Physical and chemical controls on subsurface contaminant fate and transport
Open Access
- Author:
- Jahn, Kalle He
- Graduate Program:
- Geosciences
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- May 05, 2021
- Committee Members:
- John Watson, Outside Unit & Field Member
Kate Freeman (she/her), Co-Chair of Committee
Roman DiBiase, Major Field Member
Demian Saffer, Co-Chair & Dissertation Advisor
Mark Patzkowsky, Program Head/Chair - Keywords:
- groundwater
contaminant
transport
PFAS
nitrate
vadoze zone
modeling
Living Filter
Oxisol
perfluoroalkyl - Abstract:
- When anthropogenic contaminants are released as solids and liquids into the natural environment, subsurface soils and bedrock are the primary control on their long-term fate. Accounting for complexity in the subsurface is the central challenge in solving field-scale contaminant transport problems. Yet, the subsurface is difficult to observe at the field scale. Even though field data offer an incomplete glimpse into the complexity of natural systems, they can significantly benefit subsurface contaminant research. This dissertation investigates subsurface contaminant transport behavior by making quantitative observations of soil and bedrock properties and subsurface water and contaminant distributions, developing conceptual models of subsurface processes based on those field data, and subsequently testing those conceptual models using analytical and numerical modeling. The subsurface fate and transport behavior of two sets of contaminants are investigated: nitrate and poly- and perfluoroalkyl substances, both of which have significant ecological and societal consequences. A wide range of field methods are used to measure subsurface properties and processes, including soil and bedrock hydraulic properties, water table elevations, water contents, soil infiltration rates, water chemistry. These quantitative data are interpreted alongside analytical and numerical models of water flow and solute transport to investigate the processes behind observed contaminant distributions. This dissertation highlights the importance of direct measurements of subsurface properties for accurately assessing contamination of water resources, yielding new insights into the fundamental processes governing the subsurface transport of water and solutes, and generating the quantitative data needed to address the ever-evolving threats to human water security.