Department of Environmental Science and Engineering, School of Space and Environment, Beihang University, Beijing, 10191, China; Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beihang University, Beijing, 100191, China.
Graduate School of Fundamental Science and Technology, Keio University, Yokohama, Kanagawa, 223-8522, Japan.
Ecotoxicol Environ Saf. 2020 Jan 30;188:109834. doi: 10.1016/j.ecoenv.2019.109834. Epub 2019 Nov 1.
Monitoring dissolved organic matter (DOM) content in aquatic environments is crucial for not only understanding the dynamics of heavy metals but also predicting their bioavailability. Fluorescence spectroscopy is typically employed to characterise DOM. Here, the interaction between DOM and trace metals was investigated by combining excitation-emission matrix (EEM) quenching with two-dimensional Savitzky-Golay second-order differentiation (2D-SG-2nd-df) analysis. The 2D-SG-2nd-df analysis decomposed the EEM spectra of commercial humic acid (HA) samples into six separate fluorescence peaks, which agreed with the results obtained through conventional parallel factor (PARAFAC) analysis. Compared with PARAFAC modeling, the 2D-SG-2nd-df approach provided more valid and reliable results when the dataset contained distinct samples. Moreover, since the results obtained from 2D-SG-2nd-df for each sample are independent, shifts in the peak wavelength can be reproduced more efficiently using this method. Triplicate titration experiments showed clear differences in HA-copper interactions for samples with different HA composition and molecular weight. The binding strength between copper and low-molecular-weight DOM in water was weaker than that observed for high-molecular-weight DOM. The results obtained in this study will serve as a basis for applying 2D-SG-2nd-df not only to DOM but also to other samples studied using EEM measurements.
监测水生环境中的溶解有机物质（DOM）含量对于理解重金属动力学以及预测其生物利用度至关重要。荧光光谱通常用于表征 DOM。在这里，通过将激发-发射矩阵（EEM）猝灭与二维 Savitzky-Golay 二阶导数（2D-SG-2nd-df）分析相结合，研究了 DOM 与痕量金属之间的相互作用。2D-SG-2nd-df 分析将商用腐殖酸（HA）样品的 EEM 光谱分解为六个单独的荧光峰，这与通过常规平行因子（PARAFAC）分析获得的结果一致。与 PARAFAC 建模相比，当数据集包含明显不同的样品时，2D-SG-2nd-df 方法提供了更有效和可靠的结果。此外，由于 2D-SG-2nd-df 为每个样品提供的结果是独立的，因此使用该方法可以更有效地再现峰波长的偏移。重复滴定实验表明，具有不同 HA 组成和分子量的样品中 HA-铜相互作用存在明显差异。水中铜与低分子量 DOM 之间的结合强度弱于与高分子量 DOM 之间的结合强度。本研究的结果将为不仅在 DOM 而且在其他使用 EEM 测量研究的样品中应用 2D-SG-2nd-df 提供依据。
