Final answer:
The two most persistent sources of oil pollution in the marine environment are oil spills and natural oil seeps option (a). Oil spills float on the surface and can solidify into asphalt lumps over time, impacting marine wildlife.
Step-by-step explanation:
The two most persistent sources of oil pollution that keep oil in the marine environment for sustained periods are natural oil seeps and oil spills. Natural oil seeps are cracks in the Earth's surface where oil can flow out and into marine environments naturally, while oil spills are usually the result of human activities, such as drilling accidents or shipwrecks.
During an oil spill on water, oil floats to the surface because it is less dense than water. Some of the lightest hydrocarbons evaporate, decreasing the spill size but polluting the air. Over time, bacteria decompose the remaining oil, but this process can take years.
oil that remains can solidify into thick asphalt lumps, posing harm to birds, fish, and shellfish. Cleanup efforts can involve skimmer ships, controlled burning, dispersants, and bioremediation. However, each method comes with drawbacks and potential harm to the ecosystem.
On the other hand, atmospheric deposition, industrial discharges, and river runoff are significant sources of pollution but are not typically as persistent in the marine environment as oil spills and natural seeps.
Industrial discharges may contain a variety of pollutants, and river runoff can carry contaminants into the ocean; however, atmospheric deposition refers to the pollution that is deposited from the air and typically does not constitute a major sustained source of oil pollution.