@article{abit_amoozegar_vepraskas_niewoehner_2012, title={Soil and hydrologic effects on fate and horizontal transport in the capillary fringe of surface-applied nitrate}, volume={189}, ISSN={["1872-6259"]}, DOI={10.1016/j.geoderma.2012.05.029}, abstractNote={Substantial horizontal solute transport has been demonstrated to occur in the capillary fringe (CF) above a flowing ground water, yet the importance of the CF for solute movement has generally been ignored. This study was conducted to evaluate the fate and horizontal transport of surface-applied nitrate (NO3−) in the CF under simulated hydrologic conditions that varied flow rates. Two soils of different organic carbon content were packed in separate 240-cm long, 60-cm high and 25-cm thick flow cells. A simulated water table (WT) was established at 20 cm above the bottom of each flow cell and different pore-water velocities across the flow cell were simulated while a solution containing NO3− and bromide (Br−) was continuously applied over a small area on the surface of the soil in the flow cell. Soil solution samples were collected from two depths below the WT and two depths within the CF above the WT at four locations along the flow cell. Subsurface horizontal transport of surface-applied NO3− tended to occur exclusively in the CF as the pore-water velocity was increased. In the flow cell with soil having a small amount of organic carbon (0.3 g kg− 1), normalized concentration of NO3− and Br− remained very comparable at all monitoring locations above and below the WT. Nitrate loss via denitrification in this case was not observed as conditions were oxidizing. In flow cells with soils having an organic carbon content of 35 g kg− 1, some Br− was detected below the WT while NO3− was essentially absent. Conditions below the WT favored NO3− loss via denitrification as reflected by very low redox potentials (< 250 mV). These results suggest that collection of samples from the CF should be considered when monitoring subsurface fate and transport of surface-applied NO3− in locations with laterally moving shallow ground water.}, journal={GEODERMA}, author={Abit, Sergio M., Jr. and Amoozegar, Aziz and Vepraskas, Michael J. and Niewoehner, Christopher P.}, year={2012}, month={Nov}, pages={343–350} }
 @article{abit_amoozegar_vepraskas_niewoehner_2008, title={Fate of nitrate in the capillary fringe and shallow groundwater in a drained sandy soil}, volume={146}, ISSN={["1872-6259"]}, DOI={10.1016/j.geoderma.2008.05.015}, abstractNote={It is commonly assumed that nitrate (NO3−) and other anions entering the soil move downward through the vadose zone, and then move horizontally in the groundwater. Recent laboratory studies, however, indicate that water movement and transport of pollutants can also take place in the capillary fringe (CF) above the water table (WT). This field study evaluated the fate of NO3− in the CF and shallow groundwater (SGW) for a sandy soil (Aeric Alaquod) with shallow water table. Ten L of a solution containing approximately 18 mmol L− 1 nitrate [2.66 g L− 1 Mg(NO3)2] and 77 mmol L− 1 bromide (9.12 g L− 1 KBr) were applied to the soil above the CF. The movement of both NO3− and Br− was monitored for 84 days by using tension lysimeters installed at depths between 45 and 105 cm at radial distances of 20, 60, 120, 220 and 320 cm from the application point. Nitrate and Br− plumes that entered the CF from the unsaturated zone moved horizontally in the CF until both species were partially carried into the groundwater by the fluctuating WT following rain events. Normalized concentrations of NO3−N and Br− remained comparable as they moved horizontally in the CF up to 320 cm from the tracer application spot. However, below the WT the detected normalized concentration of Br− was higher than that for NO3− indicating nitrate loss, perhaps due to denitrification. When monitoring subsurface NO3−, solely relying on collection of groundwater samples may lead to an underestimation of the extent of NO3− contamination and transport in the subsurface.}, number={1-2}, journal={GEODERMA}, author={Abit, Sergio M. and Amoozegar, Aziz and Vepraskas, Michael J. and Niewoehner, Christopher P.}, year={2008}, month={Jul}, pages={209–215} }
 @article{abit_amoozegar_vepraskas_niewoehner_2008, title={Solute transport in the capillary fringe and shallow groundwater: Field evaluation}, volume={7}, DOI={10.2136/vzj.2007.0102}, number={3}, journal={Vadose Zone Journal}, author={Abit, S. M. and Amoozegar, Aziz and Vepraskas, Michael and Niewoehner, C. P.}, year={2008}, pages={890–898} }