Ashley Womer

Date of Award

Spring 2022

Document Type

Open Access Thesis


Chemistry and Biochemistry

First Advisor

John Ferry


The freshwater harmful algae Microcystis spp produces a family of toxins called microcystins1. These species of algae are known to release microcystins from their cells directly into the surrounding water2. This creates an array of human health risks depending on the fate and transport of the toxins in the water column3,4. Risk modelling and previous literature has shown that sediment is a sink for free microcystin, microcystin can be stably adsorbed to sediment for hundreds of years, and its adsorption to sediment is determined by the sediment adsorption partitioning coefficient (Kd)5,6,7. In this work it is hypothesized that the sediment phase is only a metastable reservoir for microcystin given that varying water conditions can affect Kd values of microcystin8,9. In particular, sudden environmental disruptions that alter water quality such as flooding, storm surges, industrial chemical release, fire suppression runoff, etc. can result in the destabilization of adsorbed microcystin with an accompanying release into the water column on a relatively rapid timescale. Although many surface waters are monitored for microcystin, the monitoring systems are triggered by visible algae in the water, implying that unmonitored toxins could enter drinking water supplies or the food chain. Work supported includes experiments that measure the functional aspects of Kd for the various microcystins with the goal of developing predictive models for the potential release of historically adsorbed microcystin reservoirs. Where possible, strategies to degrade or stabilize adsorbed microcystin to inhibit future release will also be pursued.

Included in

Chemistry Commons