Oil pollution of water

Oil pollution of water is mainly caused when oil—whether from ships, industrial activities, or accidents like oil spills—ends up in lakes, rivers, or oceans. This can happen in a few different ways. One of the most dramatic events leading to oil pollution is a major oil spill, such as when a tanker leaks or breaks apart. But oil can also enter the water in much smaller quantities from everyday sources, like stormwater runoff carrying oil dripped from cars onto roads, or from shipping operations when tankers clean out their tanks at sea. Oil also seeps out naturally from rocks underground, but human activities are responsible for most of the large and sudden additions to ocean, lake, and river environments.

When oil gets into the water, it tends to float because it is less dense than water. As it spreads out, it forms a thin layer on the surface called an oil slick. How quickly the oil spreads, and how thick the slick becomes, depends on the type of oil and the conditions at sea like temperature, wind, and waves. Heavy oils move more slowly; lighter oils spread out quickly and can evaporate, but even temporary slicks can cause serious harm.

Once an oil slick forms, both the oil and some toxic chemicals in it begin to evaporate into the air, but some harmful components remain in the water or sink to the sediment below. Oil doesn't easily break down, especially in deep or cold water, so the pollution can last for a long time. Sunlight and certain types of bacteria can gradually help break oil down, but this process—called biodegradation—can take weeks, months, or even years depending on the size and location of the spill.

Oil pollution causes a range of environmental problems, beginning with immediate effects on marine and coastal life. Birds and mammals are among the most visible victims. Birds that dive for fish or rest on the water can get coated in oil, which destroys the waterproofing of their feathers. This makes it impossible for them to stay warm and float, and trying to clean themselves can lead to them swallowing oil, which is toxic. Seals, sea otters, and other mammals that rely on their thick fur for warmth can also become dangerously chilled if their fur gets oily.

Fish and other creatures living in the water can absorb toxic chemicals from oil through their gills or skin, and eggs and juvenile stages of animals are particularly sensitive. Long-term problems can develop as oil sinks into the seabed, impacting the many tiny plants and animals that live in the sediment. These small organisms form the base of much larger food webs, so disruptions at this level can cause trouble higher up the chain, harming fish, birds, and eventually even humans who rely on seafood.

Coral reefs and coastal wetlands are especially vulnerable to oil pollution. Reefs are made up of delicate living corals, which can be smothered by oil or poisoned by its chemicals, leading to large areas of dead reef. Wetlands, such as marshes and mangroves, are vital for many species and act as nurseries for young fish and other animals. Oils that get into these habitats can persist for years, long after a spill seems to be gone from the surface, leading to long-term declines in wildlife and plant populations.

Beyond direct effects on animals and plants, oil pollution can disrupt entire ecosystems. The food chain can be altered if large numbers of fish or plankton die off, impacting the animals that eat them. Sometimes, this can lead to an increase in other species that are less sensitive to oil, which changes the balance of the ecosystem in ways that may be difficult to reverse. Commercial fishing areas can be closed for months or years after major spills, and seafood from affected areas may be contaminated or unsafe to eat. This also causes significant economic problems for people living in nearby communities who depend on fishing and tourism.

Oil pollution doesn't just impact the water it’s spilled in. Waves and currents can carry oil hundreds or thousands of miles from where it was originally spilled, causing unpredictable harm to distant beaches, islands, and wildlife reserves. Clean-up of major oil spills requires huge efforts and resources, but even then, the environment is often not restored to what it was before the spill. Most techniques for cleaning up oil, such as dispersants and burning, have their own environmental drawbacks.

Preventing oil pollution is challenging because oil is used in so many ways in modern life, and the demand for oil is still high around the world. Ship regulations have improved, and double-hulled tankers now make accidents less likely, but spills and leaks still occur. Reducing oil pollution will require ongoing effort, better technology for both transportation and clean-up, stricter regulation and enforcement, and, ultimately, finding cleaner alternatives to fossil fuels.

In summary, oil gets into the water mainly through spills, leaks, and runoff from human activities. Once there, it causes serious environmental problems ranging from immediate harm to wildlife and habitats, to long-term damage to ecosystems, economic losses, and human health risks. While clean-up is possible, preventing oil pollution in the first place is far more effective, and necessary for the protection of aquatic environments and the plants, animals, and people who rely on them.