他们 保守性保守的性质，因此非常适合这样的应用。在第二种方法中，我们 稳定同位素标记的HOCs与SPME的结合性能 标准化合物，使固相微萃取可在短采样的非平衡条件下使用 时间到了。同位素交换法可用于非原位评价，而稳定同位素可用于非原位评价。 固相微萃取方法既可用于离位测量，也可用于原位测量。我们将系统地开展 研究以证明潜在的假设，开发和优化使用SPADED的方法 沉积物，通过使用一种常见的鱼类猎物进行广泛的生物积累测试来验证方法 (多毛虫)和一种以沉积物为食的鱼(加利福尼亚大比目鱼)，然后将这些方法应用于EX Palos Verdes大陆架超级基金对滴滴涕和多氯联苯生物有效性的现场和现场测量 洛杉矶海岸外的一个地点，已经进行了试点补救试验，计划开采沙子 在2012年封顶。在这个项目结束时，我们希望产生一系列经过严格测试的方法 可方便地用于沉积物修复场地的异地或现场监测，以评估 补救行动的有效性，并预测人类接触潜力的变化。

Project Summary/Abstract Human exposure to sediment-borne contaminants is not directly related to chemical concentrations in the bulk sediment, but is instead controlled by the bioavailable concentration or bioavailability. Remediation practices, such as dredging, sand capping, sorbent amendment, and even monitored natural recovery (MNR) may all affect the bioavailability of sediment contaminants differently than the bulk sediment chemical concentration. In particular, bioavailability is a key to better assessing human exposure to hydrophobic organic contaminants (HOCs) such as DDT, PCBs, PAHs and dioxins through consumption of fish from contaminated areas. However, current methods for determining sediment HOC bioavailability suffer from method-specific limitations. Partial extraction techniques to estimate bioaccessibility are invariably influenced by types of extractants and extraction conditions selected. Passive samplers, including solid phase microextraction (SPME), must be used under equilibrium conditions that may take months to reach. In this project we exploit the wide availability of stable isotope labeled HOC compounds and GC-MS systems in two novel applications aiming to greatly improve the efficiency and accuracy of bioavailability measurement. The first approach uses the concept of isotope exchange (or dilution), similar to what has been done for trace elements, to derive the exchangeable concentration as an approximation of bioaccessible concentration. The fact that most HOCs are highly stable lends them the quality of being conservative and thus ideal for such an application. In the second approach, we incorporate stable isotope labeled HOCs with SPME by using the labeled HOCs as performance reference compounds so that SPME may be used under non-equilibrium conditions with short sampling time. The isotope exchange approach may be applied to ex situ assessment while the stable isotope- SPME method may be used for both ex situ and in situ measurements. We will carry out systematic studies to prove the underlying assumptions, develop and optimize the methods using spiked sediments, validate the methods through extensive bioaccumulation assays using a common fish prey (polychaete worm) and a deposit-feeding fish (California halibut), and then apply the methods for ex situ and in situ measurement of bioavailability of DDTs and PCBs at the Palos Verdes Shelf Superfund site off the coast of Los Angeles that has undergone pilot remediation trials and is scheduled for sand capping in 2012. At the end of this project, we expect to produce a range of rigorously tested methods that may be easily adopted for ex situ or in situ monitoring of sediment remediation sites to evaluate the effectiveness of remediation operations and predict changes in human exposure potential.