FIG. 7. (A) Chlorofluorocarbon and SF6 concentrations at the Northern High Plains irrigated corn site UMA measured in May 2003 compared with simulated profiles for porosity, moisture content, and tortuosity data shown in Table 2; and (B) comparison of simulated to measured N2O concentrations for root-zone production of 2.3 kg N2O-N ha–1 yr–1 occurring seasonally. X in line represents mean and range of groundwater equivalent equilibrium concentration in water-vapor-saturated air (GW EEC).