δ13C Record in forest soil using a rapid method for preparing carbon dioxide samples

Abstract

Abstract 13C/12C variations of organic carbon have been investigated in forest soil down to a depth of 40 cm by using a fast method of sample preparation. The measured values of the various soil horizons are in good agreement with measurements applying the classical procedure. The experimental results show a distinct increase of the 13C/12C ratio with increasing depth. Within 40 cm the δ13C value is enriched by about 2.5%. With our fast method, samples are quantitatively burned in an oxygen gas stream at 1100 K and condensed in cooling traps at 123 K. The experimental setup does not require time-consuming recycling processes of the produced carbon dioxide gas for complete conversion. Therefore, the whole procedure from burning the sample to condensing the carbon dioxide into a vial takes only 35 min. In addition the equipment permits the determination of the carbon content.