Increasing nitrogen deposition has become one of major environmental concerns in coastal wetlands. However, little is known about the response of soil nitrous oxide (N₂O) emissions, a powerful greenhouse gas, to the different levels and forms of nitrogen addition, in salt-affected coastal soils. To close the knowledge gap, a laboratory factorial incubation experiment with four nitrogen addition levels (0, no N addition; low-N, 45; medium-N, 90; high-N, 270 mg N kg⁻¹), three forms (NO₃⁻ (KN); NH₄⁺ (NH); DN, NH₄NO₃ (DN)), and three levels of salt addition (0, no salt addition; 12 ppt, low-salt; 35 ppt, high-salt) was carried out in two coastal soils with different initial salinity levels (LW: lower salinity wetlands; HW: higher salinity wetlands) in the Yellow River Delta, China. Results showed that, in no salt addition treatments, the cumulative N₂O emissions were linearly related to nitrogen addition, and high nitrogen addition significantly promoted N₂O emissions by 213% in LW soils and 848% in HW soils (p < 0.05), indicating that the mitigate effects of nitrogen addition to the deleterious salt stress were stronger in HW soils. Meanwhile, the promoting effects of DN and KN treatments were more obvious than NH treatments, suggesting that denitrification was responsible for the N₂O emission. However, with salt addition, the nonlinear response pattern and reduced response sizes were observed for KN and DN treatments (p < 0.05), suggesting the alteration in responses of N₂O emission to nitrogen addition by salt stress. In addition, the reduction and modification of response pattern was more obvious in soil with lower initial salinity. The findings of this work suggest the uniqueness and complexity of N₂O emission responses to nitrogen inputs related to the salinity levels in coastal wetlands.

氮沉积增加已成为沿海湿地的主要环境问题之一。但是，对盐分侵蚀的沿海土壤中氮氧化物（N ₂ O）排放（一种强大的温室气体）对不同水平和形式的氮添加的响应的了解却很少。为了弥合知识鸿沟，我们采用三种形式的氮添加水平（0，无氮添加；低氮，45；中氮，90；高氮，270 mg N kg ^-1）进行实验室析因培养实验。NO ₃ ^-（KN）; NH ₄ ⁺（NH）; DN，NH ₄ NO ₃（DN）），并在两种初始盐度水平不同的沿海土壤（LW：低盐度湿地）中进行了三个水平的盐添加（0，不添加盐； 12 ppt，低盐； 35 ppt，高盐） ；硬件：盐度较高的湿地）。结果表明，在不加盐的情况下，累积的N ₂ O排放与氮的添加呈线性关系，而高氮的添加显着促进了低渗土壤中N ₂ O的排放，分别为213％和848％（p <0.05），表明在土壤中氮肥对盐分胁迫的缓解作用较强。同时，DN和KN处理的促进作用比NH处理更明显，表明反硝化是N ₂ O排放的原因。然而，在添加盐的情况下，观察到KN和DN处理的非线性响应模式和减小的响应大小（p  <0.05），表明盐胁迫下N ₂ O排放对氮添加的响应发生了变化。此外，在初始盐度较低的土壤中，响应模式的减少和改变更为明显。这项工作的发现表明N ₂的独特性和复杂性O排放对氮输入的响应与沿海湿地盐度水平有关。