Physical chemistry and bacteriology of watercourses

Naturally present elements in water make up what is known as water’s physical chemistry. These elements can be dissolved or suspended and derive from many natural sources: soil and bedrock; vegetation and wildlife; precipitation and watershed runoff; and biological, physical and chemical processes occurring in the watercourse itself. In addition, human activities can alter water’s natural physical chemistry and are the source of microbiological contamination, particularly by bacteria of fecal origin. The physical chemical and bacteriological parameters measured by the MELCCFP Réseau-rivières are: nutrients (total filtered nitrogen, filtered ammonia nitrogen, filtered nitrites-nitrates, total phosphorus), turbidity, dissolved organic carbon, suspended solids, chlorophyll a, fecal coliforms, conductivity, pH and temperature. The MELCCFP has also developed the bacteriological and physical chemical quality index or IQBP (French), to assess the general water quality of Québec’s rivers.

Documentation :

• Loadings of six physical chemical and bacteriological parameters at the mouths of the main tributaries of the St. Lawrence River – 2013–2017 (French, PDF, 3 MB)
• Water quality of Baie Missisquoi tributaries: 1999–2017 temporal evolution and recent profile (2015–2017) (French, PDF, 3 MB)
• Territory and water quality: developing predictive models
• Water quality of Lac Saint-Pierre tributaries: 1979–2014 temporal evolution and recent profile (2012–2014) (French, PDF, 9.3 MB)
• Phosphorus, nitrogen and suspended solid loadings at the mouths of Québec’s rivers – 2009 to 2012
• Water quality trends from 1999 to 2008 in ten Québec agricultural watersheds

Total phosphorus

Since the early 1980s, Québec has invested heavily in preventing phosphorus pollution of rivers and lakes. Phosphorus is the main cause of eutrophication in lakes and watercourses, and managing its effects on water bodies remains a major issue for all human activities.

Documentation:

• Comparison of two analytical methods for measuring phosphorus in aquatic environments
• Establishing water quality criteria and reference values for phosphorus, according to eco-regions: opportunity, feasibility and initial exploratory exercise

Total nitrogen

Since the 900s, nitrogen loading in the St. Lawrence has quadrupled, contributing significantly to eutrophication of the waters of the St. Lawrence estuary and the resulting effects (hypoxia, deep-water acidification and red tides). Diffuse inputs, notably from agricultural activities, are the main sources of nitrogen transiting through the St. Lawrence River and its tributaries towards the estuary. Other nitrogen inputs can largely be attributed to the intermittent discharge of municipal wastewater.

• Literature review – Eutrophication in the marine environment (French, PDF, 8.6 MB)

Useful links

• Rivers (watersheds): State of aquatic environments
• 2020 Water Report: Physical chemistry and bacteriology of the St. Lawrence River’s tributaries (French, PDF, 120 MB)
• 2020 Water Report: Physical chemistry and bacteriology of agricultural watercourses (French, PDF, 120 MB)