A Comprehensive Combined ICP-MS/XAFS Study of Transition Metal Sorption on a Natural Organic Substrate

人们早就知道，大多数金属在天然沃茨中的吸附涉及有机表面和普遍存在于所有无机表面上的有机涂层。不幸的是，有机表面没有显示出在无机表面研究中如此有利的性质。例如，它们拥有各种各样令人眼花缭乱的官能团，其主导地位随环境pH值复杂地变化，从而产生大的金属亲和力动态范围。此外，生物体对金属的吸附除了被动的化学过程外，还可能受到主动生理过程的驱动。在这个项目中，研究人员在切萨皮克生物实验室的大学马里兰州中心环境科学将进行一种新的组合的解决方案（ICP-MS）和表面（XAFS）的实验，以研究过渡金属的吸附上的绿色macrophage石莼，一个有机体具有许多属性的一个？原型？有机基质初步工作表明，最初选择的美国。莴苣和化学相干钇和稀土元素（YREE）系列允许以比将单一金属与简单生物体配对的已发表研究更直接的方式解决未解决的问题（例如，浮游植物）或相当精细的（例如，维管植物）。特别是，表面站点标识可以从相对YREE分布系数的模式和EXAFS技术独立验证。实验策略是专门设计来回答这样的基本问题：（A）在溶液中与金属相互作用的主要官能团是什么？(B)分配系数如何随pH值和其他关键参数而变化？(C)三元复合物能在有机表面形成吗？(D)金属吸附是否受外聚合物鞘和有机配体渗出物的影响？(E)金属吸附的主动生理和被动化学途径之间发生了什么样的相互作用？预计该项目将在与过渡金属与水生和海洋系统中有机表面相互作用有关的各种研究领域产生广泛的影响。 这些包括活生物体的表面以及具有复杂有机涂层的其他固体表面。 该项目将作为一个或两个研究生的硕士论文研究，如果可能的话。

It has long been known that most metal sorption in natural waters involves organic surfaces and the organic coatings ubiquitously present on all inorganic surfaces. Unfortunately, organic surfaces display none of the properties that are so advantageous in studies of inorganic surfaces. For instance, they boast a bewildering variety of functional groups whose dominance shifts intricately with ambient pH, yielding a large dynamic range of metal affinities. Moreover, metal sorption on living organisms may be driven by active physiological in addition to passive chemical processes. In this project, researchers at the Chesapeake Biological Laboratory of the University of Maryland Center for Environmental Sciences will conduct a novel combination of solution (ICP-MS) and surface (XAFS) experiments to study the sorption of transition metals on the green macroalga Ulva lactuca, an organism possessing many attributes of a ?prototype? organic substrate. Preliminary work has demonstrated that the initial choice of U. lactuca and the chemically coherent yttrium and rare earth element (YREE) series allows unresolved problems to be addressed in a more straightforward manner than published studies that paired single metals with simple organisms (e.g., phytoplankton) or fairly elaborate ones (e.g., vascular plants). In particular, surface site identifications can be made from patterns of relative YREE distribution coefficients and verified independently with EXAFS techniques. The experimental strategy is specifically designed to answer such fundamental questions as: (A) Which are the dominant functional groups interacting with metals in solution? (B) How do distribution coefficients vary as a function of pH and other key parameters? (C) Do ternary complexes form on organic surfaces? (D) Is metal sorption affected by exopolymer sheaths and organic ligand exudates? (E) What interplay occurs between active physiological and passive chemical pathways of metal sorption? The project is expected to have significant broader impacts in a variety of research areas related to transition metal interactions with organic surfaces in aquatic and marine systems. These include the surfaces of living organisms as well as other solid surfaces with complex organic coatings. The project will serve as the M.Sc. thesis research of one or, if possible, two graduate students.