春季东海溶存氧化亚氮的分布和海气交换通量

Distribution and air-sea fluxes of dissolved nitrous oxide in the East China Sea in spring

于2011年5至6月在东海采集不同深度海水样品,研究了其中溶存氧化亚氮（N2O）的分布并估算其海-气交换通量。结果表明,春季东海表层海水中溶存N2O浓度范围为6.31-11.88 nmol/L,平均值为（9.13±1.45） nmol/L；底层海水中N2O浓度范围为7.53-39.75 nmol/L,平均值为（13.71±7.76） nmol/L。随着深度的增加, N2O浓度逐渐升高。温度是影响春季东海N2O分布的主要因素, N2O浓度与温度呈负相关关系。长江冲淡水和黑潮水是东海N2O的重要来源。东海表层海水中 N2O 的饱和度范围为92.5%-139.3%,平均值为118.5%±10.3%,绝大多数站位都处于过饱和状态,因此,春季东海是大气N2O的净源。利用LM86公式和W92公式求得东海的海-气交换通量分别为（4.96±6.12）μmol/（m^2·d）和（10.25±17.18）μmol/（m^2·d）,初步估算出东海年释放N2O通量约为0.061-0.127 Tg/a,占全球海洋释放总量的2.0%,远高于其所占的面积比0.2%。

In this manuscript, the distribution and air-sea fluxes of nitrous oxide （N2O） in the East China Sea during May-June 2011 were investigated. The N2O content increased from surface to bottom in the water column. The distribution of dissolved N2O showed a negative correlation with the temperature. The Changjiang diluted water and Kuroshio were the major sources of dissolved nitrous oxide in the East China Sea. The N2O saturation in the surface waters ranged from 92.5%to 139.3%, with an average of 118.5%±10.3%. The sea-to-air fluxes of N2O were estimated to be （4.96±6.12） μmol/（m^2·d） and （10.25±17.18） μmol/（m^2·d）, using the LM86 and W92 equations, respectively. The annual emission of N2O from the East China Sea was estimated to be 0.061-0.127 Tg N2O/a, which accounted for about 2.0%of the global annual oceanic N2O fluxes, suggesting that the East China Sea is an active area for N2O emission and a net source of atmospheric N2O.