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引用本文:李芳芳,徐华成,江和龙.胶体TiO2颗粒对不同来源溶解性有机质光降解的影响:基于分子量差异分析.湖泊科学,2021,33(4):1163-1174. DOI:10.18307/2021.0417
Li Fangfang,Xu Huacheng,Jiang Helong.Effects of colloidal TiO2 particles on photodegradation of dissolved organic matter from different sources: Based on molecular weight difference analysis. J. Lake Sci.2021,33(4):1163-1174. DOI:10.18307/2021.0417
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胶体TiO2颗粒对不同来源溶解性有机质光降解的影响:基于分子量差异分析
李芳芳1,2, 徐华成1, 江和龙1
1.中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008;2.中国科学院大学, 北京 100049
摘要:
溶解性有机质(DOM)广泛存在于多种水环境介质,其光降解过程显著影响水体污染物的化学形态及生态风险.本文以典型陆源天然有机质(NOM)和藻源有机质(AlgOM)为研究对象,采用切向超过滤技术将初始DOM样品(Bulk,<0.45 μm)分为高分子量(HMW,1 kDa~0.45 μm)和低分子量(LMW,<1 kDa)组分,研究胶体TiO2颗粒存在下不同分子量有机组分的光降解行为差异.表征结果表明,DOM样品的有机质均相对较多地分布在LMW组分中(55.3%~57.8%),但HMW的芳香性比LMW组分高;三维光谱结果表明AlgOM富含类蛋白和类腐殖物质,而NOM只含类腐殖物质;进一步分析发现类蛋白物质主要分布于HMW组分,类腐殖物质则主要分布于LMW组分.胶体颗粒的存在通过吸附作用抑制AlgOM中有机质及芳香性物质的光降解,而通过催化作用促进NOM中有机质及芳香性物质的光降解.胶体颗粒不改变不同分子量DOM中有机质的光降解效率顺序,均为HMW>Bulk>LMW,说明HMW有机质更易光降解.但无胶体颗粒时AlgOM和NOM芳香物质的光降解效率为LMW>Bulk>HMW,且胶体颗粒的存在改变不同分子量NOM芳香性物质的光降解顺序.另外,无胶体颗粒存在时陆源类腐殖物质比藻源类腐殖物质更易光降解,而胶体颗粒的存在均可促进藻源和陆源类腐殖质物质光降解;相比于HMW类腐殖质,LMW类腐殖物质具有较高的光敏性和优先降解特性.
关键词:  溶解有机质  分子量分布  超过滤  光降解  胶体TiO2颗粒
DOI:10.18307/2021.0417
分类号:
基金项目:国家自然科学基金项目(51922101,51979265)资助.
Effects of colloidal TiO2 particles on photodegradation of dissolved organic matter from different sources: Based on molecular weight difference analysis
Li Fangfang1,2, Xu Huacheng1, Jiang Helong1
1.State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, P. R. China;2.University of Chinese Academy of Sciences, Beijing 100049, P. R. China
Abstract:
Dissolved organic matter (DOM) exists widely in water environmental media, and its photodegradation process significantly affects the chemical species and ecological risk of pollutants in waters. This study took the typical terrestrial natural organic matter (NOM) and algal-derived organic matter (AlgOM) as the research objects, fractionating the initial DOM sample (Bulk, <0.45 μm) into high molecular weight (HMW, 1 kDa-0.45 μm) and low molecular weight (LMW, <1 kDa) fractions via tangential ultrafiltration technique, to analyze the difference of photodegradation behavior of organic components with different molecular weights in the presence of colloidal TiO2 particles. The characterization results showed that organic matter of DOM samples was relatively more distributed in LMW components (55.3%-57.8%), but HMW was more aromatic than LMW components. Three-dimensional fluorescence spectrum showed that AlgOM was rich in protein-like and humus-like substances, while NOM only contained humus-like substances. Further analysis revealed that protein-like substances were mainly distributed in HMW components, and humus-like substances were mainly distributed in LMW components. The presence of colloidal particles promoted the photodegradation of organic matter and aromatic substances in NOM by catalytic effect, while inhibited the photodegradation of organic matter and aromatic substances in AlgOM by adsorption effect. Colloidal particles did not change the photodegradation efficiency order of organic matter in DOM with different molecular weights, all of which were HMW>Bulk>LMW, indicating that HMW organic matters were easier to be photodegraded. However, without colloidal particles, the photodegradation efficiency of AlgOM and NOM aromatics was LMW>Bulk>HMW, and the presence of colloidal particles changed the photodegradation order of NOM aromatics with different molecular weights. In addition, terrestrial humus was more easily degraded than algal humus in the absence of colloidal particles, and the presence of colloidal particles promoted the photodegradation of both algal and terrestrial humus. Compared with HMW humus, LMW humus had higher photosensitivity and preferential degradation characteristics.
Key words:  Dissolved organic matter (DOM)  molecular weight distribution  ultrafiltration  photodegradation  colloidal TiO2 particles
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