Date of Award
Doctor of Philosophy
Environmental & Occupational Health
Todd R. Miller
Michael Laiosa, Dale Robertson, Matthew Smith, Michael Carvan
Freshwater harmful algal blooms (FHABs) present a threat to ecological and public health in inland lakes. Problems associated with FHABs include human and animal illness, production of taste and odor compounds, and declining water quality and property values. Despite increased awareness and research on FHABs in recent decades, questions remain regarding long-term growth and diversity of FHABs in lakes that have taken measures toward slowing or reversing eutrophication, environmental factors impacting toxin occurrence, the most appropriate toxin analysis methods for protecting public health, and evidence for cyanotoxins detected in finished drinking water as a connection to exposure for potentially causing disease; this dissertation research seeks to add evidence to the field for answering such questions. Chapter 1 proposes maximum acceptable concentrations for a variety of cyanotoxins, in advance of recent US Environmental Protection Agency guidelines, and reviews childrens’ risk to cyanotoxin exposure, as well as possible clinical biomarkers. A long-term analysis of major FHAB-forming cyanobacteria and cyanobacterial community composition (CCC) in Chapter 2 demonstrates connections to organic nitrogen, changes in ice cover, total phosphorus, Schmidt stability and rainfall correlating with cyanobacterial abundance and CCC. Chapter 3 presents novel preservation methods for cyanotoxins in lake water samples for intercontinental shipping or storage, as well as describes patterns of occurrence for 13 cyanopeptides (e.g. microcystins, anabaenopeptins, cyanopeptolins, nodularin, microginin) in 22 lakes on a semi-global scale using liquid chromatography with tandem mass spectrometry quantification methods. These patterns in cyanotoxin occurrence are then analyzed based on characteristics of their lakes, including mussel invasion, dominant surrounding land usage, trophic status, and lake size. Finally, Chapter 4 characterizes amounts and types of cyanopeptides in raw and finished drinking water and efficiency of their removal among four drinking water treatment process trains. The resulting work demonstrates that other peptides are as common as microcystins in lakes and drinking water, and a variety of cyanopeptides at low doses are detectable in finished water from modern water treatment plants, while providing novel storage, extraction, and detection methods and defining parameters of interannual cyanobacterial dominance in a eutrophic lake with suggested future directions for monitoring.
Weirich, Chelsea, "Cyanobacteria and Cyanotoxin Ecology in Lakes and Drinking Water" (2017). Theses and Dissertations. 1553.