Sediment Nitrate Dissimilatory Reduction Processes along a Salinity Gradient in an Estuarine and Coastal Wetland, China

Nitrate (NO3−) dissimilatory reduction processes (denitrification, anammox and NO3− to ammonium (DNRA)) in estuarine coastal ecosystems play a crucial role regulating reactive nitrogen loadings. However, nitrate process rates relative proportions along the salinity gradient remain poorly understood. Here, denitrification, DNRA were explored simultaneously Yangtze Estuary based on isotope-tracing experiments. Measured range of 2.33–28.21 nmol g−1 h−1, 0.43–1.87 h−1 0.28–0.74 respectively, with large spatio-temporal variation. The changes these mainly affected by TOC, TN, NH4+ NOx− concentrations, rather than related functional gene abundance. Denitrification dominated total (67.52 93.85%), while (3.67 25.01%) (2.48 11.21%) also played substantially important reduction. denitrification gross high-salinity areas generally lower those freshwater, but opposite was true for DNRA. Overall, our study reported simultaneous observation estuary highlighted that sediment environmental variables human activities can alter distribution patterns processes.