Acquisition of Advanced Equipment for Measurement of Metal Speciation in Fresh Waters

该拨款为布林克曼自动化伏安系统（VA痕量分析仪，型号746）和MARS 5微波消解系统（CEM公司）的采购提供支持，以促进测量淡水系统中由于自然生物地球化学过程和点和非点源污染而发生的化学形态的快速变化。布林克曼伏安系统自动化基本伏安功能，并结合自动滴定系统和80位自动进样器这种能力。MARS 5微波消解系统能够快速、完全地消解多个样品中的胶体和颗粒，并具有通过消解基质蒸发提高分析物浓度的独特能力。分析消化样品所提供的总金属浓度信息是评价化学形态过程中必不可少的组成部分。MARS 5微波消解系统提高的样品处理效率和再现性将补充Brinkmann自动伏安法系统提高的样品吞吐量，以提高我们实验室研究人员测量淡水系统中金属物种快速变化的能力。目前对天然有机物与金属络合作用的研究旨在确定易于测量的NOM特征（如光谱），这些特征可用于估计其络合特性（结合位点的丰度和强度）。未来关于NOM的工作将评估在风暴事件期间和随着土壤中水流路径的变化而发生的数量和质量的快速变化。其他项目研究全氧地表水中还原性硫化合物的金属结合。人们对这类新发现的配体知之甚少，但在许多情况下可能与NOM一样重要。＊＊＊

0132428BenoitThis grant provides support for the acquisition of a Brinkmann automated voltammetry system (VA Trace Analyzer, Model 746) and a MARS 5 microwave digestion system (CEM Corp.) to facilitate measurement of rapid changes in chemical speciation that occur in freshwater systems as a result of both natural biogeochemical processes and point and nonpoint source pollution. The Brinkmann voltammetry system automates basic voltammetric functions and combines this ability with an automatic titration system and 80 position autosampler. The MARS 5 Microwave Digestion system is able to digest colloids and particles in multiple samples rapidly and completely, and has the unique ability to increase analyte concentration through evaporation of the digestion matrix. The information on total metal concentrations provided by analysis of digested samples is a necessary component in the process of evaluating chemical speciation. The increased sample processing efficiency and reproducibility of the MARS 5 microwave digestion system will complement the increased sample throughput of the Brinkmann automated voltammetry system in improving the ability of researchers in our laboratory to measure rapid changes in metal speciation within freshwater systems. Current research on metal complexation by NOM (natural organic matter) aims to identify easily measurable characteristics of NOM (e.g., spectroscopic) that can be used to estimate their complexation characteristics (abundance and strength of binding sites). Future work on NOM will evaluate rapid variations in quantity and quality that occur during storm events and with changing water flowpaths through soils. Other projects study metal binding by reduced sulfur compounds in fully-oxygenated surface waters. This newly discovered class of ligands is poorly understood, but may be as important as NOM in many instances. ***