XAS AND XAS IMAGING OF ORGANISMS IN THE ENVIRONMENT

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 人们越来越关注金属和类金属对环境中的生物体以及最终对人类的影响。有些元素，如汞，是臭名昭著的有毒元素。相比之下，硒的作用比较模糊，因为尽管硒在较高水平下具有毒性，但在微量浓度下，它是哺乳动物和许多其他生物的必需元素。然而，对于这些元素中的每一种，化学形态都严重影响着元素的性质，包括其在地下水中的流动性、生物可利用性和毒性，特别是对鸟类、鱼类和人类等高等生物。同步加速器X射线技术，如本提案中所描述的，提供了金属和类金属，如Se或Hg的形态和定位信息。这样的研究可以在各种材料中进行，如湖床沉积物或鱼类组织，而不需要经常扰乱基质化学从而影响物种形成的侵入性方法。因此，同步加速器为研究环境感兴趣的复杂样品提供了独特的工具。此外，在SSRL，我们已经实现了这种高灵敏度的测量，使这些方法成为在自然条件下研究样品的理想方法。浓度。在这个项目中，我们提出了两条截然不同的研究路线。一种是研究受地雷影响的地点中硒的影响的整体方法，其结果应该对水中冷水环境中的硒有广泛的影响。第二项是以斑马鱼幼体为基础的实验室研究，详细调查汞、硒等元素的影响部位。这项研究不仅对环境毒理学有影响，而且对人类毒理学也有影响，因为斑马鱼已被用作人类发展的模型。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. There is growing concern regarding the impact of metals and metalloids on organisms in the environment and ultimately on humans. Some elements such as mercury are notorious as toxic elements. In contrast the role of selenium is more ambiguous, since though toxic at higher levels, it is an essential element for mammals and many other organisms at trace concentrations. However, with each of these elements the chemical speciation critically affects the properties of the element, including its mobility in groundwater, bioavailability and toxicity especially to higher organisms such as birds, fish and humans. Synchrotron x-ray techniques, such as are described in this proposal, provide speciation and localization information for metals and metalloids such as Se or Hg. Such studies can be carried out in materials as diverse as lakebed sediments or tissues of fish without intrusive methods that often perturb the chemistry of the matrix and therefore the speciation. Thus, the synchrotron provides unique tools for studying complex samples of environmental interest. Furthermore, at SSRL we have achieved such measurements with high sensitivity making these methods ideal for studying samples at ?natural? concentrations. In this program we propose two contrasting lines of research. One is a holistic approach to study the effects of selenium in a mine-impacted site, the results of which should have widespread implications for selenium in aquatic coldwater environments. The second is a laboratory-based study using larval zebrafish to investigate in detail the localization of impact of mercury, selenium and other elements. Such a study has ramifications not only for environmental toxicology but also for human toxicology, as zebrafish have been used as a model for human development.