CO2, Hydrographic, and Chemical Data Obtained During the R/V Meteor Cruise 15/3 in the South Atlantic Ocean (WOCE Section A9, February March 1991)

This data documentation discusses the procedures and methods used to obtain data on total carbon dioxide (TCO2), total alkalinity (TALK), and discrete partial pressure of CO2 (pCO2) during the Research Vessel (R/V) Meteor Expedition 15/3 in the South Atlantic Ocean (Section A9). Conducted as part of the World Ocean Circulation Experiment (WOCE), the cruise began in Vitoria, Brazil, on February 10, 1991, and ended in Pointe-Noire, Congo, on March 23, 1991. WOCE zonal Section A9 began at ~38 degrees W and continued along the 19oS parallel until ~8 degrees E. Samples were collected for TCO2 from 28 stations along the 19th parallel and at 3 diversions north and south of the 19th parallel. The latter stations were occupied to track bottom water movements. Measurements made along WOCE Section A9 included pressure, temperature, salinity, and oxygen measured by conductivity, temperature and depth sensor (CTD); bottle salinity, oxygen, phosphate, nitrate, nitrite, silicate, CFC-113, CCl4, CFC-12, CFC-11, TCO2, TALK, and pCO2 measured at 20 degrees C. Replicate samples from ten Niskin bottles at four stations were also collected for later shore-based reference analyses of TCO2 and TALK by vacuum extraction and manometry in the laboratory of Dr. Charles Keeling, Scripps Institution of Oceanography (SIO). The TCO2 was measured using an automated sample processor (SOMMA) for extracting CO2 from seawater samples coupled to a Coulometer for detection of the extracted gas. The precision and accuracy of the system was +/- 1.0 micro-mol/kg. R/V Meteor Cruise 15/3 was an initial test of an experimental system for measuring pCO2 on discrete water samples: a batch equilibration technique was used followed by headspace gas chromatography with flame ionization detection. While the quality of some pCO2 data is poor compared with that collected more recently (i.e., precision and accuracy ~2-3%), all data have been included for completeness. Samples collected for TALK were measured using standard potentiometric techniques; precision was +/- 2.6 micro-mol/kg.

本数据文档阐述了南大西洋A9断面（隶属于世界大洋环流实验（WOCE）的流星号（R/V Meteor）15/3航次）中总二氧化碳（TCO2）、总碱度（TALK）以及离散二氧化碳分压（pCO2）数据的获取流程与方法。该航次于1991年2月10日从巴西维多利亚港启航，1991年3月23日于刚果黑角港结束。WOCE的A9纬向断面西起约38°W，沿19°S纬线向东延伸至约8°E。研究人员沿19°纬线布设了28个站位采集TCO2样品，并在该纬线南北两侧增设3个偏移站位，以追踪底层水团运动。沿A9断面开展的测量项目包括：通过温盐深传感器（CTD）获取的压力、温度、盐度与溶解氧数据；以及在20℃条件下测定的采水瓶水样盐度、溶解氧、磷酸盐、硝酸盐、亚硝酸盐、硅酸盐、CFC-113、四氯化碳（CCl4）、CFC-12、CFC-11、TCO2、TALK与pCO2数据。此外，研究人员在4个站位的10个尼斯金采水器中采集了平行样品，用于后续在斯克里普斯海洋研究所（SIO）查尔斯·基林博士实验室开展的基于真空萃取与压力测定法的TCO2与TALK岸基对照分析。TCO2的测定采用自动化样品处理器（SOMMA）提取海水样品中的CO2，并通过库仑计检测所提取气体，该系统的精密度与准确度为±1.0微摩尔/千克。流星号15/3航次是对离散水样pCO2测定实验系统的首次测试：该系统采用分批平衡技术，后续通过顶空气相色谱-火焰离子化检测法完成分析。尽管部分pCO2数据的质量（精密度与准确度约为2%-3%）相较近年采集的数据稍逊，但为保证数据完整性，所有数据集均已收录。TALK的测定采用标准电位滴定技术，其精密度为±2.6微摩尔/千克。