Dissertation/Thesis Abstract

Fluridone Extraction and Degradation in Water and Alluvial Deltaic Sediment, Analytical Estimation of Fluridone Subsurface Transport
by Wickham, Patrick Connor, M.S., University of California, Davis, 2019, 73; 13808351
Abstract (Summary)

Fluridone is a commonly used herbicide for the control of invasive aquatic weeds in surface water. After application, fluridone can sorb strongly to bed sediment, which can complicate both analytical fluridone quantification and estimations of fluridone persistence. When present in high concentrations in sediment and water, fluridone can cause damage to non-target plants and aquatic life. Here we developed a simple method for the extraction of fluridone from complex clay-based alluvial sediments, compared this method with an existing and well-established pesticide extraction method, validated both extraction methods in laboratory samples spiked with fluridone, and successfully applied both methods to field samples collected from ongoing fluridone applications in the California delta. These extraction techniques were then utilized to quantify the persistence of fluridone in sediment and water samples monitored for over two months to determine the effect of temperature, UV light, and sediment clay content on fluridone’s half-life. Temperature impacted degradation of fluridone in both sediment and water. In water, results suggest a linear relationship between temperature and decreasing half-life. In sediment, results suggest a preference for mesophilic microbial degradation, meaning that degradation is increased and statistically identical between 20°C-40°C. UV light greatly increased degradation in water but displayed insignificant impact on degradation in sediment. Increased clay content slightly prolonged the persistence of fluridone in sediment. To estimate the transport of fluridone through the subsurface, a simple Ogata-Banks based analytical transport model was tested in various scenarios of initial concentration, half-life, and groundwater velocity. Results suggest that subsurface lateral transport of fluridone is limited to less than 10 meters over a 1-month period. Water velocity contributes the most to overall transport of fluridone in subsurface water, while half-life and initial application concentration have smaller localized effects. The findings of this study can be used to further understand of the fate and transport of fluridone in deltaic environments and help make informed decisions regarding fluridone application in ambient water bodies.

Indexing (document details)
Advisor: Pandey, Pramod K.
Commitee: Harter, Thomas, Sandoval Solis, Samuel
School: University of California, Davis
Department: Hydrologic Sciences
School Location: United States -- California
Source: MAI 81/1(E), Masters Abstracts International
Subjects: Hydrologic sciences, Environmental science, Chemistry
Keywords: Degradation, Extraction, Fluridone, Herbicide, Sediment, Transport
Publication Number: 13808351
ISBN: 9781085557900
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