The extraction of soil water by the suction‐cup method: a review

Abstract

This article deals with the extraction of soil water using the suction-cup method and its accompanying problems. This method has become well-developed over the past 20 years. It allows continuous sampling during any period and, if necessary, at several different depths of a soil profile. The installation of the suction probe is easy and the profile is only negligibly disturbed. Some problems may occur when this technique is used. The spatial variability of the properties investigated is often underestimated and must be clarified by sufficient replication. An important point of discussion is the bypassing of water flowing through macropores. The problems of alteration of the sample by the sampling system also deserve attention. These can be the 'filter effect' as regards macromolecules and colloids, the sorption of trace substances, and the gas exchange between the sample and the atmosphere of the sampling system.

Electrical Conductivity and Chemical Composition of Soil Solution: Comparison of Solution Samplers in Tropical Soils

“…Some sampler membranes have selective pore diameters that prevents the entrance of clay particles and organic materials, altering the composition of the soil solution (Litaor, 1988;Spangenberg et al, 1997). Variation in the volume of solution collected by the sampler is also commonly reported (Grossmann and Udluft, 1991), as well as pore plugging, which prevents the use of samplers in successive extractions of the solution (Di Bonito et al, 2008;Falcon-Suarez et al, 2014). All the aforementioned factors determine the relative efficiency of samplers and may further alter the determinations of chemical composition of the soil solution.…”

Short Report: Identifying Sources of Subsurface Flow—A Theoretical Framework Assessing Hydrological Implications of Lithological Discontinuities

“…Hereby different soil depths will be characterized by their geochemical compositions and concentrations. Soil water samples will be captured by soil solution access tubes as described by [17] installed in different depths depending on the lithological discontinuities. By investigating several soil profiles along a hillslope (upper, middle, foot slope) we will capture the spatial variability of depth-dependent geochemical compositions regarding the catena concept [18].…”

Overview of Selected Soil Pore Water Extraction Methods for the Determination of Potentially Toxic Elements in Contaminated Soils: Operational and Technical Aspects

“…With increasing sample volume the concentration of a trace metal recorded by the suction cup comes closer to the concentration in the pore water because of the equilibration of the cation exchange surface of the suction cup with the solution. However, the extraction of large sample volumes can cause a significant disturbance of the system (Grossmann and Udluft, 1991). More recently, ceramic cups were found to adsorb PO 4 3-, DOC, major and minor cations (Na + , K + , Ca 2+ , Mg 2+ , Fe 3+ , Al 3+ , Mn 2+ , and Zn 2+ ) and SO 4 2-and NO 3 -anions.…”

“…slowly percolating) water is therefore possible only as long as the capillary pressure in the soil lies above this value. As a result of the low sampling rates at capillary pressures below -70 kPa, the use of this system is limited in the majority of soils (Grossmann and Udluft, 1991).…”

“…In general, the approach employed for extracting pore water in situ is to use tension samplers such as porous cups (for a complete review see Litaor, 1988;Grossmann and Udluft, 1991). Porous cups are designed to replicate the function of a plant root, by applying suction to the soil.…”