地下水中溶解性有机物的季节变化特征及成因

为阐明地下水中溶解性有机物(DOM)的分布特征与环境效应,联合三维荧光光谱、平行因子分析及主成分分析,研究了地下水中DOM的来源及随季节和空间变化特征,探究了地下水DOM组成对无机盐分布的影响.结果显示,地下水DOM主要来自微生物源,可鉴别出4种荧光组分,4种组分中,组分1和3为类蛋白组分,组分2和4属于类腐殖质组分.类蛋白组分来源差异较大,组成不稳定,其含量随季节变化明显,春冬季含量低而夏秋季含量高;类腐殖质组分来源相似,组成稳定,随季节变化小.两类荧光组分,尤其是类蛋白组分,是地下水氨氮的主要来源,可以影响地下水p H值.结果表明,三维荧光光谱结合平行因子和主成分分析,可以解析地下水中有机物的组成特征和季节变化规律.

The seasonal distribution characteristics and its reasons of dissolved organic matter in groundwater

To illuminate the distribution characteristics and environmental influences of dissolved organic matter (DOM) in groundwater, the source, spatial and temporal distribution characteristics of DOM were studied by fluorescence excitation-emission matrix spectra (EEM) combined with parallel factor (PARAFAC) analysis, and the influence of DOM on the distribution of inorganic salts was investigated as well. The results showed that the groundwater DOM was mainly microbial-derived. Four florescence components were identified by EEM spectra coupled with PARAFAC analysis, and components 1 and 3 originated from protein-like materials, while components 2 and 4 were ascribed to humic-like substances. The protein-like components had different sources and their composition was variable and changed with time, i.e., the concentration of them was higher in the summer and fall but lower in the winter and spring. On the other hand, the humic-like components had a similar source, and their composition was stable and showed no obvious change with season. The DOM, especially the protein-like components, was a source of ammonia nitrogen, and had an important influence on the groundwater pH value. The results demonstrated that, EEM spectra coupled with PARAFAC and principle component analysis can be used to analyze the composition and seasonal variation of the DOM in groundwater.