| 摘要: |
| 湿地的水文和水化学在时间尺度上会产生显著变化，进而会引发光化学反应的变化，光活性中间体（photochemically produced reactive intermediates，PPRIs）是水体间接光反应的产物，具有极强的氧化性，对水环境中污染物的归驱具有重要的影响。本文通过捕获剂法监测了鄱阳湖春季、夏季、秋季和冬季水体中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，以此揭示鄱阳湖不同季节水体中的DOM的光化学反应特性。结果发现：（1）鄱阳湖水体的理化性质呈现明显的季节性变化特征，冬春季水体中硝酸盐含量、荧光指数（FI）和新鲜度指数（β/α）值较高，而夏秋季水体中可溶性有机碳（DOC）、吸收系数比（E2/E3）和腐殖质指数（HIX）水平较高；（2）不同季节水体中PPRIs的产生速率和稳态浓度同样具有显著的季节性变化，总体呈现夏秋季高于冬春季，即丰水期高于枯水期的变化趋势；（3）通过傅立叶变换离子回旋共振质谱进一步分析发现，鄱阳湖水体中PPRIs的产生差异性与水体中DOM的组分密切相关，尤其是其中光敏性物质（木质素）的增加，促使了更高PPRIs的产生。综上，通过对不同时期湿地来源DOM的PPRIs产生过程的研究，明确了影响湿地水体中PPRIs产生的关键DOM的组分，本研究增加了对湿地水体中光化学活性物种的产生、转化、及其作用机制的认识。 |
| 关键词: 湿地 可溶性有机质 光化学 光生活性中间体 季节变化 |
| DOI： |
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| 基金项目:国家自然科学基金（42377258，51879256；5187091383）；江苏省揭榜挂帅双碳项目（BE2022305） |
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| Effect of photochemical properties of dissolved organic matter on seasonal variation of photoactive intermediates (PPRIs) in Poyang Lake wetland |
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liu xin,wei yi,wu ding gui,jin wei,jiang he long,song na
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Nanjing Institute of Geography and Limnology
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| Abstract: |
| The hydrology and hydrochemistry of wetlands will have significant changes in time scale, 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. It has an important influence on the flooding of pollutants in water environment. The production rate and steady-state concentration of three PPRIs (1O2, ·OH and 3CDOM*) in Poyang Lake in spring, summer, autumn and winter were monitored by trapping agent method. The chemical characteristics of soluble organic matter (DOM) in water were analyzed by ultraviolet absorption spectrum, three-dimensional fluorescence spectrum and Fourier transform ion cyclotron resonance mass spectrometry, so as to reveal the photochemical reaction characteristics of DOM in water in Poyang Lake in different seasons. The results showed that: (1) The physical and chemical properties of Poyang Lake showed obvious seasonal changes. Compared with the higher values of nitrate, fluorescence index (FI) and freshness index (β/α) in winter and spring, the water showed higher levels of soluble organic carbon (DOC), absorption coefficient ratio (E2/E3) and humus index (HIX) in summer and autumn. This is related to the large amount of input of terrigenous organic matter into more complex DOM components during the wet period. (2) The production rate and steady-state concentration of PPRIs in water bodies in different seasons also have significant seasonal changes, showing a trend of higher in summer and autumn than in winter and spring, that is, higher in wet season than in dry season; (3) Further analysis by Fourier transform ion cyclotron resonance mass spectrometry showed that the difference in the production of PPRIs in Poyang Lake water body was closely related to the composition of DOM in the water body, especially the increase of photosensitive substances (lignin), which promoted the production of higher PPRIs. In summary, the key DOM components that affect the production of PPRIs in wetland water were identified through the study on the production process of PPRIs in wetland DOM at different periods. This study has increased the understanding of the generation, transformation and action mechanism of photochemically active species in wetland water. |
| Key words: wetland soluble organic matter photochemistry photoliving intermediates seasonal variation |
