CARBON-14 MEASUREMENTS
423
a rather severe memory effect for CO,. Using ‘C-labeled CO., we have
verified that Fergusson’s pretreatment method reduces the memory
effect to less than 1%, which is entirely adequate for extended field use
of the material.
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EXPERIMENTAL PROCEDURES
A photograph of one of the samplers used in this study is shown in
Fig. 1. The sieve material is contained in a double-top 1-gal paint can
through which air is drawn by means of a suction unit located in the
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Fig. 1—Air sampler used to collect samples of CO; at ground levels.