Field-scale transport of conservative and reactive solutes through a deep vadose zone was analyzed by means of two different model processes for the local description of the transport. The first is the advection-dispersion equation (ADE) model, and the second is the mobile-immobile (MIM) model. The analyses were performed by means of three-dimensional (3-D), numerical simulations of flow and transport considering realistic features of the flow system, pertinent to a turf field irrigated with treated sewage effluents (TSE). Simulated water content and concentration profiles were compared with available measurements of their counterparts. Results of the analyses suggest that the behavior of both solutes in the deep vadose zone of the Glil Yam site is better quantified by the MIM model than by the ADE model. Reconstruction of the shape of the measured solute concentration profiles using the MIM model required relatively small mass transfer coefficient, c, and relatively large volume fraction of the immobile water h im . This implies that for an initially nonzero solute concentration profile, as compared with the MIM model, the ADE model may significantly overestimate the rate at which solutes are loaded in the groundwater. On the contrary, for an initially zero solute concentration profile, as compared with the MIM model, the ADE model may significantly underestimate solute velocities and early arrival times to the water table. These findings stem from the combination of relatively small c and relatively large h im taken into account in the MIM model. In the first case, this combination forces a considerable portion of the solute mass to reside in the immobile region of the water-filled pore space, while the opposite is true in the second case.

Six boreholes were drilled during the course of a year to a depth of 2 m beneath the water table, located at a depth of about 28 m, under agricultural land sprinkler irrigated with treated sewage efluents in the Coastal Plain aquifer of Israel to determine the extent of penetration of 20 pharmaceuticals and personal care products (PPCPs) into the unsaturated zone. The ields were planted to turf and had different histories of efluent irrigation. From each borehole, 7 to 21 samples were taken for analysis of PPCPs, as was the underlying groundwater. Nine PPCPs (carbamazepine and its metabolite 10-hydroxy-10,11-dihydrocarbamazepine, acridone and acridine, venlafaxine, sulfamethoxazole, oxcarbazepine, O-desmethylvenlafaxine, and caffeine) were detected in the vadose zone of the study area to a depth of 27 m. For example, the detected concentrations of carbamazepine were up to 109 ng/kg, of caffeine up to 36,700 ng/kg, and of venlafaxine up to 50 ng/kg. Only ive of the compounds (carbamazepine, acridone, venlafaxine, sulfamethoxazole, and caffeine) were found in the underlying groundwater with concentrations in the nanogram per liter range. The results of this work show that signiicant amounts of PPCPs can penetrate even a thick vadose zone of 27 m with sections containing up to 50% clay and up to 0.40% soil organic C. Venlafaxine, for example, penetrated the vadose zone at an average velocity of 2.8 to 4 m/yr. Irrigation with treated sewage efluents or contaminated water should be carefully considered if the penetration of PPCPs into groundwater is undesirable.

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