Use of gas sampling tubes for direct measurement of 14CO2 in soil air

Abstract Commercially available chromatographic tubes for detection of gases in industrial air were utilized in experiments where CO 2 from soil respiration carried a 14 C label. Using a series of different gas mixtures, the equipment was examined in the laboratory and demonstrated to be accurate in measuring CO 2 contents over the range from 0.03 to 5%. Activity measurements were made by transferring the chromatographic packing, with absorbed 14 C, from the tubes into scintillation solution for counting. In field experiments, 14 CO 2 from soil air was examined over time after labeling wheat plants and monitoring their maturation and decomposition.