Predominance of organic versus inorganic carbon exports from glacier and permafrost watersheds in Qinghai-Tibet Plateau

Abstract:

Land-to-water carbon mobilization in a warming climate is increasing in glacier and permafrost area. Most of the glacier and permafrost distributes in the arctic, subarctic area and high mountain area. Research showed that the hydrologic exports of dissolved inorganic (DIC) and organic carbon (DOC) can reflect the permafrost conditions in the arctic and subarctic river basin. The confirmation of a high correlation between the DIC and DOC and the permafrost and glacier source stream in inland high altitude mountain area could help us to estimate the change amount of carbon which would be exported from land to water in the climate changing environment. To identify the connection between exported river carbon content and the permafrost or glacier condition in the high altitude mountain area, we studied the DOC and DIC concentration in three streams in Qinghai-Tibet Plateau, which was in the Continuous permafrost, seasonal permafrost and glacial basin, respectively. The river water samples along the three streams were collected in the summer in 2015. We found that in the inland high-altitude mountain area, the glacial river showed lower DIC/DOC ratio compared with the permafrost dominant rivers. Glacier exported more DOC than DIC. In the permafrost area, discontinuous permafrost recharged river had higher DIC/DOC ratio than the river in the continuous permafrost region. It suggests that carbonate weathering by carbonic acid is more dominant in discontinuous than in continuous permafrost. Continuous permafrost can contribute more DOC to the water system. With climate warming, more DOC would exported from glacier while more DIC would come from thawed permafrost in the high mountainous area.