LIFE-THREATENING CONTAMINANTS

While nutrients such as phosphorus and nitrogen are part of a healthy ecosystem, an excess or oversupply can have serious consequences for freshwater health. Intensive agriculture is contributing to this excess. When it rains, or when crops are overwatered, nutrient-rich fertilizers runoff into watersheds, contributing to rapid algae growth – and sometimes, large algal blooms – in freshwater sources. Through a process called eutrophication, these blooms can deplete the water’s oxygen levels, killing fish and other aquatic species. There can also be direct impacts for humans – in 2014, a summer bloom in Lake Erie caused a three-day drinking water crisis for residents of Toledo, Ohio.

You’ve probably heard of the Great Pacific Garbage Patch, but did you know that freshwater has a plastics problem, too? The tiny microplastics that enter waterways come from a variety of sources, including the microfibres from our clothing, microbeads used in cosmetic products, and the breakdown of larger plastic productions, such as water bottles and plastic bags. According to a 2017 study by Orb Media, tap water samples from major metropolitan areas on five continents showed that more than 83% were contaminated with plastic fibres. Microplastics have been linked to several serious health concerns for humans and aquatic species.

While North American cities have advanced wastewater treatment facilities, some 80% of the world’s wastewater is dumped—largely untreated—back into the environment. What does this mean? Whatever we use and consume, including chemicals and pharmaceuticals, could end up in freshwater sources.