Where does this pollution come from? Where does it go? Some of the debris ends up on our beaches, washed in with the waves and tides, some sinks, some is eaten by marine animals that mistake it for food, and some accumulates in ocean gyres. Other forms of pollution that impact the health of the ocean come from a single, known sources, such as oil spills, or from accumulation of many dispersed sources, such as fertilizer from our yards.
The majority of pollutants going into the ocean come from activities on land. Natural processes and human activities along the coastlines and far inland affect the health of our ocean. One of the biggest sources is called nonpoint source pollution, which occurs as a result of runoff. Nonpoint source pollution includes many small sources, like septic tanks, cars, trucks, and boats, plus larger sources, such as farms, livestock ranches, and timber harvest areas. Pollution that comes from a single source, like an oil or chemical spill, is known as point source pollution. Often these events have large impacts, but fortunately, they occur less often. Discharge from faulty or damaged factories or water treatment systems is also considered point source pollution.
Nutrients and algal blooms
Sometimes it is not the type of material, but its concentration that determines whether it is a pollutant. For example, the nutrients nitrogen and phosphorus are essential elements for plant growth. However, if they are too abundant in a body of water, they can stimulate an overgrowth of algae, triggering an event called an algal bloom. Some algal blooms can be harmful to humans or marine life. Excess nutrients entering a body of water, either through natural or human activities, can also result in hypoxic or dead zones. When large amounts of algae sink and decompose in the water, the decomposition process consumes oxygen and depletes the supply available to healthy marine life. Most of the marine species that live in these areas either die or, if they are mobile (such as fish), leave the area. Habitats that would normally be teeming with life become, essentially, biological deserts.
Marine debris is another persistent pollution problem in our ocean. Marine debris injures and kills marine life, interferes with navigation safety, and poses a threat to human health. Our oceans and waterways are polluted with a wide variety of marine debris, ranging from tiny microplastics to derelict fishing gear and abandoned vessels. Today, there is no place on Earth immune to this problem. A majority of the trash and debris that covers our beaches comes from storm drains and sewers, as well as from shoreline and recreational activities. Abandoned or discarded fishing gear is also a major problem because this trash can entangle, injure, maim, and drown marine wildlife and damage property.
Impact of seafood
Pollution can affect the food we eat. Heavy metals and other contaminants can accumulate in seafood and make it harmful to eat. More than one-third of the shellfish-growing waters of the United States are adversely affected by coastal pollution. NOAA monitors this contamination through the Mussel Watch program and also provides seafood safety tips through the FishWatch program.
Whether students live near the coasts or far inland, they are a part of the problem — and the solution — to ocean pollution. Through education, students can be informed of the types of pollution and actions that they can do to prevent further pollution of the ocean. This collection contains resources and and information to help students better understand ocean pollution and what they can do to prevent it.Adapted from the National Ocean Service's Ocean Facts and NOAA Marine Debris Program's Marine Debris FAQ’s.
Collection updated June 2018.