Rivers in the arid Western United States face increasing influences from anthropogenic contaminants due to population growth, urbanization, and drought. To better understand and more effectively track the impacts of these contaminants, biologically-based monitoring tools are increasingly being used to complement routine chemical monitoring. This study was initiated to assess the ability of both targeted and untargeted biologically-based monitoring tools to discriminate impacts of two adjacent wastewater treatment plants (WWTPs) on Colorado's South Platte River. A cell-based estrogen assay (in vitro, targeted) determined that water samples collected downstream of the larger of the two WWTPs displayed considerable estrogenic activity in its two separate effluent streams. Hepatic vitellogenin mRNA expression (in vivo, targeted) and NMR-based metabolomic analyses (in vivo, untargeted) from caged male fathead minnows also suggested estrogenic activity downstream of the larger WWTP, but detected significant differences in responses from its two effluent streams. The metabolomic results suggested that these differences were associated with oxidative stress levels. Finally, partial least squares regression was used to explore linkages between the metabolomics responses and the chemical contaminants that were detected at the sites. This analysis, along with univariate statistical approaches, identified significant covariance between the biological endpoints and estrone concentrations, suggesting the importance of this contaminant and recommending increased focus on its presence in the environment. These results underscore the benefits of a combined targeted and untargeted biologically-based monitoring strategy when used alongside contaminant monitoring to more effectively assess ecological impacts of exposures to complex mixtures in surface waters.
Monitoring of the Colorado River
near the Moab, Utah, wastewater
treatment plant (WWTP) outflow has detected pharmaceuticals, hormones,
and estrogen-receptor (ER)-, glucocorticoid receptor (GR)-, and peroxisome
proliferator-activated receptor-gamma (PPARγ)-mediated biological
activities. The aim of the present multi-year study was to assess
effects of a WWTP replacement on bioactive chemical (BC) concentrations.
Water samples were collected bimonthly, pre- and post-replacement,
at 11 sites along the Colorado River upstream and downstream of the
WWTP and analyzed for in vitro bioactivities (e.g.,
agonism of ER, GR, and PPARγ) and BC concentrations; fathead
minnows were cage deployed pre- and post-replacement at sites with
varying proximities to the WWTP. Before the WWTP replacement, in vitro ER (24 ng 17β-estradiol equivalents/L)-,
GR (60 ng dexamethasone equivalents/L)-, and PPARγ-mediated
activities were detected at the WWTP outflow but diminished downstream.
In March 2018, the WWTP effluent was acutely toxic to the fish, likely
due to elevated ammonia concentrations. Following the WWTP replacement,
ER, GR, and PPARγ bioactivities were reduced by approximately
60–79%, no toxicity was observed in caged fish, and there were
marked decreases in concentrations of many BCs. Results suggest that
replacement of the Moab WWTP achieved a significant reduction in BC
concentrations to the Colorado River.
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