Learn about the many sources of ocean water pollution including oil spills, plastics, and most importantly land-based runoff.
Ocean pollution leads to beach closings, contaminated seafood, and of course the destruction of marine ecosystems and wildlife. There are plenty of reasons to care about ocean pollution, but without understanding where it’s all coming from, solutions to water pollution will be hard to find.
Oil Spills: A Minor Source of Ocean Water Pollution?
Tanker oil spills and oil rig blowouts are perhaps two of the most well-known sources of ocean pollution, and large oil spills are certainly well represented in the media. However, it is important to keep in mind that over 80% of ocean pollution actually comes from land-based sources (NOAA), and of the oil that enters the ocean only 14% comes from tanker accidents and offshore oil extraction (UNEP). Despite contributing a small percentage of the overall pollution entering the ocean, oil spills can have catastrophic effects on seabirds, marine mammals, fish, and local economies.
Most Ocean Water Pollution Comes From Runoff
According to NOAA the largest source of ocean pollution is nonpoint source pollution – essentially runoff, or waste flowing from land into the sea. Pollutants in runoff can include oil from cars, fertilizers from lawns, untreated sewage discharged into streams, or toxins that escape into the air during manufacturing processes.
According to the WWF on its page “Problems: Ocean Pollution”, almost every marine organism – no matter its size – is contaminated with man-made chemicals. Further, nutrients found in sewage discharge and fertilizers can cause algal blooms in the ocean that deplete the water’s dissolved oxygen leading to the death of other marine life. The impact of runoff is one reason deforestation has a large impact on ocean health.
Ocean Pollution and Plastics
Another land-based pollutant entering the ocean includes plastics. According to The Economist in its article “A New Year’s wish for less trash” (Dec 2010) the Great Pacific Garbage Patch could be twice the size of the continental United States and further ‘trash vortices’ have been discovered in the South Pacific, North and South Atlantic, and the Indian Ocean.
The Economist quotes the charity Science and technology against Ocean Plastics (STOP) as saying large areas of the ocean contain more plastic than plankton. Plastic bags are known to kill sea turtles, which mistake the bags for food. Meanwhile, small plastic bits floating in the water can attract chemicals such as PCBs and DDT, these bits may be eaten by fish, allowing the chemicals to work their way up the food chain.
Carbon Emissions and Ocean Pollution
Ocean acidification is perhaps the form of ocean pollution least well-known among the general public. Amidst all the arguing over global warming, many have overlooked the effects increased carbon emissions have on marine life. Unrelated to climate change, it is unarguably true that carbon emissions have increased over the past century. This increase in carbon has led to chemical changes in the ocean which have in turn affected marine life. Corals and other creatures reliant on carbonate have found it difficult to create the structures they need to survive. Increased carbon emissions have also been linked to increased coral bleaching – which can often mean coral death.
Undoubtedly ocean pollution is a problem that needs to be faced with innovative solutions. Fortunately, solutions to water pollution often exist at home. Learning how individuals can help save the ocean is a great first step to protecting important ecosystems.
“FAQ”. Global Marine Oil Pollution Information Gateway. UNEP. 6 Jan 2011. oils.gpa.unep.org/.
“Most Ocean Pollution Begins on Land”. National Ocean Service. Dec 2008. NOAA. 6 Jan 2011. < oceanservice.noaa.gov.