Depth Profiles of Radiocarbon and Carbon Isotopic Compositions of Organic Matter and CO_2 in a Japanese Forest Area((2)Summaries of Research Using AMS)
Specific activities of ^<14>C and carbon isotopic compositions (Δ^<14>C) in organic matter and CO_2 in a Japanese forest soil were determined. For investigating the transport of CO_2 in soil, the specific activities of ^<14>C and Δ^<14>C within the organic layer on the top of soil surface and the atmospheric CO_2 were also determined. The specific activity of ^<14>C and Δ^<14>C in the organic matter decreased with the increasing soil depth of 0-60 cm while that of the soil CO_2 was not significantly variable at the soil depth of 13-73 cm and was larger than that in the atmospheric CO_2. Peaks of specific activities of ^<14>C appeared at the depth of 0-4 cm and Δ^<14>C values were positive in the depth range from 0 to 15 cm. These results suggested that the present soil at depth of 0-4 cm had been produced since the mid-1950s up until 1963 and the bomb C had reached the depth of 15 cm in the objective soil area. The soil CO_2 at the depth of 53-73 cm were assumed to originate only from the decomposition of soil organic matter and the respiration of live roots, the respiration of live roots was estimated to have seasonal variations and be the main source of the soil CO_2 at the deeper horizons in the present forest area.
タンデトロン加速器質量分析計業績報告 Summaries of Researches Using AMS 2005 (平成17)年度
名古屋大学加速器質量分析計業績報告書 17 155-164, 2006-03