Rivers play an important role in the global carbon (C) cycle. However, it remains unknown how long-term river C fluxes change because of climate, land-use, and other environmental changes. Here, we investigated the spatiotemporal variations in global freshwater C cycling in the 20th century using the mechanistic IMAGE-Dynamic Global Nutrient Model extended with the Dynamic In-Stream Chemistry Carbon module (DISC-CARBON) that couples river basin hydrology, environmental conditions, and C delivery with C flows from headwaters to mouths. The results show heterogeneous spatial distribution of dissolved inorganic carbon (DIC) concentrations in global inland waters with the lowest concentrations in the tropics and highest concentrations in the Arctic and semiarid and arid regions. Dissolved organic carbon (DOC) concentrations are less than 10 mg C/L in most global inland waters and are generally high in high-latitude basins. Increasing global C inputs, burial, and CO2 emissions reported in the literature are confirmed by DISC-CARBON. Global river C export to oceans has been stable around 0.9 Pg yr–1. The long-term changes and spatial patterns of concentrations and fluxes of different C forms in the global river network unfold the combined influence of the lithology, climate, and hydrology of river basins, terrestrial and biological C sources, in-stream C transformations, and human interferences such as damming.
Bibliographical noteFunding Information:
This work is part of The New Delta 2014 ALW project no. 869.15.014, which is financed by the Netherlands Organization for Scientific Research (NWO). Alexander F. Bouwman and Arthur H. W. Beusen received support from the PBL Netherlands Environmental Assessment Agency through in-kind contributions to The New Delta 2014 ALW project. Lauriane Vilmin and Junjie Wang received funding from part of the Earth and life sciences (ALW) Open Programme 2016 project no. ALWOP.230, which is financed by the Netherlands Organization for Scientific Research (NWO). Joep J. Langeveld received funding from The New Delta 2014 ALW project no. 869.15.015, which is financed by the Netherlands Organization for Scientific Research (NWO). Jack J. Middelburg and Gerrit Müller are funded by the Dutch Ministry of Education, Culture and Science through the Netherlands Earth System Science Center (NESSC) and Philip A. Pika by the European Research Council Starting Grant (THAWSOME) no. 676982.
© 2021 The Authors. Published by American Chemical Society
- carbon biogeochemistry
- global budget
- process-based hydrology-biogeochemistry model
- river fluxes
- spatiotemporal variations