Department of Environmental Engineering , Technical University of Denmark , Bygningstorvet, Building 115 , 2800 Kongens Lyngby , Denmark.
Water Environment Technology , Chalmers University of Technology, Architecture, and Civil Engineering , Sven Hultins Gata 6 , 41296 Gothenburg , Sweden.
Environ Sci Technol. 2018 Nov 20;52(22):13027-13036. doi: 10.1021/acs.est.8b04070. Epub 2018 Oct 31.
Dissolved organic matter (DOM) is linked to the heterogeneous distribution of elevated arsenic (As) in groundwater used for drinking and irrigation purposes, but the relationship between DOM characteristics and arsenic mobility has yet to be fully understood. Here, DOM from groundwater sampled in the Bengal Basin region was characterized using both conventional bulk emission-excitation (EEM) spectroscopy and high-performance size-exclusion chromatography coupled to spectroscopy (HPSEC-EEM). Notably, application of the novel HPSEC-EEM approach permitted the total fluorescence of individual samples to be independently resolved into its underlying components. This allowed the external validation of the bulk-sample fluorescence decomposition and offered insight into the molecular size distribution of fluorescent DOM. Molecular size distributions were similar for the UVA fluorescent (C and C) as well as the three visible fluorescent (C, C, and C) components. There was a greater visible fluorescence in shallow aquifer samples (10-33 m) with high As (SH, up to 418 μg/L) than in samples from the same depth with lower As (up to 40 μg/L). This indicated a link between DOM quality and As mobility within the shallow aquifer. The deep aquifer samples (170-200 m) revealed DOM characteristics similar to SH samples but had low As concentrations (<4 μg/L), signifying that the deep aquifer is potentially vulnerable to As contamination. These findings pave the way for a more comprehensive assessment of the susceptibility of drinking water aquifers, thereby supporting the management of groundwater resources.
溶解有机质（DOM）与用于饮用水和灌溉目的的地下水砷（As）异常分布有关，但 DOM 特征与砷迁移性之间的关系尚未完全了解。在这里，使用常规的批量激发-发射（EEM）光谱法和与光谱法相结合的高性能尺寸排阻色谱法（HPSEC-EEM）对孟加拉盆地地区地下水的 DOM 进行了表征。值得注意的是，应用新颖的 HPSEC-EEM 方法可以将单个样品的总荧光独立分解为其潜在成分。这允许对批量样品荧光分解进行外部验证，并深入了解荧光 DOM 的分子大小分布。UVA 荧光（C 和 C）以及三种可见荧光（C、C 和 C）组分的分子大小分布相似。浅层含水层样品（10-33 m）的可见荧光强度较高，砷含量较高（SH，高达 418μg/L），而同一深度的样品砷含量较低（高达 40μg/L）。这表明 DOM 质量与浅层含水层中 As 迁移性之间存在联系。深层含水层样品（170-200 m）表现出与 SH 样品相似的 DOM 特征，但 As 浓度较低（<4μg/L），这表明深层含水层容易受到 As 污染。这些发现为更全面评估饮用水含水层的敏感性铺平了道路，从而支持地下水资源的管理。
