Denitrification in Chongming east tidal flat sediment, Yangtze estuary, China

From July 2003 to July 2004, samples were collected on Chongming Island east tidal flat every two months. The research showed that the nitrous oxide (N₂O) production rate was very low in the water, Chongming east tidal flat (CM) sediment was the N₂O source of the water. Sediment N₂O natural production rate was between -0.08 and 1.74 μmolN·m^-2·h^-1. N₂O natural production rate was higher in the summer. The difference of the N₂O natural production rate in the different tidal flats, the correlation between the N₂O natural production rate and the denitrification rate, and those with the temperature and DO indicate that middle tidal flat sediment denitrification was the main process of the N₂O production, while in the low tidal flat sediment, the production of the N₂ O came from several processes of the nitrogen cycling. Tidal flat sediment denitrification reaction was stronger in summer and winter but relatively lower in the late autumn and early spring. Seasonal change of the sediment denitrification rate was wide, from 1.12 to 33.34 μmolN·m^-2·h^-1. Temperature, DO and the coactions of them had the prominent effect on the tidal flat sediment denitrification.