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Evaluating effects of bioactive contaminants associated with waste water treatment plant effluent discharge to the South Platte River
Citation:
Cole, A., J. Cavallin, J. Beihoffer, B. Blackwell, D. Ekman, A. Jastrow, J. Kinsey, K. Keteles, J. Parman, D. Winkelman, AND D. Villeneuve. Evaluating effects of bioactive contaminants associated with waste water treatment plant effluent discharge to the South Platte River. SETAC North America, Toronto, ON, CANADA, November 03 - 07, 2019.
Impact/Purpose:
The lack of established water quality criteria or guidelines for many contaminants of emerging concern (CECs) in surface waters represents a significant challenge to state and regional risk assessors charged with protecting our nations waters and associated aquatic ecosystems from harmful impacts of toxic chemicals. For example, recent contaminant and biological effects surveillance on the South Platte and Colorado rivers in Region 8 have detected complex mixtures of contaminants and estrogen receptor (ER), glucocorticoid receptor (GR), and peroxisome proliferator activated receptor (PPAR)-mediated biological activities in surface waters downstream of municipal waste-water treatments plants (WWTP). Their spatial and temporal variation in relation to discharge and flows, potential hazards to resident aquatic organisms, and whether adverse biological effects are occurring, are unknown. Environmental surveillance and monitoring approaches capable of detecting sublethal impacts of chemical contaminants in complex mixtures before they manifest into ecosystem-level impairments, are needed. Furthermore, approaches that provide the ability to relate these effects to potential causative agents and sources are critical for enabling Regional Offices to meet their mandates. The present RARE project (#2100) builds upon several years of preliminary chemical monitoring research on the S Platte River as a basis for further investigation of ER, GR, and PPAR-bioactive contaminants and potential responses elicited in caged fish.
Description:
The present study highlights the utility of bioeffects-based monitoring in conjunction with analytical chemical measurements of surface waters on the S. Platte River associated with a historically bioactive wastewater treatment plant effluent. Concurrent with chemical monitoring and in vitro bioactivity measurements, in situ caged fish systems were employed to evaluate the potential bioavailability of predicted biologically-active contaminants that can mimic the effects of hormones involved in regulating reproduction, sexual differentiation, stress responses, and lipid metabolism. Previous studies have detected numerous organic contaminants including biocides and pharmaceuticals in the South Platte River near Denver, CO, at concentrations that rank among the highest in the nation. Regarded as contaminants of emerging concern (CECs), some of these compounds can disturb biological pathways in exposed species. Bi-monthly sampling and analysis of surface water samples in 2018, documented increased concentrations of multiple CECs downstream of a waste water treatment plant (WWTP). In vitro bioassays conducted on the same samples detected estrogen receptor (ER; 2.9-88ng/L E2-EQ) and glucocorticoid receptor (GR; 17-117 ng/L Dex-EQ)-mediated activities downstream of the WWTP. Peroxisome proliferator activated receptor gamma (PPAR?)-mediated activities were also detected using a multifactorial Attagene assay, but not a targeted PPAR? transcriptional activation assay. Additional bi-monthly water sampling in 2019 was used to further characterize the spatial and temporal distribution of GR and PPAR?-related bioactivities along the river. In addition to bi-monthly monitoring, fathead minnows (Pimphales promelas) were exposed in situ for five days at six locations upstream and downstream of the waste water discharge (2018). In 2018, despite the ER-mediated biological activity detected in vitro, no significant differences in the expression of male hepatic vitellogenin were found between sites. Consistent with the general lack of detectable PPAR?-regulated activity, there were no significant effects on PPAR?-related gene expression in the adipose tissue of females. No site-related differences in GR-related gene expression were detected in females, despite GR-activity in the in vitro assays, suggesting either limited bioavailability or limited potency of GR-active contaminants, in vivo. Fathead minnows will be exposed in situ again in August 2019. Results will provide new insights into the significance of GR-and PPAR? active contaminants in this system.