摘要
基于2012年7月对东海的调查,剖析了其水体中各形态碳(pCO2、DIC、DOC、POC)的区域分布特征,估算了海-气界面CO2的交换通量(FCO2),探讨了影响其交换的主要因素,在此基础上,结合历史资料初步分析了近十几年来该海域海-气界面CO2交换通量的变化趋势。结果表明,2012年7月长江口邻近海域相对南部陆架区具有较低的DIC浓度,而DOC与POC的浓度相对较高。调查区域表层水pCO2变化范围为96.28~577.7μatm(1atm为101 325Pa),平均值为297.6μatm,低值区出现在长江冲淡水区(30°~33°N,123°~125°E),高值区主要分布在东海陆架的南部区域。表层水pCO2主要受控于长江冲淡水的输入和混合(盐度)、台湾暖流以及生物生产等。调查海域2012年7月海-气FCO2平均为(-6.410±7.486)mmol/(m2·d),表现东海在夏季是大气CO2的汇区,区域碳汇强度由强到弱依次为:长江冲淡水区(CDW)、黄东海混合水区(YEMW)、陆架咸淡水混合区(SMW)、近岸上升流区(CUW)和台湾暖流区(TWCW),东海夏季每日吸收大气CO2(以C计)约(18.3±19.8)kt。结合历史资料分析发现,近十几年来东海夏季碳汇强度有增强趋势,CDW区的海-气界面CO2通量平均年增速为-0.814mmol/(m2·d),即海水吸收大气二氧化碳每年增加约54.6kt,是夏季东海碳汇增加的最主要贡献者。
The surface water partial pressure of CO2 (pCO2), dissolved inorganic carbon(DIC), dissolved organic car- bon(DOC) and particulate organic carbon(POC) in the East China Sea(ECS) were investigated during the survey in July 2012. The results showed that the adjacent area of the Changjiang estuary had higher DOC and POC con- tents and lower DIC than the southern shelf. Surface pCO2 in the ECS ranged from 96.28 to 577.7μatm (mean is 297. 6 μatm,1 atm is 101 325 Pa). Low pCO2 levels were found in area (30°- 33°N, 123°- 125°E) of the Changjiang Diluted Water (CDW),whereas high pCO2 levels occurred in the southern ECS shelf affected by the Taiwan Current Warm. The surface pCO2 was mainly influenced by the Changjiang freshwater input and mixing, Taiwan warm current water and biological production. The average summer FCO2 in the ECS was(-6. 410± 7.486) mmol/(m2 · d) ,indicating that the ECS served as a CO2 sink which absorbed (1.83±1.98)× 10^4 t carbon every day in the summer. The regional carbon fluxes sorted from high to low as CDW, YEMW, SMW, CUW (Coastal Upwelling Water) and TWCW. Comparing with the historical data,the effect of the ECS as a CO2 sink was gradually enhancing in the last ten years. The CDW was the biggest contributor to the increased carbon sink in the ECS. And the FCO2 annual growth rate in the CDW area was -0. 814 mmol/(m2 ·d),meaning that every summer the CDW could take up 5.46 × 10^4 t more than last year's.
出处
《海洋学报》
CAS
CSCD
北大核心
2014年第12期18-31,共14页
基金
中国科学院先导专项课题(XDA11020102
XDA05030402)
国家重点基础研究发展计划项目课题(2010CB951802
2011CB403602)
关键词
海气界面碳通量
控制因素
碳汇
变化趋势
东海
air-sea CO2 flux
controlling factor
carbon sink
change tendency
East China Sea