FIG. 8. (A) Chlorofluorocarbon and SF6 concentrations at the Northern High Plains irrigated corn site GNT measured in May (filled symbols) and August 2003 (open symbols) compared with simulated profiles for porosity, moisture content, and tortuosity data shown in Table 2; and (B) comparison of simulated (solid line) to measured N2O concentrations for steady root-zone production of 1.3 kg N2O-N ha–1 yr–1. Inset shows mismatch between shallow and deep data. X in line represents mean and range of groundwater equivalent equilibrium concentration in water-vapor-saturated air (GW EEC).