Aquatic Chemistry and Ecotoxicology

Bryan Brooks (Department of Environmental Studies) directs interdisciplinary research in aquatic chemistry and ecotoxicology in collaboration with Dr. C. Kevin Chambliss (Department of Chemistry and Biochemistry, Baylor University) in the Center for Reservoir and Aquatic Systems Research. Our interest in this area is directed at understanding the occurrence, fate, and transport of contaminants in a variety of environmental matrices as well as their anthropogenic influence on ecosystems. Pharmaceuticals and personal care products (PPCPs) represent a class of “emerging contaminants” of particular interest in our group. This class of environmental contaminants has received unprecedented scientific attention in recent years. However, the paucity of information concerning not only the occurrence of PPCPs in the environment but also the subsequent responses of aquatic organisms to therapeutic exposures have to date precluded the establishment of ambient water quality criteria in the United States. Pharmaceuticals enter surface waters by return flows from concentrated animal feeding operations (CAFOs) and municipal wastewater treatment plants (WWTPs). Unlike non-point aquatic pesticide exposures that may result in acute toxicity to aquatic organisms, chronic lower-level PPCP exposures may subtly modulate and alter normal biochemical, physiological, reproductive, and ecological pathways.

Select effluent-dominated and CAFO-influenced ecosystems in the southwestern and south-central United States likely represent “worse-case scenarios” for studying environmental effects of PPCP contaminants because many streams do not benefit from upstream dilution. A projected doubling of human populations in Texas over the next fifty years will increase human reliance on effluent-dominated waterbodies, accentuating the importance of water quality maintenance concurrent with management of freshwater resources. Although more recent studies indicate that select pharmaceuticals discharged from WWTPs partition to sediments, the potential for pharmaceuticals to accumulate in freshwater biota remains largely unexplored.

One of our current research focuses on the potential for bioaccumulation of PPCPs in aquatic organisms. Specific activities include controlled laboratory experiments designed to identify PPCP exposure levels that result in significant bioaccumulation and field sampling to assess the magnitude of PPCP accumulation in aquatic biota collected from effluent-dominated and CAFO influenced waterbodies. From an analytical standpoint, the primary challenge in addressing these issues involves the development of reliable GC/MS and LC/MS protocols for monitoring trace amounts of PPCPs in environmental matrices (e.g., sediment, water, and tissue). Our long-term objective is to understand potential links between environmental PPCP exposure and organismal response.