| 摘要: |
| 氧化亚氮（N2O）作为一种强效应温室气体，是全球气候变暖的主要贡献者之一。受大量污染物输入的影响，城市河流一直是N2O的排放热点，但在平原地区水动力较弱的河流中其排放特征尚不清晰。研究以中国典型平原城市地区的滆湖入湖河流为对象，分析了枯水期和丰水期N2O排放特征，利用q-PCR技术定量了功能微生物丰度，探讨了潜在的作用机制。研究结果表明，N2O排放通量在枯水期和丰水期的差异不显著（p > 0.05），但表现出明显的空间异质性。N2O排放通量沿河流流向明显减少，且与湖泊距离呈显著正相关（R2 = 0.68，p < 0.001）。河流入湖距离每减少1公里，N2O排放量减少0.05 mg·m-2·d-1。N2O排放量也随着硝化细菌与反硝化细菌丰度比值的增加而增加，表明硝化作用及其底物氨氮对N2O排放起着关键调控作。此外还发现，研究区EF5r平均值比IPCC-2019默认值高约5.5倍。研究结论深化了对平原内城市河流N2O排放的认识，为区域排放估算的改进提供了科学依据。 |
| 关键词: 平原河流 N2O 脱氮 硝化作用 氨氮 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金项目（No. 42422605、42277060、42477073）和国家重点研发项目（No. 2024YFC3214500）联合资助。 |
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| Spatiotemporal characteristics of nitrous oxide emissions from urban rivers flowing into lakes on plains |
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Zhang Runyu, Liu Boyi, Zhu Lin, Wenqing Shi
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School of Environmental Science and Engineering,Nanjing University of Information Engineering
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| Abstract: |
| Nitrous oxide (N2O), a potent greenhouse gas, is a major contributor to climate warming. Urban rivers, characterized by substantial pollutant inputs, are recognized as hotspots for N2O emissions. However, N2O emissions in rivers with weak hydrodynamics in plain areas remain unclear. This study investigated N2O emission patterns in rivers flowing in to Lake Gehu, a plain urban area in China, and analyzed functional microbial abundance using quantitative PCR (q-PCR) to explore the underlying mechanisms during both the dry and wet seasons. The results showed no significant seasonal variation in N2O emissions (p > 0.05) but highlighted pronounced spatial differences (p < 0.05). N2O emissions decreased significantly along the flow direction and were positively correlated with the distance to the lake (R2 = 0.68, p < 0.001). For every 1 km decrease in distance from the lake, N2O emissions decreased by 0.05 mg·m-2·d-1. Furthermore, N2O emissions increased with the ratio of nitrifying to denitrifying bacteria, highlighting the critical roles of nitrification and its substrate, ammonium, in regulating N2O production. The average EF?r value in the study area was approximately 5.5 times higher than the default value in the IPCC-2019 guidelines. These findings enhance the understanding of N2O emissions from urban rivers in plain areas and provide a scientific basis for improving regional emission estimates. |
| Key words: Plain river nitrous oxide denitrification nitrification ammonium |
