[N2O concentration and its emission characteristics in Sanjiang plain wetland].

N2O concentration and its flux were measured in Sanjiang Plain wetland, from August to September in 2001, by using in situ closed chamber technique. The results showed that the mean N2O concentration above the ground was 281.7 x 10(-9) m3/m3, lower than the atmospheric N2O background, indicating the wetland maybe one of the important N2O sinks which scientists hadn't pay much attention to in the past. Four observation sites: Cares lasiocarpa, Alamagrostis angustifolia (I, II) and wheat land(had been harvested and in follow) were chosen according to water content and plant. The daily N2O emission models at four sites were different from each other, except site of wheat land emitted N2O persistently all day, the other sites emitted and absorbed alternately in one day. Temperature was the crucial factor for the diurnal variation. The mean N2O flux at four sites from August to September was 0.22 microgram/(m2.h), 1.75 microgram/(m2.h), 1.31 micrograms/(m2.h), 4.86 micrograms/(m2.h), respectively. Eh was the key factor for N2O emission characteristic in Sanjiang Plain wetland, and water content was another important factor.