Full title: Quantifying the susceptibility of emerging aquatic herbicides to photodegradation and sorption in freshwater environments

Presented lightning talk on April 28, 2022, by Sydney Van Frost - University of Wisconsin-Madison - at the 2022 Emerging Contaminants in the Environment Conference (ECEC22)

The herbicides fluridone and florpyrauxifen-benzyl (FPB) are commonly applied to surface waters to combat invasive aquatic plants. While these compounds are effective at limiting target plant growth, it is important to understand their persistence in the environment to prevent increased tolerance by target species and unintended harm to native vegetation. We investigate photodegradation and sorption to sediment, the two major abiotic pathways of herbicide removal from lakes. Experiments to calculate photodegradation rates are carried out in a Rayonet merry-go-round photoreactor with bulb irradiance at 311 nm and 365 nm. Sorption kinetics and equilibrium partitioning constants are measured using sediment samples collected from lakes in Wisconsin. While both herbicides undergo photodegradation under laboratory conditions, our results demonstrate that fluridone is more susceptible to photodegradation. In contrast, FPB sorbs more strongly than fluridone, which aligns with its lower solubility. Little information is available about these herbicides given their short history of use. Therefore, knowledge about their behavior in freshwater environments is critical to applying these herbicides for invasive species control.

Download slides: http://hdl.handle.net/2142/114143