Research Communications Effects of Sampling Well Construction on H2 Measurements Made for Characterization of Redox Conditions in a Contaminated Aquifer P O U L L . B J E R G , * ,† R A S M U S J A K O B S E N , ‡ HENRIK BAY,† METTE RASMUSSEN,† HANS-JØRGEN ALBRECHTSEN,† AND THOMAS H. CHRISTENSEN† Department of Environmental Science and Engineering/ Groundwater Research Centre, Building 115, Technical University of Denmark, DK-2800 Lyngby, Denmark, and Department of Geology and Geotechnical Engineering/ Groundwater Research Centre, Building 204, Technical University of Denmark, DK-2800 Lyngby, Denmark
Measurement of hydrogen, H2, has been suggested for characterization of redox levels in groundwater and has recently been used in the delineation of redox processes in contaminated aquifer. In this investigation, we evaluate the influence of materials and age of the well on the H2 measurements performed in a leachate-contaminated sandy aquifer at the Grindsted Landfill, Denmark, Four types of small diameter wells were tested, covering a range of materials (teflon, PVC, black iron, and stainless steel) and installation methods (driven wells and bailer techniques). The results suggest that the following precautions are taken in order to obtain valid measurements of H2: (1) all iron parts should be avoided as well materials, (2) PVC, teflon, and probabaly stainless steel are suitable materials for wells, (3) wells for monitoring H2 levels shall rest for a period from installation till sampling (our experiences indicate approximately 3 months) before their readings can be trusted, and (4) installation of wells or heavy mechanical work in the subsoil can affect the H2 levels in nearby wells.
conditions (methanogenic, sulfate-reducing, iron-reducing, and perhaps manganese-reduction and nitrate-reduction) may be determined by measuring H2 in the groundwater. The concentrations of H2 typically range from below the lower detection limit of the method (
