This text is part of the special Acfas Congress booklet
Emerging contaminants, drugs, pesticides and microplastics: a cocktail of substances pours into our waterways and drinking water sources every day, without our really knowing their impact on health and environment. This is what Quebec researchers taking part in the symposium remind us The health of rivers: reconciling human uses of water and the conservation of freshwater ecosystems.
“The challenge is that there are a lot of questions and unknowns,” observes Sébastien Sauvé, professor of environmental chemistry at the Université de Montréal. In drinking water, there are many pollutants that are little or not regulated. For many contaminants, we do not know what is safe or not, we are in a gray area. »
However, many potential health impacts are emerging in these gray areas, lists the expert. Endocrine disruptors can affect the fertility of fish and humans. Antibiotics can increase the resistance of bacteria to drugs. Several contaminants contribute to the prevalence of inflammation and cancer. Excess nitrogen and phosphorus can promote the proliferation of cyanobacteria generating cyanotoxins harmful to health.
Pollution is one of the issues that will be addressed at the Acfas symposium on the health of waterways which will take place on May 12. The symposium, which will bring together experts from the Quebec Center for Research on Water Management (CentrEau) and the Interuniversity Research Group in Limnology (GRIL), aims to strengthen collaboration between experts in the environment and in water management. . This collaboration is all the more important since the challenges concerning water management in Quebec are set to grow in the future, according to Sarah Dorner, professor in the Department of Civil, Geological and Mining Engineering at Polytechnique Montreal.
“We anticipate more flooding of municipal tributaries, we think of combined sewer overflows and more potential for contamination,” she explains of the impacts of climate change. The engineer gives as an example the spring floods at Lac des Deux Montagnes which flooded houses in Sainte-Marthe-sur-le-Lac in 2019. “We also regularly discover emerging contaminants, which influence the quality of the water. for ecosystems. »
“How can we put together our research orientations in order to better manage water for all uses, without forgetting ecosystem uses, while adapting to climate change”, says Sarah Dorner, who hopes that the symposium will help build bridges between different water research disciplines.
Policies to improve
The algae multiply and die, contributing to the accumulation of organic matter and reduced luminosity in the body of water. To degrade all this matter, bacteria consume oxygen, until it is exhausted. Anaerobic bacteria – which do not need oxygen – take over and cause the fermentation of organic matter by releasing noxious gases.
This accelerated aging of water bodies, also called eutrophication, is a well-documented phenomenon in the province’s lakes. Unfortunately, the phenomenon is now observed in the deep waters of the St. Lawrence estuary, which are also lacking in oxygen. The cause: excessive inputs of nitrogen and phosphorus from agricultural fertilizers, as well as municipal effluents.
“Each municipality that withdraws water had to do a vulnerability analysis of its water intake and count the discharges or tributaries with the potential to contaminate ecosystems,” notes Sarah Dorner.
The latter believes that these data could be used by a larger community of researchers to identify the main sources of nitrogen and phosphorus at the origin of the problem. “We need to bring people together to answer these questions. If we have eutrophication problems, it takes people who work in ecosystems, and people who work in engineering, ”believes the engineer.
This more concerted research work could enable municipalities to make better decisions or to adjust regulatory frameworks accordingly. At the municipal level, nitrogen is an element regulated on its toxicity and not on its total load in water, even if this last aspect is at the heart of eutrophication, illustrates the expert.
“There is a need for more transparency in the information, believes for his part Sébastien Sauvé. There is a certain change at the government level, with pesticide reports being transparent, but it is not systematic and everywhere. I think one of the ways to better understand, to advance these issues, is to have better transparency and access to data on the traces of contaminants in waterways. »