The pollution caused by an oil spillage is extremely difficult to clean. Oil contaminating a piece of land seeps into the soil, its long and complex chemical structure binding tightly to oil particles. And these bonds are hard to break, leaving the land polluted, possibly for years.
Contaminated areas can be cleaned using a variety of methods, some of which are less environmentally friendly than others, and may themselves create further environmental problems.
Flushing the soil with water, for example, may carry the pollution into groundwater sources. Another method is digging up the polluted soil and dumping it somewhere else. This only moves the problem elsewhere but may no longer be viable with the pressure to find alternatives to landfill.
A more environmentally friendly method is bioremediation, a natural method of fighting pollution where harmful contaminants are broken down by bacteria into, ultimately, carbon dioxide and water.
Bacteria are hardy organisms that can thrive and multiply in regions scarred by environmental hazards, including toxic waste sites.
In the Sligo Institute of Technology's department of environmental science, Dr Michael Broaders and Ph.D student Mr Gary Canny are developing an environmentally friendly way of enhancing the bioremediation process, which they hope will remove the most persistent pollutants.
Dr Broaders says their method focuses on cleaning the more "tenacious" pollutants which stick to the soil particles.
The chemical structure of oil binds closely and tightly. Bacteria cannot get through the tight bond to free the chemicals and break down the pollution.
The Sligo scientists have found a way which may make it possible to ease the oil's surface bonds and in the process free the land of its pollutant. They are investigating how to clean polluted soil by manipulating the microbiology of the soil itself.
They focus on the work of substances called surfactants, which work like a detergent. When a greasy pan is washed, for example, the detergent lifts the fat away, making it easier to clean.
Similarly, in a contaminated site the surfactant loosens the oil's surface bonds allowing the bacterial microbes full access to the oil. Then the contaminated areas can be more fully cleansed.
Dr Broaders and Mr Canny have isolated a bacterium which, under the correct conditions, naturally produces this surfactant. This biosurfactant, as it is called, has been produced in the lab in Sligo.
While there are synthetic surfactants which can perform a similar process, an advantage of the Sligo technique is it is more environmentally friendly.
Chemicals are not added to the soil. Instead, the naturally produced biosurfactant can do its work. As well as being more ecologically acceptable, this method allows the contaminated site to be cleaned in situ, as the bacteria produce their own surfactant.
Experiments performed in the lab in Sligo have shown their method works. Their next step will be to find how to make it perform in the soil. Dr Broaders explains that this stage will need careful experimentation to study how the surfactant behaves in the chemistry of the soil.
This requires establishing the correct conditions in the soil to get the bacterium to produce the biosurfactant.