USE OF FLUORESCENT DYES TO MARK THE PATHWAYS OF SOLUTE MOVEMENT THROUGH SOILS UNDER LEACHING CONDITIONS - .1. LABORATORY EXPERIMENTS

We offer a technique to identify the pathways of solute movement down columns of sieved soil aggregates using fluorescent dyes and recording their presence by ultraviolet photography. Pyranine was found to be the most useful dye for short-term laboratory experiments because of its high fluorescence and comparatively low adsorption coefficient. The uneven distribution of pyranine across the Horizontal faces of successive soil sections, as shown by ultraviolet photography, indicated that the solute moved preferentially in some parts of the column. The technique was found to be value in checking the uniform packing of columns of soil aggregates and to have potential use under field conditions (Part 2). © 1979 The Williams & Wilkins Co.