XAS AND XAS IMAGING OF ORGANISMS IN THE ENVIRONMENT

这个子项目是许多利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 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，硒的作用则比较模糊，因为虽然在较高水平下有毒，但在痕量浓度下，它是哺乳动物和许多其他生物体的必需元素。然而，对于这些元素中的每一种，化学形态都会严重影响元素的特性，包括其在地下水中的流动性，生物利用度和毒性，特别是对鸟类，鱼类和人类等高等生物的毒性。同步加速器X射线技术，如本提案中所述，提供了金属和类金属，如硒或汞的形态和定位信息。这种研究可以在诸如湖底沉积物或鱼类组织等多种多样的材料中进行，而不需要经常干扰基质化学性质从而干扰物种形成的侵入性方法。因此，同步加速器提供了独特的工具，用于研究复杂的环境样品。此外，在SSRL，我们已经实现了高灵敏度的测量，使这些方法的理想研究样品在？自然？浓度的在这个计划中，我们提出了两个对比的研究路线。一个是一个整体的方法来研究硒在矿山影响的网站，其结果应该有广泛的影响硒在水生冷水环境中的影响。第二项是实验室研究，使用斑马鱼幼鱼详细调查汞、硒和其他元素影响的位置。这种研究不仅对环境毒理学而且对人类毒理学都有影响，因为斑马鱼已被用作人类发育的模型。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. 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.