2016年冬末长江口及邻近海域海气CO2交换特征分析

Analysis on characteristics of CO_2 fluxes across the air-sea interface of the Yangtze Estuary and adjacent sea in late winter 2016

基于2016年3月对长江口及邻近海域的调查,剖析该海域CO_2分压及相关参数的区域分布特征,估算其海-气界面CO_2的交换通量,并探讨了源/汇分布特征背后的物理机制。研究表明,调查区域海表p CO_2变化范围为321~575μatm,整体呈现出近岸高、离岸低的分布趋势。至冬季末期,海表p CO_2分布主要受控于低温低盐高p CO_2的河口水与高温高盐低p CO_2的东海陆架水的水团混合影响,水体垂直混合作用对海表p CO_2影响不大。长江口及邻近海域冬季整体表现为大气CO_2的弱汇,通量值为-4.43±7.41mmol/m2/d。从区域碳汇强度看来,近岸长江冲淡水区近乎与大气保持平衡,黄东海混合水区和台湾暖流区表现为大气CO_2的中/强汇,是冬季末期海洋吸收大气CO_2的主要贡献区域。

Based on the survey at the Yangtze Estuary and adjacent sea in March 2016,regional distributions of the surface water partial pressure of CO2 and relevant parameters were analyzed,air-sea CO2 fluxes were estimated and physical processes of CO2 source/sink distribution were discussed. Results showed that the surface p CO2 in survey area ranged from 321 ~ 575 μatm,generally exhibiting high values at the inner shelf,whereas low values off the shore. Until the end of winter,the distribution of surface p CO2 had been dominated by the mixing between the estuarine water（ low temperature,low salinity,high p CO2） and the shelf water in the East China sea（ high temperature,high salinity,low p CO2）,while vertical mixing had little effect on it. The Yangtze Estuary and adjacent sea also served as a weak sink of atmospheric CO2,with a-4. 43 ± 7. 41 mmol/m2/d average air-sea CO2 flux. In the sight of regional carbon sink intensity,its level in the Changjiang Diluted Water was nearly in balance with that in the atmosphere. The Yellow Sea-East China Sea Mixing Water and Taiwan Warm Current Water were moderate/strong sink of the atmospheric CO2,becoming a major contributor to the ocean absorbed CO2 during winter.