Abstract Denitrification, the microbial process by which nitrate (NO 3 − ) in aquatic systems is converted to N 2 and N 2 O, is widely recognized as an effective and environmentally friendly method for mitigating NO 3 − pollution in water bodies. However, the complex role of salinity, which could significantly influence the denitrification process, in salt‐affected agricultural catchments remains insufficiently understood. This study investigated how the denitrification rate, dissolved nitrous oxide (N 2 O), and nitrate nitrogen (NO 3 − ‐N) removal efficiency respond to varying nitrate concentrations, salinity levels, and carbon availability under controlled laboratory conditions. The results revealed that increased salinity inhibited net denitrification rates, whereas low salinity promoted N 2 O accumulation. The availability of carbon sources significantly affected the balance between the positive effects of NO 3 − ‐N and the negative effects of salinity on denitrification. Under sufficient carbon conditions, the enhancing effect of NO 3 − ‐N concentration on denitrification clearly outweighed the inhibitory effect of salt. Under low‐salinity conditions, the efficiency of NO 3 − ‐N removal from water was greater. A portion of the nitrate (14.5%–25.0%) was converted to N 2 and N 2 O, while the remaining nitrate was converted to NH 4 + ‐N and retained in the water and soil. This study provides important theoretical insights and practical guidance for mitigating nitrogen pollution in water bodies within salt‐affected agricultural catchments.
Zhao et al. (Fri,) studied this question.