Oil biodegradation is a natural but slow process, limited mainly by the scarcity of nitrogen and phosphorus. To enhance hydrocarbon breakdown by indigenous microbial communities, a fertilizer formulation that would keep nutrients in contact with oil was sought. A research project established for this purpose 12 years ago has resulted in the development of an oleophilic fertilizer known as Inipol EAP22. The product is an oil-soluble fertilizer formulated as an oleophilic microemulsion. It contains not only nitrogen and phosphorus, but also an easily biodegradable carbon source. Numerous experiments, in both laboratory and field, have shown that, even in cold climates, application of this fertilizer increases the number of hydrocarbon-degrading organisms and the extent and rate of biodegradation. Kinetic studies show that the amount of nitrogen and phosphorus in the fertilizer is sufficient to allow the indigenous bacteria to consume all of the carbon source contained in Inipol EAP22. Once this carbon is consumed and the number of hydrocarbon degrading bacteria has increased, oil biodegradation can begin. In addition, adding fertilizer has a marked effect on the oil's consistency and increases its bioavailability. The recent large bioremediation project in Alaska has shown that it is possible to enhance the biodegradation of oil on shorelines through the application of such a fertilizer. Enhanced oil biodegradation can be considered today as a new tool in oil spill cleanup, to be used in conjunction with other treatments.

Biodegradation of oil is a natural and universal process. Unfortunately, it is a slow one, and most attempts to enhance it have failed. A new approach has been devised to try to render this enhancement process operational. A nutrient including nitrogen, phosphorus and carbon has been developed and formulated as an oleophilic micro-emulsion. It is, therefore, not dispersed in seawater. The nutrient has been tested in laboratory and field situations in temperate and cold climates. Biodegradation rates have ranged from 60 percent to 85 percent depending on conditions. Combined with natural evaporation, enhanced oil biodegradation can lead to a reduction in oil content of at least 65 percent in less than one week.

The oil spill simulation model GULFSLIK III is applied to simulate an oil spill in the Mar jan oil field, an important offshore field in the Arabian Gulf. The model incorporates several new changes over previous versions, including a surface spreading formula developed from measurements of experimental spills in the gulf. Other features are a variable release rate for the spilled oil, a two-component evaporation model, and dispersion in the vertical and horizontal directions. The currents in the region are simulated using a multilayer hydrodynamical model, in which the driving forces include wind stress and density gradients produced by evaporation, fresh water inflow, and radiative heat transfer.The three-dimensional transport and dispersion of the oil from the Mar jan simulated spill are mapped to examine their impact on the surrounding marine environment. Changes in the oil as it weathers are recorded. Results show that Bahrain is the area most threatened by surface oil and Qatar waters by subsurface oil. Evaporation removes a significant amount of the spilled oil.

The use of exposure biomarkers in measuring the impact of aqueous waste holds out promise because such tools have short response times, are of flexible use and give an indication of the type of pollution. However, their ecological significance has not yet been demonstrated. During field studies focusing on aqueous industrial waste, the correlations obtained between several biocoenotic indicators and biomarkers measured in a fresh-water bivalve (Corbicula fluminea), demonstrate the need for work to be carried out under controlled conditions. Working in partnership with the Adour Garonne Water Board, the ELF company has developed a pilot scheme incorporating such controlled conditions. This pilot is made up of 16 canals 40 m in length supplied by river water. The pilot scheme, which is currently at the validation stage, makes it possible to reconstitute an aquatic ecosystem which, once established, will be exposed to perfectly controlled pollution conditions. The responses provided by all the indicators--biocoenotic and microbiological indicators, biomarkers--will then be correlated in order to attribute an ecological significance to the biomarkers.

Ten years ago, Elf Aquitaine began developing the technologies for the acceleration of hydrocarbon biodegradation. The continuation of this work has involved the study of new additives to complement the oleophilic nutrient, INIPOL EAP 22. In particular, it has been shown in both laboratory and in situ tests that hydrocarbon degradation can be accelerated by animal meals, which are natural products. Preliminary laboratory studies carried out under batch conditions, have shown that the use of these products has resulted in considerable growth of the bacteria, coupled with a notable increase in the biological degradation kinetics of the hydrocarbons. These results are comparable with the performance of the nutrient INIPOL EAP 22. In situ experiments undertaken on soils polluted by hydrocarbons have shown that by using animal meals, 50 percent biodegradation was obtained after six weeks and this increased to 80 percent when mechanical aeration was also employed. Under nutrient-free control conditions, 25 percent biodegradation was obtained with no aeration and 35 percent with mechanical aeration. In trials using coastal sandy sediments, the use of these nutrients has resulted in an increase of both the number of hydrocarbon specific bacteria and the hydrocarbon degradation. It can be concluded from these pilot experiments that in the development of bioremediation as an operational tool in the response to accidental oil spills, these nutrients of natural origin represent an interesting advance.