Microcosmic simulation of temperature and humidity regulation on greenhouse gas emissions from sediments of the Erdao Baihe River in Changbai Mountain under drought-flood abrupt alternation events

Global greenhouse gas emissions are increasing at an alarming rate and are driving the process of global warming, resulting in an upward trend in both the intensity and frequency of extreme weather events. In particular, in the north-eastern region, the phenomenon of extreme weather events: drought-flood abrupt alternation events compounded by droughts and extreme rainfall is becoming more frequent, and this drastic climate change is expected to further affect greenhouse gas emissions in the future. The study selected sediment samples in the northern foothills of Changbai Mountain from July to October in 2024, and conducted indoor microcosm experiments from October to December. This study investigated the emission characteristics of greenhouse gases (CO₂, CH₄ and N₂O) from river sediments and their influencing factors in the situation of warming and humidification caused by increasingly frequent drought-flood abrupt alternation events in late spring and early summer. The emission characteristics of sediment GHGs under different temperature (15 ℃ and 30 ℃) and moisture conditions in spring and summer were analyzed through indoor incubation experiments, which simulated the changes of flood and drought environments to highlight the environmental changes of flood to drought and drought to flood. The results showed that GHG emissions were significantly affected by the drought-flood abrupt alternation, and the cumulative CO₂ emissions in the 30 ℃ treatment group were 2.31 times higher than those in the 15 ℃ treatment group. The rate of CO₂ emission increased sharply to the peak during drought-flood transition, while the emissions of CH₄ and N₂O also showed significant sensitivity to these environmental changes. In addition, dissolved organic matter (DOM) provides sources and substrate for microbial activity, thereby contributing to greenhouse gas emissions. The study emphasized the impacts of the sharp transition events from drought to flood on the regional carbon cycle, and provided key data to support the prediction of carbon emissions under future climate change, which is of great significance for addressing global climate change.