极锋以南洋区N2O源汇特性初析

SINK AND SOURCE CHARACTERISTICS OF SURFACE WATER SOUTH OF THE POLAR FRONT IN THE SOUTHERN OCEAN

N_2O是大气中最重要的温室气体之一,目前已经有大量的研究对海洋N_2O循环及海洋对N_2O收支的贡献进行追踪报道。然而,极区相关研究仍然十分有限。本研究利用中国第25、26次南极科学考察的机会,对南大洋进行的采样以及实验室分析,结果显示,南大洋表层海水存在亚热带锋附近N_2O过饱和,亚南极锋附近接近饱和,和极锋以南洋面的不饱和的特征。海冰融化后,其融冰水的注入是N2O不饱和特征形成的主要原因。运用正态分布选取站观测风速95%以上的风速范围进行平局估算出极锋以南洋区海气通量,结果显示,极锋区以南表层海水是大气N_2O的汇区,年吸收通量约为3.5×10^(-4)—7.7×10-4Tg·a-1(百万吨氮/年)。

Nitrous oxide （N2O） is one of the most important greenhouse gases and the levels of N2O have been closely monitored over the past five decades. However, there are very few studies have investigated the role of polar oceans in the global N2O budget. During the 25th and 26th Chinese National Antarctic Research Expeditions, surface samples were collected in the Southern Ocean and analyzed. The results indicated that N2O is oversaturated the Subtropical Front, close to equilibrium near the Subantarctic Front, and undersaturated south of the Front. The air-sea flux south of the Polar Front was evaluated and that region was found to be a sink of atmosp N2O.