How does crude oil cause pollution?

Answer 1

The oil penetrates into the structure of the plumage of birds and animals, reducing its insulating ability, thus making the birds more vulnerable to temperature fluctuations and much less buoyant in the water. It also impairs or disables birds' flight abilities to forage and escape from predators. As they attempt to preen, birds typically ingest oil that covers their feathers, causing kidney damage, altered liver function, and digestive tract irritation. This and the limited foraging ability quickly causes dehydration and metabolic imbalances. Hormonal balance alteration including changes in luteinizing protein can also result in some birds exposed to petroleum.[3]

Most birds affected by an oil spill die unless there is human intervention.[4][5] Some studies have suggested that, even after cleaning, less than 1% of oil soaked birds survive.[6] Marine mammals exposed to oil spills are affected in similar ways as seabirds. Oil coats the fur of Sea otters and seals, reducing its insulation abilities and leading to body temperature fluctuations and hypothermia. Ingestion of the oil causes dehydration and impaired digestions. Because oil floats on top of water, less sunlight penetrates into the water, limiting the photosynthesis of marine plants and phytoplankton. This, as well as decreasing the fauna populations, affects the food chain in the ecosystem.[citation needed] There are three kinds of oil-consuming bacteria. Sulfate-reducing bacteria (SRB) and acid-producing bacteria are anaerobic, while general aerobic bacteria (GAB) are aerobic. These bacteria occur naturally and will act to remove oil from an ecosystem, and their biomass will tend to replace other populations in the food chain. Oil may also cause the death of an animal by entering the animal's lungs or liver. The animal will then be poisoned by the oil. Oil also can kill an animal by blinding it. The animal will not be able to see and be aware of their predators. If they are not aware of other animals, they may be eaten.