Other valuable mineral products of the Atlantic include gems, sand and gravel, and sulfur. Pollution Pollutants enter the ocean from many sources. Rivers and runoff from land bring many wastes to the sea. Many coastal cities discharge treated and untreated wastes into the ocean. Some pollutants are transported through the atmosphere to the ocean.
Some wastes enter the ocean from ships.
Spills of petroleum and hazardous wastes occur when ships run aground or are damaged by storms. Before the 1980's, factories and power plants commonly discarded industrial and radioactive wastes into the ocean. Ships also incinerated hazardous wastes at sea. Phytoplankton thrives on certain nutrients produced by the decay of organic matter. Thus, organic pollution can lead to a huge increase in the population of phytoplankton off the continental shelf.