## 4 Discussion  
Different wetland ecosystems exhibit varying net ecosystem CO2 exchange rates across different time scales. Similarly, CO2 exchange rates differ among wetland types. Even within the same wetland type, interannual CO2 exchange varies notably. Currently, wetlands generally act as carbon sinks, with an average carbon sequestration rate of 118 gC\(\cdot\)m\({}^{-2}\).yr\({}^{-1}\)[7]. Numerous studies have indicated that need wetlands and peatlands are significant carbon sinks [15]. Our study confirmed this by indicating that the Momoge salt marsh acted as a carbon sink in the years 2015-2017 and 2021. A study monitoring the NEE in the reed wetland of the Liaohe Delta in 2006 showed that this area also acted as a carbon sink, with a carbon sequestration intensity of 230 g CO2\(\cdot\)m\({}^{-2}\).yr\({}^{-1}\)[16]. In the Nanji wetland of Poyang Lake, during the non-flooded period of 2015, the ecosystem acted as a carbon sink with a carbon sequestration rate of 667.62 g C\(\cdot\)m\({}^{-2}\).yr\({}^{-1}\). However, in the subsequent years of 2016 and 2017, it shifted to a carbon source [17]. A study of CO2 fluxes for the entire year of 2005 in the Haibei wetland of the Qinghai-Tibet Plateau showed that it released around 86.18 g C\(\cdot\)m\({}^{-2}\).yr\({}^{-1}\) into the atmosphere, making it a carbon source as well [18]. The interannual variations in NEE in wetland ecosystems are closely linked to climate [19; 20; 21], hydrology [22], and vegetation conditions [23]. These factors collectively play a significant role in shaping the carbon sink functions of specific ecosystems. Furthermore, related studies have indicated that even within the same wetland ecosystem, the carbon source/sink status can exhibit uncertainty across interannual periods due to variations in vegetation composition, hydrological conditions, human disturbances, and climate change [24]. Since wetland greenhouse gas balances are highly sensitive to changes in wetland area, the future impact of wetlands on the climate depends on the balance between degradation and restoration. This study found that the NEE of wetlands exhibited a pattern of functioning as a carbon sink with greater fluctuations during the growing season and as a carbon source with smaller fluctuations during the non-growing season. During the spring, as plants start sprouting and growing, the amount of carbon fixed through photosynthesis is initially less than the carbon released through respiration. As a result, the wetland continues to act as a carbon source. However, as plant growth progresses and photosynthesis becomes stronger than respiration, the wetland transitions to a carbon sink. Along with the peak of plant growth, the maximum values of NEE typically occur in July and August. Subsequently, as temperatures decrease and plants enter their senescence phase, their photosynthetic capacity gradually diminishes. This reduction in photosynthesis leads to a significant decrease in the NEE. This pattern is consistent with findings from previous research [25]. By November, the wetland vegetation is completely widhered. Due to ecosystem respiration, the wetland transitions entirely to functioning as a carbon source. A significant amount of research has indicated that when the solar radiation intensity is low, net CO2 exchange increases with the increase in PAR, following a hyperbolic trend. Many studies have shown a significant correlation between NEE and PAR. Ecosystems such as forests, grasslands, and croplands exhibit a positive relationship between solar radiation intensity and net carbon exchange, following a hyperbolic curve [26]. Similar conclusions were drawn by [PERSON] et al. [27] in the context of wetland ecosystems. The current study also revealed that in the reed wetland, the net CO2 exchange initially increases rapidly with an increase in PAR. However, after PAR exceeds a certain threshold, the rate of the increase in the net CO2 exchange slows, eventually converging to an asymptote value.