The visual image of oil spills is that they are only surface spills in large bodies of water. The idea is that such huge areas should be able to absorb the injury and heal over time.
But the reality is that oil becomesa permanent part of a biome. It continues to travel in the water, incorporates into the surrounding soil and land mass and takes forever to break down from atmospheric and aquatic weathering.
There are still massive amounts of oil that are travelling and leaching from the shoreline and soil as a result of the Exxon Valdez oil spill, the Exxon Houston spill in Hawaii and from other military, and non military spills that have occurred throughout history.
The other image is of strictly oceanic involvement, as opposed to rivers, marshes, tidal zones and other waterways. The general classification is that water is either saline or fresh. Marine water is ocean and other saltwater, with the concentrations of salt at a specific level. Brackish water zones are a mix of saline and freshwater. Freshwater involves more inland environments. The term “aquatic” applies to marine, brackish and freshwater environments.
There is a tendency to think that inland aquatic environments are protected, but marine oil masses will follow the tides and can be pushed miles inland during periods of high winds, including hurricanes. The lighteror more dissipated components of the oil, mixes with water, can actually be picked up and moved for thousands of miles through the air via waterspouts. “pineapple expresses” and atmospheric rivers.
The qualities of the oil are important. Visually, there is the oil slick that rides on the surface, but there are other things that go on to make the oil interact with the water in various ways. The four main factors are water temperature, surface tension, viscosity and specific gravity.
As we tend to think of oil as a singular, unified substance, oil is actually composed of many substances, which is why we get so many different things from a barrel of oil. As a result, oil can float as a unified mass in one place or move and spread quickly. The oil can stay on the surface or denser components left after evaporation can form into tar balls that sink to aquatic floors or can end up on surface land.
In addition, the man made substances that are used to break up the oil can also introduce extremely harmful environmental toxins and hazards.
Oil has many components, including gases, chemicals and physical qualities that can poison and smother living things. Eggs, larvae, skins, fur and feathers, aquatic light penetration, and the ability of land plants to gestate are all parts of the emerging and established life chains that are trapped, injured, sickened, killed or even extincted by mass incursions of oil.
When the oil incorporates into the land mass or aquatic floor, it can encapsulate or release depending on the temperature, the volatility of wave action, other natural events that physically disturb rocks and soil. Atmospheric weathering introduces rain, acid rain, wind and other atmospheric affects on the mass of oil. Just as rock weathers over long periods, oil will weather over long periods of time, making it a substance that will never go away in many lifetimes, but which will eventually break down. In the aquatic floor, however, there is no telling whether the oil will ever break down.
The environmental damage from oil spills thus becomes a short term process of a unified mass of oil which can go through various process of change. Then the damage evolves into a medium term process as man made toxins and mechanical events are introduced to break up or remove the oil. Then, the environmental damage becomes permanent process as the remaining oil moves in and out with tides or permanently incorporates into the soil and land mass.
As a result, there is no foreseeable end to the existing oil spills of mankind, so the 2010 Gulf oil spill is just the beginning of a long, long journey of environmental disaster and permanent change to a biome that happens to be one of the most unique, full of life and fragile in the world.
US EPA, “The Behavior and Effects of Oil Spills In Aquatic Environments”