<b>Patterns</b><b> </b><b>and</b><b> </b><b>controls</b><b> </b><b>of</b><b> </b><b>greenhouse</b><b> </b><b>gas</b><b> </b><b>emissions</b><b> </b><b>from</b><b> </b><b>urban</b><b> </b><b>rivers</b><b> </b><b>in plain river network region</b><b>,China</b>

Climate change has emerged as a global focus, and the emission of greenhouse gases (GHG) exerts a crucial influence on global climate change. The patterns and controls of GHG emissions in urban rivers remain unclear. GHG fluxes in different types of urban river in Changzhou city of China were calculated respectively by the floating static chamber method and boundary layer equation method. Ultraviolet-visible (UV-vis) absorption spectrum and three-dimension excitation emission matrix fluorescence spectroscopy (3D-EEM) were employed to explore the sources and characteristics of dissolved organic matter (DOM) in rivers. The physical and chemical indicators of river and sediment were monitored on-site and analyzed in the laboratory. Also, the species and quantity of bacteria in the sediment were determined. The Spearman correlation analysis was utilized to identify the key factors influencing GHG emission. The results indicated that, (1) the intensity of sunlight has an effect on the activity of pseudomonas, and thus affects N2O flux; (2) the CO2 flux measured by two methods showed a significant difference and negative correlation (p&lt;0.05), which may because low wind speed influence the robustness of the boundary layer model. Therefore, using only the boundary layer equation method cannot accurately measure GHG of rivers in urban areas with low wind speed (3) the CO2 flux was highly positively correlated with total phosphorus and ammonia nitrogen in water (p&lt;0.01). Pollution control and input control play a crucial role in reducing GHG emissions, (4) DOM in urban rivers is mainly derived from autochthonous sources, which are protein-like substances related to the metabolism of phytoplankton. GHG emission flux is negatively correlated with autochthonous parameters, indicating that the less interference by human activities, the less GHG emission.气候变化已成为全球关注的焦点，温室气体（Greenhouse Gas, GHG）排放对全球气候变化具有关键影响。当前城市河流温室气体排放的规律与调控机制仍不明确。本研究分别采用浮箱式静态箱法与边界层方程法，对中国常州市不同类型城市河流的温室气体通量进行了测算；采用紫外-可见（Ultraviolet-visible, UV-vis）吸收光谱与三维激发发射矩阵荧光光谱（Three-dimension Excitation Emission Matrix Fluorescence Spectroscopy, 3D-EEM）技术，探究了河流中溶解性有机质（Dissolved Organic Matter, DOM）的来源与特征；对河流与沉积物的理化指标开展了现场监测与实验室分析，并测定了沉积物中细菌的群落组成与丰度。随后通过斯皮尔曼相关性分析，识别了影响温室气体排放的关键因素。 研究结果表明： （1）光照强度会影响假单胞菌（Pseudomonas）的活性，进而对氧化亚氮（Nitrous Oxide, N₂O）通量产生影响； （2）两种方法测得的二氧化碳（Carbon Dioxide, CO₂）通量存在显著差异且呈负相关关系（p＜0.05），这可能是由于低风速会影响边界层模型的稳健性，因此仅采用边界层方程法无法准确测算低风速城市区域河流的温室气体通量； （3）水体中的二氧化碳通量与总磷、氨氮呈显著正相关关系（p＜0.01），污染管控与输入调控对减少温室气体排放具有重要意义； （4）城市河流中的溶解性有机质主要来源于内源，即与浮游植物代谢相关的类蛋白物质；温室气体排放通量与内源参数呈负相关关系，表明人类活动干扰越少，温室气体排放量越低。