Revetment Affects Nitrogen Removal and N2O Emission at the Urban River–Riparian Interface

River–riparian interface (RRI) plays a crucial role in nitrogen removal and N2O emissions, but different revetment constructions can significantly alter the associated outcomes. Identifying which type of revetment can reduce N2O emissions while still removing nitrogen is a key issue in urban development. This study constructed three types of revetments along the same river section, and measured soil, vegetation, microbial, denitrification, and N2O emission characteristics to explore the synergistic effects of revetment types on nitrogen removal and N2O emissions. The study showed that revetments affected nitrogen removal and N2O emissions in RRI by influencing denitrification. nirK mainly affected nitrogen removal, while nosZII mainly influenced N2O emissions. Environmental factors in the permeable revetment led to significantly higher gene abundances of nirK and nosZII compared to those in the natural and impermeable revetments. As a result, the denitrification potential of the permeable revetment (34.32 ± 1.17 mg/(kg·d)) was 22.43% and 8.84% higher than those of the natural and impermeable revetments, respectively. The N2O emission rate (0.35 ± 0.01 mg/(m2·h)) was 29.22% and 22.19% lower than those of the natural and impermeable revetments, respectively. Permeable revetment could have been the best for the nitrogen removal and N2O emission reduction. These results provide a theoretical basis and guidance for urban ecological construction.