Spatial and Temporal Analysis of Pharmaceuticals, Water Quality, and Their Relationship in the Surface Water of a Rural, Urbanizing, and Urban Sub-Watersheds in Middle Tennessee
The incidence of pharmaceuticals in the environment, especially in freshwater systems, is a concern for water scientists and managers. Their presence in the environment has been linked to high consumption volume, low metabolism and degradation, improper disposal of unused drugs, and incomplete removal by the wastewater treatment plants. On a national scale, pharmaceuticals have been detected in different environmental matrices, including wastewater effluents, surface water, and drinking water, at concentrations ranging from parts-per-trillion to parts-per-billion. While little is known about the potential health effects to humans or aquatic organisms exposed to trace levels of pharmaceuticals found in surface water, the need to monitor these chemicals in rivers, streams, and lakes, abounds. The central hypothesis of the study is that the incidence of pharmaceuticals in surface water in rural, urbanizing, and urban watersheds exist, partly due to catchment land uses and outfall discharges. The overarching goal of the study was to provide a comprehensive assessment of two broad classes of pharmaceuticals, based on their end-use for heart treatment ailments and as anti-inflammatory drugs. The objectives of the dissertation are 1) Detection and Quantification of Selected Heart Treatment Drugs and Non-Steroidal Anti-Inflammatory Drugs (NSAIDs); 2) Evaluation of the Spatial and Temporal Variation of Selected Heart Treatment Drugs and Non-Steroidal Anti-Inflammatory Drugs (NSAIDs); 3) Determination of Water Quality Parameters of Interest and Evaluation of the Relationship with Targeted Pharmaceuticals; 4) Assessment of Total Organic Carbon (TOC) and River Discharge and Their Effect on the Concentration of Pharmaceuticals of Interest. The pharmaceuticals of interest are atenolol, clofibrate, diclofenac, ibuprofen, metoprolol, naproxen, and propranolol. These pharmaceuticals were selected based on their production volumes, availability over-the-counter, the number of prescriptions filled, and extended uses. Grab water samples were collected weekly for five consecutive weeks from Collins River, East Fork Stones River, and Cumberland River for four seasons; summer 2018, fall 2018, summer 2019, and fall 2019. These rivers drain rural, urbanizing, and urban watersheds, respectively. Simultaneously, water quality parameters were determined in situ using Eureka™ multi-parameter sondes. The water samples were analyzed for the targeted pharmaceuticals using GC-MS. Method validation was performed by evaluating the specificity, reproducibility, and linearity of the GC-MS response. The absolute recoveries for the target pharmaceuticals were above 90 percent; relative standard deviations were below 8 percent. Total organic carbon was analyzed for the respective water samples using a TOC analyzer (Shimadzu™). The discharge data were obtained from the United States geological survey and then used for further analysis. Heart treatment drugs and anti-inflammatory drugs were detected in Collins River, East Fork Stones River, and Cumberland River at concentrations ranging from N.D. (not detected) to 20 ng/L and N.D to 390 ng/L, respectively. The dissertation data indicated that the concentration of pharmaceuticals exhibited significant seasonal variation during the study period except for clofibric acid, metoprolol, and naproxen. Seasonal dynamics of pharmaceutical concentrations tend to be controlled by the physicochemical properties of surface water, such as temperature, pH, specific conductance, and turbidity. Variation in pharmaceutical concentration negatively correlated with temperature, pH, and specific conductance; and positively correlated with turbidity. Similarly, the concentration of pharmaceuticals negatively correlated with total organic carbon as well as the river discharge. The risk quotient for targeted pharmaceuticals was below 0.1; indicating that the risk to exposed biota (organisms) was minimal during the sampling period.
Environmental science|Agriculture|Environmental Studies
"Spatial and Temporal Analysis of Pharmaceuticals, Water Quality, and Their Relationship in the Surface Water of a Rural, Urbanizing, and Urban Sub-Watersheds in Middle Tennessee"
ETD Collection for Tennessee State University.