Occurrence and Spatiotemporal Dynamics of Pharmaceuticals in a Temperate-Region Wastewater Effluent-Dominated Stream: Variable Inputs and Differential Attenuation Yield Evolving Complex Exposure Mixtures

Abstract

Effluent-dominated streams are becoming increasingly common in temperate regions and generate complex pharmaceutical mixture exposure conditions that may impact aquatic organisms via drug–drug interactions. Here, we quantified spatiotemporal pharmaceutical exposure concentrations and composition mixture dynamics during baseflow conditions at four sites in a temperate-region effluent-dominated stream (upstream, at, and progressively downstream from effluent discharge). Samples were analyzed monthly for 1 year for 109 pharmaceuticals/degradates using a comprehensive U.S. Geological Survey analytical method and biweekly for 2 years focused on 14 most common pharmaceuticals/degradates. We observed a strong chemical gradient with pharmaceuticals only sporadically detected upstream from the effluent. Seventy-four individual pharmaceuticals/degradates were detected, spanning 5 orders of magnitude from 0.28 to 13 500 ng/L, with 38 compounds detected in >50% of samples. “Biweekly” compounds represented 77 ± 8% of the overall pharmaceutical concentration. The antidiabetic drug metformin consistently had the highest concentration with limited in-stream attenuation. The antihistamine drug fexofenadine inputs were greater during warm- than cool-season conditions but also attenuated faster. Differential attenuation of individual pharmaceuticals (i.e., high = citalopram; low = metformin) contributed to complex mixture evolution along the stream reach. This research demonstrates that variable inputs over multiple years and differential in-stream attenuation of individual compounds generate evolving complex mixture exposure conditions for biota, with implications for interactive effects.

Occurrence and Distribution of Pharmaceuticals and Their Transformation Products in Luxembourgish Surface Waters

“…Figures – show the dynamic nature of pharmaceutical contamination in surface water, demonstrating that aquatic organisms in these rivers are exposed to varying mixtures over time. Since recent studies have highlighted the ecological risks associated with exposure to mixtures in surface water systems, , this work helps show how suspect screening may support the identification of more chemicals in surface waters and thus help improve the ecological risk assessment of mixtures in future works.…”

“… show the dynamic nature of pharmaceutical contamination in surface water, demonstrating that aquatic organisms in these rivers are exposed to varying mixtures over time. Since recent studies have highlighted the ecological risks associated with exposure to mixtures in surface water systems,48,49 this work helps show how suspect screening may support the identification of more chemicals in surface waters and thus help improve the ecological risk assessment of mixtures in future works.The stimulant caffeine, antidepressant metabolite Odesmethylvenlafaxine, antihypertensive drugs irbesartan and telmisartan, the antidiabetic drug sitagliptin, and the opioid analgesic tramadol were among the most concentrated pharmaceuticals found in Luxembourgish surface waters (Figures3 and 4) in both 2019 and 2020. From a temporal point of view (Figure5), the highest median concentrations of the pharmaceuticals were detected in September and October of 2019 and are consistently lower during the spring.…”

A Comprehensive Statewide Spatiotemporal Stream Assessment of Per- and Polyfluoroalkyl Substances (PFAS) in an Agricultural Region of the United States

“…58 Previous research has documented wastewater input to streams to be an important source of contaminants. 59 In particular, effluent-affected streams have been shown to have numerous water quality effects from WWTP effluent discharge, 60,61 including PFAS. 62 While PFAS exposures were more sporadic in basins dominated by agriculture, such exposures were observed (Table S3), indicating that agricultural activities may also be contributing to stream PFAS concentrations or there were other unidentified PFAS sources in these basins.…”

Spatio-Temporal Distribution and Influencing Factors of Human and Veterinary Pharmaceuticals in the Tributary Surface Waters of the Han River Watershed, South Korea

“…Higher usage of pharmaceuticals was found to occur in the cold season, which was evidenced by their high mass loads in surface water during this season [88][89][90][91][92]. However, hydrolysis, photodegradation, and biodegradation are typically more pronounced in the warm season [78], leading to faster attenuation of pharmaceuticals in the river [28]. In this study, seasonal variations appeared to be compound-dependent and may additionally be associated with either societal factors (e.g., production, consumption, and excretion) or environmental factors (e.g., solar irradiance, precipitation, and temperature).…”

“…Various factors influence the distribution patterns of pharmaceuticals in urban and rural surface water, including intake and usage patterns [15][16][17], population growth [18,19], population size of animals [20,21], land use [22,23], and physicochemical properties [24,25]. Particularly, the main reason for the existence of pharmaceuticals in the environment is that they cannot be completely treated in wastewater treatment facilities and very small quantities are removed by photolysis, adsorption, photodegradation, hydrolysis, electrolysis, and biodegradation in nature [26][27][28][29][30][31].…”