Gong Jiang-Chen, Li Bing-Han, Liu Chun-Ying, Li Qin-Dao, Hu Jing-Wen, Li Pei-Feng, He Dan, Yang Gui-Peng
Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, and College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao Marine Science and Technology Center, Qingdao 266237, China.
Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, and College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao Marine Science and Technology Center, Qingdao 266237, China.
Sci Total Environ. 2024 Dec 1;954:176660. doi: 10.1016/j.scitotenv.2024.176660. Epub 2024 Oct 1.
Nitrogen oxides (NO = NO + NO) have essential impacts on global climate and the environment, making it essential to study the contribution of wetland-generated NO to environmental problems. With exogenous nitrogen input from anthropogenic activities, wetland sediments become active emission hotspots for NO. In this study, we conducted field experiments in a typical salt marsh wetland to measure nitric oxide (NO, the primary component of NO from sediments) exchange fluxes in both mudflat and vegetated sediments. We found that NO fluxes in vegetated sediments (0.40 ± 0.15 × 10 kg N m s) were relatively higher than in mudflat sediments (-1.31 ± 1.39 × 10 kg N m s), with this difference occurring only during the vegetation-dying season (autumn). Correlations between sediment NO fluxes and environmental parameters revealed that NO flux variation during the observation period was primarily influenced by sediment respiration, temperature, water content, and substrate availability. However, the influence of these factors on NO fluxes differed between mudflat and vegetated sediments. In-situ data analysis also suggested that tidal horizontal migration, which affects sediment substrate and salinity, may regulate sediment NO emissions. Furthermore, in-situ incubations with nitrogen addition (ammonia, nitrite, and nitrate) were conducted to study the response of sediment NO emissions to exogenous nitrogen. We observed that nitrogen addition caused a 259.7 % increase in NO emissions from vegetated sediments compared to the control during the effective period of nitrogen addition (days 1-3). However, although nitrogen addition markedly stimulated sediment NO emissions, the overall NO production capacity constrained the extent of this increase.
氮氧化物（NO = NO + NO）对全球气候和环境有着至关重要的影响，因此研究湿地产生的NO对环境问题的贡献至关重要。随着人为活动带来的外源氮输入，湿地沉积物成为NO的活跃排放热点。在本研究中，我们在一个典型的盐沼湿地进行了野外实验，以测量潮滩和植被覆盖沉积物中一氧化氮（NO，沉积物中NO的主要成分）的交换通量。我们发现，植被覆盖沉积物中的NO通量（0.40 ± 0.15 × 10 kg N m s）相对高于潮滩沉积物（-1.31 ± 1.39 × 10 kg N m s），且这种差异仅在植被枯萎季节（秋季）出现。沉积物NO通量与环境参数之间的相关性表明，观测期内NO通量变化主要受沉积物呼吸、温度、含水量和底物可用性的影响。然而，这些因素对NO通量的影响在潮滩和植被覆盖沉积物之间有所不同。原位数据分析还表明，影响沉积物底物和盐度的潮汐水平迁移可能会调节沉积物NO排放。此外，进行了添加氮（氨、亚硝酸盐和硝酸盐）的原位培养实验，以研究沉积物NO排放对外源氮的响应。我们观察到，在氮添加的有效期间（第1 - 3天），与对照相比，添加氮导致植被覆盖沉积物中的NO排放增加了259.7%。然而，尽管添加氮显著刺激了沉积物NO排放，但总体NO产生能力限制了这种增加的程度。
