A land surface C-14 transfer model and numerical experiments on belowground C-14 accumulation and its impact on vegetation C-14 level

作者：Ota Masakazu^*; Nagai Haruyasu; Koarashi Jun

来源：Journal of Environmental Radioactivity, 2012, 107: 13-22.

DOI：10.1016/j.jenvrad.2011.11.016

• (CO2)-C-14
• Photosynthesis
• Carbohydrate
• Soil organic carbon
• Decomposition

A model simulating transport and exchange for C-14 (or (CO2)-C-14) in a land surface ecosystem was developed and the belowground C-14 accumulation and its impact on vegetation C-14 accumulation at a hypothetical cultivated field were studied with the model through numerical experiments. The developed model involved physical (CO2)-C-14 transport in surface atmosphere and soil and physiological (CO2)-C-14 exchanges in leaves, and was incorporated into a dynamical model (SOLVEG-II) that calculates transport and exchange for heat, water and CO2. The model was tested through a simulation of an existing-experiment on an acute exposure of grape plants to (CO2)-C-14. The calculated C-14 amount in leaves agreed with the observations within a factor of 1.7. A hypothetical scenario used for the numerical experiments considered an annual C-14 input into surface soil layers via C-14-enriched foliage or root litter under a continually heightened atmospheric (CO2)-C-14 concentration. The specific activity of C-14 in the surface soil layers increased with time and several decades after the start of accumulation it eventually converged to eight times the initial specific activity. At this equilibrium state, the increased belowground (CO2)-C-14 production enhanced the atmospheric (CO2)-C-14 level and, consequently, (CO2)-C-14 uptake by vegetation increased to 1.1 times the control calculated without belowground C-14 accumulation. The model results also demonstrated that C-14 accumulated in soil can maintain an enhanced vegetation C-14 level for at least several decades even after the end of accumulation.

• 出版日期2012-5