LAUSR

Most aquatic ecosystems contribute elevated N2O to atmosphere due to increasing anthropogenic nitrogen loading. To further understand the spatial heterogeneity along an aquatic continuum from the upriver to wetland to lake to downriver, the study was conducted on spatial variations in N2O emission along Poyang Lake aquatic continuum during the flood season from 15 July 2013 to 10 August 2013. The results showed the N2O concentrations, the ratio of N2O/dinitrogen (N2) gases production, N2O emission and denitrification rates ranged from 0.10 to 1.11μgN/L, -0.007% to 0.051%, -9.73 to 127μgN/m2/hr and 1.33×104 to 31.9×104μgN2/m2/hr, respectively, across the continuum. The average N2O concentrations, the ratio of N2O/N2 and N2O emission was significantly lower in wetlands as compared to the rivers and lake (p<0.01). The significantly high denitrification rate and low N2O emission together highlighted that most N2O can be converted into N2 via near complete denitrification in the Poyang Lake wetlands. Our study suggests that the wetlands might impact N2O budget in an integrated aquatic ecosystems. Moreover, N2O emission from different aquatic ecosystem should be considered separately when quantifying the regional budget in aquatic ecosystem.