Syllabus Edition
First teaching 2024
First exams 2026
Sources of Water Pollution (DP IB Environmental Systems & Societies (ESS))
Revision Note
Written by: Alistair Marjot
Reviewed by: Bridgette Barrett
Sources of Water Pollution
Water pollution has multiple sources and has major impacts on marine and freshwater systems
Types of aquatic pollutants include:
Organic material
Inorganic nutrients (nitrates and phosphates)
Industrial effluent
Urban run-off
Solid waste disposal
Toxic metals
Synthetic compounds
Suspended solids
Hot water
Oil
Radioactive pollution
Pathogens
Light
Noise
Invasive species
Water Pollution Effects
Pollutant | Description | Effect |
---|---|---|
Organic material | Excessive organic matter from untreated human sewage, animal waste, or decaying plant material | Leads to oxygen depletion, harmful algal blooms and eutrophication in water bodies |
Inorganic nutrients | Excess nitrates and phosphates from agricultural run-off, sewage and fertilisers | Causes nutrient enrichment, leading to algal overgrowth and water quality degradation |
Industrial effluent | Wastewater discharged by industrial facilities after being used in production processes, containing a variety of pollutants e.g. heavy metals, toxic chemicals, organic matter and pathogens | Can be toxic to aquatic life, disrupt ecosystems, and contaminate drinking water sources |
Urban run-off | Rainwater or melted snow that flows over impervious surfaces, such as roads, pavement and rooftops, picking up pollutants along the way e.g. oil, grease, pesticides, fertilisers, pet waste and litter | Degrades water quality, harming aquatic life, promoting algae blooms, and contaminating drinking water sources |
Solid waste disposal | Rain falling on landfills leaches contaminants into soil and groundwater, whilst litter can end up in waterways, entangling wildlife and releasing harmful chemicals into the water | Contaminates groundwater sources and harms aquatic life |
Heavy metals | Heavy metals such as mercury, lead and arsenic from industrial activities, mining, or improper waste disposal | Metals accumulate in aquatic organisms, leading to toxic effects and posing risks to human health |
Synthetic compounds | Human-made chemicals, including pesticides, herbicides, pharmaceuticals and industrial pollutants | Enter water bodies through run-off, discharges, or improper disposal, potentially harming aquatic life and human health |
Suspended solids | Solid particles in water, typically sediment, silt, or fine particles from erosion, construction, or dredging activities | High concentrations can impair water clarity, clog fish gills, smother benthic habitats and impact aquatic organisms such as invertebrates and their larvae |
Hot water | Release of heated water into aquatic systems, often associated with industrial processes or power generation | Disrupts aquatic ecosystems, reduces oxygen levels and negatively impacts fish and other organisms (e.g. disrupting migration patterns or natural breeding cycles) |
Oil | Oil spills, leaks, or discharges from shipping, oil exploration, or industrial activities | Oil coats the water surface, affecting marine and freshwater ecosystems, harming aquatic life such as seabirds and leading to long-term environmental damage |
Radioactive pollution | Release of radioactive substances, often associated with nuclear accidents, mining, or waste disposal | Severe ecological and human health impacts, with prolonged exposure potentially leading to genetic mutations and cancer |
Pathogens | Presence of disease-causing microorganisms, including bacteria, viruses and parasites, often originating from sewage or animal waste | Contaminate water sources, leading to waterborne diseases (e.g. cholera) and posing risks to human and animal health |
Light | Excessive artificial lighting, particularly in coastal areas | Disrupts natural light cycles, affecting nocturnal marine species and disrupting reproduction, navigation and feeding patterns of marine organisms |
Noise | Noise from human activities such as shipping, sonar, construction, or offshore energy production | Disrupts communication, feeding and migration patterns of marine species (e.g. whales), leading to ecological disturbances |
Invasive species | Introduction of non-native species into aquatic ecosystems, often through ballast water or occasionally intentional release (e.g. for biological control or recreational fishing purposes) | Outcompete native species, alter habitat structure, disrupt food webs and cause severe ecological imbalances (e.g. the invasion of lionfish into U.S. Atlantic coastal waters) |
Last updated:
You've read 0 of your 10 free revision notes
Unlock more, it's free!
Did this page help you?