Graduation Year

2025

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Geosciences

Major Professor

Matthew A. Pasek, Ph.D.

Committee Member

Aurelie Germa, Ph.D.

Committee Member

Gregory Herbert, Ph.D.

Committee Member

Maheen Gull, Ph.D.

Committee Member

Heather Abbott, Ph.D.

Keywords

Phosphate, Olivine, Fulgurites, Phosphogypsum

Abstract

The element phosphorus is a key biogenic element that is often the limiting reagent for life. Phosphorus is quickly bound by metal divalent cations making it virtually insoluble and inert in water (forming the phosphate mineral apatite). Due to this, it becomes imperative to understand alternative pathways to increase biogenically available phosphorus in environments. To that end, this dissertation involved examining olivine as an alternative source of phosphorus to apatite, analyzing a novel grain of iron silicide found via lightning reduction in a fulgurite, and finally sought to understand the impact of phosphate mining through phosphogypsum stacks. Olivine is a silicate mineral that composes most of the upper mantles of planets. It has been demonstrated that the silicon in olivine can be replaced with phosphorus during rapid formation. I examined the phosphorus content in ten olivine samples from various localities and found phosphorus present in all ten. I then examined a unique grain of iron silicide in a fulgurite. Fulgurites are glassy mineraloids that primarily form through lightning strikes. The lightning strike produces a localized reducing environment. Iron silicides are a semi-rare occurrence that seem to be common in fulgurites. This grain is unique due to affording us a glimpse of the iron silicide reduction process from core to rim. Finally, the phosphate industry has been a sizable portion of the Florida economy since the late 1800’s. It unfortunately produces millions of tons of a radioactive byproduct known as phosphogypsum per year. Phosphogypsum must be stored in large open-air piles known as phosphogypsum stacks. I provided an overview of phosphogypsum, examining the issues present (heavy metals, radionuclides, and phosphate/fluoride) while also discussing potential remediation measures.

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