With oil spills in the news everywhere today everyone is searching for a fix. Oil spills affect everything living in and around the body of water including animals and plants. Birds can easily land and drown in the oil, fish larvae become damaged causing the hatched fish to suffer from deformities, or fish, birds and other animals may ingest the oil causing extreme illness or death. The plants that are affected are important feeding or breeding grounds for many creatures living in the sea as well. Also plants such as algae are crucial for waterway ecosystems and need to be functioning properly. Lastly, there is the affect on animals living within the sand in the sea. When oil sinks to the bottom of the sea it poisons the creatures living there and anything that feeds on these creatures. With such problems we must find an answer to save our ecosystems.
A study done at the US National Oil Spill Responses Test Facility operated by the Minerals Management Service of the US Department of the Interior completed a study to see the limit of chemical dispersants on crude oil. The study was done by using a 203m long by 20m wide by 3.3m deep wave tank. The tank simulated sea conditions with the same salinity for saltwater and similar waves using a wave generating system. Many studies had been done before involving smaller sample sizes simulating similar conditions as well as studies done in the sea with exact conditions. This study was done to close the gap between the two. The study used the same dispersant as bench and at sea studies have been using recently: Corexit 9500. First, they had a control which only tested the dispersion based on waves simulated and secondly, they added Corexit to view the chemical dispersion.
Two tests were done for this experiment, one in 2005 and one in 2008. In the 2005 trial viscosities of crude oil used were between 2000cP and 50 000cP. The 2005 results were far less impressive then the 2008 results. Firstly, the 2005 results showed that with just waves the crude oil of all viscosities dispersed an average of 18%. After adding Corexit 9500 the lowest viscosities dispersed another 80% and the highest viscosities dispersed another 9-12%. This means at lowest viscosity of crude oil the dispersion effectiveness is almost 100%! However, after the viscosity was 33 000cP or above the change was indistinguishable. In 2008 viscosities of 2565cP or less were used as well as two samples between 6000cP and 33 000cP. In this trial the control dispersion rate had an average of 20%. When Corexit 9500 was added all viscosities 2565cP or less dispersed 100%. When viscosities were between 6000cP and 33 000cP the dispersion rate was 47%-54% including the affect of the control. This was a significant change compared to the results in the trial completed in 2005.
In general from this study, oils with viscosities less then 2500 will disperse about 100% with Corexit 9500, oils with viscosities between 2500 and 18 690 will have a significant dispersion, and any oils with viscosity at 33 000 or above will have no visible or measurable change in dispersion.
What does this mean for oils spills today? It is true that this is not to the extent of some of the oils spills happening today such as the spill in the Gulf of Mexico but this brings us closer to solving problems involving oil spills. This means small oil spills may be easily cleaned up from the sea reducing the environmental impact on animals and plants living there. As well, this means scientists are on the right tract for finding a solution to larger oil spills. In the future we may be able to fix the damage we have done to our seas and ecosystems. Just imagine a beautiful clean beach. One day we can make it there.
Trudel, Ken., Belore, Randy C., Mullin, Joseph V., and Guarino, Alan. Marine Pollution Bulletin Vol. 60, no. 9, pp. 1606-1614. Sep 2010