Date of Award

2018-01-01

Degree Name

Master of Science

Department

Geological Sciences

Advisor(s)

Nicholas E. Pingitore

Abstract

The Paso Del Norte airshed is shared by two cities, El Paso, Texas, U.S.A. and Ciudad Juarez, Chihuahua, Mexico. Population growth in both cities and their desert climate has created persistent challenges in meeting air quality standards for particulate matter, which is generated from both natural and anthropogenic sources.

In Europe, ceria or cerium dioxide (CeO2), introduced into diesel road fuel as nanoparticles, has significantly reduced emissions as well as increased vehicle mileage. Concerns have been raised there about the fate and potential health risks associated with the nanoceria (n-Ce) emitted in diesel exhaust. In the U.S.A on-road use of n-Ce additives is still under regulatory study. Because of possible future use, it is important to establish baseline data on current levels of airborne cerium. This is of special interest in El Paso should n-Ce be used in neighboring Cd. Juarez, Mex.

This study analyzed weekly total concentrations of cerium in El Paso air at 8 sampling stations during 2006 to 2009. A PM10 dichotomous sampler had been used to simultaneously collect PMC (the PM10 to PM2.5 fraction) and PMF or PM2.5. An X-ray fluorescence instrument had been used to measure 61 elements, of which cerium was one, in the two PM fractions.

Results indicate higher levels of airborne cerium in PMC (~2 ng/m3 average for all sites for entire study period) than in PMF (~1 ng/m3). Higher values for coarse and to a lesser degree for fine PM are associated with sites proximal to the core of the binational contiguous El Pasoâ??Cd. Juarez metroplex. This indicates a significant anthropogenic contribution to airborne cerium in El Paso; abrasion of vehicle parts that incorporate cerium-doped alloys, residual cerium catalysts from gasoline refining, open burning of solid waste, and other commercial and industrial debris are the likely sources. No overall seasonal patterns were evident other than a possible decrease in PMC during the summers; this is consistent with a significant anthropogenic contribution.

Language

en

Provenance

Received from ProQuest

File Size

48 pages

File Format

application/pdf

Rights Holder

Esenam Adzo Fumador

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