ABSTRACT
Protection of ground water quality requires accurate knowledge of chemical transport through the vadose zone, which is, in large part, limited by the accuracy of available sampling techniques. Methods for continuous sampling of soil solutes generally involve the acquisition of water drained either by the force of gravity (e.g., gravity pan samplers, agricultural tile lines, and shallow wells), or by applying a “capillary” suction (e.g., porous cup samplers and wick pan samplers). While all these sampling techniques result in a solute concentration for the vadose zone, only tile lines and pan samplers define the sampling volume and, hence, allow a mass balance and prediction of solutes moving to the aquifer. In this chapter, the effectiveness of wick and gravity pan samplers in assessing solute transport in the vadose zone is discussed. Concentrations measured with the pan samplers are compared to those obtained from porous cup samplers.
