Spatial variability of greenhouse gas effluxes and their controlling factors in the Poyang lake in China

CO2, CH4, and N2O (GHG) emissions are globally important in China , but few field observations have been made in freshwater lakes. In this paper, we measured the GHG effluxes from 44 sampling locations among four sub-regions in Poyang Lake in China in October 2010 using floating chambers. The mean CO2, CH4, and N2O effluxes were 0.23 mu mol m(-2).s(-1), 3.0 nmol.m(-2).s(-1), and 0.11 nmol m(-2).s(-1), ranging from -0.25 to 0.54 mu mol.m(-2).s(-1), 1.4 to 8.9 nmol m(-2).s(-1), and 0.012 to 0.21 nmol.m(-2).s(-1) for the CO2, CH4, and N2O efflux, respectively. We found differently related tendencies between GHG effluxes and environmental parameters for each sub-region and, totally, four sub-regions together. The 16 environmental factors explained the GHG effluxes with 55%, 70%, and 89% of the variation in CO2, CH4, and N2O efflux, respectively, in Poyang Lake . Our analysis revealed that sediment C/N ratio, water depth, and the difference of air-water temperature were significantly contributing variables for GHG effluxes in the lake .