Date of Award

2011-01-01

Degree Name

Doctor of Philosophy

Department

Geological Sciences

Advisor(s)

Thomas E. Gill

Second Advisor

Philip C. Goodell

Abstract

Substantial dust loads are transported from drylands including the Saharan, Asian, and Chihuahuan Desert deposits by localized to planetary-scale processes to nearby and distal sites. These dusts may carry harmful constituents. To evaluate dust movement patterns and characteristics relative to carried constituents, three studies are presented comprising (A) Localized displacement of uranium and progeny radionuclides from high-grade uranium ore storage piles at Peña Blanca, Chihuahua, Mexico; (B) Long-distance transport of plutonium via Saharan and Asian aeolian pathways; and (C) Dust movement patterns in military maneuvering and non-maneuvering areas at White Sands Missile Range (WSMR), New Mexico. Study (A) evaluated surface soil, resuspended and naturally accreted sediment over a 2.4 year period from three sites on, upwind, and downwind of the ore piles. Study (B) investigated plutonium levels in dust aerosols at Izaña, Canary Islands (IZT); Barbados (BAT); Gosan, South Korea (GOS); and Mauna Loa Observatory, Hawaii (MLO). In study (C), 24 sampling sites amassed sediment in military maneuvering and non-maneuvering areas over ten seasonal phases. Methodologies applied to collect and analyze data at the various sites included passive sediment/dust collectors and high volume aerosol samplers; laser diffraction particle-sizing; X-ray diffraction for mineralogy; gamma-ray spectroscopy for nuclide radioactivity levels; electron microprobe analysis for element mapping; inductively coupled plasma mass spectroscopy (ICP-MS) for element concentrations; and alpha spectrometry for plutonium levels. Key findings included for: (A) Geochemical analyses indicated uranophane and uranium progeny radionuclides displaced in aeolian pathways to a small degree downwind from the ore pile via saltation, but effectively not at all upwind. (B) Plutonium activity/dust mass concentrations (Bq/μg) at the four sites had the following rank order: GOS > MLO > BAT > IZT. GOS reflected Pu levels plausibly attributable to new wind erosion of Asian deserts, while IZT, BAT, and MLO aerosol plutonium levels derived from re-entrained global fallout. (C) Spring and summer yielded the highest and least sediment mass amounts, respectively. Sediment yield was greater for dune areas than for shrublands irrespective of location in maneuvering or non-maneuvering areas; local geomorphology appears to play the key role in aeolian sediment transport at WSMR.

Language

en

Provenance

Received from ProQuest

File Size

356 pages

File Format

application/pdf

Rights Holder

Roberto Velarde

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