Open AccessIn Situ Calibration Checking Technique for Permanently Installed Oxygen Probes in the Vadose Zone
Author(s) -
Patterson Bradley M.,
Furness Andrew J.,
Woodbury Robert J.
Publication year - 2012
Publication title -
vadose zone journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.036
H-Index - 81
ISSN - 1539-1663
DOI - 10.2136/vzj2011.0157n
Subject(s) - calibration , vadose zone , in situ , remote sensing , environmental science , sampling (signal processing) , geology , meteorology , soil science , engineering , soil water , statistics , physics , mathematics , filter (signal processing) , electrical engineering
Oxygen probes used for long‐term in situ monitoring in the vadose zone generally cannot be retrieved for calibration purposes. Therefore, a method is needed for confirming the calibration of permanently installed O 2 probes. We developed a novel in situ calibration checking technique for use with permanently installed probes. The technique was tested at a pyritic tailings disposal site where O 2 probes were installed below a bentonite–polypropylene composite cover. The technique involved (i) opening a gas sampling tube to allow atmospheric O 2 ingress to the probe's location via barometric pumping and (ii) analyzing the resultant probe data collected during periods of stable, maximum probe response. Probe calibration checking was done six times during a 12‐yr period, and results showed that response data were within 5% of the original calibration. This confirmed the long‐term reliability of the probes and identified that the probes' useable life span extended to at least 12 yr.