Mullins, Angela
(2021)
Characterizing Sources and Identifying Pathways of Urban Metal Contamination at the Groundwater-Soil Interface.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
This is the latest version of this item.
Abstract
Urban processes modify the landscape, disturbing natural groundwater flow and introducing chemical contaminants to the soil and groundwater. Therefore, urban groundwater can reroute contaminants, transporting metals and nutrients from surface runoff through the subsurface environment and reintroducing them to soils and rivers. Although groundwater connects surface runoff to receiving rivers and streams, few studies have documented the long-term impacts of urbanization on groundwater chemistry or the effects of contaminated groundwater on soil contamination patterns.
This dissertation examines metal contamination in both surface soils and near surface groundwater. The observed interaction between urban hydrology and legacy contamination reveals critical zone chemical dynamics with important implications for urban environments. In particular, the fate of urban metal contamination through the groundwater-soil interface in Pittsburgh, PA is examined by 1) exploring geochemical consequences of human interventions to reduce rapid runoff and associated hydrogeochemical impacts from green infrastructure installation, 2) analyzing transport of contaminants through urban groundwater systems using an elevational transect of discharging springs, and 3) examining the potential for soil metal accumulation at points of interaction between contaminated groundwater and soils.
This research revealed fundamental interactions between urban soils and groundwater: 1) Stormwater captured and introduced to shallow groundwater through road-side infiltration-based green infrastructure changed water chemistry. The primary drivers were winter loadings of road de-icer and the formation of a reducing environment in the summer. 2) Groundwater spring chemistry is remarkably consistent across a series of strata aquifers despite substantial differences in distance from recharge zones. Further, this consistency in chemistry occurred even as silicon concentrations indicated the waters are a mix of short and long residence time waters. 3) Spring water discharge enriched with transition metals increases soil metal concentrations downslope of the springs. Using total, exchangeable, and pore water metal chemistries, records of legacy metal enrichment were found in soils receiving spring water over multiple time scales from months to decades. This pattern has the potential to create hot spots of soil metal contamination in urban landscapes.
This dissertation characterizes the fate of urban contaminants through the groundwater-soil interface, improving our ability to predict spatial patterns of urban soil contamination.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
20 January 2021 |
| Date Type: |
Publication |
| Defense Date: |
9 October 2020 |
| Approval Date: |
20 January 2021 |
| Submission Date: |
22 October 2020 |
| Access Restriction: |
2 year -- Restrict access to University of Pittsburgh for a period of 2 years. |
| Number of Pages: |
125 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Geology and Environmental Science |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
groundwater, urban contamination, green infrastructure, legacy metal contamination |
| Date Deposited: |
20 Jan 2021 19:02 |
| Last Modified: |
20 Jan 2023 06:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/39847 |
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