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
Heavy-Metal Transport in a Sand and Gravel Aquifer with Variable
Chemical Conditions, Cape Cod, Massachusetts
by
James A. Davis (U.S. Geological Survey, Menlo Park, Calif.),
Douglas B. Kent (U.S. Geological Survey, Menlo Park, Calif.), Jennifer A.
Coston (U.S. Geological Survey, Menlo Park, Calif.), and Kathryn M. Hess
(U.S. Geological Survey, Marlborough, Mass.)
Abstract
An overview is presented of a field-based research program that is examining
the significance of chemical speciation and variable aquifer chemistry on
the transport of toxic metals in ground water. Natural-gradient tracer tests
and laboratory experiments with subsurface materials have been used to identify
the most important chemical reactions that influence the transport of chromium(VI)
and metal-ethylenediaminetetra-acetic acid (EDTA) complexes in the aquifer
at the Cape Cod Toxic-Substances Hydrology Research site. The field experiments
are being conducted in an uncontaminated, recharge zone and a mildly reducing,
sewage-contaminated zone of the shallow, sand and gravel aquifer. The results
of several years of research at the site have been used to design a large-scale
tracer test at the site (begun in April 1993) involving eight tracers (bromide,
chromium, zinc, copper, lead, nickel, EDTA, and potassium). The new experiment
will be the most complex and detailed investigation of multispecies, multireaction
transport ever conducted in the field. The pertinent results of previous
small-scale tracer tests are reviewed, and the objectives and expected results
of the new tracer test are discussed.
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