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A Method to Infer In Situ Reaction Rates from Push‐Pull Experiments
Author(s) -
Snodgrass Mark F.,
Kitanidis Peter K.
Publication year - 1998
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.1998.tb02839.x
Subject(s) - tracer , sampling (signal processing) , advection , mechanics , work (physics) , flow (mathematics) , reaction rate , dispersion (optics) , zero order , slug test , volumetric flow rate , environmental science , computer science , thermodynamics , chemistry , soil science , mathematics , first order , physics , hydraulic conductivity , soil water , biochemistry , filter (signal processing) , optics , computer vision , catalysis , nuclear physics
A method to evaluate first‐order and zero‐order in situ reaction rates from a push‐pull test is presented. A single‐well push‐pull test starts with the rapid injection of a well‐mixed slug containing a known quantity of a conservative tracer and a reactive solute into the saturated zone. The slug is then periodically extracted and sampled from the same well. For zero‐ or first‐order reactions, in the absence of sorption and assuming negligible background concentrations, these measurements can be used to evaluate reaction rate coefficients directly. The method does not involve computer‐based solute transport models and requires no knowledge of regional ground water flow or hydraulic parameters. The method performs well when the dominate processes are advection, dispersion, and zero‐ or first‐order irreversible reactions. Regional flow velocities must be sufficiently low such that the slug stays within the area of the well during the sampling phase. In the case of zero‐order reactions, results using the method proposed here are compared with those obtained through the traditional method of calibrating a computer‐based transport model. The two methods give similar estimates of the reaction rate coefficient. The method is general enough to work with a broad range of push‐pull experiment designs and sampling techniques.