|
Section 1: Cleanup of contaminated land and groundwater |
1 Department of Biological Sciences, Napier University, 10 Colinton Road, Edinburgh EH10 5DT, UK
2 Institute of Ecology and Genetics of Microorganisms, The Russian Academy of Sciences, Urals Branch, Perm, Russia
Oil spillage on land accounts for the majority of hydrocarbon contamination of our planet and bioremediation of these habitats is possible because of the existence of hydrocarbon-oxidizing microorganisms in situ and in culture collections. A number of physical, chemical and environmental factors affect the degradation of oil in soils including soil pore structure, aeration, toxic oil constituents and nutrient availability. In addition, strongly sorbed hydrophobic constituents, such as polycyclic aromatic hydrocarbons, are difficult to solubilize and make available for degradation. Various remediation techniques were used in field experiments on bioremediation of oil contaminated agricultural soils after an accidental oil-spill which occurred on the territory of the Mezhevskoe oilfield (‘Polaznaoil’ company). Composting systems were utilized to increase oxygen transfer with degradation further enhanced by combination of nutrient additions, bulking with straw and inoculations of Rhodococcus-biosurfactant complexes. After a three-month bioremediation the content of chloroform extracts decreased to 2.85–1.60% (from an initial amount of 3.75%). The percentage oil degraded varied from 24.0 to 57.1 depending on the remediation methods used. C02 evolution rates (36.1–54.6 µg g-1 day-1) indicated the intensity of aerobic oil degradation. It is not clear whether fertilization with NPK, and bulking, increased oil degradation rates in the systems used. Our initial results show that soil remediation progresses more effectively if composting systems are used with increased ventilation, nutrient additions and, particularly, inoculation of Rhodococcus-biosurfactant complexes.
