Abstract:
Arsenic presents complex spatial occurrence trends that can be difficult
to identify and understand. This project sought to understand geographic
trends in arsenic occurrence using a visualization technique. The
approach taken was to link geospatially referenced arsenic concentration
information from a water quality database with elevation data contained
in Digital Terrain Elevation Data (DTED) files. DTED files are available
for all land masses across the world for public download. This allows for
the development of three-dimensional plots of arsenic concentration and
topography. The plots developed in this manner show that high arsenic is
associated with the transition from plains to piedmont on the western
side of the Delaware River Valley in New Jersey. In Oklahoma high arsenic
is found along the North Canadian River Valley. In New Mexico high
concentrations are generally high in the Rio Grande Valley but with an
area of low concentration in the southern portion of this valley. In
California, arsenic concentrations are high in the middle of the Central
Valley but moderate somewhat toward the edges. These results are
consistent with mobilization of arsenic by reductive processes in
the organic-rich sediments of river valleys, but further statistical
analysis is required to confirm the significance of this association.
The visualization software used here is broadly applicable and a user
guide for this software is available on request.