MOVEMENT OF SYNTHETIC MICROSPHERES IN SATURATED SOIL COLUMNS

Publisher Website
Google Scholar
Abstract
We studied the mobility of synthetic, negatively charged (carboxylic groups) microspheres in the size range of a few microns, under various conditions, in saturated soil columns ranging from sand to heavy soil. We pumped pulses of the microsphere suspension through the column and recorded spectrophotometrically the optical density of the effluent. Retention of microspheres took place mainly near the entrance site of suspension, determined by scanning electron microscopy, and increased considerably with decreasing of flow rate. Consecutive runs on the same column resulted in a small but steady decrease in the recovery of microspheres. The presence of 6 mM CaCl2 decreased the recovery considerably. Scanning electron microscopy of the effluent indicates that large microspheres are intercepted more readily than small ones. Latex particles of 0.12 and 0.21 μ were mobile in both heavy and light soils and were similarly affected by CaCl2 concentration.This work serves as an experimental background for a newly proposed method for incorporating agrochemicals into the root zone. The agrochemicals under study will be incorporated into tiny particles of the order of magnitude of a few microns, dispersed in the irrigation water just before application, and carried by the water into the soil, where they will slowly release their content near the target zone (root or microbial population) without suffering excess dilution, deactivation, or leaching. We studied the mobility of synthetic, negatively charged (carboxylic groups) microspheres in the size range of a few microns, under various conditions, in saturated soil columns ranging from sand to heavy soil. We pumped pulses of the microsphere suspension through the column and recorded spectrophotometrically the optical density of the effluent. Retention of microspheres took place mainly near the entrance site of suspension, determined by scanning electron microscopy, and increased considerably with decreasing of flow rate. Consecutive runs on the same column resulted in a small but steady decrease in the recovery of microspheres. The presence of 6 mM CaCl2 decreased the recovery considerably. Scanning electron microscopy of the effluent indicates that large microspheres are intercepted more readily than small ones. Latex particles of 0.12 and 0.21 μ were mobile in both heavy and light soils and were similarly affected by CaCl2 concentration. This work serves as an experimental background for a newly proposed method for incorporating agrochemicals into the root zone. The agrochemicals under study will be incorporated into tiny particles of the order of magnitude of a few microns, dispersed in the irrigation water just before application, and carried by the water into the soil, where they will slowly release their content near the target zone (root or microbial population) without suffering excess dilution, deactivation, or leaching. © Williams & Wilkins 1980. All Rights Reserved.

This publication has 0 references indexed in Scilit: