Evaluation of porous cup soil‐water samplers under laboratory conditions: Comparison of ceramic and PTFE cups

Abstract

Three different types of soil solution samplers (two ceramic cups and PTFE) were tested in the laboratory to validate their use for collecting soil‐water samples and for monitoring the chemical composition of soil solutions. Interactions between porous materials and chemical solutions were examined under different experimental conditions for several major cations (Ca2+, Mg2+, Na+ and K+) and anions (HCO‐ 3, NO‐ 3, SO4 2‐ and Cl‐) and for several minor ions (NH+ 4, NO‐ 4, PO4 3‐and B). The results show that ceramic cups are not inert for bicarbonate, calcium and phosphate ions. Their use is only valid for a limited number of ions such as chloride and nitrate which, however, are the most studied ions in field experiments. PTFE cups have less restrictions although their use in measuring sulphates, phosphates and ammonium presents some problems. Choosing the appropriate type of cup depends on the objectives. In any case, laboratory experiments must be performed before installation.