Department of Civil Engineering, University of Arkansas, 4190 Bell Engineering Center, Fayetteville, AR 72701, USA.
J Chromatogr A. 2011 Jul 8;1218(27):4167-78. doi: 10.1016/j.chroma.2010.12.039. Epub 2010 Dec 21.
Using asymmetrical flow field-flow fractionation (AF4) and fluorescence parallel factor analysis (PARAFAC), we showed physicochemical properties of chromophoric dissolved organic matter (CDOM) in the Beaver Lake Reservoir (Lowell, AR) were stratified by depth. Sampling was performed at a drinking water intake structure from May to July 2010 at three depths (3-, 10-, and 18-m) below the water surface. AF4-fractograms showed that the CDOM had diffusion coefficient peak maximums between 3.5 and 2.8 x 10⁻⁶ cm² s⁻¹, which corresponded to a molecular weight range of 680-1950 Da and a size of 1.6-2.5 nm. Fluorescence excitation-emission matrices of whole water samples and AF4-generated fractions were decomposed with a PARAFAC model into five principal components. For the whole water samples, the average total maximum fluorescence was highest for the 10-m depth samples and lowest (about 40% less) for 18-m depth samples. While humic-like fluorophores comprised the majority of the total fluorescence at each depth, a protein-like fluorophore was in the least abundance at the 10-m depth, indicating stratification of both total fluorescence and the type of fluorophores. The results present a powerful approach to investigate CDOM properties and can be extended to investigate CDOM reactivity, with particular applications in areas such as disinfection byproduct formation and control and evaluating changes in drinking water source quality driven by climate change.
利用不对称流场流分离（AF4）和荧光平行因子分析（PARAFAC），我们展示了比弗湖水库（阿肯色州洛厄尔）中有色溶解有机物（CDOM）的理化性质按深度分层。2010 年 5 月至 7 月，在水面以下 3、10 和 18 米三个深度从饮用水进水结构进行采样。AF4 馏分图显示，CDOM 的扩散系数峰值最大值在 3.5 到 2.8 x 10⁻⁶ cm² s⁻¹ 之间，对应于分子量范围为 680-1950 Da 和尺寸为 1.6-2.5 nm。全水样和 AF4 生成馏分的荧光激发-发射矩阵用 PARAFAC 模型分解成五个主要成分。对于全水样，10 米深度样品的平均总最大荧光最高，而 18 米深度样品的荧光最低（约低 40%）。虽然在每个深度，腐殖质样荧光体构成了总荧光的大部分，但在 10 米深度的蛋白质样荧光体的丰度最低，表明总荧光和荧光体类型都存在分层。结果提供了一种研究 CDOM 性质的有力方法，并可扩展用于研究 CDOM 反应性，特别是在消毒副产物形成和控制以及评估气候变化驱动的饮用水源质量变化等领域。
