Sources of Water Pollution (DP IB Environmental Systems & Societies (ESS))

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)