Fate of carbon influenced by the in-situ growth of phototrophic biofilms at the soil–water interface of paddy soil

Phototrophic biofilms (PBs) are commonly found in the sediment/soil-water interface of paddy soils and have a significant impact on carbon cycles. However, the specific carbon fate influenced by the in-situ growth of PBs in paddy soil remains unclear. In this study, we investigated the effect of in situ PBs growth on methane and carbon dioxide emissions, as well as dissolved organic matter (DOM) transformation. Our findings demonstrated a negative correlation between PBs growth and methane and carbon dioxide emissions, while showing a positive correlation with DOM composition. The in-situ growth of PBs reduced methane emissions by approximately 79 % and carbon dioxide emissions by approximately 33 % in the daytime, and also slowed down the degradation rate of dissolved organic matter from over 30.4 % to