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

人们早就知道，大多数金属在天然水中的吸附涉及有机表面，而有机涂层普遍存在于所有无机表面。不幸的是，有机表面没有表现出在无机表面研究中如此有利的性质。例如，它们拥有令人眼花缭乱的各种官能团，其主导地位随着环境pH值的错综复杂地变化，产生了很大的金属亲和力的动态范围。此外，金属在生物体上的吸附除了受被动化学过程的影响外，还可能受到主动生理过程的驱动。在这个项目中，马里兰大学环境科学中心切萨皮克生物实验室的研究人员将进行一种新的溶液(ICP-MS)和表面(XAFS)组合实验，以研究过渡金属在绿色大型藻石笋上的吸附，石笋是一种具有许多原型属性的生物。有机底物。初步工作表明，与将单一金属与简单生物(例如浮游植物)或相当精细的生物(例如维管植物)配对的已发表研究相比，最初选择生菜和化学上一致的Y和稀土元素(YREE)系列可以更直接地解决尚未解决的问题。特别是，可以根据相对YREE分配系数的模式进行表面位置识别，并使用EXAFS技术进行独立验证。实验策略是专门为回答以下基本问题而设计的：(A)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值和其他关键参数的变化而变化？(C)三元络合物是否在有机表面形成？(D)外聚物鞘和有机配体渗出物是否影响金属吸附？(E)金属吸附的主动生理途径和被动化学途径之间发生了什么相互作用？该项目预计将在与水生和海洋系统中过渡金属与有机表面相互作用有关的各种研究领域产生重大而广泛的影响。这包括活的有机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M.Sc。一个或两个研究生的论文研究，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.