Dissolved organic matter characterization in high and low ammonium groundwater of Dongting Plain, central China

作者：Yanwen Huang, Yao Du, Teng Ma, Yamin Deng, Yanqiu Tao, Yu Xu, Zhichao Leng · 发表于：Ecotoxicology and Environmental Safety · 年份：2020 · DOI：10.1016/j.ecoenv.2020.111779 · 被引用次数：65 · 研究领域：Marine and coastal ecosystems、Groundwater and Isotope Geochemistry、Water Quality Monitoring and Analysis

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 NH4+-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 (f450/500) 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 f450/500 and BIX. The ammonium concentration in groundwater correlates well with molecular weight and increases significantly w...