Date of Award

2017-01-01

Degree Name

Master of Science

Department

Geology

Advisor(s)

Deana Pennington

Second Advisor

Jorge Gardea-Torresdey

Abstract

The former El Paso ASARCO Smelting and Refining Co. operated between 1877 and 1999, the pyrometallurgic activity was estimated to have discharged excess of a 1,000 tons of lead (Pb) into the atmosphere from 1969-71. It was estimated 96 tons of (Pb) were emitted on an annual basis from the standing ore and fluid beds. The Environmental Protection Agency (EPA) determined that lead (Pb) is the heavy metal of the highest concentration within the vicinity of the smelter. After the smelter production ceased, flash flooding common to the southwest, such as the 2006 historic flood, increased transportation of superficial contaminants and was expected to have reduced initial concentrations located on the mountain east of the demolition zone of impact. This served as a "new" time stamp to base retrospective analysis of (Pb) distribution. Lead absorption by humans has been epidemiologically associated with delayed effects after exposure and chronic health issues including, but not limited to, renal disease, neurodegenerative disease, hypertension, and cognitive dysfunction at sub-regulatory levels < 10 µg/dL. The ASARCO smoke stacks were demolished in 2013. A discrepancy in the duration of run-time among the air-quality monitors the day of the demolition suggests that bystanders observing this event may have been exposed to (Pb) and other heavy metal contaminants. This study sought to investigate temporal changes in lead concentration within the vicinity of the former ASARCO site using pre-demolition recorded (Pb) concentrations and observations collected in 2015 to determine the extent to which lead may have been redistributed during the demolition event, or other plausible environmental agents governing redistribution processes. Lead concentrations were measured in the leaves of Creosote Bush (Larrea tridentata) and soil at the base of the plant. Creosote is a known bioaccumulator of lead that is susceptible to aeolian deposition, and to similar lead protein interactions that may result in oxidative stress as observed from human exposure to lead. This has rationalized it as a suitable bioindicator for lead recontamination and health impacts indicative of air quality corresponding to sub-regulatory Blood Lead Levels (BLL) < 10 µg/dL. Temporal comparison and analysis of soil (Pb) concentrations from 1993, 2001, and 2015 showed anomalously high (Pb) concentrations in 2015, suggesting the force of impact from the demolition of the former ASARCO smoke stacks in 2013 caused a localized re-contamination event 0.5 to 0.75 mile east of the designated demolition zone. Spatial analysis of azimuthal trends in (Pb) distribution provided evidence that long-term trends in wind direction appear to have been the dominant source of (Pb) distribution during the smelter operation. However, after smelter production seized, seasonal rain events and flash flooding likely served as the primary mode of transportation of these surficial contaminants, which is complicated by topography, flow dynamics, metal speciation, and particulate size and mass.

Language

en

Provenance

Received from ProQuest

File Size

120 pages

File Format

application/pdf

Rights Holder

Stephanie A Robinson

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