Dutch JGOFS - Dissolved oxygen measured during the North Atlantic Pilot Project (Leg 3)

Leg 4, 2-29 June 1990 (Benthic Processes) The following oxygen data set originated during Leg 3. Dissolved oxygen was measured according to the high precision Winkler titration method developed by Tijssen (Hartwig and Michael 1978, Tijssen 1989, Williams and Jenkinson 1982). Over 900 oxygen samples were taken at 16 stations from depths of 5 m until more than 4000 m.

From each depth, duplicate-or, if time and the amount of water available allowed it, triplicate samples were taken. It was attempted to lead the water through a 200 micron zooplankton filter first. However, duplicate values were less accurate after that.

At all stations from 2 depths seawater blanks were taken and analyzed. The mean value is 0.77 microMol/m3. There is no trend to be seen in the value of seawater-blanks from 33N to 60N.

Immediately after sampling the reagentia were added while in a separate bottle the "sample temperature" was measured. Before starting each titration the temperature of the thiosuolphate solution was measured. Data are corrected (salinity) as to arrive at the reported micromol/kg.

Differences between the values of the duplicate/triplicate samples are generally smaller than 0.5 micro mol/kg. Hartwig, E.O. and J.A. Michael (1978). A sensitive photoelectric Winkler titrator for respiration measurements.

Environmental Science & Technology 12(6): 712-715 Tijssen,S.B. (1981). Anmerkungen zur photometrisched Winkler. Sauerstofftitration und ihre Anwendung zur Schatzung der Primarproduktion im Meer.

In: III Internationales mikorbiologisches Symposium, Smolenice, 3-6 Juni 1980. Editor L. Daubner. Veda, Verlag der Slowakischen Akademie der Wissenschafter, Bratislava 1981.

Williams, P.J. LeB, and N.W. Jenkinson (1982). A transportable micro- processor controlled precise Winkler titration suitable for field station and shipboard use. Limnol.

Oceanogr. 27(3): 576-584