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Real Time Continuous Sampling and Analysis of Solutes in Soil Columns
Author(s) -
Chendorain Michael,
Ghodrati Masoud
Publication year - 1999
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1999.03615995006300030007x
Subject(s) - tracer , dispersion (optics) , sampling (signal processing) , displacement (psychology) , peristaltic pump , soil water , analytical chemistry (journal) , environmental science , materials science , chemistry , soil science , detector , chromatography , optics , physics , psychology , meteorology , nuclear physics , psychotherapist
Many of the current in situ techniques for breakthrough curve (BTC) analysis of water tracers involve incremental collection and subsequent analysis of pore water using a solution sampler. Solution samplers are still widely used due to their low cost and ease of use. We have developed an automated method for continuous sampling and analysis of pore water during displacement studies. The system consists of a small tube sampler (STS) connected to a peristaltic pump that continuously draws a sample of solution and passes it through a UV absorbance detector. The STS is a small (1.4 mm i.d., 2.3 mm o.d) stainless steel tubing with a screen mesh covered tip that can be inserted into a soil column during or after packing. The STS length can be modified. The soil solution is analyzed continuously in nearly real time and is then discarded or collected. Using nitrate as a tracer and a multimeter connected to a computer, we have been able to obtain and monitor the development of continuous BTCs in nearly real time (time delay ≈ 1–2 min). This system was tested in homogenous laboratory soil‐column studies using three soils. The convection‐dispersion equation was used to estimate transport parameters. The system produced BTCs with mass balances of 1.02 ± 0.04 and transport parameters that compared well with conventional measurement techniques. The STS is useful for miscible displacement studies and produces high resolution BTCs that can be used to estimate average pore water velocity and dispersion coefficients.