Characterization of Fluvial Suspended Matter Using Field-Flow Fractionation and Related Methods.

9614186先令将确定不同粒度的河流悬浮物的组成和性质，特别是亚微米尺寸范围内的颗粒。这项工作很重要，因为悬浮颗粒承载着河流中许多元素的大部分负荷，而且颗粒表面可以通过吸附来控制溶解浓度。然而，关于颗粒组成和吸附性能如何随颗粒大小变化-特别是在亚微米(或胶体)尺寸范围内--知之甚少。这项工作将利用相对较新的悬浮颗粒分级技术，特别是场流分级(FFF)和分流薄层横向传输(Splitt)分级。这些方法的能力已经在文献中得到了证明；然而，它们在环境问题上的应用仍处于初级阶段。因此，这项拟议工作的一个主要目标是进一步开发环境FFF方法并进行质量保证测试。其他目标包括将FFF和Splitt应用于表征各种河流环境中的河流悬浮物，分析样品处理中的过滤伪影，调查细菌引起的颗粒成分变化，以及开发研究吸附随颗粒大小变化的方法。该项目将有两种类型的结果：1)发展FFF和Splitt方法，使其能够更常规地应用于自然水域中的颗粒表征；2)解决一些特定的环境问题。这些具体问题包括如何最好地过滤样品以进行溶解的微量元素分析，悬浮颗粒的多大小部分包含什么类型的材料(以及这如何影响痕量元素的吸附)，以及细菌如何影响颗粒表面。这项工作将包括与超滤、光SCA滴定和电子显微镜对FFF结果的检查和比较。此外，我们还将使用不同的样品前处理和分级条件进行粒度分级工作。这将阐明这些技术的潜在人工制品。虽然这是一个独立的项目，但这项工作将与美国地质调查局的同事合作进行。

9614186 Shiller The composition and properties of size-fractioned riverine suspended matter will be determined, with special emphasis on particles in the sub-micron size range. This work is important because suspended particles carry much of the load of many elements in rivers and because particle surfaces can control dissolved concentrations through adsorption. However, little is known about how particle composition and adsorbing properties vary with particle size---especially in the sub-micron (or colloidal) size range. The work will utilize relatively new technologies for size fractioning suspended particles, specifically field-flow fractionation (FFF) and split-flow thin-cell lateral transport (SPLITT) fractionation. The capabilities of these methods have been demonstrated in the literature; however, their application to environmental problems is still in its infancy. Thus, a primary objective of this proposed work is the further development and quality assurance testing of environmental FFF methodology. Other objectives include the application of FFF and SPLITT to the characterization of fluvial suspended matter from a variety of fluvial environments, analysis of filtration artifacts in samples processing, investigation of bacterially-induced changes in particulate composition, and development of methodology for investigating variation of adsorption with particle size. The project will have two types of results: 1) development of FFF and SPLITT methods to the point where they can be applied more routinely for particle characterization in natural waters and 2) solution of some specific environmental questions. These specific questions include how best to filter samples for dissolved trace element analysis, what size fractions of the suspended particles contain what types of materials (and how this affects adsorption of trace elements), and how bacteria affect particle surfaces. The work will include examination and comparison of FFF results with ultrafiltration, light sca ttering, and electron microscopy. Additionally, we will do the size fractionation work using different sample pre-treatments and fractionation conditions. This will shed light on potential artifacts of the techniques. Although this is a stand alone project, the work will be pursued collaboratively with colleagues at the US Geological Survey.