U.S. Geological Survey Toxic Substances Hydrology Program--Proceedings
of the Technical Meeting, Colorado Springs, Colorado, September 20-24, 1993,
Water-Resources Investigations Report 94-4015
  
Difficulties with Intermediate-Scale Experiments for Studies
of Iron Chemistry in Streams Affected by Acidic Mine Drainage
by
Diane M. McKnight (U.S. Geological Survey, Boulder, Colo.), Kenneth
E. Bencala (U.S. Geological Survey, Menlo Park, Calif.), Richard A. Harnish
(U.S. Geological Survey, Boulder, Colo.), and Robert L. Runkel (U.S. Geological
Survey, Boulder, Colo.)
Abstract
Iron chemistry in streams affected by acidic mine drainage is driven
by many dynamic processes, such as precipitation, dissolution, photoreduction
of ferric iron and microbial oxidation of ferrous iron. These processes
can be studied with a variety of approaches, ranging from controlled
laboratory experiments to field, stream-scale perturbation experiments.
Experiments that are intermediate between laboratory and field experiments
using sediments and water from the Snake River have been conducted. These
experiments have been useful in demonstrating the general nature of iron
biogeochemistry. However, difficulties reproducing results occur both within
and among experiments. The heterogeneous nature of the stream sediments
and seasonal variations in trace phases of iron oxides confound interpretation
of the results and limit the predictive value of such experiments.
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