| Description |
Keratinized tissues such as hair, horn, hoof, and nail are environmental recorders integrating information of local hydrological cycle, biosphere recycling, geological sources, and airborne particulate matter. Many studies during the last decades have applied trace element and Sr isotopic analysis in keratin to retrieve relevant environmental information. However, these efforts were hampered by two related problems: both endogenous levels and the extent of contamination are usually unknown, and both are different for each chemical element considered. There is some evidence of sorption and leaching processes that can change the chemical composition of keratinized tissues over time. In this project, we (1) studied the rate and extent of the incorporation of exogenous Sr into human scalp hair, (2) provided direct evidence of diffusion of Sr in hair, (3) developed a new standard based on an amorphous carbohydrate (isomalt) that can be doped with nine trace elements with concentrations up to 1000s of μgg for quantitative in situ inductively coupled plasma mass spectrometry (ICP-MS) analysis of trace elements in keratinized tissues, and (4) established reference endogenous intervals of trace elements in keratin from the range of values measured in horn interior samples. In this way, we have improved the fundamental understanding of the behavior of trace elements in keratinized tissues, provided new methodologies to determine accurate trace elemental distribution at the microscale, assessed contamination and leaching versus endogenous levels, and quantified diffusional transport in keratinized tissue. The results of this project are divided into four chapters in this dissertation. |
