| dc.description.abstract | Aquatic herbicides are a class of organic compounds that are used in surface water bodies to
manage the persistence of invasive and nuisance aquatic plants. Understanding their
degradation and transformation pathways are critical for managing herbicide effectiveness and
target species resistance. This study examines the fate and transport of two aquatic herbicides,
fluridone and florpyrauxifen-benzyl (FPB). A field campaign was conducted during the
summer of 2022 to collect concentrations of the herbicides and their degradation products over
time in three study lakes in Wisconsin. These field studies were followed by supplemental
laboratory experiments to further analyze the dominant environmental transformation
pathways for each herbicide. Photolysis, sorption, biodegradation, and hydrolysis can all be
quantified separately under isolated conditions in the lab. Combined, the conclusions from
these experiments along with mass balance modeling can illustrate which processes dictate the
persistence of the herbicides in aquatic environments. Hydrolysis experiments show that FPB
is transformed into its primary degradation product, florpyrauxifen, through base-promoted
hydrolysis. Florpyrauxifen is then degraded microbially as determined by microcosm batch
reactors. Photolysis experiments show that FPB, florpyrauxifen, and fluridone all undergo
direct photodegradation and that indirect photodegradation is negligible. Fluridone differs
from FPB in that it is very resistant to both abiotic and biotic processes, which is reflected by
its longer half-life observed in lakes. Overall, a deeper understanding of aquatic herbicide
behavior will allow resource managers to develop better application strategies, as well as have
broader implications for further understanding processes that impact organic compounds in
freshwater systems. | en_US |
