An improved oxygen method for measuring primary production in lakes

The accuracy of the Winkler technique for measuring dissolved oxygen was increased to 0.002–0.005 mg O₂/l with a photometric endpoint detection method. This precision is valuable for accurate measurements of primary production only if an oxygen release on illuminating dark adapted samples and the instability of the oxygen concentration of undersaturated water are taken into account. This work was supported by the ‘Swiss National Science Foundation’.