Effects of a major municipal effluent on the St. Lawrence River: A case study

Abstract

The St. Lawrence River (SLR) is the second largest waterway in North America. The discharge of the City of Montreal wastewater treatment plant (WWTP) represents the largest volume of treated wastewaters being released into the river. It also ranks as the largest sewage treatment plant of its kind in North America. Over the last decade, intensive multidisciplinary research has focused on assessing the impacts of Montreal wastewater effluents on the SLR. We describe the major findings of these investigations, including the determination of the fate of contaminants, bioaccumulation in fish and invertebrates, ecotoxicological measurements of aquatic animal health, evaluation of endocrine disruption, parasitism in fish, and combined effects of multiple stressors on the SLR. Impacts of the effluents from the WWTP on aquatic organisms from the SLR are both toxicological and ecological, demonstrating the need for an integrated view of the impacts of municipal effluents on aquatic ecosystems.

Hydrological and biological processes modulate carbon, nitrogen and phosphorus flux from the St. Lawrence River to its estuary (Quebec, Canada)

“…Such measures are warranted in light of the (unquantified albeit most likely) significant contribution of overflows to C, N, and P loads and their anticipated rise with extreme rain events under climate change. Far from being local, both the chemical signature and the ecosystemic effects of the plume of the City of Montreal treated wastewater effluent were detectable several km downstream of its release point (Marcogliese et al 2014).…”

“…In the greater Montreal area alone, the SLR receives the primary-treated municipal effluents of over 3 million inhabitants (Fig. 1, circle, Marcogliese et al 2014). The Ottawa River (watershed: 146,334 km 2 ) and other north shore tributaries (watershed: 63,790 km 2 ) largely drain boreal forests growing on the Precambrian Shield, whereas south shore tributaries (watershed: 56,840 km 2 ) originate from the Appalachian mountain range and mostly drain Ordovician and Silurian limestone (Douglas 1970).…”

“…Over the last few decades, however, major changes in urban wastewater treatment (Marcogliese et al 2014), farming practices (Clair et al 2013), and temperature and hydrological regimes (Hudon et al 2010) have occurred in the SLR watershed, most likely inducing changes in the C, N, and P flux to the estuary. Although degradation of the estuarine environment is increasingly attributed to river enrichment, riverine contribution must be assessed in comparison with oceanographic processes (e.g.…”

Disruption of the stress response in wastewater treatment works effluent-exposed three-spined sticklebacks persists after translocation to an unpolluted environment

“…Biota within the aquatic ecosystem are particularly vulnerable to chemical exposure given the range and quantity of anthropogenic contaminants introduced into watercourses, both deliberately and inadvertently (Henze and Comeau 2008;Marcogliese et al 2015).…”

Urban Pollution Increases Sensitivity to Temperature Changes in Elliptio complanata Mussels Exposed to Municipal Wastewaters

“…This results in an increase in urban pollution (untreated wastewater diluted by rain), which can lead to increased contamination of watercourses and deleterious effects on aquatic biota. Municipal wastewaters are recognized as a source of pollutants such as polyaromatic hydrocarbons, heavy metals, cyclic aliphatic hydrocarbons (steroids), antibiotics and many other pharmaceutical products [2,3]. Municipal effluents are well known to contain endocrine disrupters which can cause reproductive, developmental and behavioral changes in fish and other organisms.…”