Acta Geographica Sinica ›› 2019, Vol. 74 ›› Issue (7): 1319-1332.doi: 10.11821/dlxb201907004

• Climate Change and Surface Processes • Previous Articles     Next Articles

Estimation of carbonate rock weathering-related carbon sink in global major river basins

LI Chaojun1,2,WANG Shijie2,3,BAI Xiaoyong2,3(),TAN Qiu1,LI Huiwen2,LI Qin2,DENG Yuanhong2,YANG Yujie1,2,TIAN Shiqi1,2,HU Zeyin2   

  1. 1.School of Geography and Environmental Sciences, Guizhou Normal University, Guiyang 550025, China
    2.State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, CAS, Guiyang 550081, China
    3.Puding Karst Ecosystem Observation and Research Station, CAS, Puding 562100, Guizhou, China
  • Received:2018-10-23 Revised:2019-03-03 Online:2019-07-25 Published:2019-07-23
  • Contact: BAI Xiaoyong E-mail:baixiaoyong@126.com
  • Supported by:
    United Fund of Karst Science Research Center(U1612441);National Key Research & Development Program of China(2016YFC0502102);National Key Research & Development Program of China(2016YFC0502300);"Western Light" Talent Training Plan of Chinese Academy of Sciences (Class A 2018);Science and Technology Services Network Initiative Plan(KFJ-STS-ZDTP-036);International Cooperation Agency International Partnership Program(132852KYSB20170029);International Cooperation Agency International Partnership Program(2014-3);Guizhou High-level Innovative Talent Training Program "Ten" Level Talents Program([2016]5648);National Natural Science Foundation of China(41571130074);National Natural Science Foundation of China(41571130042);Science and Technology Plan of Guizhou Province of China(2017-2966)

Abstract:

Atmospheric CO2 uptake by carbonate rock weathering is continuously transported from the land to the ocean by rivers in the form of HCO3 -, and it has become an important carbon sink of terrestrial ecosystems. In the existing research, the estimation and distribution of carbonate weathering-related carbon sink in global major river basins are still unclear. In this study, we collect hydrochemical and discharge data of multiyear average (runoff modulus, main ion concentration, and dissolved inorganic carbon) in large river basins over 100, 000 km 2. By using hydrochem-discharge method, we estimate that the CO2 uptake rates (Fv) of carbonate weathering in global major river basins is 0.43 ± 0.15 Pg CO2 yr -1 and the average CO2 uptake flux(F) is 7.93 ± 2.8 t km -2 yr -1. The CO2 uptake F and uptake Fv are substantially different under various climatic zones. The annual uptake Fv of tropical and warm regions accounts for 62.95% of the total annual Fv. The cold temperate zone is widely distributed, and its CO2 uptake Fv accounts for 33.05%, which is second only to the tropics. We also propose the nine critical zones of global CO2 uptake F (four in the middle and low latitudes, two in the western hemisphere and three in the eastern hemisphere). The CO2 uptake F in the intersection of the critical zones is high. The average CO2 uptake F in the karst-outcropped basins is 8.50 t km -2 yr -1, which is approximately three times that in the non-karst basins. Carbonate weathering carbon sinks in global karst-outcropped basins play an important role in the study of global carbon cycle, water cycle, and carbon budget balance estimation. On the basis of river basin scales, various factors (e.g., carbonate composition, exogenous acid, and climatic environment) for carbonate weathering carbon sinks should be considered. The hydrochem-discharge method should be further improved in future research. Moreover, the effects of the photosynthesis of river aquatic organisms on rock weathering carbon sinks should be considered, and carbonate rock weathering carbon sinks should be refined and extrapolated to the world.

Key words: carbonate rock, assessment of carbon sink, global major river basins, hydrochem-discharge method