NDP-045

Carbon Dioxide, Hydrographic, and Chemical Data Obtained During the R/V Meteor Cruise 11/5 in the South Atlantic and Northern Weddell Sea Areas (WOCE sections A-12 and A-21) (1994)

D. W. Chipman, T. Takahashi, D. Breger, and S. C. Sutherland

This document presents the procedures and methods used to obtain carbon dioxide (CO₂), hydrographic, and chemical data during the R/V Meteor Expedition 11/5 in the South Atlantic Ocean, including the Drake Passage (Section A-12); the Northern Weddell Sea; and the Eastern South Atlantic Ocean (Section A-21). This cruise was conducted as part of the World Ocean Circulation Experiment (WOCE).

The cruise started from Ushuaia, Argentina, on January 23, 1990, and ended at Capetown, South Africa on March 8, 1990. Samples were collected at 78 stations that covered the Drake Passage (56° 63°S); the Northern Weddell Sea (45° 35°W); a section along the 58°W parallel (25°W prime meridian); and two segmented S-N sections between the Northern Weddell Sea and Capetown, South Africa. Measurements taken at WOCE sections A-12 and A-21 included pressure, temperature, salinity measured by the Conductivity, Temperature and Depth sensor (CTD); bottle salinity, oxygen; phosphate; nitrate, nitrite; silicate, total carbon concentration (TCO₂); and partial pressure of CO₂ (pCO₂) measured at 20°C. In addition, potential density at 0 decibar (dbar) and potential temperature were calculated from the measured variables.

The TCO₂ concentration in seawater samples was measured using a coulometer with an estimated precision of approximately ±1 mol/kg. The coulometer was calibrated frequently at sea by using a high-precision gas pipette and CO₂ gas (99.998%). The pCO₂ value in seawater samples was measured at 20°C by means of a constant-volume (500 ml seawater) equilibrator and a gas chromatograph. CO₂ in equilibrated gas was first converted to methane, by using a ruthenium catalyst, and then measured by a flame-ionization detector. The precision of pCO₂ measurements has been estimated to be approximately ±0.1%.

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