Development of Stable Isotope Based Methods to Predict Bioavailability of Hydroph

项目总结/摘要 人类接触沉积物携带的污染物并不直接关系到 大量沉积物，而是由生物可利用浓度或生物利用度控制。 补救措施，如疏浚，砂盖，吸附剂修正，甚至监测 自然恢复（MNR）可能会影响沉积物污染物的生物利用度不同， 整体沉积物化学浓度特别是，生物利用度是更好地评估人类健康的关键。 暴露于疏水性有机污染物（HOCs），如DDT、PCB、PAH和二恶英， 食用来自受污染地区的鱼类。然而，目前确定沉积物的方法 HOC的生物利用度受到方法特异性的限制。部分提取技术估计 生物可利用性总是受到提取剂类型和所选提取条件的影响。 被动采样器，包括固相微萃取（SPME），必须在平衡下使用 可能需要几个月才能达到的条件。 在这个项目中，我们利用稳定同位素标记的HOC化合物的广泛可用性和GC-MS 系统在两个新的应用，旨在大大提高效率和准确性， 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， 类似于对微量元素所做的，以获得可交换浓度作为 接近生物可及浓度。事实上，大多数HOC是高度稳定的， 保守的性质，因此对于这样的应用是理想的。在第二种方法中，我们 通过使用标记的HOCs作为性能，将稳定同位素标记的HOCs与SPME结合 参考化合物，以便SPME可以在非平衡条件下短时间取样 时间同位素交换法可用于非原地评价，稳定同位素法可用于非原地评价。 SPME方法可用于非原位和原位测量。我们将进行系统的 研究，以证明基本假设，开发和优化的方法，使用加标 沉积物，验证方法，通过广泛的生物积累试验，使用一个共同的鱼类猎物 （多毛类蠕虫）和沉积物喂养的鱼（加州大比目鱼），然后应用该方法， 帕洛斯弗迪斯大陆架超级基金滴滴涕和多氯联苯生物利用度的现场和现场测量 位于洛杉矶海岸的一个场地，该场地已经进行了试点修复试验，并计划用于沙子 2012年封顶。在这个项目的最后，我们期望产生一系列经过严格测试的方法 这可能很容易被用于沉积物补救地点的非现场或现场监测，以评估 补救行动的有效性和预测人类接触可能性的变化。

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.