An evaluation of abiotic carbon sinks in deserts.

Recent field studies have reported anomalous CO2 uptake using eddy-covariance techniques in arid and semiarid ecosystems. The rates of CO2 uptake are incompatible with changes in situ of organic carbon pools. Here, I examine several potential mechanisms of abiotic CO2 uptake in arid and semiarid soils: atmospheric pressure pumping, carbonate dissolution, and percolation of soil water through the vadose zone. Each mechanism is deemed inadequate to explain the observations of the eddy-covariance systems, which must now be questioned for their accuracy in desert ecosystems.