Spatial Trends in Groundwater Arsenic Concentrations

J. Bradshaw, P. Gurian, A. Kumar and D. Breen ``Spatial Trends in Groundwater Arsenic Concentrations,'' Proceedings of AWWA Annual Conference and Exhibition, June 2009.

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.

Last modified on August 18, 2009.