Nitrous oxide emissions from a waterbody in the Nenjiang basin, China

Using static, closed chambers and gas chromatography techniques, nitrous oxide (N2O) emissions have been monitored for 1 year (2009-2010) on an inland running waterbody downstream of the Nenjiang basin, China. During the freezing period, holes were dug in the ice in order to obtain nitrous oxide samples. Here, we have focused on water-air gas exchange and factors which might influence N2O emissions and flux. Initial results indicate: (1) N2O flux rates reach peak emission in January and the annual emissions of N2O were low, being estimated at 0.35 +/- 0.20 mu gm(-2) h(-1); significant seasonal differences only appeared between January and July; (2) N2O flux rates have strong regularity and ice has been the main barrier to nitrous oxide release during winter; (3) 24-hour monitoring revealed that N2O flux remained steady during 9:00-17:00; (4) N2O emissions have significant relationships with ammonium nitrogen and total phosphorus concentrations in water (r = 0.4467, p = 0.020 and r = 0.4793, p = 0.011, respectively). The N2O flux released from the waterbody is determined by the chemical concentrations in the water. Following these results, we suggest that moderate use of N and P fertilizer at intensive agricultural areas will be beneficial in decreasing greenhouse gas emissions from this waterbody.