Plasma Vitellogenin Reveals Potential Seasonal Estrogenicity in Fish from On-Site Wastewater Treatment Systems in Semi-Arid Streams Influenced by Snowmelt.

Effluents from on-site wastewater treatment systems can influence surface water quality, particularly when infrastructure is aging, malfunctioning, and improperly installed. Municipal wastewater often contains chemical compounds that can lead to adverse biological effects, such as reproductive impairment, in organisms that are chronically exposed. A significant number of these compounds are endocrine-disrupting chemicals. Water quality influences of on-site systems are poorly studied in semi-arid regions where instream flows are seasonally dependent on snowmelt, and when instream dilution of wastewater effluents is minimal during other times of the year. Here we examined surface water estrogenicity in low order tributaries of two unique semi-arid streams with on-site wastewater treatment systems, for which seasonal instream flow fluctuations occur in Park City, UT, USA. Water samples were collected from a total of five locations along two lotic systems downstream from active on-site treatment systems. Samples were extracted for targeted chemical analyses and to perform in vivo and in vitro bioassays with juvenile rainbow trout. Estrogenic activity was measured by quantifying the concentration and expression of vitellogenin (VTG) in plasma and liver, respectively. Plasma VTG presented elevated levels in fish exposed to water samples collected at the two sites in close proximity to on-site systems and during seasons with low stream discharge, though the levels observed did not suggest severe endocrine disruption. However, long-term exposure to these surface water could compromise the fish populations. While the sensitivity of in vitro bioassays was low and targeted chemical analyses did not identify causative compounds, the use of complementary lines of evidence (e.g., in vivo biological models) was advantageous in identifying estrogenic activity in waters influenced by effluents from on-site wastewater systems.

Multi-approach assessment for the evaluation of spatio-temporal estrogenicity in fish from effluent-dominated surface waters under low instream flow.

Current practices employed by most wastewater treatment plants (WWTP) are unable to completely remove endocrine disrupting compounds (EDCs) from reclaimed waters, and consistently discharge these substances to receiving systems. Effluent-dominated and dependent surface waters, especially during low instream flows, can increase exposure and risks to aquatic organisms due to adverse biological effects associated with EDCs. Given the ecological implications that may arise from exposure to such compounds, the present a multi-approach study examined spatio-temporal estrogenic potential of wastewater effluent to fish in East Canyon Creek (ECC), Utah, USA, a unique urban river with instream flows seasonally influenced by snowmelt. Juvenile rainbow trout (Oncorhynchus mykiss) were caged at different upstream and downstream sites from an effluent discharge during the summer and fall seasons. In the summer, where approximately 50% of the streamflow was dominated by effluent, fish from the upstream and a downstream site, located 13 miles away from the effluent discharge, presented significantly elevated concentrations of plasma vitellogenin (VTG). Similarly, significantly high 17ß-estradiol to 11-ketotestosterone ratios were measured in the summer across all sites and time points, compared to the fall. In the laboratory, juvenile fish and primary hepatocytes were exposed to concentrated effluent and surface water samples. Quantification of VTG, although in significantly lower levels, resembled response patterns observed in fish from the field study. Furthermore, analytical quantification of common EDCs in wastewater revealed the presence of estriol and estrone, though these did not appear to be related to the observed biological responses, as these were more significant in sites were no EDCs were detected. These combined observations suggest potential estrogenicity for fish in ECC under continuous exposures and highlight the advantages of following weight-of-evidence (WoE) approaches for environmental monitoring, as targeted analytically-based assessments may or may not support the identification of causative contaminants for adverse biological effects.

Spatial and seasonal occurrence of semi-volatile organic compounds (SVOCs) in fish influenced by snowmelt and municipal effluent discharge.

In the present study we examined spatial and seasonal trends in the levels of a wide suite of semi-volatile organic compounds (SVOCs) in brown trout (Salmo trutta) and mottled sculpin (Cottus bairdii) in East Canyon Creek, Utah, USA, an effluent-dominated stream during summer months. Fish samples were collected from four sampling sites, including one reference site upstream, and three sites at incremental distances downstream of the effluent discharge over multiple seasons. The samples were analyzed for 218 lipophilic contaminants, including pesticides and their metabolites, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and polybrominated diphenyl ethers (PBDEs) and other flame retardants. Some PAHs, pesticides and their metabolites, PCBs, PBDEs and other flame retardants were measured in mottled sculpin (11 analytes) and brown trout (17 analytes). Hexachlorobenzene (HCB), p,p'-DDE, BDE-47 and triphenyl phosphate (TPHP) were the most frequently detected contaminants in mottled sculpin and brown trout, while BDE-47 and p,p'-DDE were measured at the highest concentrations, reaching up to 73 and 19 ng/g wet weight, respectively. Our results indicated that snowmelt did not alter accumulation of the examined lipophilic contaminants, and no consistent seasonal differences were observed in their accumulation. A spatial pattern was observed for PBDE congeners, where lowest levels were measured in fish tissues from a reference site, and highest concentrations were measured in fish collected downstream of the effluent discharge, indicating that municipal effluent discharge contributes to the elevated PBDE levels in fish residing in this effluent-dominated stream. We further calculated screening level consumption risks following United States Environmental Protection Agency (EPA) methods, and identified the importance of considering discharge gradients in effluent-dominated systems during bioaccumulation assessments.

Pharmaceutical uptake kinetics in rainbow trout: In situ bioaccumulation in an effluent-dominated river influenced by snowmelt.

Whether seasonal instream flow dynamics influence bioaccumulation of pharmaceuticals by fish is not well understood, specifically for urban lotic systems in semi-arid regions when flows are influenced by snowmelt. We examined uptake of select pharmaceuticals in rainbow trout (Oncorhynchus mykiss) caged in situ upstream and at incremental distances downstream (0.1, 1.4, 13 miles) from a municipal effluent discharge to East Canyon Creek in Park City, Utah, USA during summer and fall of 2018. Fish were sampled over 7-d to examine if uptake occurred, and to define uptake kinetics. Water and fish tissues were analyzed via isotope dilution liquid chromatography tandem mass spectrometry. Several pharmaceuticals were consistently detected in water, fish tissue and plasma, including carbamazepine, diphenhydramine, diltiazem, and fluoxetine. Pharmaceutical levels in water ranged up to 151 ng/L for carbamazepine, whereas the effluent tracer sucralose was consistently observed at low µg/L levels. During both summer and fall experiments at each of three downstream locations from effluent discharge, rainbow trout rapidly accumulated these pharmaceuticals; tissue levels reached steady state conditions within 24-96 h. Spatial and temporal differences for pharmaceutical levels in rainbow trout directly corresponded with surface water exposure concentrations, and uptake kinetics for individual pharmaceuticals did not vary among sites or seasons. Such observations are consistent with recent laboratory bioconcentration studies, which collectively indicate inhalational exposure from water governs rapid accumulation of ionizable base pharmaceuticals by fish in inland surface waters.

Spatio-temporal bioaccumulation and trophic transfer of ionizable pharmaceuticals in a semi-arid urban river influenced by snowmelt.

Bioaccumulation of pharmaceuticals in aquatic organisms is increasingly reported in the peer-reviewed literature. However, seasonal instream dynamics including occurrence and bioaccumulation across trophic positions are rarely studied, particularly in semiarid streams with flows influenced by seasonal snowmelt and municipal effluent discharges. Thus, we selected East Canyon Creek in Park City, Utah, USA to examine spatio-temporal bioaccumulation of select ionizable pharmaceuticals across trophic positions using trophic magnification factors calculated at incremental distances (0.15, 1.4, 13 miles) downstream from a municipal effluent discharge during spring (May), Summer (August), and fall (October). Nine target analytes were detected in all species during all sampling events. Trophic dilution was consistently observed for amitriptyline, caffeine, diphenhydramine, diltiazem, fluoxetine, and sertraline, regardless of seasonal instream flows or distance from effluent discharge. Calculated TMFs ranged from 0.01-0.71 with negative slopes observed for all regressions of chemical residue in tissue and trophic position. We further presents the first empirical investigation of normalizing pharmaceutical concentrations to lipid, phospholipid or protein fractions using pair matched fish samples. Empirical results identify that normalization of ionizable pharmaceutical residues in aquatic tissues to neutral lipids, polar lipids, or the total protein fraction is inappropriate, though bioaccumulation studies examining influences of internal partitioning (e.g., plasma proteins) are needed.