胶州湾及周边海域大气和海水中N_2O和CH_4的分布及海气交换通量

分别于2006年8月,12月和2007年4月,10月采集胶州湾及周边海域大气和海水样品,对氧化亚氮(N2O)和甲烷(CH4)浓度进行了测定,并设置1个连续站进行24 h连续观测.结果表明:大气中N2O春、夏、秋、冬的平均浓度(体积分数)分别为(3.17±0.03)×10-7,(3.24±0.15)×10-7,(3.19±0.02)×10-7和(3.08±0.25)×10-7;大气中CH4春、夏、秋、冬的平均浓度(体积分数)分别为(1.89±0.04)×10-6,(1.79±0.04)×10-6,(2.09±0.21)×10-6和(2.01±0.09)×10-6.胶州湾表、底层海水中N2O和CH4的浓度和饱和度表现出明显的季节变化,其中N2O浓度和饱和度冬季最高,春、秋季次之,夏季最低;CH4浓度和饱和度夏季最高,冬季最低.利用Liss and Merlivat(1986)公式和Wanninkhof(1992)公式估算出胶州湾海域N2O的年平均海-气交换通量分别为(11.16±14.15)和(22.42±27.56)μmol m-2·d-1;CH4分别为(7.75±6.19)和(17.76±14.84)μmol m-2·d-1.胶州湾大部分海域表层海水中N2O和CH4呈过饱和状态,是大气中N2O和CH4的净源.

The Distributions and Atmospheric Fluxes of Nitrous Oxide and Methane in Jiaozhou Bay and Its Adjacent Coastal Area

Nitrous oxide(N2O) and methane(CH4) were measured in the waters and atmosphere of Jiaozhou Bay during 4 surveys from 2006 to 2007. The average atmospheric concentration of N2O in spring, summer, autumn and winter were(3.17±0.03)×10-7, (3.24±0.15)×10-7, (3.19±0.02)×10-7 and(3.08±0.25)×10-7. The average atmospheric concentration of CH4 in spring, summer, autumn and winter were(1.89±0.04)×10-6, (1.79±0.04)×10-6, (2.09±0.21)×10-6 and(2.01±0.09)×10-6, respectively. The concentrations and saturations of dissolved N2O and CH4 in the surface and bottom waters of Jiaozhou Bay had seasonal variations. N2O showed the highest concentrations and saturations in winter and lowest in summer, while CH4 showed the highest in summer and lowest in winter. The estimated atmospheric fluxes of N2O using the Liss and Merlivat(1986) and Wanninkhof(1992) formula were(11.16±14.15) and(22.42±27.56)μmol·m-2·d-1; and atmospheric fluxes of CH4 were(7.75±6.19) and(17.76±14.84) μmol·m-2·d-1, respectively. N2O and CH4 were supersaturated in most surface waters. Hence Jiaozhou Bay were net sources of the atmospheric N2O and CH4.