Stable carbon isotopes as indicators for permafrost carbon vulnerability in upper reach of Heihe River basin, northwestern China

To examine the permafrost carbon vulnerability of the Eboling Mountain in the upper reach of Heihe River basin, Qinghai-Tibet Plateau, the distributions of concentrations and delta C-13 values of TOC (total organic carbon), DOC (dissolved organic carbon) and HWC (hot water soluble carbon) with soil depth in permafrost were analyzed. Our results indicated the potential CH4 emission in the soils near the permafrost table and deep permafrost (414-448 cm) with climate warming. The labile carbon (DOC) and microbial biomass carbon (HWC) in deep permafrost (280-350 cm) have been utilized during soil forming processes, with an increase of delta C-13(DOC) and delta C-13(HWC) values about 3 parts per thousand. The lower delta C-13 values showed that HWC was more easily available for microbial utilization. The delta C-13 values of TOC suggested that C-3 plants prevailed on the Eboling Mountain during the last 7000 years. (C) 2013 Elsevier Ltd and INQUA. All rights reserved.