中文关键词岩溶流域岩溶含水系统溶解有机质三维荧光光谱迁移转化 英文关键词karst catchmentkarst aquifer systemdissolved organic matter (DOM)three-dimensional fluorescence spectroscopymigration and transformation

作者	单位	E-mail
张连凯	中国地质科学院岩溶地质研究所, 国土资源部、广西岩溶动力学重点实验室, 桂林 541004 国土资源部岩溶生态与石漠化治理重点实验室, 桂林 541004 中国科学院地球化学研究所环境地球化学国家重点实验室, 贵阳 550081	zhangliankai@karst.ac.cn
刘朋雨	中国地质科学院岩溶地质研究所, 国土资源部、广西岩溶动力学重点实验室, 桂林 541004
覃小群	中国地质科学院岩溶地质研究所, 国土资源部、广西岩溶动力学重点实验室, 桂林 541004
单晓静	国土资源部岩溶生态与石漠化治理重点实验室, 桂林 541004 青岛大学环境科学与工程学院, 青岛 266071
刘文	山东省地矿工程勘察院, 济南 250014
赵振华	山东省地矿工程勘察院, 济南 250014
姚昕	聊城大学环境与规划学院, 聊城 252059
邵明玉	中国地质科学院岩溶地质研究所, 国土资源部、广西岩溶动力学重点实验室, 桂林 541004 国土资源部岩溶生态与石漠化治理重点实验室, 桂林 541004

中文摘要 溶解性有机质（DOM）的荧光物质是一种较好的示踪剂，用于鉴别DOM的来源及其在水文系统中的地球化学行为.该物质在岩溶水系统中的研究较少，并且要作为潜在示踪剂，系统中有很多因素影响其光谱信息.实验选取一典型岩溶流域，通过三维荧光光谱技术（EEMs）和平行因子分析（PARAFAC），结合水化学数据分析，揭示DOM荧光物质在不同岩溶含水空间的组成和转化关系，刻画流域尺度DOM的来源，探讨水化学因素对DOM荧光物质转移的影响机制.结果表明，流域外源地表水和岩溶地表水中的DOM以类蛋白色氨酸为主，浅层岩溶水和深层岩溶水以类蛋白色氨酸和酪氨酸为主.荧光指数（FI）、生物指数（BIX）和腐殖化指数（HIX）的综合分析认为，浅层岩溶水和深层岩溶水的DOM主要来自于内源微生物分解，岩溶地表水和外源地表水的DOM既有陆源输入又有内源微生物分解，且内源贡献占有较大比例.受岩溶水化学参数的影响，3种荧光物质具有明显的分异特征：类酪氨酸物质对Ca²⁺和HCO₃^-具有较强的适应性，在岩溶水中存在的比例比较大.类色氨酸物质则相反，类富里酸物质则与TDS、浊度、Cl^-、SO₄^2-等呈现极显著正相关关系.流域上游浅层岩溶水中的DOM主要来自内源.出露地表以后，其有机质同时来自内源和外源输入.在流域下游渗入深层岩溶地下水以后，DOM逐渐向低芳香烃有机质化合物转化，大分子DOM逐渐减少，荧光强度减弱.主成分分析（PCA）提取出3个主成分，分别为反映岩溶水渗滤、转化、水流条件的水体矿化指标，反映土壤淋滤和自然渗滤关系的TOC、NO₃^-及类蛋白质指标，以及反映岩溶水系统水化学、生物化学过程的Ca²⁺、HCO₃^-、荧光指数和类富里酸指标.此外研究还认为，总荧光强度，类富里酸物质和类蛋白物质可以分别作为岩溶水快速渗流、转化及岩溶含水层脆弱性的示踪剂.研究结果有助于认识岩溶地下水DOM的生物地球化学循环，进行岩溶系统有机污染控制，为岩溶水系统中物质的地球化学过程表征提供一种新的工具. 英文摘要 Fluorescent substances are used as good tracers in dissolved organic matter (DOM) to identify the source of DOM and its geochemical behavior in a hydrological system. However, there are few studies on the karst aquifer system. Many parameters in karst systems affect the DOM spectral information. A typical karst watershed in Northern China was selected in this research. Excitation-emission matrices (EEMs), parallel factor analysis (PARAFAC), and hydrochemical data were applied to reveal the relationship between the composition and transformation of DOM fluorescent substances in different karst water-bearing spaces. The source of DOM and the effect of water chemistry on DOM transfer were also discussed. The results showed that DOM in exogenous surface water and karst surface water in the Yufu River watershed were mainly composed of tryptophan-like substances, while the DOM in shallow karst water and deep karst water consisted of tryptophan-like and tyrosine-like substances. A comprehensive analysis by fluorescence index (FI), biological index (BIX), and humification index (HIX) displayed that the DOM in shallow and deep karst water resulted from microbial decomposition. In contrast, the DOM in karst surface water and exogenous surface water resulted from land-based input and endogenous microbial decomposition, in which endogenous contributions occupy a large proportion. Due to the chemical parameters of karst water, these three kinds of fluorescent substances extracted by PARAFAC had obviously different characteristics, i.e., ① the tyrosine-like substances had a strong adaptability to Ca²⁺ and HCO₃^-, and the proportion of the tyrosine in karst water was relatively large; ② the tryptophan substance followed an opposite trend; and ③ there was a significant positive correlation between fulvic acid and TDS, turbidity, Cl^-, and SO₄^2-. Observations of the watershed runoff revealed that the DOM in shallow karst water in the upper reaches came mainly from the soil and microbial degradation. The organic matter underwent a large amount of microbial decomposition and exogenous input when the water was rejuvenated with springs. After infiltration to the deep karst water in the lower reaches, the DOM gradually were converted to low aromatic hydrocarbon organic compounds and decreased macromolecules of DOM. Subsequently, the fluorescence intensity was weakened. The principal component analysis (PCA) extracted three principal components. They were the water mineralization index, soil leaching index, and hydrochemical/biochemical process index. The water mineralization index consists of hydrochemical parameters reflecting the water infiltration, transformation, and flow conditions in the karst system. The soil leaching index contains TOC, NO₃^-, and protein-like indicators relating to the relationship between protein-like substances and soil and natural leaching. The hydrochemical/biochemical process index is composed of Ca²⁺, HCO₃^-, FI, and fulvic acid indicators that illustrate the water chemistry and biochemical processes in the karst water system. In addition, the study also showed that total fluorescence intensity, fulvate-like substances, and protein-like substances can be used as a tracer for rapid seepage, transformation, and aquifer fragility for karst water, respectively. The results of the study are important in understanding the biogeochemical cycle of DOM in the karst water system and also helpful for controlling organic pollution. It also provides a new tool for characterizing the geochemical processes of organic matter in karst system.

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