To unravel the crucial components of natural organic matter that respond to the process of anthropogenic groundwater recharge (AGR) from different recharge water sources, dissolved organic matter (DOM) and base-extractable particulate organic matter (POM) in groundwater and surface water were analyzed using excitation–emission matrix spectroscopy coupled with parallel factor analysis (EEM–PARAFAC). The EEM and traditional spectral indices of samples show that the fluorescent intensity, molecular weight, and humification degree of the DOM were relatively higher than those of the POM, and the groundwater in the reclaimed water recharge area (RWRA) was more contaminated than in the south-to-north water recharge area (SNWRA). PARAFAC analysis indicates that the DOM was dominated by an allochthonous humic-like substance (C1), whereas the POM was dominated by tryptophan-like substances associated with microbial activity (C2). Partitioning of PARAFAC components between DOM and POM showed that the humic-like substances (C1 and C4) were more likely to be distributed into a dissolved phase compared to the protein-like substances (C2 and C3), which suggested the potential use of C1 and C4 as a tracking indicator. In particular, the clear gradient distributions along both the hydrogeological profile and different aquifer systems in terms of the concentration and composition of C1 also discriminated between the RWRA and SNWRA with regard to the effects of various AGRs on the groundwater. The association between C1 and water-quality indicators revealed by principal component analysis further indicated that refractory humic-like substances would track the environmental impacts of intentional AGR processes.

中文翻译：

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耐火腐殖质：追踪人为地下水补给对环境的影响

为了揭示对不同补给水源的人为地下​​水补给（AGR）过程做出响应的天然有机物的关键成分，分析了地下水和地表水中的溶解性有机物（DOM）和可从碱提取的颗粒有机物（POM）。使用激发-发射矩阵光谱结合并行因子分析（EEM-PARAFAC）。样品的EEM和传统光谱指数表明，DOM的荧光强度，分子量和腐殖化程度相对高于POM，并且再生水回灌区（RWRA）中的地下水污染程度高于POM。南北水补给区（SNWRA）。PARAFAC分析表明，DOM主要由异质腐殖质（C1）占据，而POM以与微生物活性（C2）相关的色氨酸样物质为主。PARAFAC组分在DOM和POM之间的分配表明，与类蛋白物质（C2和C3）相比，类腐殖质（C1和C4）更可能分布在溶解相中，这表明可能使用C1和C4作为跟踪指标。特别是，就各种AGR对地下水的影响而言，在RWRA和SNWRA之间，在C1的浓度和组成方面，沿水文地质剖面和不同含水层系统的清晰梯度分布也有所区别。