Date of Award:

5-2026

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Civil and Environmental Engineering

Committee Chair(s)

Randal Martin

Committee

Randal Martin

Committee

Joan E. McLean

Committee

Jessica Haskins

Abstract

The Great Salt Lake (GSL), located in northern Utah, is one of the world's saltiest lakes and an essential resource for industry. It is also a significant hotspot for halogen emissions, including chlorine (Cl) and bromine (Br) from both natural and human sources. Although their concentrations in the atmosphere are low, they influence tropospheric chemistry by forming criteria pollutants such as ozone and particulate matter. These pollutants are detrimental to air quality, impacting public health and property. This study investigates the spatial and seasonal variability of halogen species (gas- and particulate-phase of Cl and Br) in the Northern Wasatch Front (NWF) region and in the vicinity of GSL. Historically, NWF was designated a nonattainment area (air quality standards exceeded) by the U.S. Environmental Protection Agency due to elevated levels of ground-level ozone (O3) and particulate matter (PM2.5).

Air samples were collected using both active (Air Metric MiniVols) and passive sampling (Radiello diffusive sampler) across multiple sites (15 sites) and seasons (two summers and two winters). These samples were quantified at the Utah Water Research Laboratory (UWRL) and subjected to rigorous procedures. Additional data from meteorological stations and ambient air monitors from the Utah Department of Air Quality (UDAQ) and MesoWest were also integrated. The results highlight distinct seasonal patterns: higher HCl values were observed during the summertime, with an average value of 1.2 parts per billion (ppb). Likewise, spatial gradients in hydrochloric acid mixing ratios show from west-east during summer and east-west during winter across northern Utah. These findings highlight the expansion of monitoring sites, the integration of halogen chemistry into atmospheric models, and the consideration of additional species to better understand halogen chemistry in the troposphere.

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