Project description:Wastewater treatment plant (WWTP) effluent-dominated streams provide critical habitat for aquatic and terrestrial organisms but also continually expose them to complex mixtures of pharmaceuticals that can potentially impair growth, behavior, and reproduction. Currently, few biomarkers are available that relate to pharmaceutical-specific mechanisms of action. In the experiment reported in this paper, zebrafish (Danio rerio) embryos at two developmental stages were exposed to water samples from three sampling sites (0.1 km upstream of the outfall, at the effluent outfall, and 0.1 km below the outfall) during base-flow conditions from two months (January and May) of a temperate-region effluent-dominated stream containing a complex mixture of pharmaceuticals and other contaminants of emerging concern. RNA-sequencing identified potential biological impacts and biomarkers of WWTP effluent exposure that extend past traditional markers of endocrine disruption. Transcriptomics revealed changes to a wide range of biological functions and pathways including cardiac, neurological, visual, metabolic, and signaling pathways. These transcriptomic changes varied by developmental stage and displayed sensitivity to variable chemical composition and concentration of effluent, thus indicating a need for stage-specific biomarkers. Some transcripts are known to be associated with genes related to pharmaceuticals that were present in the collected samples. Although traditional biomarkers of endocrine disruption were not enriched in either month, a high estrogenicity signal was detected upstream in May and implicates the presence of unidentified chemical inputs not captured by the targeted chemical analysis. This work reveals associations between bioeffects of exposure, stage of development, and the composition of chemical mixtures in effluent-dominated surface water. The work underscores the importance of measuring effects beyond the endocrine system when assessing the impact of bioactive chemicals in WWTP effluent and identifies a need for non-targeted chemical analysis when bioeffects are not explained by the targeted analysis.
Project description:Aquatic organisms, such as fish, are in constant contact with various anthropogenic stressors present in their environments, including contaminants from wastewater treatment plant effluents (WWTPE). WWTPE represents a pervasive source of pharmaceutically active compounds in surface waters This study investigates the effects of WWTPE exposure on Etheostoma spp. (darters) using hepatic transcriptomic profiling. Wild darters—Etheostoma caeruleum (rainbow darter), Etheostoma blennioides (greenside darter), Etheostoma flabellare (fantail darter), and Etheostoma nigrum (Johnny darter)—were collected upstream and downstream of the Waterloo municipal WWTP effluent outfall (Grand River, ON).
Project description:Soil Aquifer Treatment (SAT) is recognized as a cost-effective approach to reduce contaminants of emerging concern (CECs) from Wastewater Treatment Plant (WWTP) effluents. However, its efficiency in removing the associated biological effects is still poorly understood. Here, we evaluated the efficiency of three pilot SAT systems, two of them enhanced with reactive barriers containing different proportions of sand and organic materials, in removing toxicity associated to CECs. SATs were fed with secondary effluents from the Palamós WWTP (N.E. Spain) during two consecutive campaigns scheduled before and after the summer of 2020. Fifteen water samples were collected from the WWTP effluent, below the barriers and 15 m into the aquifer. Transcriptomic analyses of zebrafish embryos exposed to the corresponding water extracts revealed a wide range of toxic activities in the WWTP effluents. Results demonstrated that the associated responses were reduced by more than 70% by SAT, achieving control levels in some cases. Similar results were obtained when human HepG2 hepatic cells were tested for cytotoxic and dioxin-like responses. Toxicity reduction appeared to be partially determined by the reactive barrier composition and/or SAT managing and was correlated with the removal of CECs by SAT. In conclusion, SAT appears to be a very promising approach for efficiently reducing the effects of recalcitrant pollutants from WWTP secondary effluents on the environment and human health.
Project description:We investigated the impacts of wastewater effluent exposure on gene expression in adult fathead minnows, a freshwater fish commonly used as an ecotoxicological model.
