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引用本文:刘新,尉艺,李文康,吴定桂,金伟,江和龙,徐华成,宋娜.鄱阳湖湿地溶解性有机质的光化学属性对水体光活性中间体(PPRIs)季节性变化的影响.湖泊科学,2024,36(3):807-816. DOI:10.18307/2024.0327
Liu Xin,Wei Yi,Li Wenkang,Wu Dinggui,Jin Wei,Jiang Helong,Xu Huacheng,Song Na.Effect of photochemical properties of dissolved organic matter on seasonal variation of photoactive intermediates (PPRIs) in Lake Poyang wetland. J. Lake Sci.2024,36(3):807-816. DOI:10.18307/2024.0327
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鄱阳湖湿地溶解性有机质的光化学属性对水体光活性中间体(PPRIs)季节性变化的影响
刘新1, 尉艺1,2, 李文康2, 吴定桂3, 金伟4, 江和龙2, 徐华成2, 宋娜2
1.南京林业大学生态与环境学院,南京 210037;2.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;3.浙江大学地球科学学院,浙江省地学大数据和地球深部资源重点实验室,杭州 310058;4.南京高科建设发展有限公司,南京 210038
摘要:
湿地的水文和水化学在时空尺度上会呈现显著差异,进而会引发光化学反应的变化,光活性中间体(PPRIs)是水体间接光反应的产物,具有极强的氧化性,对水环境中有机物和污染物的归驱具有重要的影响,因此迫切需要探究湿地中PPRIs的产生过程。本研究通过捕获剂法监测了鄱阳湖湿地4个季节水体中3种PPRIs(1O2、·OH及3CDOM*)的产生速率和稳态浓度的变化,并通过紫外吸收光谱、三维荧光光谱、以及傅立叶变换离子回旋共振质谱等技术对水体中可溶性有机质(DOM)组分的化学特征进行分析,揭示了鄱阳湖湿地不同季节水体中的DOM的光化学反应特性及与PPRIs产生的相关性。结果发现:鄱阳湖夏季和秋季水体的pH值、溶解有机碳(DOC)浓度较高,相反,硝酸盐、亚硝酸盐浓度在夏季和秋季较低。夏季和秋季的DOM中芳香族化合物丰度较高,并且木质素丰度明显高于冬季和春季。不同季节鄱阳湖水体有色可溶性有机物产生能力依次为秋季>夏季>冬季>春季。夏季和秋季水体中1O2和·OH产生速率和稳态浓度显著高于春季和冬季水体。pH、DOC、E2/E3、脂类、蛋白类及木质素类与PPRIs产生速率展现出了良好的正相关关系,尤其是其中的DOC与木质素类组分;另外在三维荧光指标结果中,荧光指数(FI)和新鲜度指数(β/α)与PPRIs呈现负相关关系,证明FI值越低即DOM陆源性越高、非新生DOM比例越高,则PPRIs产生速率越高。综上,PPRIs的光化学产生与植物源DOM密切相关。与春季和冬季相比,夏季和秋季鄱阳湖水体的有机质高,而其中DOM组分中芳香族化合物丰度较高,主要来自陆生植物和土壤有机质,其有机质的腐殖化水平较高,而在春季和冬季水体有机质主要来自湖泊本身和微生物产生的有机质,属于内源。淹水植物残体降解过程释放的有机组分,对夏、秋季DOM的来源和组成有着极易被忽视的影响和作用,而其中光化学活性较强的有机组分如木质素是造成其PPRIs产率更高的主要原因。
关键词:  鄱阳湖湿地  可溶性有机质  光化学  光生活性中间体  季节变化
DOI:10.18307/2024.0327
分类号:
基金项目:国家自然科学基金项目(42377258,51879256,5187091383)和江苏省揭榜挂帅双碳项目(BE2022305)联合资助。
Effect of photochemical properties of dissolved organic matter on seasonal variation of photoactive intermediates (PPRIs) in Lake Poyang wetland
Liu Xin1, Wei Yi1,2, Li Wenkang2, Wu Dinggui3, Jin Wei4, Jiang Helong2, Xu Huacheng2, Song Na2
1.College of Ecology and Environment, Nanjing Forestry University, Nanjing 210037, P. R. China;2.State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, P. R. China;3.College of Earth Sciences, Zhejiang University, Zhejiang Provincial Key Laboratory of Geoscience Big Data and Deep Earth Resources, Hangzhou 310058, P. R. China;4.Nanjing Gaoke Construction Development Co. Ltd, Nanjing 210038, P. R. China
Abstract:
The hydrology and hydrochemistry of wetlands show significant differences in time and space scales, which will lead to changes in photochemical reactions. Photochemically produced reactive intermediates (PPRIs) are the products of indirect photoreaction in water bodies and have strong oxidation properties. They have an important impact on the regression of organic matter and pollutants in the water environment, so it is imperative to explore the production process of PPRIs in wetlands. In this study, the production rate and steady-state concentration of three kinds of PPRIs (1O2, ·OH and 3CDOM*) in water during spring, summer, autumn and winter of Lake Poyang wetland were monitored using trapping agent method. The chemical characteristics of dissolved organic matter (DOM) in water were analyzed by ultraviolet absorption spectrum, three-dimensional fluorescence spectrum and fourier transform ion cyclotron resonance mass spectrometry. The photochemical reaction properties of DOM in water at different seasons in the Lake Poyang wetland and the correlation between DOM and PPRIs had been revealed. The results showed that pH value and dissolved organic carbon (DOC) contents of Lake Poyang were higher in summer and autumn, while nitrate and nitrite concentrations were lower in summer and autumn. The abundance of aromatic compounds was higher in DOM during summer and autumn, and the lignin abundance was significantly higher than that during winter and spring. The production capacity of colored soluble organic matter in Lake Poyang in different seasons was in the order of autumn >summer >winter >spring. The production rates and steady-state concentrations of 1O2 and ·OH in summer and autumn were significantly higher than those in spring and winter. pH, DOC, E2/E3, lipids, proteins, and ligins showed a good positive correlation with the production rate of PPRIs. In addition, from the three-dimensional fluorescence index results, fluorescence index (FI) and freshness index (β/α) showed a negative correlation with PPRIs, which proved that the lower FI value and the higher land-based DOM caused the higher the PPRIs generation rate. In summary, the photochemical production of PPRIs was closely related to the DOM of plant sources. Compared with spring and winter, the water organic matter of Lake Poyang was higher in summer and autumn. The aromatic compounds and humus in DOM components were also more abundant in spring and winter, mainly from terrestrial plants and soil organic matter. These DOM were mainly from the lake itself and generated by microorganisms, which belonged to the internal source. Organic components released during the degradation of flooded plant residues had an easily overlooked effect on the origin and composition of DOM in summer and autumn, and those with strong photochemical activity, such as lignin, were the main reason for the higher yield of PPRIs.
Key words:  Lake Poyang wetland  soluble organic matter  photochemistry  photoactive intermediates  seasonal variation
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