MAGNETIC SUSCEPTIBILITY AND SOIL POLLUTION IN EL PASO, TEXAS

Elevated levels of lead, copper, and arsenic in the soils of El Paso, Texas, (Barnes, 1993, U.S. EPA, 2002) have raised environmental and health concerns for area residents. To determine the possible source(s) and risk, our investigation (funded by the National Institute of Health) uses a combination of magnetic susceptibility measurements, chemical analyses, and toxicity screenings. Soil samples were collected from residential, industrial, and undeveloped areas in El Paso. Magnetic susceptibility measurements ranged from 0.38 e-04 to 4.42 e-04 (cgs). High magnetic susceptibilities were found in the northeast near a former artillery range and in the west side near four major potential anthropogenic sources: the ASARCO smelter, El Paso Electric power plant, a dismantled oil refinery, and the I-10 freeway. Curie temperature data indicate the main magnetic mineral is magnetite. Chemical analyses will be done to identify the concentration of Pb, As, and Cu in the soils. Initial comparisons indicate that the magnetic susceptibility measurements positively correlate to metal concentrations previously measured by Barnes (1993) in the sampled areas. Initial studies have indicated that the water-soluble (bioavailable) concentrations of the metals found in tested soils, most specifically copper, are not toxic using Botsford’s (2000) toxicity assay. Our magnetic susceptibility measurements imply that several sources may have contributed to the pollution.

Barnes (1993) An Evaluation of Metals concentrations in surficial soils, El Paso County, Texas, Thesis, University of Texas at El Paso. Botsford (2000) A Simple, Inexpensive, and rapid method to determine toxicity using a bacterial indicator organism, Proceedings of the 2000 Conference on Hazardous Waste Research, p. 22-35. U.S. EPA (2002) El Paso County Metals Survey.