Phragmites australis effects on N₂O emission in the Chongming eastern tidal flat

We investigated the emission fluxes of N₂O from the Phragmites australis marsh of Chongming Dongtan in the Yangtze estuary, using a static chamber combined with a gas chromatograph. The results showed that within the growth seasons, the changes of NO₃^--N in the high tidal flat without vegetation cover were similar to those in the reed rhizospheric sediments. Compared with NO₃^--N, the variations of NH₄⁺-N differed between bare and vegetated sediments. The reed was observed to significantly enhance the release of N₂O from sediments. N₂O effluxes were respectively 0.71 and -4.02μg · m^-2 · h^-1 in bare sediments in July and January whereas they increased to 566.28 μg · m^-2 · h^-1 and 67.54 μg · m^-2 · h^-1 in rhizospheric sediments in both seasons. Besides NO₃^--N, NH₄⁺-N, temperature and water content, the physiological processes of plant also controlled the N₂O emission.