Construction and Testing of a Durable Platinum Wire Eh Electrode for In Situ Redox Measurements in the Subsurface |
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| Authors: | G. D. W. Swerhone J. R. Lawrence J. G. Richards M. J. Hendry |
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| Affiliation: | George D.W. Swerhone is a research technician with the National Water Research Institute of Environment Canada, Saskatoon, Saskatchewan (11 Innovation Blvd., Saskatoon, Saskatchewan, Canada S7N 3H5). He holds a B.Sc. in biology from the University of Saskatchewan and has 17 years experience in environmental research, working extensively with electronic monitoring of environmental parameters.;John R. Lawrence is a microbial ecologist with the National Water Research Institute in Saskatoon, Saskatchewan. He received his Ph.D. in soil microbiology from the University of Saskatchewan. His research areas include microbial formation of biofilms, transformations of contaminants by degradative consortia, and investigation of microbial processes using model systems.;Jack Richards obtained his M.Sc. in hydrogeochemistry from the University of Saskatchewan in 1998. He is currently working as an environmental supervisor for Cogema Resources Inc.;Jim Hendry obtained his Ph.D. in hydrogeochemistry from the University of Waterloo in 1984 and is presently professor and research chair of aqueous and environmental geochemistry at the University of Saskatchewan-Department of Geological Sciences (114 Science Pl., Saskatoon, Saskatchewan, Canada S7N 5E2, (306) 966-5720 phone, (306) 966-8593 fax, e-mail). His research interests include the fate and transport of solutes in aquitards and the rates of biogeochemical reactions in unsaturated zones. |
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| Abstract: | We have developed a rugged, durable platinum wire Eh electrode for application in subsurface environments. The electrode design is described in detail and its performance under aerobic and anaerobic steady-state and transient conditions is assessed. The electrode consists of a 0.5-mm-diameter platinum wire (99.99% purity) cast in a glass fiber-reinforced epoxy jacket. The construction allowed installation through direct insertion into sandy media to depths up to several meters. Data collection was through connection to a datalogger with high impedance input; data points were collected every 10 seconds and averaged and stored once an hour. The electrodes functioned in situ for periods of more than three years and gave reliable readings during oxic, anoxic, and transitional conditions. Performance testing and examination of electrodes recovered after three years in situ indicated that they were not impacted by corrosion, dissolution, or poisoning. |
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