Abstract

Atmospheric deposition (AD) is a significant but poorly understood source of nutrients to many aquatic systems around the world. Accurate characterization of the nutrient budgets of aquatic systems is critical to good management decisions, so a better understanding of AD-related nutrient loads is essential, especially for water bodies where nutrient loads from atmospheric deposition are significant. Due to its large surface area, proximity to Great Basin dust sources, high values of atmospheric particulates due to inversions, and the high phosphorus content of local soils, Utah Lake, in the semi-arid Utah Valley, USA, experiences significant phosphorus loading from AD. The lake is eutrophic and has a history of impaired water quality and HABs, which has motivated significant study and debate over nutrient loads to the lake. Previous studies that measured phosphorus AD to Utah Lake showed a large portion of the AD was associated with a few high-volume deposition events, with the data exhibiting unexpectedly high peaks at some locations on a few dates. These issues cast doubt on the data. We used statistical analyses and machine learning models to characterize AD to Utah Lake. In addition to determining the distribution of AD events, we analyzed the relationship between phosphorus AD and local weather events. We used this analysis to determine whether the high phosphorus measurements were outliers due to sampling errors or represented actual conditions. Our analysis shows that AD events followed an XXX distribution, similar to the distribution of precipitation events on the lake. We found the high phosphorus deposition events were correlated with instances of high wind occurring when the ground was dry. We also observed regular cycles of higher and lower measurements throughout the year that are like measures of atmospheric particulate matter. We conclude that atmospheric phosphorus deposition on Utah Lake is episodic and driven by weather conditions around the lake, with the most important factors being the number of hours with high winds during a collection period and the percentage of those hours where the ground was dry during a collection period followed by dry deposition from particulate matter. This is an important finding for the management of Utah Lake and also has implications for the management of other eutrophic lakes in which atmospheric deposition of nutrients impacts water quality.

Degree

MS

Rights

https://lib.byu.edu/about/copyright/

Date Submitted

2023-04-17

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd12772

Keywords

atmospheric deposition, nutrients, episodic events

Language

english

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