Study Emissions Of CH₄and N₂O From A Wetland Of Different Water And Fertilization In Sanjiang Piain

Increasing greenhouse gases emission can lead to climate change all over the world. It is known that CH4and N2O are the other important greenhouse gases which are nearly after CO2. Sanjiang plain wetland is the classic one of northern wetlands. Recently, because lots of amount underground water is exploited and fertilizer are used, the wetland hydrology conditions have changed greatly. Lots of outer source fertilizer input can have influence on emission regularity of CH4and N2O.It used static chamber-gas chromatogram method, through field observation and analysis in lab, to study emission characteristics of CH4and N2O which are under the conditions of different water level、fertilizer amount and fertilization methods. It discussed the factor which affects emission of CH4and N2O in Sanjiang plain and got some conclusions following:1. In the whole growth period of Sanjiang plain wetland, the emission flux of CH4is the highest in July, September the lowest, June and August middle; the high emission flux of N2O lasts from early June to middle July, in August the emission flux maintains lower level, in September the emission flux gets back to high with a peak.2. According to amount of CH4emission flux, the water level order is40>60>20>0cm of which average value are35.25、16.09、12.2、7.91mg·m-2·h-1in the two growth periods, as an emission source of CH4. Compared with emission flux in the level of0cm, the average emission fluxes in the level of20、40and60cm are55.5%、346.0%and103.5%higher. The CH4emission flux and water depth of which belongs to parabolic. The emission flux of N2O decreases with increasing water level. In the two observation periods, only in the60cm of water depth N2O absorption appears in late September, all of the other treatmen ts in any period are sources, in the whole growth period they are emission sources of N2O, which average value are0.072,0.058,0.051,0.033mg·m-2·h-1in the two growth periods. Compared with wet zone, the emission fluxes in the level of20、40and60cm are19.7%、28.5%、55.5%lower. The N2O emission flux and water depth of wetland is in linear relation with.3. Compared with in natural condition,the CH4emissions in the conditions of using inorganic nitrogen which refers to N20、N40and N60, increase by66.6%、92.1%、123.5%, which shows that the CH4emission flux in wetland increases with increasing amount of nitrogen fertilizer; Compared with in natural condition, in the conditions of organic nitrogen, which treated with Y20、Y40,the CH4emission flux separately increases by61.7%、67.0%. Compared with control treatment, the N2O emission flux in the conditions of inorganic nitrogen which refers to N20、N40、N60, increases by57.1%、117.1%、137.1%;Compared with in natural condition, in the conditions of organic nitrogen, which refers to Y20、Y40,the N2O emission flux separately reduce by14.3%、25.7%.4. CH4emissions flux and40cm water depth significant positive correlation, the emissions of CH4are important environmental factors to soil temperature. In the experiment zone, the height and biomass of plant called Narrow leaf small reed have highly significant positive correlation with accumulated emission amount of CH4and N2O.5. It analyzed the emission fluxes change of CH4and N2O in the conditions of surface pond and fertilization. In the condition of pond surface, the N2O emission flux decreases, and in the other conditions the N2O and CH4emission flux increases. In the fertilization zone, the increasing emissions of N2O and CH4are higher than in the condition of pond surface. On the whole, the best method to decrease greenhouse gases is maintaining some certain water depth on the surface.