River Pollution (Cambridge (CIE) IGCSE Geography) : Revision Note

Human causes of river pollution

• Human activity is the main source of river pollution

• River pollution occurs when harmful substances contaminate the water

Agriculture

• Pollutants from agriculture enter the water in several ways:

  • Wastewater from silage and slurry

  • Fertilisers, herbicides and pesticides dissolve in rainwater

  • Soil erosion

  • Traces of medicine from those used to treat animals

Industry

• Industry pollutes water in several ways, including:

  • Spillages of oil

  • When water is used as a coolant and returned to rivers at higher temperatures

  • Toxic substances from industrial processes being released into rivers

Domestic

• Domestic premises also discharge polluted water into rivers through:

  • Untreated sewage

  • Water which has been used for washing clothes and bathing

  • Water which has been used for leisure may be treated with chlorine

  • Traces of medicines taken by humans

Impacts of river pollution

Agriculture

• Pesticides, herbicides, and fertilisers entering the water lead to the following:

  • Death of fish and other river wildlife which introduces bacteria into the water

  • Eutrophication

  • Poisoning fish and other wildlife

  • More sediment entering the river which increases turbidity, leading to a decrease in oxygen levels

Industry

• The impacts of industry on the water quality are that:

  • Oil stays on the surface of the water, wildlife and plants become coated in oil and cannot eat/move/fly 

  • Animals and plants within the water system cannot survive in higher temperatures

  • Toxins enter the food chain and are harmful to wildlife and humans

Domestic

• Sewage and water used in cleaning or that has been treated with chlorine may:

  • Increase the levels of nitrogen in the water and introduce bacteria

  • Be harmful to wildlife

  • Causes chemical burns

• Medicines are difficult to remove in water treatment so remain in the water

  • These may contain a range of ingredients which are harmful to humans or wildlife

Management of river pollution

• There are three levels of pollution management:

  • Changing human activity

  • Regulating and reducing quantities of pollutants released at the point of emission

  • Cleaning up the pollutants and restoring the ecosystem after pollution has occurred

Reducing human activities that produce pollutants

• Alternative practices and technologies:

  • Identifying and adopting alternatives to fertilisers and detergents that have less harmful environmental impacts

  • For example, promoting the use of organic fertilisers and eco-friendly detergents can reduce the release of pollutants into water bodies

• Public awareness and education:

  • Educating the public about the environmental consequences of certain human activities and encouraging changes in behaviour

  • This includes promoting sustainable agricultural practices, responsible waste management, and water conservation

Reducing the release of pollution into the environment

• Wastewater treatment:

  • Implementing effective wastewater treatment systems to remove pollutants, such as nitrates and phosphates, before the water is discharged back into the environment

  • This includes processes like biological treatment, chemical precipitation, and advanced filtration techniques

• Industrial regulations:

  • Enforcing strict regulations and standards for industries to control and reduce the release of pollutants into water bodies

  • This can include effluent discharge limits, mandatory pollution control measures, and regular monitoring and reporting of pollution levels

Removing pollutants from the environment and restoring ecosystems

• Remediation and restoration projects:

  • Introducing strategies to remove pollutants from contaminated sites and restore ecosystems

  • This can involve techniques including:

    • Dredging to remove accumulated sediment, using activated carbon or other absorbents to capture pollutants

    • Re-establishing native vegetation and aquatic species

• Ecosystem management:

  • Adopting holistic approaches to manage ecosystems and their water quality

  • This includes implementing integrated watershed management plans (sometimes known as the Catchment Based Approach), promoting natural filtration systems (e.g. constructed wetlands), and restoring riparian buffers to minimise pollution runoff