| 卤水中溶解性有机质的光谱学性质和光降解行为研究 |
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| 引用本文： | 杨克利,董亚萍,李武,彭姣玉,刘海宁.卤水中溶解性有机质的光谱学性质和光降解行为研究[J].地学前缘,2021,28(6):187-195. |
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| 作者姓名： | 杨克利 董亚萍 李武 彭姣玉 刘海宁 |
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| 作者单位： | 1.中国科学院 青海盐湖研究所 中国科学院盐湖资源综合高效利用重点实验室, 青海 西宁 810008;2.青海盐湖资源综合利用技术研究开发中心, 青海 西宁 810008;3.青海省盐湖资源化学重点实验室, 青海 西宁 810008 |
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| 基金项目： | 国家重点研发计划项目(2017YFC0602805); 国家自然科学基金项目(U20A20150); 青海省自然科学基金项目(2020-ZJ-940Q); 中国科学院西部之光项目(E010GC09)和青年创新促进会项目(E010GC15) |
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| 摘 要： | 卤水中溶解性有机质(dissolved organic matter,DOM)会对盐田日晒工艺和产品质量产生不利影响,如盐田卤水的蒸发速率减缓、蒸发度减小以及提取的矿物产品带有刺鼻的气味、浓重的颜色等。因此,对具有资源开发利用价值的卤水体系中DOM结构和性质的研究可以为后续DOM的有效去除或在DOM共存体系中调控无机盐结晶工艺路线提供有效的指导意见。本文以自然界中广泛存在的两种不同类型的卤水体系,即盐湖卤水DOM(SLDOM)和油田卤水DOM(OFDOM)为研究对象,采用溶解性有机碳(dissolved organic carbon,DOC)分析、光谱学分析和平行因子分析等手段对DOM的含量、分子量分布特征、光谱学结构和光降解行为开展了研究。DOC和荧光分析表明SLDOM和OFDOM的DOC含量和生物指数(BIX)值相似;与OFDOM相比,SLDOM的腐质化指数(HIX)值和高分子量组分(HMW)比例偏高;特别吸收光谱(SUVA254)和糖类化合物含量检测结果表明,SLDOM和OFDOM的HMW组分中含有的芳香类和糖类化合物所占比例比低分子量组分(LMW)高;三维荧光谱图分析(EEM)结果表明,SLDOM主要以腐殖质类物质为主,而OFDOM以蛋白质类组分为主。此外,DOM的荧光组分在不同分子量中的分布也存在明显差异:对于SLDOM,富里酸主要分布在HMW DOM中,而腐殖酸主要在LMW DOM中;对于OFDOM,芳香胺类蛋白组分主要分布在HMW DOM中,色氨酸和酪氨酸类蛋白组分主要分布在LMM DOM中。在光降解实验中,SLDOM和OFDOM的DOC含量随光照时间增加而逐渐减少,分别下降了29.32%和15.11%。进一步的分析表明,光照过程中两种卤水中糖类化合物均减少,小分子量的DOM优先分解。此外,在光照过程中SLDOM芳香类化合物增加,腐质化程度基本不变;OFDOM芳香类化合物减少,腐质化程度增加。EEM平行因子分析(PARAFAC)结果表明,SLDOM荧光组分在光降解过程中荧光强度增加,而OFDOM荧光强度减少。
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| 关 键 词： | 溶解性有机质 盐湖卤水 油田卤水 光谱学 光降解 |
| 收稿时间： | 2020-09-20 |
Spectral and photodegradation properties of dissolved organic matter in brines |
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| YANG Keli,DONG Yaping,LI Wu,PENG Jiaoyu,LIU Haining.Spectral and photodegradation properties of dissolved organic matter in brines[J].Earth Science Frontiers,2021,28(6):187-195. |
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| Authors: | YANG Keli DONG Yaping LI Wu PENG Jiaoyu LIU Haining |
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| Institution: | 1. CAS Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China;2. Qinghai Technology Research and Development Center of Comprehensive Utilization of Salt Lakes Resources, Xining 810008, China;3. Qinghai Provincial Key Laboratory of Resources and Chemistry of Salt Lakes, Xining 810008, China |
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| Abstract: | Dissolved organic matter (DOM) in brines has adverse effects on solar pond performance and evaporite product quality, such as slowing down evaporation rate, reducing evaporation level, and causing pungent smell and heavy coloration in evaporate products. Therefore, characterization of DOM in brines in terms of utilization values is essential to guide DOM removal and new technologies development for better mineral extraction. Here, DOM from salt lake (SLDOM) and oilfield (OFDOM) were size-fractionated into high (MW>1 kDa) and low (MW≤1 kDa) molecular weight fractions and analyzed through dissolved organic carbon (DOC) analysis, absorption spectroscopy, fluorescence parallel factor (PARAFAC) analysis to determine their spectral and photodegradation properties. DOC analysis and fluorescence indexes indicated that SLDOM and OFSDOM had comparable organic carbon contents and BIX (biological index), and they both had higher FIX (fermentation index) than DOM from natural water. Compared to OFDOM, SLDOM had higher HIX and HMW DOM. SUVA254 and carbohydrates measurements revealed that aromatic compounds and carbohydrates were mainly in the HMW fraction regardless of sample types. Fluorescence spectra showed that SLDOM mainly consisted of humic-substance, while OFDOM mainly protein-like substances. As for MW fractionation, for SLDDOM, fulvic acids were mainly in HMW DOM while humic acids in LMW DOM; for OFDOM, aromatic amino acids were abundant in HMW DOM. Photodegradation experiment indicated that DOC content in SLDOM and OFDOM decreased by 29.32% and 15.11%, respectively, with increasing light radiation. Further analysis showed that decreasing carbohydrate content and preferential degradation of LMW DOM occurred for both sample types. Moreover, during light irradiation, aromatic content increased and humification status remained stable in SLDOM, whereas in OFDOM aromatics decreased and humification increased. PARAFAC analysis showed that fluorescence intensities of PARAFAC components were enhanced for SLDOM, but reduced for OFDOM. |
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| Keywords: | dissolved organic matter salt lake brine oilfield produced brine spectral photodegradation |
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