[Seasonal variations of fluxes and distributions of dissolved N2O in the North Yellow Sea].

The concentrations and air-sea fluxes of dissolved N2O were investigated in the North Yellow Sea during March 2005, April and August 2006, April and October 2007. Seasonal variations of dissolved N2O concentrations (about 12 nmol x L(-1)) in the North Yellow Sea were not obvious. The saturations of dissolved N2O in the North Yellow Sea showed obvious seasonal variations with higher values occurring in summer and autumn and lower in spring, and the dissolved N2O of the surface water was from undersaturated to oversaturated with the water temperature gradually increasing during three cruises in Spring. The correlation analysis shows that temperature was the main factor to influence N2O saturations. The estimated average N2O fluxes using the Liss and Merlivat (LM86) and Wanninkhof formula (W92) were (0.6 +/- 1.7), (5.8 +/- 8.4), (7.9 +/- 8.2) micromol x (m2 x d)(-1) and (1.1 +/- 2.7), (10.2 +/- 13.6), (13.8 +/- 14.3) micromol x (m2 x d)(-1), respectively, for spring, summer and autumn. Air-sea fluxes of dissolved N2O showed obvious seasonal variations, with the N2O fluxes of summer and autumn higher than those of spring. Based on the average annual N2O flux and the area of the North Yellow Sea, the annual N2O emission from the studied area was estimated to be (5.3 x 10(-3) -9.2 x 10(-3)) Tg x a(-1). From the above results, it can be seen that the North Yellow Sea was a net source of atmospheric N2O.