Karen Sem

M.E. Student, Environmental Engineering Sciences, UF

Growing up near Lake Okeechobee, Karen Sem regularly read about the effects of its water quality on the health and prosperity of its surrounding communities. At the University of Florida, where she is pursuing a Masters of Engineering degree in Environmental Engineering Sciences, Karen is researching these water quality effects through studying an entirely different medium under the guidance of Dr. Myoseon Jang in the Air Resources group.

Though naturally found in the Gulf of Mexico and Caribbean, blooms of the dinoflagellate Karenia brevis – commonly known as “red tide” – have increased in frequency and longevity along Florida’s coasts due to increased nutrient pollution from runoff. K. brevis produces polyether neurotoxins known as brevetoxins, which can induce bronchoconstriction, asthma attacks, and other negative respiratory symptoms when inhaled in sea spray aerosol. The adverse health effects drive up hospitalization and discourage tourism in coastal areas affected by red tide.

In her work at Dr. Jang’s lab, Karen’s goal is to characterize the environmental conditions that determine brevetoxin concentrations in sea spray aerosol. To identify major reactions that contribute to brevetoxin degradation, aerosols containing known concentrations of the toxin are nebulized into UF’s Atmospheric Photochemical Outdoor Reactor (APHOR) under various environmental conditions. As the aerosol ages through exposure to UV or atmospheric oxidants, their composition is analyzed to determine its methods of degradation. Karen is using data from these outdoor chamber experiments to develop a kinetic model which can predict the toxicity of sea spray aerosol generated from red tide under various environmental conditions.

Knowledge of the processes that determine brevetoxin degradation in sea spray aerosol can be combined with field data to form a public health risk model for K. brevis blooms. Dr. Zechen Yu, a postdoctorate in Dr. Jang’s lab, is developing an immunoassay to detect brevetoxin levels in aerosol in situ rather than in a laboratory setting. The overall risk model will help residents and visitors of coastal communities near red tides by minimizing their exposure to generated aerosols.