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Geological And Geochemical Analysis Of Phosphorus Bearing Minerals And Natural Glasses On Earth And In Meteorites: Implications Of The Origin Of Life, Tian Feng

USF Tampa Graduate Theses and Dissertations

Phosphorus is a key element in biogenic molecules and the mineral schreibersite is a major reactive phosphorus source for organic compounds on the prebiotic Earth. In this dissertation, a suite of reactions of phosphorus species, which originate from schreibersite minerals on chondrite meteorites and on the early Earth, have been studied to determine the intermediate geochemical pathways between phosphides and common minerals on meteorites and on the early earth.

I first investigated a unique blue fulgurite that was studied to clarify if this blue color was caused by rich phosphorus content, as has been reported for impact glasses that also …

Modeled Affinity Constants For Phosphorus Adsorption And Desorption Due To Saltwater Intrusion, Yasemin Taşcı

USF Tampa Graduate Theses and Dissertations

It is important to understand the processes that regulate phosphorus (P) fluxes to coastal environments, because P is an important nutrient in coastal ecosystems. Phosphorus adsorbs to the surface of minerals in sediment and bedrock, and an influx of seawater can cause some of that P to desorb, raising the P concentration of ambient water. Although seawater-induced P desorption is thought to be an important source of P to coastal environments, the chemical reactions that underlie it have not been established. Previous work provides some relevant surface reactions and associated affinity constants between various aqueous P species and the surface …

Modeling Potential Chemical Environments: Implications For Astrobiology, Brian Craig Szenay

USF Tampa Graduate Theses and Dissertations

Modeling chemical environments is an important step to understanding the diversity of prebiotic systems that may have formed on the early earth or potentially can occur on other worlds. By using the modern Earth as a test case, these models predict scenarios with systems more conducive to the formation of the organic molecules that are important to life. Here we use the equilibrium thermodynamic modeling program HSC Chem to investigate prebiotic environments. This program uses the raw material that the user inputs into the system in order to calculate the change in amounts of chemical species forming as a function …

Something Is Askew In Florida's Water: Arguing For A Better Descriptive Statistic For Positively Skewed Water-Quality Data, Amie October West

USF Tampa Graduate Theses and Dissertations

ABSTRACT

It may be of no surprise that water quality data is right-skewed, but what appears to be overlooked by some is that the arithmetic mean and standard deviation most often fail as measures of central tendency in skewed data. When using the arithmetic mean and arithmetic standard deviation with nutrient data, one standard deviation about the arithmetic mean can capture nearly all of the data and extend into negative values. Representing nutrient data this way can be misleading to viewers who are using the statistics, and making assumptions, to understand the characteristics of those waters. Through an in-depth statistical …