Simple plastic fiber-based optode array for the in-situ measurement of ground air oxygen concentrations

Martin Koelling; Henrik Hecht; Gerhard A. Holst

doi:10.1117/12.456952

22 February 2002 Simple plastic fiber-based optode array for the in-situ measurement of ground air oxygen concentrations

Martin Koelling, Henrik Hecht, Gerhard A. Holst

Author Affiliations +

Proceedings Volume 4576, Advanced Environmental Sensing Technology II; (2002) https://doi.org/10.1117/12.456952
Event: Environmental and Industrial Sensing, 2001, Boston, MA, United States

Abstract

A fiberoptical optode array for the in-situ measurement of ground air oxygen concentrations has been used in both, lab and field experiments to monitor subsurface oxygen consumption in a lignite mine tailing affected by acid mine drainage formation. The single sensors are constructed from plastic fibers (core diameter 1 mm) with an oxygen sensitive fluorescent dye film attached to the fiber tip. Measurements were performed with a commercially available oxygen measuring instrument (MICROX 1, PreSens, Regensburg, Germany) which had been modified for the use with 1 mm plastic fibers. The instrument evaluates the oxygen dependent change of the luminescence lifetime of an oxygen indicator using a phase modulation technique. First measurements show a strong oxygen consumption by pyrite oxidation indicated by a ground air oxygen concentration gradient pointing to a depth of approximately 6 m. The measurement of the pyrite depth distribution of the material confirms the assumption that the 40 year old tailing has been depyritized down to a depth of 6 m and that pyrite oxidation and acid mine drainage formation are still going on. Investigations will proceed in order to assess long-term sensor stability under strongly acid conditions.

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Martin Koelling, Henrik Hecht, and Gerhard A. Holst "Simple plastic fiber-based optode array for the in-situ measurement of ground air oxygen concentrations", Proc. SPIE 4576, Advanced Environmental Sensing Technology II, (22 February 2002); https://doi.org/10.1117/12.456952

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