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 μgm^–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.