Date of Award:

5-2020

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Civil and Environmental Engineering

Committee

Joan E. McLean

Committee

R. Ryan Dupont

Committee

Laurie S. McNeill

Abstract

Arsenic is a naturally occurring element known for its chronic and acute toxicity. The solubility of arsenic is highly dependent on environmental conditions. The soils of Cache Valley, UT, contain naturally occurring arsenic.

Bioretention systems rely on a combined plant-soil system to remove pollutants carried by stormwater, typically nitrogen, phosphorus, dissolved organic carbon, and select metals. Phosphate from stormwater potentially increases arsenic mobility, which makes stormwater pollutant loading an important factor for evaluating risks associated with stormwater bioretention. Pollutant removal in these systems occurs through sorption of contaminants onto the soils, physical filtration by the soil media, and uptake by plants. Plants play an important role in bioretention systems since many of the stormwater pollutants are also plant nutrients. Rhizosphere biological processes can alter soil chemistry; an adverse effect of those alterations is the mobilization of naturally occurring arsenic.

The aim of this study was to determine which factors influenced arsenic mobilization in soil pore water in stormwater bioretention systems. To do so, a variety of plant types and stormwater pollutant concentrations were applied as treatments to a bioretention site in Cache Valley, UT. From this study, certain plant types were determined to result in minimal arsenic concentrations in the soil pore water and mobile soils minerals phases.

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