| 摘要: |
| 淡水养殖池塘溶解性有机质(DOM)的光化学过程具有重要的环境效应，而其具体过程尚不清楚。本文利用光谱和分子探针技术探究太湖流域2个典型淡水养殖池塘(中华绒螯蟹塘和克氏原鳌虾塘)DOM在不同光辐照强度下的光化学行为。通过紫外吸收光谱和三维荧光光谱技术揭示了养殖池塘DOM组分性质随光辐照时间的变化过程，分子探针技术定量DOM光化学过程产生的光敏活性中间体(PPRIs)——3DOM*、1O2和·OH生成速率、稳态浓度和量子产率。结果表明，淡水养殖池塘DOM可分离出2个类腐殖质组分(C1和C2)和1个类蛋白组分(C3)，淡水养殖池塘DOM腐殖化程度低，强自生源特征明显，兼具陆源与内源属性。中华绒螯蟹塘溶解性有机碳浓度和富营养化程度以及DOM各荧光组分强度均高于克氏原鳌虾塘。淡水养殖池塘DOM的组分性质在不同光辐照强度下的变化存在差异。低光辐照强度下，DOM各组分性质均无明显变化，但高光辐照强度下，淡水养殖池塘DOM的荧光强度、分子量、芳香性和疏水性随辐照时间的增加而下降。中华绒螯蟹塘DOM中C1、C2和C3荧光组分的光降解速率分别为0.014、0.007和0.021 h-1，均高于克氏原鳌虾塘DOM对应组分光降解率(0.012、0.004和0.02 h-1)，C3组分占比小但表现出更强的光化学活性。PPRIs的生成潜能随着光辐照强度的增加而增加，中华绒螯蟹塘DOM在高光辐照强度下3DOM*、1O2和?OH生成速率分别为1.41×10-8、1.32×10-8和5.52×10-12 mol/(L·s)，高于克氏原鳌虾塘DOM对应PPRIs的生成速率(9.77×10-9、6.34×10-9和2.50×10-12 mol/(L·s))。本研究为丰富淡水养殖池塘DOM环境行为机制，防控养殖池塘有机污染物提供理论支撑。 |
| 关键词: 淡水养殖池溏 光辐照强度 溶解性有机质 光敏活性中间体 光化学行为 |
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| 基金项目:国家自然科学基金项目（42307090），国家环境保护长江中下游水生态健康重点实验室开放课题（AEHKF2023008）联合资助 |
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| Photochemical characterization of dissolved organic matter in typical freshwater aquaculture ponds under different light irradiance intensities |
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Zheng Jingcheng1, Chen Bingfa2, Gu Xincai1, Liu Hong1, Feng Muhua3, Zhang Cheng1, Han Shiqun2
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1.School of Environmental Science and Engineering,Suzhou University of Science and Technology;2.Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Key Laboratory of Agricultural Environment in the Lower Yangtze Plain, Ministry of Agriculture;3.ChinaState Key Laboratory of Lake Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences
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| Abstract: |
| The photochemical processes of dissolved organic matter (DOM) in freshwater aquaculture ponds have significant environmental effects, yet the specific mechanisms remain unknown. This study investigateds the photochemical behaviors of DOM in two typical freshwater aquaculture ponds (Eriocheir sinensis pond and Procambarus clarkii pond) in the Taihu Basin under varying light irradiation intensities using spectroscopic and molecular probe techniques. UV absorption and three-dimensional fluorescence spectroscopy were employed to elucidate changes in the properties of DOM components derived from freshwater aquaculture ponds during light exposure, while molecular probe techniques quantified production rates, steady-state concentrations, and quantum yields of photochemically produced reactive intermediates (PPRIs) (3DOM*, 1O2, and ·OH) generated by the photochemical processes of DOM. Results revealed that two humus-like fractions (C1 and C2) as well as one protein-like fraction (C3) could be modeled from DOM in freshwater aquaculture ponds, which exhibited low degrees of humification but distinct characteristics associated with strong autochthonous sources along with terrestrial and endogenous origins. Dissolved organic carbon concentration, eutrophication degree, and intensity of each fluorescent component were higher in Eriocheir sinensis pond compared to Procambarus clarkii pond. Furthermore, properties of DOM components varied under different light irradiance intensities; no significant changes occurred at low intensities, whereas fluorescence intensity, molecular weight, aromaticity, hydrophobicity declined with increasing irradiation time at high intensities. The photodegradation rates of C1, C2, and C3 of DOM from the Eriocheir sinensis pond were 0.014, 0.007 and 0.021 h-1, respectively, higher than the corresponding components in DOM from Procambarus clarkii pond (0.012, 0.004 and 0.02 h-1). Notably, the C3 component exhibited a relatively small proportion but displayed stronger photochemical activity. The production potential of PPRIs increased with the increment of light irradiation intensity. Moreover, the production rates of 3DOM*, 1O2, and ?OH were measured as 1.41×10-8, 1.32×10-8, 5.52×10-12 mol/(L·s) respectively at high light irradiation intensities in the Eriocheir sinensis pond, higher than the corresponding PPRIs production rates for DOM in Procambarus clarkii pond (9.77×10-9, 6.34×10-9, 2.50×10-12 mol/(L·s)). This study provided theoretical support for enriching the mechanisms of DOM environmental behavior in freshwater aquaculture ponds and preventing and controlling organic pollutants in aquaculture ponds. |
| Key words: freshwater aquaculture ponds light irradiation intensities dissolved organic matter photochemically produced reactive intermediates photochemical behavior |
