摘要：Soil CO2 efflux ( F soil ) is commonly considered equal to soil CO2 production ( R soil ), and both terms are used interchangeably. However, a non-negligible fraction of R soil 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 R soil not previously captured by F soil . We present the first study using continuous ARQ estimates to evaluate annual CO2 losses of carbon produced from R soil . We found that up to 1/3 of R soil was emitted directly to the atmosphere, whereas 2/3 of R soil was removed by subsurface processes. These subsurface losses are attributable to dissolution in water, biological activities and chemical reactions. Having better estimates of R soil is key to understanding the true influence of ecosystem production on R soil , as well as the role of soil CO2 production in other connected processes within the critical zone.
