Syllabus Edition
First teaching 2015
Last exams 2025
Sources of Fresh Water & Marine Pollution
Written by: Alistair Marjot
Reviewed by: Bridgette Barrett
Sources of Fresh Water & Marine Pollution
Causes of Water Pollution
There are a variety of freshwater and marine pollution sources
Types of aquatic pollutants include:
Organic material
Inorganic nutrients (nitrates and phosphates)
Toxic metals
Synthetic compounds
Suspended solids
Hot water
Oil
Radioactive pollution
Pathogens
Light
Noise
Invasive species
Water Pollution Effects
Pollutant | Description | Effect |
---|---|---|
Organic material | Pollution caused by excessive organic matter such as untreated human sewage, animal waste, or decaying plant material | Excessive organic material can lead to oxygen depletion, harmful algal blooms, and eutrophication in water bodies |
Inorganic nutrients | Pollution from excess nitrates and phosphates primarily originating from agricultural runoff, sewage, and fertilisers | Elevated levels of these nutrients can cause nutrient enrichment, leading to algal overgrowth and water quality degradation |
Toxic metals | Pollution caused by heavy metals such as mercury, lead and arsenic, often originating from industrial activities, mining, or improper waste disposal | These metals can accumulate in aquatic organisms, leading to toxic effects and posing risks to human health and ecosystems |
Synthetic compounds | Pollution resulting from human-made chemicals, including pesticides, herbicides, pharmaceuticals, and industrial pollutants | These compounds can enter water bodies through runoff, discharges, or improper disposal, potentially harming aquatic life and human health |
Suspended solids | Pollution caused by the presence of solid particles in water, typically sediment, silt, or fine particles from erosion, construction, or dredging activities | High concentrations of suspended solids can impair water clarity, clog fish gills, smother benthic habitats, and impact aquatic organisms such as invertebrates and their larvae |
Hot water | Pollution from the release of heated water into aquatic systems, often associated with industrial processes or power generation | Elevated water temperatures can disrupt aquatic ecosystems, reduce oxygen levels, and negatively impact fish and other organisms (e.g. disrupting migration patterns or natural breeding cycles) |
Oil | Pollution resulting from oil spills, leaks, or discharges from shipping, oil exploration, or industrial activities | Oil can coat the water surface, affecting marine and freshwater ecosystems, harming aquatic life such as seabirds, and leading to long-term environmental damage |
Radioactive pollution | Pollution caused by the release of radioactive substances, often associated with nuclear accidents, mining, or waste disposal | Radioactive pollution can have severe ecological and human health impacts, with prolonged exposure potentially leading to genetic mutations and cancer |
Pathogens | Pollution from the presence of disease-causing microorganisms, including bacteria, viruses, and parasites, often originating from sewage or animal waste | Pathogens can contaminate water sources, leading to waterborne diseases (such as cholera) and posing risks to human and animal health |
Light | Pollution resulting from excessive artificial lighting, particularly in coastal areas | Light pollution can disrupt natural light cycles, affecting nocturnal marine species and disrupting reproduction, navigation, and feeding patterns of marine organisms |
Noise | Pollution caused by anthropogenic noise from activities such as shipping, sonar, construction, or offshore energy production | Excessive noise can disrupt communication, feeding, and migration patterns of marine species (such as whales), leading to ecological disturbances |
Invasive species | Pollution resulting from the 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) | Invasive species can 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) |
It is important for countries, governments, industries and the general public to try and prevent and mitigate these forms of aquatic pollution through proper waste management, wastewater treatment, responsible industrial practices, and the implementation of environmental regulations and policies
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