Bioaccumulation of contaminants of emerging concern in dynamic ecosystems.

Abstract

The aquatic environment includes complex systems on which society relies to provide ecosystem services and support biodiversity. In recent years, the demand for aquatic-ecosystem commodities has greatly increased due to rapid population growth and industrialization. This burgeoning population stresses the global water cycle in many ways including increased fossil-fuel consumption promoting climate change, altered snowpack decreasing instream flows, multiple cities utilizing the same waterways, and increased nutrient loading due to agricultural expansion. And poorly treated sewage Such alterations to aquatic systems leads to unique exposure scenarios of contaminants of emerging concern such as pharmaceuticals and cyanotoxins. Thus, an understanding of exposure, hazards, and bioaccumulation of contaminants of emerging concern in dynamic aquatic systems in necessary to support sustainable management of aquatic resources. In this dissertation, the first study examined bioaccumulation of diphenhydramine, an ionizable weak base pharmaceutical, across different life stages in an organism that demonstrated ontogenetic diet changes in an urban estuary. The findings of this study demonstrated that ontogenetic dietary shifts do not affect the bioaccumulation of diphenhydramine, but exposure difference in water does. The second study investigated whether ionizable weak base compounds with differing properties demonstrated trophic dilution within the food web of urbanizing rivers receiving runoff from snowmelt. This study observed that multiple ionizable weak base pharmaceuticals trophicly diluted with increasing trophic position and that inhalational uptake was the main driver of bioaccumulation in rainbow trout. The third study examined the spatial and temporal fate and transport of ionizable pharmaceuticals within a dynamic aquatic system that shifted from being influenced by spring snowmelt to effluent-dominated conditions. The findings of the third study reported decreasing concentrations with increasing distance downstream regardless of season and the presence of secondary inputs from onsite waste-water systems. The fourth study developed a novel analytical method and then investigated the bioaccumulation potential of various cyanobacterial toxins in a highly eutrophic Texas reservoir. The fourth study identified several novel methodological approaches to analytically identify cyanotoxins and reported the presence of cyanotoxins in Lake Waco, Texas, USA for the first time. These observations collectively provided novel environmental assessment approaches to support an advanced understanding of bioaccumulation within dynamic aquatic ecosystems.