Wednesday, April 2, 2008 : 9:20 a.m.
A simple pore-water hyrogen diffusion sampler for understanding redox conditions in saturated sediment
Molecular hydrogen (H2) is an important and diagnostically useful intermediate product and electron donor in microbial metabolism. Concentrations of dissolved H2 often are diagnostic of the predominant terminal electron accepting processes (TEAPs) in ground-water systems or aquatic sediments. H2 concentrations are routinely measured in ground-water monitoring wells, but are rarely measured in saturated aquatic sediments, due to a lack of simple and practical sampling methods. Laboratory and field tests presented here demonstrate that a simple, syringe-based diffusion sampler can be used to collect representative samples for analysis of H2 concentrations in saturated sediments. The syringe-based H2 samplers described here are easy to assemble and deploy, environmentally robust, suitable for a variety of hydrologic settings, including saturated sediments and low-permeability aquifers. The ability of the samplers to provide a sample readily transferable to stable serum vials allows the samples to be shipped offsite for analysis if onsite analysis is not available.
Don Vroblesky, Ph.D., U.S. Geological Survey Dr. Don A. Vroblesky is a research hydrologist with the U.S. Geological Survey in Columbia, South Carolina. He is the inventor of the passive diffusion bag sampler and of a method to use tree cores as a tool to examine the distribution of volatile organic compound contamination in ground water.
Paul B. Bradley, Ph.D., U.S. Geological Survey Dr. Paul Bradley is a research ecologist with the U.S. Geological Survey.
Francis H. Chapelle, Ph.D., U.S. Geological Survey Dr. Francis Chapelle is is a research microbiologist with the U.S. Geological Survey.