Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang 050061, China; Hebei Key Laboratory of Groundwater Remediation, Shijiazhuang 050061, China; School of Environmental Studies & State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China.
School of Environmental Studies & State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China.
Sci Total Environ. 2015 Oct 1;529:131-9. doi: 10.1016/j.scitotenv.2015.05.051. Epub 2015 May 22.
The sources of dissolved organic matter (DOM) in groundwater are important to groundwater chemistry and quality. This study examined similarities in the nature of DOM and investigated the link between groundwater DOM (GDOM) and sedimentary organic matter (SOM) from a lacustrine-alluvial aquifer at Jianghan Plain. Sediment, groundwater and surface water samples were employed for SOM extraction, optical and/or chemical characterization, and subsequent fluorescence excitation-emission matrix (EEM) and parallel factor analyses (PARAFAC). Spectroscopic properties of bulk DOM pools showed that indices indicative of GDOM (e.g., biological source properties, humification level, aromaticity and molecule mobility) varied within the ranges of those of two extracted end-members of SOM: humic-like materials and microbe-associated materials. The coexistence of PARAFAC compositions and the sustaining internal relationship between GDOM and extracted SOM indicate a similar source. The results from principal component analyses with selected spectroscopic indices showed that GDOM exhibited a transition trend regarding its nature: from refractory high-humification DOM to intermediate humification DOM and then to microbe-associated DOM, with decreasing molecular weight. Correlations of spectroscopic indices with physicochemical parameters of the groundwater suggested that GDOM was released from SOM and was modified by microbial diagenetic processes. The current study demonstrated the associations of GDOM with SOM from a spectroscopic viewpoint and provided new evidence supporting SOM as the source of GDOM.
地下水中溶解有机质（DOM）的来源对地下水化学和水质很重要。本研究从江汉平原湖泊冲积含水层考察了 DOM 与沉积物有机质（SOM）之间的相似性。对沉积物、地下水和地表水样本进行 SOM 提取、光学和/或化学特性分析，以及随后的荧光激发-发射矩阵（EEM）和平行因子分析（PARAFAC）。DOM 库的光谱特性表明，指示 GDOM 的指数（例如生物源特性、腐殖化程度、芳香度和分子迁移率）在 SOM 的两个提取端元（腐殖质样物质和微生物相关物质）的范围内变化。PARAFAC 组成的共存以及 GDOM 和提取 SOM 之间的持续内在关系表明它们具有相似的来源。选择光谱指数的主成分分析结果表明，GDOM 的性质表现出一种转变趋势：从难降解高腐殖化 DOM 到中等腐殖化 DOM，然后到微生物相关 DOM，分子量逐渐降低。光谱指数与地下水理化参数的相关性表明，GDOM 是从 SOM 中释放出来的，并受到微生物成岩作用的修饰。本研究从光谱学角度证明了 GDOM 与 SOM 的相关性，为 SOM 是 GDOM 来源的观点提供了新的证据。
