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Assessing the impact of wastewater treatment plant effluent on downstream drinking water-source quality using a zebrafish (Danio Rerio) liver cell-based metabolomics approach
Zhen, H., D. Ekman, Tim Collette, S. Glassmeyer, M. Mills, E. Furlong, D. Kolpin, AND Q. Teng. Assessing the impact of wastewater treatment plant effluent on downstream drinking water-source quality using a zebrafish (Danio Rerio) liver cell-based metabolomics approach. WATER RESEARCH. Elsevier Science Ltd, New York, NY, 145:198-209, (2018). https://doi.org/10.1016/j.watres.2018.08.028
The past several decades have witnessed a rapidly increasing demand for water resources due to global economic development and an ever-increasing population. In many densely populated or arid regions, the lack of sufficient potable water has led to the use of treated wastewater (e.g., discharges from waste water treatment plants (WWTPs)) for many non-potable applications, such as agricultural and landscape irrigations and groundwater recharge. Unfortunately, the discharge of treated wastewater into natural systems, e.g., rivers and lakes, has also inadvertently resulted in introduction of a complex mixture of organic contaminants to local aquatic ecosystems and, importantly, surface-water derived drinking water supplies.
Cell-based metabolomics was used in a proof-of-concept fashion to investigate the biological effects of contaminants as they traveled from a wastewater treatment plant (WWTP) discharge to a drinking water treatment plant (DWTP) intake in a surface water usage cycle. Zebrafish liver (ZFL) cells were exposed to water samples collected along a surface water flowpath, where a WWTP was located ~14.5 km upstream of a DWTP. The sampling sites included: 1) upstream of the WWTP, 2) the WWTP effluent discharging point, 3) a proximal location downstream of the WWTP outfall, 4) a distal location downstream of the WWTP outfall, 5) the drinking water intake, and 6) the treated drinking water collected prior to discharge to the distribution system. After a 48-hour laboratory exposure, the hydrophilic and lipophilic metabolites in ZFL cell extracts were analyzed by proton nuclear magnetic resonance (1H NMR) spectroscopy and gas chromatography-mass spectrometry (GC-MS), respectively. Multivariate statistical analysis revealed distinct changes in metabolite profiles in response to WWTP effluent exposure. These effects on the hydrophilic metabolome gradually diminished downstream of the WWTP, becoming non-significant at the drinking water intake (comparable to upstream of the WWTP). However, effects on the lipophilic metabolome increased significantly as the river flowed from the distal location downstream of the WWTP to the drinking water intake, suggesting a source of contamination in this watershed other than the WWTP. ZFL cells exposed to treated drinking water did not exhibit significant changes in either the hydrophilic or lipophilic metabolome (compared to the upstream site), suggesting that constituents in the WWTP effluent were efficiently removed by the drinking water treatment process. Impacts on ZFL cells from the WWTP effluent included disrupted energy metabolism, a global decrease in amino acids and altered lipid metabolism pathways. Overall, this study demonstrated the utility of cell-based metabolomics as an effective tool for assessing the biological effects of complex pollutant mixtures, particularly when used as a complement to conventional chemical monitoring.
Record Details:Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL EXPOSURE RESEARCH LABORATORY
SYSTEMS EXPOSURE DIVISION