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| 河口区溶解性有机质特征及其对温室气体排放的影响: 以灌河、淮河入海水道为例 |
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林晗琪1,2, 尹一帆2,3, 谢艾玉2,4, 次珍2,3, 张一泉2,5, 谢璇2,3, 陈雯2, 刘蕾1, 冯慕华2
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1.南京信息工程大学生态与应用气象学院, 江苏 南京 210044;2.中国科学院 南京地理与湖泊研究所, 江苏 南京 211135;3.河海大学 水文水资源学院, 江苏 南京 210024;4.南京信息工程大学环境科学与工程学院, 江苏 南京 210044;5.中国科学院大学, 北京 100049
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| 摘要: |
| 河口作为陆海碳交换的关键界面, 其溶解性有机质(DOM)的组成特征显著影响温室气体(GHGs)的生成与排放。本研究以江苏省灌河和淮河入海水道为研究对象, 综合运用三维荧光光谱(EEM)、平行因子分析(PARAFAC)及原位通量监测, 解析DOM的陆海协同迁移规律及其对CO2、CH4和N2O排放的驱动机制。结果表明, (1)灌河、淮河入海水道河口区DOM由类腐殖质组分(C1、C3)和类蛋白质组分(C2)构成, 陆源输入(工业与农业废水)主导其空间分异,灌河DOM以工业源类蛋白为主(C2占比45.6%), 淮河则以农业源腐殖质为主(C1+C3占比57.8%); (2)温室气体通量呈河道向近岸递减趋势, 平水期CO2、CH4和N2O通量分别为14.15±27.32 mmol·m-2·d-1、45.71±92.33 μmol·m-2·d-1和11.46±36.91 μmol·m-2·d-1, 显著高于丰水期(P<0.05); (3)DOM分子特性通过微生物代谢与光化学途径调控GHGs排放, 类腐殖质(C1、C3)促进CO2与N2O生成(R2=0.67), 而类蛋白(C2)通过共代谢作用间接驱动CH4释放。(4)盐度梯度(S> 25)抑制近岸CH4排放, 而丰水期河口锋面区N2O负通量(-3.39 μmol·m-2·d-1)与硝化-反硝化失衡相关。研究揭示了高强度人类活动下河口DOM的碳归宿机制及其对温室气体排放的多路径驱动作用, 为河口区“蓝碳”增汇与低碳管理提供理论支撑。 |
| 关键词: 溶解性有机质 温室气体 污染来源 入海河口 碳循环 |
| DOI：10.11759/hykx20250402002 |
| 分类号:X55 |
| 基金项目:江苏省海洋科技创新项目(JSZRHYKJ202205); 江苏省碳达峰碳中和科技创新专项资金(BK20220043); 国家自然科学基金项目(41877482, 41471075); 江苏省高校水处理技术与材料协同创新中心项目联合资助 |
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| Characteristics of dissolved organic matter in estuarine and its influence on greenhouse gas emissions: A case study of the Guanhe and Huaihe River estuaries |
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LIN Hanqi1,2, YIN Yifan2,3, XIE Aiyu2,4, CI Zhen2,3, ZHANG Yiquan2,5, XIE Xuan2,3, CHEN Wen2, LIU Lei1, FENG Muhua2
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1.School of Ecology and Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China;2.State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Nanjing 211135, China;3.College of Hydrology and Water Resources, Hohai University 210089, China;4.School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China;5.University of Chinese Academy, Beijing 100049, China
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| Abstract: |
| As a key interface of carbon exchange between land and sea, the composition of dissolved organic matter (DOM) in estuaries significantly influences the generation and emission of greenhouse gases (GHGs). In this study, the Guanhe River and Huaihe River estuaries in Jiangsu Province were investigated using three-dimensional excitation–emission matrix fluorescence spectroscopy, parallel factor analysis, and in situ flux monitoring to examine the land–sea co-migration patterns of DOM and their driving mechanisms for CO2, CH4, and N2O emissions. The results indicated several key findings. (1) DOM in both estuaries consisted of humic-like components (C1 and C3) and protein-like components (C2), with spatial differentiation primarily controlled by land-based inputs (industrial and agricultural wastewater). DOM in the Guanhe River was dominated by industrial protein (C2, 45.6%), whereas DOM in the Huaihe River was dominated by agricultural humic matter (C1 + C3, 57.8%). (2) Greenhouse gas fluxes decreased from the river channel to the nearshore. During the normal water period, the fluxes of CO2, CH4, and N2O were 14.15 ±27.32, 45.71 ±92.33, and 11.46 ±36.91 μmol·m-2·d-1, respectively, which were significantly higher than those in the wet season (P< 0.05). (3) DOM molecular properties regulated GHG emissions through microbial metabolism and photochemical pathways. Humic-like substances (C1 and C3) promoted CO2 and N2O production (R2 = 0.67), whereas protein-like substances (C2) indirectly drove CH4 release through co-metabolism. (4) The distribution of GHG fluxes and DOM in riverine areas was mainly controlled by phytoplankton activity (Chlorophyll a) and nitrogen and phosphorus inputs, whereas in coastal waters it was dominated by salinity gradients and nitrogen transformation processes (nitrification/denitrification). This study reveals the mechanisms governing the carbon fate of estuarine DOM under high-intensity human activities and provides theoretical support for enhancing “blue carbon” sinks and advancing low-carbon management in the Yangtze River Delta estuary. |
| Key words: dissolved organic matter greenhouse gases pollution sources estuaries carbon cycle |
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