NITRATE FATE AND TRANSPORT IN A LARGE SOIL AND GROUNDWATER-MODELING TANK

Conventional fate and contaminant framework assumes that as water and contaminants travel through the ground surface, the vadose zone, and eventually the groundwater table, the infiltration is uniform and an average hydraulic conductivity for the strata is used. However, as more recent research has demonstrated, this framework is not adequate; water passes through the vadose zone through the soil strata’s macropores, referred to as preferential pathway flow. These preferential pathways transport both water and contaminants at much higher rates and through less area, drastically reducing travel time and soil attenuation. This study focuses on the investigation of interaction between macropores and preferential pathway flow and nitrate fate and transport to the groundwater table through the vadose zone. The methods used in this research include a lab experiment using a soil-groundwater tank and mathematic modeling with GMS (Groundwater Modeling System). This study will result in a better understanding of the controlling factors of contaminant fate and transport through the vadose zone and allow for the proper nitrate mitigation framework to be implemented.