Runoff / Nonpoint Source Pollution

Unique identifier / Notation

EN0006

Synonyms

None identified.

Nonpoint sources of pollution refer to pollution sources that are diffused and without a single point of origin or not introduced into a receiving freshwater or maritime environment from a specific outlet. The pollutants are generally carried off the land by storm-water run-off. The commonly used categories for nonpoint sources are agriculture, forestry, urban areas, mining, construction, dams and channels, land disposal and saltwater intrusion (UN data, no date).

Primary reference(s)

UN Data, no date. Non-point Source Pollution. UNdata: A world of information. Accessed 15 October 2020.

Additional scientific description

Nonpoint source pollution generally results from land runoff, precipitation, atmospheric deposition, drainage, seepage or hydrologic modification. Nonpoint source pollution, unlike pollution from industrial and sewage treatment plants, comes from many diffuse sources. Nonpoint source pollution is caused by rainfall or snowmelt moving over and through the ground. As the runoff moves, it picks up and carries away natural and human-made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters and ground waters (US EPA, 2020; NOAA, no date).

Nonpoint source pollution can include: excess fertilisers, herbicides and insecticides from agricultural lands and residential areas; oil, grease and toxic chemicals from urban runoff and energy production; sediment from improperly managed construction sites, crop and forest lands, and eroding streambanks; salt from irrigation practices and acid drainage from abandoned mines; bacteria and nutrients from livestock, pet wastes and faulty septic systems; and atmospheric deposition and hydromodification (US EPA, 2020).

Metrics and numeric limits

Not identified.

Key relevant UN convention / multilateral treaty

The Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter 1972 (IMO, 1972), the ‘London Convention’ for short, is one of the first global conventions to protect the marine environment from human activities and has been in force since 1975. Its objective is to promote the effective control of all sources of marine pollution and to take all practicable steps to prevent pollution of the sea by dumping of wastes and other matter. Currently, 87 States are Parties to this Convention.

The International Convention for the Prevention of Pollution from Ships (MARPOL) 1996 (IMO, 1996) is the main international convention covering prevention of pollution of the marine environment by ships from operational or accidental causes. The MARPOL Convention was adopted on 2 November 1973. The Protocol of 1978 was adopted in response to a spate of tanker accidents in 1976-1977. As the 1973 MARPOL Convention had not yet entered into force, the 1978 MARPOL Protocol absorbed the parent Convention. The combined instrument entered into force on 2 October 1983. In 1997, a Protocol was adopted to amend the Convention and a new Annex VI was added which entered into force on 19 May 2005. MARPOL has been updated by amendments through the years to the London Convention (the ‘London Protocol’).

Examples of drivers, outcomes and risk management

Marine debris is defined as any persistent solid material that is manufactured or processed and directly or indirectly, intentionally or unintentionally, disposed of or abandoned into the marine environment. Marine debris takes many forms, including derelict fishing gear and vessels, abandoned recreational equipment, and discarded consumer plastics, metals, rubber, paper, and textiles.

For example, the International Union for Conservation of Nature provides information on marine plastics (IUCN, 2018):

Over 300 million tons of plastic are produced every year for use in a wide variety of applications.
At least 8 million tons of plastic end up in the oceans every year and make up 80% of all marine debris from surface waters to deep-sea sediments.
Marine species ingest or are entangled by plastic debris, which causes severe injuries and deaths.
Plastic pollution threatens food safety and quality, human health, coastal tourism, and contributes to climate change.
There is an urgent need to explore the use of existing legally binding international agreements to address marine plastic pollution.
Recycling and reuse of plastic products, and support for research and innovation to develop new products to replace singleuse plastics are also necessary to prevent and reduce plastic pollution.