Collaborative Research: An Integrated Study of the Fractionation of Natural Dissolved Organic Matter Upon Sorption to Mineral Surfaces

9628166 下巴 天然有机物（NOM）是一种重要的 它是土壤、河流、湖泊、地下沃茨和河口沃茨的重要组成部分，在矿物生长和溶解、微量金属循环和全球地球化学碳收支等多种环境现象中起着关键作用。 也许最重要的是，NOM在有机和无机污染物通过多孔介质的运输中起着至关重要的作用。 一方面，结合到矿物表面的NOM可以从水柱中去除痕量金属、非极性有机化合物（NOC）和其他污染物。 另一方面，NOM在水柱中保持游离或胶体形式，可能会增加污染物的流动性。 因此，了解和量化固体和溶解相之间的NOM的大部分分区是根本的广泛的污染物传输现象。 此外，由于NOM由各种疏水和亲水分子组成，具有可变的结构，功能和反应性，我们不仅需要了解NOM如何分区，而且还需要了解它如何在吸附到矿物表面时分馏。例如，更疏水的组分的优先吸附可增加NOC通过多孔介质的阻滞。 大量的现场和实验室研究表明，NOM分馏吸附，并提供线索分馏过程。 然而，许多问题仍然存在关于NOM组合物，溶液特性，矿物表面性质和动力学考虑分馏的影响。 此外，很少有人知道矿物溶解，金属络合，和NOM凝聚对表观分馏的影响。 最后，我们目前对分馏的理解主要是基于间接证据。 例如，虽然观察到的动力学效应分馏已被归因于一些吸附NOM分子的构象的变化，这一假设还没有被直接测试。 为了更好地了解NOM分馏过程，我们提出了一个为期3年的跨学科的研究工作相结合的实地采样在一个精心选择的淡水湿地流域，麦当劳分支盆地在新泽西Pinelands，与新开发的分子水平的方法，研究NOM吸附和分馏在一个更直接的方式比以前已经可能。 NOM样品将从地表沃茨、土壤以及在仔细记录的补给区和排泄区的浅层和深层地下沃茨中采集。 McDonalds分支和标准NOM样品的吸附分馏将通过表征吸附前后的溶液来定量，使用分析技术的组合，包括：13 C NMR和1H NMR; UV-Vis、荧光和衰减傅立叶变换红外光谱。所述方法包括：红外光谱法（ATR-FTIR）光谱法;高压尺寸排阻色谱法（HPSEC）;总有机碳分析（TOC）;蒸气压渗透压测定法;电位滴定法;和元素分析。 扫描隧道和原子力显微镜（STM和AFM），包括新的轻敲模式AFM，将用于确定吸附的有机分子的结构，以及结构变化在吸附和分馏中的作用。 高压液相色谱（HPLC）和AA将用于研究氧化物溶解和NOM-金属结合现象。 表面FTIR将有助于阻止吸附机制，以及它们如何影响分馏。 我们相信，这个项目是水质研究的许多领域的基础，我们选择了一个真正的端元自然实验室流域进行实地调查。 上述最先进的实验室技术的结合将使我们能够以比以前更定量、更机械的方式解决这个问题。 在这项研究的过程中，金属络合分析的新技术将得到完善，吸附的有机分子的STM/AFM成像的新方法将得到进一步发展，并将促进NOM结构，组成和反应性的实验室和现场调查相结合的新方法。 拟议的研究将为广泛的其他研究奠定坚实的基础。 例如，该方法可以扩展到包括在具有不同NOM特征的更大多样性的流域类型中进行采样。 我们预计，这项研究将使广泛的未来研究如何NOM分馏影响运输的疏水性和亲水性污染物。 最后，鉴于淡水湿地的重要性，以及它们从我们的景观中消失的速度，我们认为，涉及湿地NOM演变的调查是至关重要的，以进一步了解这种复杂而脆弱的生态系统。

9628166 Chin Natural organic matter (NOM) is an important component of soils, streams, lakes, ground waters, and estuarine waters, and it plays a key role in such diverse environmental phenomena as mineral growth and dissolution, cycling of trace metals, and the global biogeochemical C budget. Perhaps most importantly, NOM plays a crucial, though complex, role in the transport of organic and inorganic pollutants through porous media. On the one hand, NOM that is bound to mineral surfaces may remove trace metals, nonpolar organic compounds (NOCs ) and other pollutants from the water column. On the other hand, NOM that remains free or in colloidal form within the water column may increase the mobility of pollutants. Hence, understanding and quantifying the bulk partitioning of NOM between solid and dissolved phases is fundamental to a wide range of pollutant transport phenomena. Moreover, because NOM consists of a variety of hydrophobic and hydrophilic molecules with variable structure, functionality, and reactivity, we need to understand not only how NOM partitions but also how it fractionates upon sorption to mineral surfaces. For example, preferential sorption of the more hydrophobic components may increase the retardation of NOCs through porous media. Numerous field and laboratory studies have suggested that NOM fractionates upon sorption, and provided clues to fractionation processes. Nevertheless, many questions remain regarding the effects of NOM composition, solution characteristics, mineral surface properties and kinetic considerations on fractionation. Additionally, little is known about the effects of mineral dissolution, metal complexation, and NOM coagulation on apparent fractionation. Finally, much of our current understanding of fractionation is based on largely indirect evidence. For example, although observed kinetic effects on fractionation have been attributed by some to changes in conformations of sorbed NOM molecules, this hypothesis has not been tes ted directly. To better understand NOM fractionation processes, we propose a 3-year interdisciplinary research effort combining field sampling at a carefully chosen freshwater wetland watershed, McDonalds Branch basin in the New Jersey Pinelands, with newly developed molecular-level methodologies, to study NOM sorption and fractionation in a far more direct manner than previously has been possible. NOM samples will be collected from surface waters, soils, and shallow and deep ground waters in carefully documented recharge and discharge zones. Fractionation on sorption of McDonalds Branch and standard NOM samples will be quantified by characterizing solutions prior to and following adsorption, using a combination of analytical techniques, including: 13C NMR and 1H NMR; UV-Vis, fluorescence, and attenuated fourier transform infra-red (ATR-FTIR) spectroscopies; high pressure size exclusion chromatography (HPSEC); total organic carbon analysis (TOC); vapor pressure osmometry; potentiometric titration's; and elemental analysis. Scanning-tunneling and atomic-force microscopy (STM and AFM), including the new tapping mode AFM, will be used to determine the structure of sorbed organic molecules, and the role of structural changes in sorption and fractionation. High pressure liquid chromatogrphy (HPLC) and AA will be used to study oxide dissolution and NOM-metal binding phenomena. Surface FTIR will assist in deterring sorption mechanisms, and how they influence fractionation. We believe that this project is fundamental to many areas of water quality research, and that we have chosen a true end-member natural laboratory watershed to conduct the field investigation. The combination of state-of-the-art laboratory techniques listed above will allow us to tackle this problem in a far more quantitative, mechanistric manner than previously has been possible. Over the course of this research, new techniques of metal-complexation analysis will be refined, new methods of STM/AFM imaging of sorbed organic molecules will be furthered, and a new approach to integrating laboratory and field investigations of NOM structure, composition, and reactivity will be fostered. The proposed research will lay a strong foundation for a broad spectrum of additional research. For example, the approach may be expanded to encompass sampling at a greater diversity of watershed types, with different NOM characteristics. We anticipate that this research will enable a wide range of future studies of how NOM fractionation influences the transport of hydrophobic and hydrophilic pollutants. Finally, given the importance of freshwater wetlands, and the rapidity with which they are disappearing from our landscape, we feel that investigations involving NOM evolution in wetlands are crucial to further our understanding of such complex but fragile ecosystems.