Final answer:
After a surface oil spill, oil spreads on the ocean, impacting light and oxygen penetration, with some oil evaporating and polluting the air. Bacteria slowly decompose the oil, but thick, harmful lumps can remain. Cleanup involves skimming, burning, dispersants, and bioremediation, with significant efforts directed at reducing environmental damage and aiding recovery.
Step-by-step explanation:
After a surface oil spill, several things happen. Initially, due to being less dense than water, oil spreads on the surface of the ocean. This process can have various environmental impacts, including a reduction in the amount of light and oxygen that can penetrate the ocean surface. Larger spills may form noticeable thick films or slicks on the water, which adversely affect marine and coastal wildlife. As lighter hydrocarbons evaporate, they reduce the spill volume but contribute to air pollution.
Next, some of the remaining oil undergoes biological degradation by bacteria in a process that can be very slow, often taking years. Over time, and particularly after several months, only a fraction of the original spill may remain, but as thick, sticky asphalt lumps which can be especially damaging to birds, fish, and shellfish.
Cleanup operations are critical after an oil spill. Techniques include using skimmer ships to remove oil, controlled burns to eliminate oil from the surface, dispersants to break up the oil and speed decomposition, and bioremediation efforts to introduce or support microorganisms that specialize in decomposing oil. However, these methods have limitations and can sometimes cause further environmental issues. For instance, controlled burns and dispersants can pollute the air and potentially harm the ecosystem, respectively.
Physical methods like using booms to corral, and then skim the oil are common. In the aftermath of events like the Valdez oil spill in Alaska, workers sprayed hot water to wash off oil from beaches before corralling and skimming it. This illustrates one effective combination of mechanical and chemical cleanup methods.
One of the most catastrophic outcomes of oil spills is the extensive damage to fauna due to the toxic nature of oil and its physical effects such as coating animals, leading to suffocation or poisoning. Oil on the surface also hampers the normal movement of marine animals and can dramatically affect ecosystems by causing the death of phytoplankton, which form the base of many food chains.