Wednesday, November 7, 2007 - 10:00 AM
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Measurement of Redox Potentials in Soils: How Is It Done? What Does It Mean?.

Martin C. Rabenhorst1, W. Dean Hively2, and Bruce James1. (1) Department of Environmental Science and Technology, University of Maryland, 1109 HJ Patterson Hall, College Park, MD 20742, (2) USDA-ARS Hydrology and Remote Sensing Laboratory, Bldg. 007, Rm. 7, BARC-West, Beltsville, MD 20705

Researchers working in wetlands have commonly measured soil redox potentials using Pt electrodes, but there has been some variety in the approach and methodology used. Some install the Pt electrodes in the soil for only short periods (minutes or hours) while others leave electrodes installed in the soil for periods ranging up to months or even years.  In addition, various devices have been utilized for measuring the voltages generated.  Most field measurements are made using generic multimeters or lab grade volt meters (if measurements are made manually) or else the electrodes are connected to an automatic recording device such as a data logger expanded to accommodate additional channels by using a multiplexer. We conducted a mesocosm experiment to compare and evaluate the impact of these various approaches. We will discuss our observations and experiences measuring soil redox potentials and will raise questions that have serious implications for interpreting Eh measurements when conducting soil and wetland research.