We all know that oil and water do not mix. Oil molecules are repelled by water so the water molecules attract each other and the oil molecules stick together forming two separate layers. So when oil ends up in the ocean, water molecules sink and the oil sits on top of the water.
Oil pollution is a bigger problem than you might think. Considering the size of the ocean, it is difficult to get exact numbers; but sources estimate that between 1.3 – 3.2 millions tons of oil enter the ocean every year from a variety of sources. Since oil and water do not mix, even an oil spill of less than a liter can create an oil slick of two acres (8000m2)!
Not all oil entering the ocean comes from humans. Globally as much as 40% enters the ocean naturally as oil under the sea bed can seep into the water from cracks in the searock floor. In areas of natural seeps, marine bacteria have evolved to consume much of these oil molecules. Unfortunately, these marine bacteria have only evolved in areas with natural oil seeps. When oil pollution enters the water in other areas, the ocean has little or no natural ability to cope with the contamination.
Petroleum hydrocarbons, which are found in oil, are toxic to all forms of life and can kill many organisms. Oil cannot dissolve in water and forms a thick sludge in the water which can do external damage to many species. Additionally, toxic compounds in oil can cause long-term problems in animals (and humans) such as heart damage, stunted growth, immune system effects, and even death.
The damage done by oil pollution depends upon the amount of oil and where the oil enters the ocean. In cold water, a dime-sized drop of oil could kill a seabird. More dramatically, the Deepwater Horizon spill in the Gulf of Mexico is estimated to have killed over 82,000 birds, 25,900 marine mammals, 6,000 sea turtles and tens of thousands of fish, among others.
Here are some examples of the damage marine oil pollution can cause.
Since they need to come to the surface for air, marine mammals are directly affected by oil pollution at the surface.
Other Marine Animals
Oil enters the ocean from three main sources: natural oil seeps, land-based sources, and sea-based sources.
Although big oil spills in the ocean get a lot of media attention and cause an incredible amount of localized damage, they only account for about 12% of marine oil. In fact, more oil reaches the ocean each year as a result of leaking automobiles and other land-based accumulation than the oil spilled by the Exxon Valdez or the Deepwater Horizon!
Three times as much oil is carried to the sea via runoff from our roads, rivers and drainpipes as from big oil spills. Have you seen a rainbow-colored sheen on wet pavement? This is the oil that leaks from our vehicles on a regular basis. When it rains, the dripping oil that has accumulated on roads and parking lots washes down storm drains. Storm drains are not connected to any water treatment facilities so this polluted water ends up in our streams and rivers, and eventually, the ocean.
Land-based oil doesn’t only come from leaking automobiles. Animal fats and vegetable oils can have the same or similar impacts on the aquatic environment as petroleum oils when not disposed of properly.
And as for other sea-based sources? Accidental (or intentional) oil releases from tankers, offshore platforms, and drilling rigs as well as leaking commercial shipping vessels and recreational boats or illegal tank-cleaning at sea account for the rest.
Controlling and preventing land-based marine oil pollution sources should be everyone’s responsibility. There are many things all of us can do to help, including:
Make Personal Changes
Fortunately, if an oil spill occurs around the world, many local and international organizations are quick to help!
These organizations regularly work to spread the word about oil pollution and its effects and help to minimize the damage to the ocean.
Yellow Fish Campaign, United Kingdom
Groundwork, a UK group who focuses on practical community action is calling for “only rain, down the drain!” Through their yellow fish campaign, they are painting yellow fish next to street drains as a reminder not to put oil, chemicals, or litter down the drain.
Reduction in Tanker Spills, International Maritime Organization
Over the past 50 years, due to increased safety and procedures, oil spills from tankers have decreased dramatically despite the increase in oil shipping. The International Maritime Organization put together an exhibition showcasing this success.