Natural degradation of hydrocarbons in sandy soils and its potential application to disposal of oil-contaminated materials

Hydrocarbon-degrading micro-organisms are found in marine, freshwater and terrestrial environments. Investigations of possible cost-effective methods of disposal of oil-contaminated beach sand (OBS) relying on the enrichment and activity of these micro-organisms in sandy coastal soils have been carried out. A range of scales has been used; from small scale experiments to field trials, using both contaminated beach sand from an actual oil spill and artificially prepared OBS. Consistent results have been obtained, indicating rapid development of soil microbial populations, providing quick and effective breakdown of a significant proportion of weathered oil without the application of cultured organisms or the addition of fertiliser. Patterns of degradation of weathered oils consistently follow a power function under field conditions, without the application of special cultures, or the addition of fertiliser. Evidence is presented to show that environmental risk from movement of hydrocarbons into surrounding soil or groundwater are minimal. Advantages and limitations associated with this potential clean-up and disposal method are discussed. (author)