2016年冬末长江口及邻近海域海气CO2交换特征分析

基于2016年3月对长江口及邻近海域的调查，剖析该海域CO₂分压及相关参数的区域分布特征，估算其海-气界面CO₂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pCO₂变化范围为321~575 μatm，整体呈现出近岸高、离岸低的分布趋势。至冬季末期，海表pCO₂分布主要受控于低温低盐高pCO₂的河口水与高温高盐低pCO₂的东海陆架水的水团混合影响，水体垂直混合作用对海表pCO₂影响不大。长江口及邻近海域冬季整体表现为大气CO₂的弱汇，通量值为-4.43±7.41 mmol/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CO₂的中/强汇，是冬季末期海洋吸收大气CO₂的主要贡献区域。

Analysis on characteristics of CO2 fluxes across the air-sea interface of the Yangtze Estuary and adjacent sea in late winter 2016

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 pCO₂ 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 pCO₂ had been dominated by the mixing between the estuarine water (low temperature, low salinity, high pCO₂) and the shelf water in the East China sea(high temperature, high salinity, low pCO₂), 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.