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Effects-based monitoring of bioactive contaminants associated with exposure to wastewater treatment plant discharge on the Colorado River
Citation:
Cavallin, J., W. Battaglin, J. Beihoffer, B. Blackwell, P. Bradley, D. Ekman, J. Kinsey, K. Keteles, E. Lai, R. Weissinger, D. Winkelman, AND Dan Villeneuve. Effects-based monitoring of bioactive contaminants associated with exposure to wastewater treatment plant discharge on the Colorado River. SETAC North America, Sacramento, CA, November 04 - 08, 2018.
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 (#1956) builds upon several years of preliminary chemical monitoring research on the Colorado River as a basis for further investigation of ER, GR, and PPAR-bioactive contaminants and potential responses elicited in caged fish.
Description:
Over the last several years, chemical monitoring of the Colorado River near Moab, UT, has detected a variety of chemicals of emerging concern (CECs). However, given the lack of available effects data for most of the compounds detected, potential ecological risks, if any, associated with these contaminants are unclear. To help address this question, extracts of surface water samples were analyzed using a multiplexed in vitro bioassay that evaluated activity with regard to human nuclear receptors and related transcription factors. Estrogen receptor (ER), glucocorticoid receptor (GR), and peroxisome proliferator activated receptor (PPAR) activities were associated with surface water near the Moab wastewater treatment plant (WWTP). In vitro ER activation was also confirmed in surface water near the WWTP outflow using the estrogen-responsive T47D-Kbluc bioassay. To evaluate the potential bioavailability and significance of these biologically-active contaminants, adult fathead minnows (Pimephales promelas) were caged at five sites along the Colorado River near Moab, UT, at various proximities to the WWTP. After four days of exposure, skin mucus, plasma, livers, and gonads were collected for measurement of a variety of biological endpoints (e.g., transcriptomics, metabolomics, steroid concentrations). An autosampler was simultaneously deployed to collect a composited surface water sample reflective of the four-day fish exposure. Composite water samples were analyzed for a suite of pharmaceuticals, pesticides, steroid hormones, wastewater indicators, and in vitro biological activities (e.g., ER, GR, and PPAR activities). Consistent with previous monitoring, total estrogenic activity of surface water was confirmed using the T47D-Kbluc bioassay, with approximately 45 ng/L of 17â-estradiol equivalents (E2-EQ) estimated at the WWTP discharge site and 2 ng/L E2-EQ at the proximal downstream site. Consistent with downstream dilution of estrogenic activity, no statistically significant differences were observed in male liver vitellogenin mRNA expression among any of the sites, excluding the WWTP site in which 100% mortality was observed. Results suggest rapid dilution of biologically-active contaminants downstream of the WWTP discharge and will be discussed relative to the potential effects of CECs in the Colorado River.