Aquatic Toxicity of Pharmaceuticals and Personal Care Products to Algae
This dissertation research provides a comprehensive study on aquatic toxicity of Pharmaceuticals and personal care products (PPCPs) to algae. The research studied dose- and time-dependent effects, multiple endpoint responses, algae species sensitivity, interactive environmental factors, and interactive multiple contaminents, as well as advanced emerging techniques. The toxicity of triclosan and carbamazepine to Chlorococcum sp. was studied using synchrotron-based Fourier transform infrared (SR-FTIR) spectromicroscopy. Triclosan can affect algae by inhibiting fatty acid synthesis and causing protein aggregation. Carbamazepine can disorganize phospholipid bilayers and attack specific proteins to disturb the transportation of ions and CO2. Carbamazepine-exposed cells developed a resistance with time extension. The acute and chronic toxicity of triclosan under multiple environmental factors to Chlorococcum sp. was examined. A factorial design was used to explore interactive effects of environmental factors on algal biophysiological changes. Algae become more resistant against triclosan in phosphorus-enriched environment. Short time exposure did not show significant differences among treatments. Long time exposure can intensify toxic effects of triclosan. Long time exposure data can be used to do toxicity prediction by stepwise-cluster analysis. The long-term impacts of a pulse disturbance of triclosan on multiple algae species in Lake Erie were investigated. Environmentally relevant concentrations under long time exposure may cause either of inhibition, resilience, resistance and stimulation in algae. Triclosan may alter algal community composition. Different endpoint can select different sensitive species. The interactive impacts of nano-TiO2 and triclosan on Eremosphaera viridis were investigated using Lake Erie water. Different effects were shown based on different triclosan concentrations and different endpoints. Co-exposure showed synergetic inhivition effects at higher triclosan concentrations. Stimulations were shown under co-exposure to low triclosan concentrations and nano-TiO2. Toxic effects alleviated when nano-TiO2 interacting with medium concentrations of triclosan. The effects of a mixture of nano-TiO2, nano-ZnO and triclosan on Asterococcus superbus were explored under varied illuminations using Lake Erie water. Illumination was the most significant factor. Synergetic effects on oxidative stress were shown in nano-TiO2 * nano- ZnO * triclosan and nano-TiO2 * nano-ZnO. Significant oxidative stress can be caused by nano-ZnO * triclosan in visible light, not only by nano-ZnO/Zn2+. The findings can provide scientific data for missing knowledge on aquatic toxicity of PPCPs. They have introduced the application of synchron-based technologies to toxicity study, and are instructive for environmental evaluation and risk management of real-world PPCPs toxicity.