With BP and the authorities still struggling to find a way to stop oil pouring into the Gulf of Mexico, we wanted to look back at what has happened so far and examine the potential long-term implications for the waters and wildlife of the region, and to try and give a jargon-free account of events (because frankly we don't understand a lot of the terminology out there!).

Failed Attempts to Stop the Oil

On April 20, in the process of disconnecting the Deepwater Horizon rig a massive explosion killed 11 workers and began what has now become the largest oil spill in history. The equivalent of up to 19,000 barrels of oil a day are still flowing, contaminating an ever-growing area of some 2,500 square miles.

So what have BP tried so far to stop the flow of oil? The first attempt was to lower a huge dome over the main leak to try and to pipe the oil to the surface. This was unsuccessful.

Next, they inserted a four-inch tube into the burst pipe. This managed to siphon off some of the oil and gas but has since been removed so that efforts can continue to try and stem the flow completely.

Then came the "top kill" approach; this involved pumping heavy drilling fluids through the blowout preventer on top of the well-head to try and reduce the flow of oil to a level where the well could be permanently sealed with cement. Despite early positive noises from BP, on May 29 they announced that this too had failed.

In its latest attempt, BP has tried to cut and remove the damaged pipe that sends oil to the surface in the hope of fitting a new cap that will divert most of the oil and gas. This too has been plagued by difficulties with the diamond blade becoming stuck and cutting a ragged hole which will make fitting a new cap all the more difficult.

What Next?

BP is currently drilling relief wells but these will not help to stem the flow of oil until August at the earliest. It remains to be seen if the company can find a short-term fix. Operating at such depth, it is a difficult job and there is a chance the oil will keep flowing for some time to come.

The US government has deployed more than one million feet of boom along the coast in Louisiana and is dropping more and more sandbags along the barrier islands and marshes to try and keep as much oil as possible away from sensitive habitats close to shore. But oil is getting through.

Long-Term Impact

With oil still flowing, it is difficult to assess what the true extent of the damage might be on the marine environment (BP has set up a $500m fund to research this). Currents and winds will force the oil slick to drift over ever-larger areas and tides will continue to bring more oil to coastal areas. All of this will have an impact on the open water, coastal areas, and marine and land habitats.

As more and more oil waste reaches the cost, it interacts with sediments such as sand, gravel, and vegetation contaminating them and reducing their ability to protect and nurture vegetation and animals. Not to mention the direct impact on animals that find themselves coated in oil or the long-term potential damage to fishing and fisheries that will have huge knock on effects for the local economy.

As the blame game continues in Washington, the world waits and hopes that the authorities and BP will be able to stem the flow of oil and begin the long and arduous clean-up operation. It is going to take a long time and the true impact on both the marine and land environments will not be known for many years.