Estimation of Carbon Sink Capacity Caused by Rock Weathering in China

Rock weathering caused by the carbonic acid reaction with minerals to produce dissolved bicarbonates carried by rivers to the oceans is an important part in carbon cycle. The process causes significant carbon dioxide consumption, the accurate calculation of which may partly explain the missing sink of carbon. The CO₂ uptaken by carbonate dissolution on the continents is counterbalanced by the CO₂ release carbonate precipitation in the ocean. The same is not true for silicate weathering. Silicate weathering is more important than carbonate weathering as a long-term control on atmospheric CO₂. A global erosion model (GEM-CO₂) developed by Amiotte Suchet allows us to calculate the flux of atmospheric/soil CO₂ consumed by chemical erosion of continental rocks. In this paper, the CO₂ consumption by rock weathering in China is estimated based on GEM-CO₂ and the Chinese Resources and Environment Database, whose distribution is shown in a GRID map with a spatial resolution of 1 000 m×1 000 m. The total carbon consumption is about 4.72×10⁷ t/a, about 52.65% of which are caused by carbonate. The model results are close to previous estimation of other researches. The flux of CO₂ consumed by rock weathering increases where carbonate rock outcrops are more abundant and when drainage intensity increases. The results show that the main consumption of CO₂ is localized in Guangxi, Guizhou and Chongqing provinces, and west Hubei Province and southwest Hunan Province, because of a high proportion of carbonate rocks and high humidity in a large area.