What you need to know about oil spill pollution

Oil, in its crude form or as refined product, then it has to be transported to various parts of the world dependent on this resource. The increased demand for oil and the resulting increase in the trade in petroleum and its products has led to an increase in the occurrence of accidents, spills, fires and explosions along sea routes, land routes and at terminals. The sea lanes throughout the wider Caribbean region form a complex and extensive lattice with the routes used in trade being almost limitless.

Sources of oil to the environment
Sources of oil to the environment may be from on-shore. On-shore sources include disposal of automobile and industrial lubricants, spillage from oil-storage facilities, leakage from motor vehicles, transportation accidents and oil refinery operations.

These onshore sources are often carried to the marine environment by terrestrial run-off after rainfall events or from river discharges. Offshore sources include natural seeps. Off-shore exploration and production, routine tanker discharges and shipping operations and tanker accidents.

How oil behaves
When oil spills it spread very quickly and rate of spreading is dependent on physical and chemical properties of the oil such as viscosity and density, as well as prevailing environmental conditions. Oil will behave differently whether it is on water or on land, the type of terrain, wind speed and in waves and currents and natural or man-made obstacles. Generally, when oil is spilled, it is redistributed relatively quickly through the processes of spreading evaporation, dispersion, solution, adsorption and sinking, degradation, commonly called weathering, will also occur through chemical process, the effect of sunlight and by biological processes.

Effect of oil on living resources
Oil can affect living resources by causing immediate death due to coating and the effect of toxic components. These are called lethal effects and occur because the oil or its components interfere with cellular with processes and death follows quickly. Sometimes death does not occur immediately, but the organism may be affected by changes in physiological processes or behavior patterns that eventually lead to death. 

These are called sub-lethal effects. Whether effects are lethal or sub-lethal depends on the type of environment, the type of oil (crude or relined), the organism, the stage of life-cycle of the organism and the length of exposure time.

Oil can severely damage plants, and the most effected groups are salt marshes and mangroves because of their habitat in the coastal environment. Oil can kill plants or stop their future growth by forming a physical barrier (coating the leaves and steams) that prevents exchange of gases such as oxygen and carbon dioxide; by being contaminating soil and affecting soil properties; or by affecting the ability of surrounding plants to grow.

Animals, being mobile, may fare better than plants, as they are able to move away from a spill. However, their mobility may lead to them getting contaminated if they are unaware of a contaminated environment. Groups that are most affected by oil spills include marine mammals such as manatees, whales and dolphins, and shore birds. 

Marine mammals that swim through a slick can be damaged from oil coating the skin, getting in the eyes, or being ingested. Birds are also at risk and the most common form of damage is to the plumage, which provides them with natural insulation and waterproofing. 

Oil can cause the plumage to become matted, which allows water to enter spaces between the feathers and the skin; the birds can then lose buoyancy and may sink and drown. An attempt to clean the feathers by preening can lead to ingestion or the oil, which can cause death. The surfaces of the most fish are coated with a mucous to which oil does not readily stick, but the use of dispersants can destroy this protective coating. Fish are sometimes affected by the toxic components that dissolve in the water or by oil clogging the gills. Sea turtles may be affected by swimming through oil, or by a slick preventing them access to a beach on which they lay their eggs, oiling or the eggs after they are laid or ingestion balls of tar in mistake for food.

Invertebrates, particularly sessile ones, are at risk as they are unable to move away from the contamination. Most of these are filler-feeding organism that ingest large volumes or water during the feeding process and have the potential to ingest large volumes of dispersed components of oil. Studies have shown that increasing levels of dissolved hydrocarbons in the environment can result in a reduction in the natural defense mechanism (immune system) of these animals. This means that animals may suffer from diseases that they ordinarily be able to resist and this has implications for the success of large populations particularly in mariculture areas.
Oil spill clean-up method 
There are many methods for dealing with oil spills depending on the quantity and type of oil, the distance from the shoreline, existing and expected weather conditions, the proximity of habitats, the time to reporting the incident the response time after reporting and the resources available. Some of the methods are;

1. Natural clean-up (do nothing which may be valid in some environments).

2. Mechanical (use of booms, skimmers, sorbents, pumping, use of earth moving equipment, high pressure hosting, hot water/stem treatment).

3. Chemical (use of dispersants _surface-active agents and gels).

4. Sinking (sprinkling of sand on the oily water which then sinks).

5. Burning (of floating oil on water as well as absorbed oil from other clean-up methods).

6. Enhanced biodegradation (biodegradation of oil naturally).

Research is no-going for environment friendly and cost effective clean-up methods.