School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, PR China.
School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, PR China.
Ecotoxicol Environ Saf. 2021 Jan 15;208:111779. doi: 10.1016/j.ecoenv.2020.111779. Epub 2020 Dec 11.
High levels of ammonium in groundwater is a potential threat to drinking water security and ecological status. The role of dissolved organic matter (DOM) in mobilization of natural ammonium in groundwater is crucial but the intrinsic link between them has still been poorly understood. This study used high-pressure size exclusion chromatography (HPSEC) and fluorescence excitataion-emission-matrix spectra (EEMs) with parallel factor analysis (PARAFAC) to elucidate the influence of DOM characteristics in groundwater systems having contrastive ammonium levels in Dongting Plain, central Yangtze River. The results indicate that NH-N concentration in groundwater of western plain (0-16.75 mg/L) are much higher compared with southern plain (0-1.5 mg/L). The groundwater in western plain is in a more reductive environment and characterized by larger molecular weight (MW) of DOM and lower polydispersity (ρ), whereas DOM with relatively small molecular weight and high polydispersity is detected in the south with a more oxidative condition. The groundwater in western plain is characterized by lower fluorescence index (f) and biological index (BIX), and dominated by the high molecular weight terrestrial humic-like component and larger amounts of microbial humic-like components. Protein-like is the main component in groundwater of southern plain with higher f and BIX. The ammonium concentration in groundwater correlates well with molecular weight and increases significantly with the content of high molecular weight terrestrial humic-like component, indicating that mobilization of ammonium is more closely associated with the terrestrial organic matter of high molecular weight. This study further enriches the theory on mobilization of ammonium in Quaternary alluvial-lacustrine aquifer systems and provides theoretical basis for the local water supply security.
地下水高浓度氨是饮用水安全和生态状况的潜在威胁。溶解有机质（DOM）在地下水自然氨迁移中的作用至关重要，但它们之间的内在联系仍知之甚少。本研究采用高压尺寸排阻色谱（HPSEC）和荧光激发-发射矩阵光谱（EEMs）与平行因子分析（PARAFAC）相结合的方法，阐明了具有对比性铵水平的洞庭湖中部长江流域地下水系统中 DOM 特征的影响。结果表明，与南部平原（0-1.5mg/L）相比，西部平原（0-16.75mg/L）地下水的 NH-N 浓度要高得多。西部平原地下水处于更还原的环境，具有更大分子量（MW）和较低的多分散性（ρ）的 DOM，而南部氧化条件下检测到相对较小分子量和较高多分散性的 DOM。西部平原地下水的荧光指数（f）和生物指数（BIX）较低，主要由高分子量陆源腐殖质样成分和大量微生物腐殖质样成分组成。南部平原地下水以蛋白质样为主，f 和 BIX 较高。地下水氨浓度与分子量密切相关，随高分子量陆源腐殖质样成分含量显著增加，表明氨的迁移与高分子量陆地有机质关系更为密切。本研究进一步丰富了第四纪冲积-湖相含水层系统中氨迁移的理论，为当地供水安全提供了理论依据。
