Assessing the impact of wastewater treatment plant upgrades on fish health

点击翻译按钮获取中文摘要

Continued urbanization of human populations has put increasing demands on the limited water resources available in Canada. Although wastewater treatment has been effective in reducing acute toxicity and eutrophication, new emerging chemicals released in the effluents are raising concerns. These chemicals can interact with organisms through numerous interlinked mechanisms to cause adverse outcomes on ecosystem health, including fish populations. Wastewater utilities face considerable uncertainty related to the potential ecological significance of these changes and the options available to effectively remove them. The new Wastewater Effluent Systems Regulations (Fisheries Act) require all Canadian wastewater systems to achieve minimum baselines for selected effluent parameters. However, these do not include the diversity of emerging contaminants, such as environmental estrogens, that are present in effluents that can have important effects on reproduction in fish. As wastewater utilities invest in treatment process upgrades to meet the regulation and protect receiving environments, it will be important to determine how these contaminants are affected and how ecosystems respond. In the Grand River watershed, in southern Ontario, many effects have been documented in fish associated with the two major wastewater treatment plants. However, these facilities are currently undergoing major process upgrades (2012-2020). Research has been ongoing in the watershed for more than a decade at these sites and therefore has created a unique opportunity to follow the response of the ecosystem (i.e., fish) to these major investments. Past data sets, along with archived and newly collected samples, will be used to assess how biological responses (genes to populations) are altered in a sentinel fish species (rainbow darter, Etheostoma caeruleum). This will be supported with analytical chemistry and laboratory bioassays to better understand changes in exposure and risk over time. The project will strengthen the utilities' ability to assess efforts to protect the environment and guide future investment decisions.