A considerable fraction of soil-respired CO2 is not emitted directly to the atmosphere Pérez Sánchez-Cañete, Enrique Barron-Gafford, Greg A. Chorover, Jon All data used in this study are freely available (http://criticalzone.org/ catalina-jemez/data/datasets/). The authors wish to thank Rebecca Larkin Minor and Nate Abramson for their careful operation and maintenance of the field measurement devices. The program “Unidades de Excelencia Científica del Plan Propio de Investigación de la Universidad de Granada” funded the cost of this publication Soil CO2 efflux (Fsoil) is commonly considered equal to soil CO2 production (Rsoil), and both terms are used interchangeably. However, a non-negligible fraction of Rsoil can be consumed in the subsurface due to a host of disparate, yet simultaneous processes. The ratio between CO2 efflux/O2 influx, known as the apparent respiratory quotient (ARQ), enables new insights into CO2 losses from Rsoil not previously captured by Fsoil. We present the first study using continuous ARQ estimates to evaluate annual CO2 losses of carbon produced from Rsoil. We found that up to 1/3 of Rsoil was emitted directly to the atmosphere, whereas 2/3 of Rsoil was removed by subsurface processes. These subsurface losses are attributable to dissolution in water, biological activities and chemical reactions. Having better estimates of Rsoil is key to understanding the true influence of ecosystem production on Rsoil, as well as the role of soil CO2 production in other connected processes within the critical zone 2019-11-14T12:52:00Z 2019-11-14T12:52:00Z 2018-09-10 info:eu-repo/semantics/article Sánchez-Cañete, E.P., Barron-Gafford, G.A. & Chorover, J. A considerable fraction of soil-respired CO2 is not emitted directly to the atmosphere. Sci Rep 8, 13518 (2018) [doi:10.1038/s41598-018-29803-x] http://hdl.handle.net/10481/57904 10.1038/s41598-018-29803-x eng FP7-PEOPLE-2013-IOF, 625988 http://creativecommons.org/licenses/by/3.0/es/ info:eu-repo/semantics/openAccess Atribución 3.0 España Springer Nature