Systematic formulation of equations for trace-gas uptake by soil

We systematically and explicitly derived equations to estimate trace-gas uptake by soil using closed-chamber and flow-through-chamber techniques. We began from fundamental equations and reasonable assumptions, such as first-order kinetics and constant gas concentration in chambers for surface fluxes and laboratory bulk-soil experiments (emission and uptake). The important variables are deposition velocity, uptake rate in volume per unit mass of soil, and (relative) uptake rate in volume per unit of soil volume. Units of the uptake rate in volume per unit mass of soil and the (relative) uptake rate in volume per unit of soil volume are m(3) kg(-1) s(-1) and s(-1) in MKS, respectively. We discuss the concept of deposition velocity with those of destruction velocity and uptake velocity. We also mention the relatively well-conserved mass balance of surface-soil chamber measurements of trace gas uptake.