Physical and biogeochemical constraints on hexavalent chromium generation within soils and sediments
Abstract/Contents
- Abstract
- Hexavalent chromium (Cr(VI)) is an emerging contaminant of the twenty-first century of critical importance for human and ecosystem health. As our understanding of known Cr(VI) sources expands from industrial point sources to include pristine soils and sediments throughout the globe, this contaminant poses a dramatic threat to Earth's surface and groundwaters. Given the potential for naturally occurring Cr(III)- minerals to transform into toxic and highly mobile Cr(VI) within unperturbed aquifers, determining the processes responsible for Cr(VI) concentrations is critical to predict release and assess future human health risk. Within this thesis, I first evaluate Cr(VI) groundwater concentrations throughout California to investigate how industrial activity and shifts in land/water use patterns enhance Cr(VI) generation relative to native rates. Next, I explore the mechanism of Cr(VI) oxidation within physically-structured soils and sediments and examine the competitive microbial and geochemical processes that govern Cr(VI) generation and transport. Finally, I show how Cr(VI) groundwater concentrations are ultimately constrained by the physical heterogeneity in soils and sediments and fluctuations in hydrologic conditions. This research combines geospatial analysis, dynamic laboratory microcosms, and reactive transport modeling to investigate the controls on Cr cycling within the environment. Together, this multi-scale investigation of Cr(VI) generation and transport enhances our understanding of geogenically-sourced hexavalent chromium and shifts our understanding of contaminant release within aggregated soils and sediments. I provide the first direct evidence of Cr(VI) production within physically structured sediments and constrain how changes in physical and hydrologic conditions govern Cr(VI) groundwater concentrations. This knowledge not only allows us to better predict regions susceptible to hazardous Cr(VI) concentrations, but also transforms the way we interpret the release of redox active contaminants and nutrients within the subsurface environment.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2016 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Hausladen, Debra M |
|---|---|
| Associated with | Stanford University, Department of Environmental Earth System Science. |
| Primary advisor | Fendorf, Scott |
| Thesis advisor | Fendorf, Scott |
| Thesis advisor | Francis, Christopher |
| Thesis advisor | Nico, Peter |
| Advisor | Francis, Christopher |
| Advisor | Nico, Peter |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Debra M. Hausladen. |
|---|---|
| Note | Submitted to the Department of Environmental Earth System Science. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Debra Michelle Hausladen
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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