Abstract
Waste water treatment facilities are a major sources of organic micropollutants (MPs) in surface water. In this study, surface water samples were collected from seven sites along a river system in Uppsala, Sweden, during four seasons and evaluated based on the occurrence of MPs in the samples and bioactivity using in vitro bioassays. The sampling sites were differentially impacted by on-site sewage treatment facilities (OSSFs), small scale, and large scale waste water treatment plants (WWTPs). The bioassays used included activation of aryl hydrocarbon receptor (AhR), estrogen receptor (ER), nuclear factor kappa-light-chain-enhancer of activated B cells (NFkB), nuclear factor erythroid 2-related factor 2 (Nrf2), and androgen receptor (AR). Occurrence of 80 MPs, were analyzed using liquid chromatography coupled to tandem mass spectrometry. Most water samples induced AhR activity, and all sampling sites showed a similar profile regarding this activity. With the exception of one water sample, we did not detect any NFkB, Nrf2 or AR activity of the water samples. The exception was a sample impacted by OSSFs, which showed an activity in multiple bioassays, but the activity could not be explained by the occurrence of target MPs. The occurrence of MPs showed a spatial trend, with the highest number and amount of MPs detected in the samples collected downstream of the WWTPs, where up to 47 MPs were detected in one single sample. A seasonal variation was observed with highest levels of MPs and highest AhR activities in samples collected in June and September 2015. However, neither the seasonal activity nor the on-site activity could be explained by the measured MPs, suggesting unknown contributory agents in the water.
Highlights
Surface water can be contaminated with organic micropollutants (MPs), which is an environmental problem of great concern, both for human health and the ecosystem
The water samples did not lead to compromised cell viability above the cut-off value at the treatment concentration of 1% of the passive sampler eluate, except the sample collected at site 3 in June 2015, which led to toxicity just below the cut-off level at 1%, but not at 0.5% of passive sampler eluate in androgen receptor (AR)-Ecoscreen cells (Fig. SI1, Supplementary Information)
We performed an integrated toxicological and chemical characterization of passive water samples from seven sampling sites in a river system, all differentially impacted by on-site sewage treatment facilities (OSSFs) and/or waste water treatment plants (WWTPs)
Summary
Surface water can be contaminated with organic micropollutants (MPs), which is an environmental problem of great concern, both for human health and the ecosystem. Besides conventional waste water treatment plants (WWTPs), on-site sewage treatment facilities (OSSFs) can have an impact on the aquatic environment since they are usually not designed to remove MPs from wastewater[2,3,4]. We assessed the impact of discharge from OSSFs and WWTPs of various sizes on the aquatic environment by integrating chemical and toxicological analysis of surface water samples using passive sampler on a seasonal basis. The samples were analyzed for bioactivity using in vitro assays for specific toxicity endpoints; activation of AhR, nuclear factor kappa-light-chain-enhancer of activated B cells (NFkB), nuclear factor erythroid 2-related factor 2 (Nrf2), and ER, as well as AR agonistic and antagonistic activities. The chemical analysis could, not explain the observed bioactivity
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